From 3b6917ca4d75bbb0fe2142496606328f7b94d29a Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 22 Aug 2022 09:08:34 -0700
Subject: [PATCH 01/12] tsconfig.extends as array

---
 src/compiler/commandLineParser.ts             | 227 ++++++++---
 src/compiler/types.ts                         |   4 +-
 src/executeCommandLine/executeCommandLine.ts  |   8 +
 .../config/configurationExtension.ts          |  79 +++-
 src/testRunner/unittests/config/showConfig.ts |  20 +
 .../unittests/tsbuildWatch/programUpdates.ts  |  57 ++-
 .../works-with-extended-source-files.js       | 368 ++++++++++++++++--
 7 files changed, 670 insertions(+), 93 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 370461abd8559..1d17d1b8a742c 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1731,6 +1731,19 @@ namespace ts {
                             i++;
                         }
                         break;
+                    case "listOrElement": 
+                        if(opt.element.type === "string"){
+                            options[opt.name] = validateJsonOptionValue(opt, args[i] || "", errors);
+                            i++;
+                        }
+                        else{
+                            const result = parseListTypeOption(opt, args[i], errors);
+                            options[opt.name] = result || [];
+                            if (result) {
+                                i++;
+                            }
+                        }
+                        break;
                     // If not a primitive, the possible types are specified in what is effectively a map of options.
                     default:
                         options[opt.name] = parseCustomTypeOption(opt as CommandLineOptionOfCustomType, args[i], errors);
@@ -1971,6 +1984,15 @@ namespace ts {
         return commandLineTypeAcquisitionMapCache || (commandLineTypeAcquisitionMapCache = commandLineOptionsToMap(typeAcquisitionDeclarations));
     }
 
+    const extendsOptionDeclaration: CommandLineOptionOfListType = {
+        name: "extends",
+        type: "listOrElement",
+        element: {
+            name: "extends",
+            type: "string"
+        },
+        category: Diagnostics.File_Management,
+    };
     let _tsconfigRootOptions: TsConfigOnlyOption;
     function getTsconfigRootOptionsMap() {
         if (_tsconfigRootOptions === undefined) {
@@ -2002,11 +2024,7 @@ namespace ts {
                         elementOptions: getCommandLineTypeAcquisitionMap(),
                         extraKeyDiagnostics: typeAcquisitionDidYouMeanDiagnostics
                     },
-                    {
-                        name: "extends",
-                        type: "string",
-                        category: Diagnostics.File_Management,
-                    },
+                    extendsOptionDeclaration,
                     {
                         name: "references",
                         type: "list",
@@ -2219,11 +2237,11 @@ namespace ts {
             let invalidReported: boolean | undefined;
             switch (valueExpression.kind) {
                 case SyntaxKind.TrueKeyword:
-                    reportInvalidOptionValue(option && option.type !== "boolean");
+                    reportInvalidOptionValue(option && option.type !== "boolean" && (option.type !== "listOrElement" || option.element.type !== "boolean"));
                     return validateValue(/*value*/ true);
 
                 case SyntaxKind.FalseKeyword:
-                    reportInvalidOptionValue(option && option.type !== "boolean");
+                    reportInvalidOptionValue(option && option.type !== "boolean"&& (option.type !== "listOrElement" || option.element.type !== "boolean"));
                     return validateValue(/*value*/ false);
 
                 case SyntaxKind.NullKeyword:
@@ -2234,7 +2252,7 @@ namespace ts {
                     if (!isDoubleQuotedString(valueExpression)) {
                         errors.push(createDiagnosticForNodeInSourceFile(sourceFile, valueExpression, Diagnostics.String_literal_with_double_quotes_expected));
                     }
-                    reportInvalidOptionValue(option && (isString(option.type) && option.type !== "string"));
+                    reportInvalidOptionValue(option && (isString(option.type) && option.type !== "string")&& (option.type !== "listOrElement" || option.element.type !== "string"));
                     const text = (valueExpression as StringLiteral).text;
                     if (option && !isString(option.type)) {
                         const customOption = option as CommandLineOptionOfCustomType;
@@ -2252,18 +2270,18 @@ namespace ts {
                     return validateValue(text);
 
                 case SyntaxKind.NumericLiteral:
-                    reportInvalidOptionValue(option && option.type !== "number");
+                    reportInvalidOptionValue(option && option.type !== "number" && (option.type !== "listOrElement" || option.element.type !== "number"));
                     return validateValue(Number((valueExpression as NumericLiteral).text));
 
                 case SyntaxKind.PrefixUnaryExpression:
                     if ((valueExpression as PrefixUnaryExpression).operator !== SyntaxKind.MinusToken || (valueExpression as PrefixUnaryExpression).operand.kind !== SyntaxKind.NumericLiteral) {
                         break; // not valid JSON syntax
                     }
-                    reportInvalidOptionValue(option && option.type !== "number");
+                    reportInvalidOptionValue(option && option.type !== "number" && (option.type !== "listOrElement" || option.element.type !== "number"));
                     return validateValue(-Number(((valueExpression as PrefixUnaryExpression).operand as NumericLiteral).text));
 
                 case SyntaxKind.ObjectLiteralExpression:
-                    reportInvalidOptionValue(option && option.type !== "object");
+                    reportInvalidOptionValue(option && option.type !== "object" && (option.type !== "listOrElement" || option.element.type !== "object"));
                     const objectLiteralExpression = valueExpression as ObjectLiteralExpression;
 
                     // Currently having element option declaration in the tsconfig with type "object"
@@ -2284,7 +2302,7 @@ namespace ts {
                     }
 
                 case SyntaxKind.ArrayLiteralExpression:
-                    reportInvalidOptionValue(option && option.type !== "list");
+                    reportInvalidOptionValue(option && option.type !== "list" && option.type !== "listOrElement");
                     return validateValue(convertArrayLiteralExpressionToJson(
                         (valueExpression as ArrayLiteralExpression).elements,
                         option && (option as CommandLineOptionOfListType).element));
@@ -2324,8 +2342,10 @@ namespace ts {
         }
     }
 
-    function getCompilerOptionValueTypeString(option: CommandLineOption) {
-        return option.type === "list" ?
+    function getCompilerOptionValueTypeString(option: CommandLineOption): string {
+        return (option.type === "listOrElement") ?
+            `${getCompilerOptionValueTypeString(option.element)} or Array`:
+            option.type === "list" ?
             "Array" :
             isString(option.type) ? option.type : "string";
     }
@@ -2336,6 +2356,9 @@ namespace ts {
             if (option.type === "list") {
                 return isArray(value);
             }
+            if (option.type === "listOrElement") {
+                return isArray(value) || isCompilerOptionsValue(option.element, value);
+            }
             const expectedType = isString(option.type) ? option.type : "string";
             return typeof value === expectedType;
         }
@@ -2445,6 +2468,9 @@ namespace ts {
         else if (optionDefinition.type === "list") {
             return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
         }
+        else if(optionDefinition.type === "listOrElement"){
+            return (optionDefinition.element.type === "string") ? undefined : getCustomTypeMapOfCommandLineOption(optionDefinition.element);
+        }
         else {
             return optionDefinition.type;
         }
@@ -2669,6 +2695,17 @@ namespace ts {
                     return values.map(toAbsolutePath);
                 }
             }
+            else if(option.type === "listOrElement"){
+                if(option.element.type === "string"){
+                    return toAbsolutePath(value as string);
+                }
+                else{
+                    const values = value as readonly (string | number)[];
+                    if (option.element.isFilePath && values.length) {
+                        return values.map(toAbsolutePath);
+                    }
+                }
+            }
             else if (option.isFilePath) {
                 return toAbsolutePath(value as string);
             }
@@ -2943,17 +2980,19 @@ namespace ts {
         /**
          * Note that the case of the config path has not yet been normalized, as no files have been imported into the project yet
          */
-        extendedConfigPath?: string;
+        extendedConfigPath?: string | string[];
     }
 
     function isSuccessfulParsedTsconfig(value: ParsedTsconfig) {
         return !!value.options;
     }
 
+    interface ExtendsResult { options: CompilerOptions, watchOptions?: WatchOptions, include?: string[], exclude?: string[], files?: string[], compileOnSave?: boolean, extendedSourceFiles?: Set<string>}
     /**
      * This *just* extracts options/include/exclude/files out of a config file.
      * It does *not* resolve the included files.
      */
+
     function parseConfig(
         json: any,
         sourceFile: TsConfigSourceFile | undefined,
@@ -2986,34 +3025,52 @@ namespace ts {
         if (ownConfig.extendedConfigPath) {
             // copy the resolution stack so it is never reused between branches in potential diamond-problem scenarios.
             resolutionStack = resolutionStack.concat([resolvedPath]);
-            const extendedConfig = getExtendedConfig(sourceFile, ownConfig.extendedConfigPath, host, resolutionStack, errors, extendedConfigCache);
+            const result: ExtendsResult = {options: {}};
+            if(isString(ownConfig.extendedConfigPath)){
+                applyExtendedConfig(result, ownConfig.extendedConfigPath);
+            }
+            else{
+                ownConfig.extendedConfigPath.forEach(extendedConfigPath => applyExtendedConfig(result, extendedConfigPath));
+            }
+            if(!ownConfig.raw.include && result.include) ownConfig.raw.include = result.include;
+            if(!ownConfig.raw.exclude && result.exclude) ownConfig.raw.exclude = result.exclude;
+            if(!ownConfig.raw.files && result.files) ownConfig.raw.files = result.files;
+            if (ownConfig.raw.compileOnSave !== undefined && result.compileOnSave) ownConfig.raw.compileOnSave = result.compileOnSave;
+            if (sourceFile && result.extendedSourceFiles) sourceFile.extendedSourceFiles = arrayFrom(result.extendedSourceFiles.keys());
+
+            ownConfig.options = assign(result.options, ownConfig.options);
+            ownConfig.watchOptions = ownConfig.watchOptions && result.watchOptions?
+            assign(result.watchOptions, ownConfig.watchOptions) :
+            ownConfig.watchOptions || result.watchOptions;
+        }
+        return ownConfig;
+
+        function applyExtendedConfig(result: ExtendsResult, extendedConfigPath: string){
+            const extendedConfig = getExtendedConfig(sourceFile, extendedConfigPath, host, resolutionStack, errors, extendedConfigCache, result);
             if (extendedConfig && isSuccessfulParsedTsconfig(extendedConfig)) {
-                const baseRaw = extendedConfig.raw;
-                const raw = ownConfig.raw;
+                const extendsRaw = extendedConfig.raw;
                 let relativeDifference: string | undefined ;
-                const setPropertyInRawIfNotUndefined = (propertyName: string) => {
-                    if (!raw[propertyName] && baseRaw[propertyName]) {
-                        raw[propertyName] = map(baseRaw[propertyName], (path: string) => isRootedDiskPath(path) ? path : combinePaths(
-                            relativeDifference ||= convertToRelativePath(getDirectoryPath(ownConfig.extendedConfigPath!), basePath, createGetCanonicalFileName(host.useCaseSensitiveFileNames)),
+                const setPropertyInResultIfNotUndefined = (propertyName: "include" | "exclude" | "files") => {
+                    if (extendsRaw[propertyName]) {
+                        result[propertyName] = map(extendsRaw[propertyName], (path: string) => isRootedDiskPath(path) ? path : combinePaths(
+                            relativeDifference ||= convertToRelativePath(getDirectoryPath(extendedConfigPath), basePath, createGetCanonicalFileName(host.useCaseSensitiveFileNames)),
                             path
                         ));
                     }
                 };
-                setPropertyInRawIfNotUndefined("include");
-                setPropertyInRawIfNotUndefined("exclude");
-                setPropertyInRawIfNotUndefined("files");
-                if (raw.compileOnSave === undefined) {
-                    raw.compileOnSave = baseRaw.compileOnSave;
+                setPropertyInResultIfNotUndefined("include");
+                setPropertyInResultIfNotUndefined("exclude");
+                setPropertyInResultIfNotUndefined("files");
+                if (extendsRaw.compileOnSave !== undefined) {
+                    result.compileOnSave = extendsRaw.compileOnSave;
                 }
-                ownConfig.options = assign({}, extendedConfig.options, ownConfig.options);
-                ownConfig.watchOptions = ownConfig.watchOptions && extendedConfig.watchOptions ?
-                    assign({}, extendedConfig.watchOptions, ownConfig.watchOptions) :
-                    ownConfig.watchOptions || extendedConfig.watchOptions;
+                assign(result.options, extendedConfig.options);
+                result.watchOptions = result.watchOptions && extendedConfig.watchOptions ?
+                    assign({}, result.watchOptions, extendedConfig.watchOptions) :
+                    result.watchOptions || extendedConfig.watchOptions;
                 // TODO extend type typeAcquisition
             }
         }
-
-        return ownConfig;
     }
 
     function parseOwnConfigOfJson(
@@ -3033,15 +3090,27 @@ namespace ts {
         const typeAcquisition = convertTypeAcquisitionFromJsonWorker(json.typeAcquisition || json.typingOptions, basePath, errors, configFileName);
         const watchOptions = convertWatchOptionsFromJsonWorker(json.watchOptions, basePath, errors);
         json.compileOnSave = convertCompileOnSaveOptionFromJson(json, basePath, errors);
-        let extendedConfigPath: string | undefined;
+        let extendedConfigPath:  string[] | undefined;
 
         if (json.extends) {
-            if (!isString(json.extends)) {
-                errors.push(createCompilerDiagnostic(Diagnostics.Compiler_option_0_requires_a_value_of_type_1, "extends", "string"));
+            if (!isCompilerOptionsValue(extendsOptionDeclaration, json.extends)) {
+                errors.push(createCompilerDiagnostic(Diagnostics.Compiler_option_0_requires_a_value_of_type_1, "extends", getCompilerOptionValueTypeString(extendsOptionDeclaration)));
             }
             else {
                 const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
-                extendedConfigPath = getExtendsConfigPath(json.extends, host, newBase, errors, createCompilerDiagnostic);
+                if (isString(json.extends)) {
+                    extendedConfigPath = append (extendedConfigPath, getExtendsConfigPath(json.extends, host, newBase, errors, createCompilerDiagnostic));
+                }
+                else {
+                    for (const fileName of json.extends as unknown[]) {
+                        if (isString(fileName)) {
+                            extendedConfigPath = append (extendedConfigPath, getExtendsConfigPath(fileName, host, newBase, errors, createCompilerDiagnostic));
+                        }
+                        else {
+                            errors.push(createCompilerDiagnostic(Diagnostics.Compiler_option_0_requires_a_value_of_type_1, "extends", getCompilerOptionValueTypeString(extendsOptionDeclaration.element)));
+                        }
+                    }
+                }
             }
         }
         return { raw: json, options, watchOptions, typeAcquisition, extendedConfigPath };
@@ -3057,7 +3126,7 @@ namespace ts {
         const options = getDefaultCompilerOptions(configFileName);
         let typeAcquisition: TypeAcquisition | undefined, typingOptionstypeAcquisition: TypeAcquisition | undefined;
         let watchOptions: WatchOptions | undefined;
-        let extendedConfigPath: string | undefined;
+        let extendedConfigPath: string[] | undefined;
         let rootCompilerOptions: PropertyName[] | undefined;
 
         const optionsIterator: JsonConversionNotifier = {
@@ -3083,19 +3152,35 @@ namespace ts {
                 currentOption[option.name] = normalizeOptionValue(option, basePath, value);
             },
             onSetValidOptionKeyValueInRoot(key: string, _keyNode: PropertyName, value: CompilerOptionsValue, valueNode: Expression) {
-                switch (key) {
-                    case "extends":
-                        const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
-                        extendedConfigPath = getExtendsConfigPath(
-                            value as string,
-                            host,
-                            newBase,
-                            errors,
-                            (message, arg0) =>
-                                createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
-                        );
-                        return;
-                }
+                    switch (key) {
+                        case "extends":
+                            const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
+                            if (isString(value)) {
+                                extendedConfigPath = append (extendedConfigPath, getExtendsConfigPath(
+                                    value,
+                                    host,
+                                    newBase,
+                                    errors,
+                                    (message, arg0) =>
+                                        createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
+                                ));
+                            }
+                            else {
+                                for (const fileName of value as unknown[]) {
+                                    if (isString(fileName)) {
+                                        extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(
+                                            fileName,
+                                            host,
+                                            newBase,
+                                            errors,
+                                            (message, arg0) =>
+                                                createDiagnosticForNodeInSourceFile(sourceFile, (valueNode as ArrayLiteralExpression).elements[0], message, arg0)
+                                        ));
+                                    }
+                                };
+                            };
+                            return;
+                    }
             },
             onSetUnknownOptionKeyValueInRoot(key: string, keyNode: PropertyName, _value: CompilerOptionsValue, _valueNode: Expression) {
                 if (key === "excludes") {
@@ -3168,7 +3253,8 @@ namespace ts {
         host: ParseConfigHost,
         resolutionStack: string[],
         errors: Push<Diagnostic>,
-        extendedConfigCache?: ESMap<string, ExtendedConfigCacheEntry>
+        extendedConfigCache: ESMap<string, ExtendedConfigCacheEntry> | undefined,
+        result: ExtendsResult
     ): ParsedTsconfig | undefined {
         const path = host.useCaseSensitiveFileNames ? extendedConfigPath : toFileNameLowerCase(extendedConfigPath);
         let value: ExtendedConfigCacheEntry | undefined;
@@ -3188,9 +3274,11 @@ namespace ts {
             }
         }
         if (sourceFile) {
-            sourceFile.extendedSourceFiles = [extendedResult.fileName];
-            if (extendedResult.extendedSourceFiles) {
-                sourceFile.extendedSourceFiles.push(...extendedResult.extendedSourceFiles);
+            (result.extendedSourceFiles ??= new Set()).add(extendedResult.fileName);
+            if (isArray(extendedResult.extendedSourceFiles)) {
+                for (const extenedSourceFile of extendedResult.extendedSourceFiles) {
+                    result.extendedSourceFiles.add(extenedSourceFile);
+                }
             }
         }
         if (extendedResult.parseDiagnostics.length) {
@@ -3286,6 +3374,11 @@ namespace ts {
             if (optType === "list" && isArray(value)) {
                 return convertJsonOptionOfListType(opt , value, basePath, errors);
             }
+            else if (optType === "listOrElement") {
+                return isArray(value) ?
+                    convertJsonOptionOfListType(opt, value, basePath, errors) :
+                    convertJsonOption(opt.element, value, basePath, errors);
+            }
             else if (!isString(optType)) {
                 return convertJsonOptionOfCustomType(opt as CommandLineOptionOfCustomType, value as string, errors);
             }
@@ -3306,6 +3399,18 @@ namespace ts {
             }
             return value;
         }
+        if(option.type === "listOrElement"){
+            if (option.element.type === "string"){
+                return normalizeNonListOptionValue(option, basePath, value);
+            }
+            else{
+                const listOption = option;
+                if (listOption.element.isFilePath || !isString(listOption.element.type)) {
+                    return filter(map(value, v => normalizeOptionValue(listOption.element, basePath, v)), v => listOption.listPreserveFalsyValues ? true : !!v) as CompilerOptionsValue;
+                }
+                return value;
+            }
+        }
         else if (!isString(option.type)) {
             return option.type.get(isString(value) ? value.toLowerCase() : value);
         }
@@ -3728,6 +3833,12 @@ namespace ts {
             case "list":
                 const elementType = option.element;
                 return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, elementType)) : "";
+            case "listOrElement":
+                if(option.element.type === "string"){
+                    return "";
+                }
+                const typeOfElement = option.element;
+                return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, typeOfElement)) : "";
             default:
                 return forEachEntry(option.type, (optionEnumValue, optionStringValue) => {
                     if (optionEnumValue === value) {
@@ -3749,6 +3860,12 @@ namespace ts {
                 return option.isFilePath ? `./${defaultValue && typeof defaultValue === "string" ? defaultValue : ""}` : "";
             case "list":
                 return [];
+            case "listOrElement":
+                if (option.element.type === "string"){
+                    const defaultValue = option.defaultValueDescription;
+                    return option.isFilePath ? `./${defaultValue && typeof defaultValue === "string" ? defaultValue : ""}` : "";
+                }
+                return [];
             case "object":
                 return {};
             default:
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index f7567053c89cf..1671b909531b7 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6598,7 +6598,7 @@ namespace ts {
     /* @internal */
     export interface CommandLineOptionBase {
         name: string;
-        type: "string" | "number" | "boolean" | "object" | "list" | ESMap<string, number | string>;    // a value of a primitive type, or an object literal mapping named values to actual values
+        type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | ESMap<string, number | string> ;    // a value of a primitive type, or an object literal mapping named values to actual values
         isFilePath?: boolean;                                   // True if option value is a path or fileName
         shortName?: string;                                     // A short mnemonic for convenience - for instance, 'h' can be used in place of 'help'
         description?: DiagnosticMessage;                        // The message describing what the command line switch does.
@@ -6669,7 +6669,7 @@ namespace ts {
 
     /* @internal */
     export interface CommandLineOptionOfListType extends CommandLineOptionBase {
-        type: "list";
+        type: "list" | "listOrElement";
         element: CommandLineOptionOfCustomType | CommandLineOptionOfStringType | CommandLineOptionOfNumberType | CommandLineOptionOfBooleanType | TsConfigOnlyOption;
         listPreserveFalsyValues?: boolean;
     }
diff --git a/src/executeCommandLine/executeCommandLine.ts b/src/executeCommandLine/executeCommandLine.ts
index 68d2e51e9d4eb..13d1292442169 100644
--- a/src/executeCommandLine/executeCommandLine.ts
+++ b/src/executeCommandLine/executeCommandLine.ts
@@ -300,6 +300,14 @@ namespace ts {
                         // TODO: check infinite loop
                         possibleValues = getPossibleValues(option.element);
                         break;
+                    case "listOrElement":
+                        if (option.element.type === "string"){
+                            possibleValues = option.type;
+                        }
+                        else {
+                            possibleValues = getPossibleValues(option.element);
+                        }
+                        break;
                     case "object":
                         possibleValues = "";
                         break;
diff --git a/src/testRunner/unittests/config/configurationExtension.ts b/src/testRunner/unittests/config/configurationExtension.ts
index ad906411ffbca..058c21d907140 100644
--- a/src/testRunner/unittests/config/configurationExtension.ts
+++ b/src/testRunner/unittests/config/configurationExtension.ts
@@ -183,7 +183,46 @@ namespace ts {
                     "dev/tests/unit/spec.ts": "",
                     "dev/tests/utils.ts": "",
                     "dev/tests/scenarios/first.json": "",
-                    "dev/tests/baselines/first/output.ts": ""
+                    "dev/tests/baselines/first/output.ts": "",
+                    "dev/configs/extendsArrayFirst.json": JSON.stringify({
+                        compilerOptions: {
+                            allowJs: true,
+                            noImplicitAny: true,
+                            strictNullChecks: true
+                        }
+                    }),
+                    "dev/configs/extendsArraySecond.json": JSON.stringify({
+                        compilerOptions: {
+                            module: "amd"
+                        },
+                        include: ["../supplemental.*"]
+                    }),
+                    "dev/configs/extendsArrayThird.json": JSON.stringify({
+                        compilerOptions: {
+                            module: null, // eslint-disable-line no-null/no-null
+                            noImplicitAny: false
+                        },
+                        include: ["../supplemental.*"]
+                    }),
+                    "dev/configs/extendsArrayFourth.json": JSON.stringify({
+                        compilerOptions: {
+                            module: "system",
+                            strictNullChecks: false
+                        },
+                        include: null, // eslint-disable-line no-null/no-null
+                        files: ["../main.ts"]
+                    }),
+                    "dev/configs/extendsArrayFifth.json": JSON.stringify({
+                        extends: ["./extendsArrayFirst", "./extendsArraySecond", "./extendsArrayThird", "./extendsArrayFourth"],
+                        files: [],
+                    }),
+                    "dev/extendsArrayFails.json": JSON.stringify({
+                        extends: [""],
+                        compilerOptions: {
+                            types: []
+                        }
+                    }),
+                    "dev/extendsArrayFails2.json": JSON.stringify({ extends: [42] }),
                 }
             }
         });
@@ -292,9 +331,9 @@ namespace ts {
                     messageText: `Unknown option 'excludes'. Did you mean 'exclude'?`
                 }]);
 
-                testFailure("can error when 'extends' is not a string", "extends.json", [{
+                testFailure("can error when 'extends' is not a string or Array", "extends.json", [{
                     code: 5024,
-                    messageText: `Compiler option 'extends' requires a value of type string.`
+                    messageText: `Compiler option 'extends' requires a value of type string or Array.`
                 }]);
 
                 testSuccess("can overwrite compiler options using extended 'null'", "configs/third.json", {
@@ -349,6 +388,40 @@ namespace ts {
                     assert.deepEqual(sourceFile.extendedSourceFiles, expected);
                 });
             });
+
+            describe(testName, () => {
+                it("adds extendedSourceFiles from an array only once", () => {
+                    const sourceFile = readJsonConfigFile("configs/extendsArrayFifth.json", (path) => host.readFile(path));
+                    const dir = combinePaths(basePath, "configs");
+                    const expected = [
+                        combinePaths(dir, "extendsArrayFirst.json"),
+                        combinePaths(dir, "extendsArraySecond.json"),
+                        combinePaths(dir, "extendsArrayThird.json"),
+                        combinePaths(dir, "extendsArrayFourth.json"),
+                    ];
+                    parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "extendsArrayFifth.json");
+                    assert.deepEqual(sourceFile.extendedSourceFiles, expected);
+                    parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "extendsArrayFifth.json");
+                    assert.deepEqual(sourceFile.extendedSourceFiles, expected);
+                });
+
+                testSuccess("can overwrite top-level compilerOptions", "configs/extendsArrayFifth.json", {
+                    allowJs: true,
+                    noImplicitAny: false,
+                    strictNullChecks: false,
+                    module: ModuleKind.System
+                }, []);
+
+                testFailure("can report missing configurations", "extendsArrayFails.json", [{
+                    code: 6053,
+                    messageText: `File '' not found.`
+                }]);
+
+                testFailure("can error when 'extends' is not a string or Array2", "extendsArrayFails2.json", [{
+                    code: 5024,
+                    messageText: `Compiler option 'extends' requires a value of type string.`
+                }]);
+            });
         });
     });
 }
diff --git a/src/testRunner/unittests/config/showConfig.ts b/src/testRunner/unittests/config/showConfig.ts
index f8905e3412677..8a18303a71764 100644
--- a/src/testRunner/unittests/config/showConfig.ts
+++ b/src/testRunner/unittests/config/showConfig.ts
@@ -145,6 +145,26 @@ namespace ts {
                     }
                     break;
                 }
+                case "listOrElement": {
+                    if (option.isTSConfigOnly) {
+                        args = ["-p", "tsconfig.json"];
+                        if(option.element.type === "string"){
+                            optionValue = { [option.name]: "someString" };
+                        }
+                        else{
+                            optionValue = { [option.name]: [] };
+                        }
+                    }
+                    else {
+                        if(option.element.type === "string"){
+                            args = [`--${option.name}`, "someString"];
+                        }
+                        else{
+                            args = [`--${option.name}`];
+                        }
+                    }
+                    break;
+                }
                 case "string": {
                     if (option.isTSConfigOnly) {
                         args = ["-p", "tsconfig.json"];
diff --git a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
index 58d912b30c5a0..2699cc20660c0 100644
--- a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
+++ b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
@@ -566,7 +566,7 @@ export function someFn() { }`),
         verifyTscWatch({
             scenario: "programUpdates",
             subScenario: "works with extended source files",
-            commandLineArgs: ["-b", "-w", "-v", "project1.tsconfig.json", "project2.tsconfig.json"],
+            commandLineArgs: ["-b", "-w", "-v", "project1.tsconfig.json", "project2.tsconfig.json", "project3.tsconfig.json"],
             sys: () => {
                 const alphaExtendedConfigFile: File = {
                     path: "/a/b/alpha.tsconfig.json",
@@ -602,10 +602,49 @@ export function someFn() { }`),
                         files: [otherFile.path]
                     })
                 };
+                const otherFile2: File = {
+                    path: "/a/b/other2.ts",
+                    content: "let k = 0;",
+                };
+                const extendsConfigFile1: File = {
+                    path: "/a/b/extendsConfig1.tsconfig.json",
+                    content: JSON.stringify({
+                        compilerOptions: {
+                            composite: true,
+                        }
+                    })
+                };
+                const extendsConfigFile2: File = {
+                    path: "/a/b/extendsConfig2.tsconfig.json",
+                    content: JSON.stringify({
+                        compilerOptions: {
+                            strictNullChecks: false,
+                        }
+                    })
+                };
+                const extendsConfigFile3: File = {
+                    path: "/a/b/extendsConfig3.tsconfig.json",
+                    content: JSON.stringify({
+                        compilerOptions: {
+                            noImplicitAny: true,
+                        }
+                    })
+                };
+                const project3Config: File = {
+                    path: "/a/b/project3.tsconfig.json",
+                    content: JSON.stringify({
+                        extends: ["./extendsCnfig1.tsconfig.json", "./extendsConfig2.tsconfig.json", "./extendsConfig3.tsconfig.json"],
+                        compilerOptions: {
+                            composite: false,
+                        },
+                        files: [otherFile.path]
+                    })
+                };
                 return createWatchedSystem([
                     libFile,
                     alphaExtendedConfigFile, project1Config, commonFile1, commonFile2,
-                    bravoExtendedConfigFile, project2Config, otherFile
+                    bravoExtendedConfigFile, project2Config, otherFile, otherFile2,
+                    extendsConfigFile1, extendsConfigFile2, extendsConfigFile3, project3Config
                 ], { currentDirectory: "/a/b" });
             },
             changes: [
@@ -646,6 +685,20 @@ export function someFn() { }`),
                     change: noop,
                     timeouts: checkSingleTimeoutQueueLengthAndRunAndVerifyNoTimeout // Build project2
                 },
+                {
+                    caption: "Modify extendsConfigFile2",
+                    change: sys => sys.writeFile("/a/b/extendsConfig2.tsconfig.json", JSON.stringify({
+                        compilerOptions: { strictNullChecks: true }
+                    })),
+                    timeouts: checkSingleTimeoutQueueLengthAndRunAndVerifyNoTimeout // Build project1
+                },
+                {
+                    caption: "Modify project 3",
+                    change: sys => sys.writeFile("/a/b/project3.tsconfig.json", JSON.stringify({
+                        extends: ["./extendsConfig1.tsconfig.json", "./extendsConfig2.tsconfig.json"],
+                    })),
+                    timeouts: checkSingleTimeoutQueueLengthAndRun // Build project1
+                },
             ]
         });
 
diff --git a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
index 84c9d4532a8be..3cf8f534f9ac4 100644
--- a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
+++ b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
@@ -33,25 +33,43 @@ let y = 1
 //// [/a/b/other.ts]
 let z = 0;
 
+//// [/a/b/other2.ts]
+let k = 0;
 
-/a/lib/tsc.js -b -w -v project1.tsconfig.json project2.tsconfig.json
+//// [/a/b/extendsConfig1.tsconfig.json]
+{"compilerOptions":{"composite":true}}
+
+//// [/a/b/extendsConfig2.tsconfig.json]
+{"compilerOptions":{"strictNullChecks":false}}
+
+//// [/a/b/extendsConfig3.tsconfig.json]
+{"compilerOptions":{"noImplicitAny":true}}
+
+//// [/a/b/project3.tsconfig.json]
+{"extends":["./extendsConfig1.tsconfig.json","./extendsConfig2.tsconfig.json","./extendsConfig3.tsconfig.json"],"compilerOptions":{"composite":false},"files":["/a/b/other.ts"]}
+
+
+/a/lib/tsc.js -b -w -v project1.tsconfig.json project2.tsconfig.json project3.tsconfig.json
 Output::
 >> Screen clear
-[12:00:25 AM] Starting compilation in watch mode...
+[12:00:35 AM] Starting compilation in watch mode...
 
-[12:00:26 AM] Projects in this build: 
+[12:00:36 AM] Projects in this build: 
     * project1.tsconfig.json
-    * project2.tsconfig.json
+    * project2.tsconfig.json
+    * project3.tsconfig.json
+
+[12:00:37 AM] Project 'project1.tsconfig.json' is out of date because output file 'project1.tsconfig.tsbuildinfo' does not exist
 
-[12:00:27 AM] Project 'project1.tsconfig.json' is out of date because output file 'project1.tsconfig.tsbuildinfo' does not exist
+[12:00:38 AM] Building project '/a/b/project1.tsconfig.json'...
 
-[12:00:28 AM] Building project '/a/b/project1.tsconfig.json'...
+[12:00:52 AM] Project 'project2.tsconfig.json' is out of date because output file 'project2.tsconfig.tsbuildinfo' does not exist
 
-[12:00:42 AM] Project 'project2.tsconfig.json' is out of date because output file 'project2.tsconfig.tsbuildinfo' does not exist
+[12:00:53 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:00:43 AM] Building project '/a/b/project2.tsconfig.json'...
+[12:01:03 AM] Project 'project3.tsconfig.json' is up to date because newest input 'other.ts' is older than output 'other.js'
 
-[12:00:53 AM] Found 0 errors. Watching for file changes.
+[12:01:04 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -103,6 +121,14 @@ WatchedFiles::
   {"fileName":"/a/b/bravo.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
 
 FsWatches::
 
@@ -225,11 +251,11 @@ Input::
 
 Output::
 >> Screen clear
-[12:00:57 AM] File change detected. Starting incremental compilation...
+[12:01:08 AM] File change detected. Starting incremental compilation...
 
-[12:00:58 AM] Project 'project1.tsconfig.json' is out of date because output 'project1.tsconfig.tsbuildinfo' is older than input 'alpha.tsconfig.json'
+[12:01:09 AM] Project 'project1.tsconfig.json' is out of date because output 'project1.tsconfig.tsbuildinfo' is older than input 'alpha.tsconfig.json'
 
-[12:00:59 AM] Building project '/a/b/project1.tsconfig.json'...
+[12:01:10 AM] Building project '/a/b/project1.tsconfig.json'...
 
 
 
@@ -263,6 +289,14 @@ WatchedFiles::
   {"fileName":"/a/b/bravo.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
 
 FsWatches::
 
@@ -331,11 +365,11 @@ Change:: Build project 2
 Input::
 
 Output::
-[12:01:13 AM] Project 'project2.tsconfig.json' is out of date because output 'project2.tsconfig.tsbuildinfo' is older than input 'alpha.tsconfig.json'
+[12:01:24 AM] Project 'project2.tsconfig.json' is out of date because output 'project2.tsconfig.tsbuildinfo' is older than input 'alpha.tsconfig.json'
 
-[12:01:14 AM] Building project '/a/b/project2.tsconfig.json'...
+[12:01:25 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:01:25 AM] Found 0 errors. Watching for file changes.
+[12:01:36 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -367,6 +401,14 @@ WatchedFiles::
   {"fileName":"/a/b/bravo.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
 
 FsWatches::
 
@@ -427,13 +469,13 @@ Input::
 
 Output::
 >> Screen clear
-[12:01:29 AM] File change detected. Starting incremental compilation...
+[12:01:40 AM] File change detected. Starting incremental compilation...
 
-[12:01:30 AM] Project 'project2.tsconfig.json' is out of date because output 'project2.tsconfig.tsbuildinfo' is older than input 'bravo.tsconfig.json'
+[12:01:41 AM] Project 'project2.tsconfig.json' is out of date because output 'project2.tsconfig.tsbuildinfo' is older than input 'bravo.tsconfig.json'
 
-[12:01:31 AM] Building project '/a/b/project2.tsconfig.json'...
+[12:01:42 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:01:42 AM] Found 0 errors. Watching for file changes.
+[12:01:53 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -465,6 +507,14 @@ WatchedFiles::
   {"fileName":"/a/b/bravo.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
 
 FsWatches::
 
@@ -524,17 +574,17 @@ Input::
 
 Output::
 >> Screen clear
-[12:01:46 AM] File change detected. Starting incremental compilation...
+[12:01:57 AM] File change detected. Starting incremental compilation...
 
-[12:01:47 AM] Project 'project2.tsconfig.json' is out of date because output 'commonFile1.js' is older than input 'project2.tsconfig.json'
+[12:01:58 AM] Project 'project2.tsconfig.json' is out of date because output file 'other2.js' does not exist
 
-[12:01:48 AM] Building project '/a/b/project2.tsconfig.json'...
+[12:01:59 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:01:59 AM] Found 0 errors. Watching for file changes.
+[12:02:12 AM] Found 0 errors. Watching for file changes.
 
 
 
-Program root files: ["/a/b/commonFile1.ts","/a/b/commonFile2.ts","/a/b/other.ts"]
+Program root files: ["/a/b/commonFile1.ts","/a/b/commonFile2.ts","/a/b/other.ts","/a/b/other2.ts"]
 Program options: {"strict":true,"watch":true,"configFilePath":"/a/b/project2.tsconfig.json"}
 Program structureReused: Not
 Program files::
@@ -542,17 +592,20 @@ Program files::
 /a/b/commonFile1.ts
 /a/b/commonFile2.ts
 /a/b/other.ts
+/a/b/other2.ts
 
 Semantic diagnostics in builder refreshed for::
 /a/lib/lib.d.ts
 /a/b/commonFile1.ts
 /a/b/commonFile2.ts
 /a/b/other.ts
+/a/b/other2.ts
 
 Shape signatures in builder refreshed for::
 /a/b/commonfile1.ts (computed .d.ts)
 /a/b/commonfile2.ts (computed .d.ts)
 /a/b/other.ts (computed .d.ts)
+/a/b/other2.ts (computed .d.ts)
 
 WatchedFiles::
 /a/b/project1.tsconfig.json:
@@ -567,6 +620,16 @@ WatchedFiles::
   {"fileName":"/a/b/project2.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
+/a/b/other2.ts:
+  {"fileName":"/a/b/other2.ts","pollingInterval":250}
 
 FsWatches::
 
@@ -583,6 +646,11 @@ exitCode:: ExitStatus.undefined
 var z = 0;
 
 
+//// [/a/b/other2.js]
+"use strict";
+var k = 0;
+
+
 
 Change:: update aplha config
 
@@ -593,11 +661,11 @@ Input::
 
 Output::
 >> Screen clear
-[12:02:04 AM] File change detected. Starting incremental compilation...
+[12:02:17 AM] File change detected. Starting incremental compilation...
 
-[12:02:05 AM] Project 'project1.tsconfig.json' is out of date because output 'project1.tsconfig.tsbuildinfo' is older than input 'alpha.tsconfig.json'
+[12:02:18 AM] Project 'project1.tsconfig.json' is out of date because output 'project1.tsconfig.tsbuildinfo' is older than input 'alpha.tsconfig.json'
 
-[12:02:06 AM] Building project '/a/b/project1.tsconfig.json'...
+[12:02:19 AM] Building project '/a/b/project1.tsconfig.json'...
 
 
 
@@ -629,6 +697,16 @@ WatchedFiles::
   {"fileName":"/a/b/project2.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
+/a/b/other2.ts:
+  {"fileName":"/a/b/other2.ts","pollingInterval":250}
 
 FsWatches::
 
@@ -696,15 +774,15 @@ Change:: Build project 2
 Input::
 
 Output::
-[12:02:20 AM] Project 'project2.tsconfig.json' is out of date because output 'commonFile1.js' is older than input 'alpha.tsconfig.json'
+[12:02:33 AM] Project 'project2.tsconfig.json' is out of date because output 'commonFile1.js' is older than input 'alpha.tsconfig.json'
 
-[12:02:21 AM] Building project '/a/b/project2.tsconfig.json'...
+[12:02:34 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:02:32 AM] Found 0 errors. Watching for file changes.
+[12:02:48 AM] Found 0 errors. Watching for file changes.
 
 
 
-Program root files: ["/a/b/commonFile1.ts","/a/b/commonFile2.ts","/a/b/other.ts"]
+Program root files: ["/a/b/commonFile1.ts","/a/b/commonFile2.ts","/a/b/other.ts","/a/b/other2.ts"]
 Program options: {"watch":true,"configFilePath":"/a/b/project2.tsconfig.json"}
 Program structureReused: Not
 Program files::
@@ -712,12 +790,14 @@ Program files::
 /a/b/commonFile1.ts
 /a/b/commonFile2.ts
 /a/b/other.ts
+/a/b/other2.ts
 
 Semantic diagnostics in builder refreshed for::
 /a/lib/lib.d.ts
 /a/b/commonFile1.ts
 /a/b/commonFile2.ts
 /a/b/other.ts
+/a/b/other2.ts
 
 No shapes updated in the builder::
 
@@ -734,6 +814,16 @@ WatchedFiles::
   {"fileName":"/a/b/project2.tsconfig.json","pollingInterval":250}
 /a/b/other.ts:
   {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
+/a/b/other2.ts:
+  {"fileName":"/a/b/other2.ts","pollingInterval":250}
 
 FsWatches::
 
@@ -749,3 +839,219 @@ exitCode:: ExitStatus.undefined
 var z = 0;
 
 
+//// [/a/b/other2.js]
+var k = 0;
+
+
+
+Change:: Modify extendsConfigFile2
+
+Input::
+//// [/a/b/extendsConfig2.tsconfig.json]
+{"compilerOptions":{"strictNullChecks":true}}
+
+
+Output::
+>> Screen clear
+[12:02:52 AM] File change detected. Starting incremental compilation...
+
+[12:02:53 AM] Project 'project3.tsconfig.json' is out of date because output 'other.js' is older than input 'extendsConfig2.tsconfig.json'
+
+[12:02:54 AM] Building project '/a/b/project3.tsconfig.json'...
+
+[12:02:59 AM] Found 0 errors. Watching for file changes.
+
+
+
+Program root files: ["/a/b/other.ts"]
+Program options: {"composite":false,"strictNullChecks":true,"noImplicitAny":true,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/a/b/other.ts
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/a/b/other.ts
+
+Shape signatures in builder refreshed for::
+/a/lib/lib.d.ts (used version)
+/a/b/other.ts (used version)
+
+WatchedFiles::
+/a/b/project1.tsconfig.json:
+  {"fileName":"/a/b/project1.tsconfig.json","pollingInterval":250}
+/a/b/alpha.tsconfig.json:
+  {"fileName":"/a/b/alpha.tsconfig.json","pollingInterval":250}
+/a/b/commonfile1.ts:
+  {"fileName":"/a/b/commonFile1.ts","pollingInterval":250}
+/a/b/commonfile2.ts:
+  {"fileName":"/a/b/commonFile2.ts","pollingInterval":250}
+/a/b/project2.tsconfig.json:
+  {"fileName":"/a/b/project2.tsconfig.json","pollingInterval":250}
+/a/b/other.ts:
+  {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig3.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig3.tsconfig.json","pollingInterval":250}
+/a/b/other2.ts:
+  {"fileName":"/a/b/other2.ts","pollingInterval":250}
+
+FsWatches::
+
+FsWatchesRecursive::
+/a/b:
+  {"directoryName":"/a/b"}
+
+exitCode:: ExitStatus.undefined
+
+//// [/a/b/other.js] file written with same contents
+
+Change:: Modify project 3
+
+Input::
+//// [/a/b/project3.tsconfig.json]
+{"extends":["./extendsConfig1.tsconfig.json","./extendsConfig2.tsconfig.json"]}
+
+
+Output::
+>> Screen clear
+[12:03:03 AM] File change detected. Starting incremental compilation...
+
+[12:03:04 AM] Project 'project3.tsconfig.json' is out of date because output file 'project3.tsconfig.tsbuildinfo' does not exist
+
+[12:03:05 AM] Building project '/a/b/project3.tsconfig.json'...
+
+[12:03:34 AM] Found 0 errors. Watching for file changes.
+
+
+
+Program root files: ["/a/b/commonFile1.ts","/a/b/commonFile2.ts","/a/b/other.ts","/a/b/other2.ts"]
+Program options: {"composite":true,"strictNullChecks":true,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/a/b/commonFile1.ts
+/a/b/commonFile2.ts
+/a/b/other.ts
+/a/b/other2.ts
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/a/b/commonFile1.ts
+/a/b/commonFile2.ts
+/a/b/other.ts
+/a/b/other2.ts
+
+Shape signatures in builder refreshed for::
+/a/b/commonfile1.ts (computed .d.ts)
+/a/b/commonfile2.ts (computed .d.ts)
+/a/b/other.ts (computed .d.ts)
+/a/b/other2.ts (computed .d.ts)
+
+WatchedFiles::
+/a/b/project1.tsconfig.json:
+  {"fileName":"/a/b/project1.tsconfig.json","pollingInterval":250}
+/a/b/alpha.tsconfig.json:
+  {"fileName":"/a/b/alpha.tsconfig.json","pollingInterval":250}
+/a/b/commonfile1.ts:
+  {"fileName":"/a/b/commonFile1.ts","pollingInterval":250}
+/a/b/commonfile2.ts:
+  {"fileName":"/a/b/commonFile2.ts","pollingInterval":250}
+/a/b/project2.tsconfig.json:
+  {"fileName":"/a/b/project2.tsconfig.json","pollingInterval":250}
+/a/b/other.ts:
+  {"fileName":"/a/b/other.ts","pollingInterval":250}
+/a/b/project3.tsconfig.json:
+  {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig2.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
+/a/b/other2.ts:
+  {"fileName":"/a/b/other2.ts","pollingInterval":250}
+
+FsWatches::
+
+FsWatchesRecursive::
+/a/b:
+  {"directoryName":"/a/b"}
+  {"directoryName":"/a/b"}
+
+exitCode:: ExitStatus.undefined
+
+//// [/a/b/commonFile1.js] file written with same contents
+//// [/a/b/commonFile1.d.ts] file written with same contents
+//// [/a/b/commonFile2.js] file written with same contents
+//// [/a/b/commonFile2.d.ts] file written with same contents
+//// [/a/b/other.js] file written with same contents
+//// [/a/b/other.d.ts] file written with same contents
+//// [/a/b/other2.js] file written with same contents
+//// [/a/b/other2.d.ts]
+declare let k: number;
+
+
+//// [/a/b/project3.tsconfig.tsbuildinfo]
+{"program":{"fileNames":["../lib/lib.d.ts","./commonfile1.ts","./commonfile2.ts","./other.ts","./other2.ts"],"fileInfos":[{"version":"-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }","affectsGlobalScope":true},{"version":"2167136208-let x = 1","signature":"2842409786-declare let x: number;\n","affectsGlobalScope":true},{"version":"2168322129-let y = 1","signature":"784887931-declare let y: number;\n","affectsGlobalScope":true},{"version":"2874288940-let z = 0;","signature":"-1272633924-declare let z: number;\n","affectsGlobalScope":true},{"version":"2287258045-let k = 0;","signature":"3820390125-declare let k: number;\n","affectsGlobalScope":true}],"options":{"composite":true,"strictNullChecks":true},"referencedMap":[],"exportedModulesMap":[],"semanticDiagnosticsPerFile":[2,3,4,5,1],"latestChangedDtsFile":"./other2.d.ts"},"version":"FakeTSVersion"}
+
+//// [/a/b/project3.tsconfig.tsbuildinfo.readable.baseline.txt]
+{
+  "program": {
+    "fileNames": [
+      "../lib/lib.d.ts",
+      "./commonfile1.ts",
+      "./commonfile2.ts",
+      "./other.ts",
+      "./other2.ts"
+    ],
+    "fileInfos": {
+      "../lib/lib.d.ts": {
+        "version": "-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }",
+        "signature": "-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }",
+        "affectsGlobalScope": true
+      },
+      "./commonfile1.ts": {
+        "version": "2167136208-let x = 1",
+        "signature": "2842409786-declare let x: number;\n",
+        "affectsGlobalScope": true
+      },
+      "./commonfile2.ts": {
+        "version": "2168322129-let y = 1",
+        "signature": "784887931-declare let y: number;\n",
+        "affectsGlobalScope": true
+      },
+      "./other.ts": {
+        "version": "2874288940-let z = 0;",
+        "signature": "-1272633924-declare let z: number;\n",
+        "affectsGlobalScope": true
+      },
+      "./other2.ts": {
+        "version": "2287258045-let k = 0;",
+        "signature": "3820390125-declare let k: number;\n",
+        "affectsGlobalScope": true
+      }
+    },
+    "options": {
+      "composite": true,
+      "strictNullChecks": true
+    },
+    "referencedMap": {},
+    "exportedModulesMap": {},
+    "semanticDiagnosticsPerFile": [
+      "./commonfile1.ts",
+      "./commonfile2.ts",
+      "./other.ts",
+      "./other2.ts",
+      "../lib/lib.d.ts"
+    ],
+    "latestChangedDtsFile": "./other2.d.ts"
+  },
+  "version": "FakeTSVersion",
+  "size": 1171
+}
+

From a50904ebebb3156a2325118dc374cdc19e8d20fd Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 22 Aug 2022 13:41:34 -0700
Subject: [PATCH 02/12] Updated baselines

---
 .../reference/api/tsserverlibrary.d.ts        |  2 +-
 tests/baselines/reference/api/typescript.d.ts |  2 +-
 .../works-with-extended-source-files.js       | 82 ++++++++++---------
 3 files changed, 47 insertions(+), 39 deletions(-)

diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 103b3664e8b14..03f6bd87bd673 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -4949,7 +4949,7 @@ declare namespace ts {
         /**
          * Note that the case of the config path has not yet been normalized, as no files have been imported into the project yet
          */
-        extendedConfigPath?: string;
+        extendedConfigPath?: string | string[];
     }
     export interface ExtendedConfigCacheEntry {
         extendedResult: TsConfigSourceFile;
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 3ea4fe3130e4b..081139da3aa8e 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -4949,7 +4949,7 @@ declare namespace ts {
         /**
          * Note that the case of the config path has not yet been normalized, as no files have been imported into the project yet
          */
-        extendedConfigPath?: string;
+        extendedConfigPath?: string | string[];
     }
     export interface ExtendedConfigCacheEntry {
         extendedResult: TsConfigSourceFile;
diff --git a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
index 3cf8f534f9ac4..7db2e2c1c0fb8 100644
--- a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
+++ b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
@@ -46,7 +46,7 @@ let k = 0;
 {"compilerOptions":{"noImplicitAny":true}}
 
 //// [/a/b/project3.tsconfig.json]
-{"extends":["./extendsConfig1.tsconfig.json","./extendsConfig2.tsconfig.json","./extendsConfig3.tsconfig.json"],"compilerOptions":{"composite":false},"files":["/a/b/other.ts"]}
+{"extends":["./extendsCnfig1.tsconfig.json","./extendsConfig2.tsconfig.json","./extendsConfig3.tsconfig.json"],"compilerOptions":{"composite":false},"files":["/a/b/other.ts"]}
 
 
 /a/lib/tsc.js -b -w -v project1.tsconfig.json project2.tsconfig.json project3.tsconfig.json
@@ -69,7 +69,9 @@ Output::
 
 [12:01:03 AM] Project 'project3.tsconfig.json' is up to date because newest input 'other.ts' is older than output 'other.js'
 
-[12:01:04 AM] Found 0 errors. Watching for file changes.
+error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
+
+[12:01:04 AM] Found 1 error. Watching for file changes.
 
 
 
@@ -123,8 +125,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -291,8 +293,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -369,7 +371,9 @@ Output::
 
 [12:01:25 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:01:36 AM] Found 0 errors. Watching for file changes.
+error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
+
+[12:01:36 AM] Found 1 error. Watching for file changes.
 
 
 
@@ -403,8 +407,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -475,7 +479,9 @@ Output::
 
 [12:01:42 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:01:53 AM] Found 0 errors. Watching for file changes.
+error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
+
+[12:01:53 AM] Found 1 error. Watching for file changes.
 
 
 
@@ -509,8 +515,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -580,7 +586,9 @@ Output::
 
 [12:01:59 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:02:12 AM] Found 0 errors. Watching for file changes.
+error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
+
+[12:02:12 AM] Found 1 error. Watching for file changes.
 
 
 
@@ -622,8 +630,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -699,8 +707,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -778,7 +786,9 @@ Output::
 
 [12:02:34 AM] Building project '/a/b/project2.tsconfig.json'...
 
-[12:02:48 AM] Found 0 errors. Watching for file changes.
+error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
+
+[12:02:48 AM] Found 1 error. Watching for file changes.
 
 
 
@@ -816,8 +826,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -859,24 +869,22 @@ Output::
 
 [12:02:54 AM] Building project '/a/b/project3.tsconfig.json'...
 
-[12:02:59 AM] Found 0 errors. Watching for file changes.
+error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
+
+[12:02:55 AM] Found 1 error. Watching for file changes.
 
 
 
 Program root files: ["/a/b/other.ts"]
-Program options: {"composite":false,"strictNullChecks":true,"noImplicitAny":true,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
+Program options: {"strictNullChecks":true,"noImplicitAny":true,"composite":false,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
 /a/b/other.ts
 
-Semantic diagnostics in builder refreshed for::
-/a/lib/lib.d.ts
-/a/b/other.ts
+No cached semantic diagnostics in the builder::
 
-Shape signatures in builder refreshed for::
-/a/lib/lib.d.ts (used version)
-/a/b/other.ts (used version)
+No shapes updated in the builder::
 
 WatchedFiles::
 /a/b/project1.tsconfig.json:
@@ -893,8 +901,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendscnfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -910,7 +918,6 @@ FsWatchesRecursive::
 
 exitCode:: ExitStatus.undefined
 
-//// [/a/b/other.js] file written with same contents
 
 Change:: Modify project 3
 
@@ -921,13 +928,13 @@ Input::
 
 Output::
 >> Screen clear
-[12:03:03 AM] File change detected. Starting incremental compilation...
+[12:02:59 AM] File change detected. Starting incremental compilation...
 
-[12:03:04 AM] Project 'project3.tsconfig.json' is out of date because output file 'project3.tsconfig.tsbuildinfo' does not exist
+[12:03:00 AM] Project 'project3.tsconfig.json' is out of date because output file 'project3.tsconfig.tsbuildinfo' does not exist
 
-[12:03:05 AM] Building project '/a/b/project3.tsconfig.json'...
+[12:03:01 AM] Building project '/a/b/project3.tsconfig.json'...
 
-[12:03:34 AM] Found 0 errors. Watching for file changes.
+[12:03:30 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -949,6 +956,7 @@ Semantic diagnostics in builder refreshed for::
 /a/b/other2.ts
 
 Shape signatures in builder refreshed for::
+/a/lib/lib.d.ts (used version)
 /a/b/commonfile1.ts (computed .d.ts)
 /a/b/commonfile2.ts (computed .d.ts)
 /a/b/other.ts (computed .d.ts)
@@ -969,12 +977,12 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/other2.ts:
   {"fileName":"/a/b/other2.ts","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 
 FsWatches::
 

From 1717b5338d913b494627d4309d9f332d07132321 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Tue, 23 Aug 2022 14:11:28 -0700
Subject: [PATCH 03/12] Changes for pr

---
 src/compiler/commandLineParser.ts             | 58 +++++--------
 .../config/configurationExtension.ts          |  5 +-
 .../unittests/tsbuildWatch/programUpdates.ts  |  2 +-
 .../works-with-extended-source-files.js       | 82 +++++++++----------
 4 files changed, 63 insertions(+), 84 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 1d17d1b8a742c..811d760e7c07f 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1731,7 +1731,7 @@ namespace ts {
                             i++;
                         }
                         break;
-                    case "listOrElement": 
+                    case "listOrElement":
                         if(opt.element.type === "string"){
                             options[opt.name] = validateJsonOptionValue(opt, args[i] || "", errors);
                             i++;
@@ -2465,12 +2465,9 @@ namespace ts {
             // this is of a type CommandLineOptionOfPrimitiveType
             return undefined;
         }
-        else if (optionDefinition.type === "list") {
+        else if (optionDefinition.type === "list" || optionDefinition.type === "listOrElement") {
             return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
         }
-        else if(optionDefinition.type === "listOrElement"){
-            return (optionDefinition.element.type === "string") ? undefined : getCustomTypeMapOfCommandLineOption(optionDefinition.element);
-        }
         else {
             return optionDefinition.type;
         }
@@ -2987,12 +2984,19 @@ namespace ts {
         return !!value.options;
     }
 
-    interface ExtendsResult { options: CompilerOptions, watchOptions?: WatchOptions, include?: string[], exclude?: string[], files?: string[], compileOnSave?: boolean, extendedSourceFiles?: Set<string>}
+    interface ExtendsResult {
+        options: CompilerOptions,
+        watchOptions?: WatchOptions,
+        include?: string[],
+        exclude?: string[],
+        files?: string[],
+        compileOnSave?: boolean,
+        extendedSourceFiles?: Set<string>
+    }
     /**
      * This *just* extracts options/include/exclude/files out of a config file.
      * It does *not* resolve the included files.
      */
-
     function parseConfig(
         json: any,
         sourceFile: TsConfigSourceFile | undefined,
@@ -3025,7 +3029,7 @@ namespace ts {
         if (ownConfig.extendedConfigPath) {
             // copy the resolution stack so it is never reused between branches in potential diamond-problem scenarios.
             resolutionStack = resolutionStack.concat([resolvedPath]);
-            const result: ExtendsResult = {options: {}};
+            const result: ExtendsResult = { options:{} };
             if(isString(ownConfig.extendedConfigPath)){
                 applyExtendedConfig(result, ownConfig.extendedConfigPath);
             }
@@ -3035,7 +3039,7 @@ namespace ts {
             if(!ownConfig.raw.include && result.include) ownConfig.raw.include = result.include;
             if(!ownConfig.raw.exclude && result.exclude) ownConfig.raw.exclude = result.exclude;
             if(!ownConfig.raw.files && result.files) ownConfig.raw.files = result.files;
-            if (ownConfig.raw.compileOnSave !== undefined && result.compileOnSave) ownConfig.raw.compileOnSave = result.compileOnSave;
+            if (ownConfig.raw.compileOnSave === undefined && result.compileOnSave) ownConfig.raw.compileOnSave = result.compileOnSave;
             if (sourceFile && result.extendedSourceFiles) sourceFile.extendedSourceFiles = arrayFrom(result.extendedSourceFiles.keys());
 
             ownConfig.options = assign(result.options, ownConfig.options);
@@ -3090,7 +3094,7 @@ namespace ts {
         const typeAcquisition = convertTypeAcquisitionFromJsonWorker(json.typeAcquisition || json.typingOptions, basePath, errors, configFileName);
         const watchOptions = convertWatchOptionsFromJsonWorker(json.watchOptions, basePath, errors);
         json.compileOnSave = convertCompileOnSaveOptionFromJson(json, basePath, errors);
-        let extendedConfigPath:  string[] | undefined;
+        let extendedConfigPath: string[] | undefined;
 
         if (json.extends) {
             if (!isCompilerOptionsValue(extendsOptionDeclaration, json.extends)) {
@@ -3275,7 +3279,7 @@ namespace ts {
         }
         if (sourceFile) {
             (result.extendedSourceFiles ??= new Set()).add(extendedResult.fileName);
-            if (isArray(extendedResult.extendedSourceFiles)) {
+            if (extendedResult.extendedSourceFiles) {
                 for (const extenedSourceFile of extendedResult.extendedSourceFiles) {
                     result.extendedSourceFiles.add(extenedSourceFile);
                 }
@@ -3392,25 +3396,14 @@ namespace ts {
 
     function normalizeOptionValue(option: CommandLineOption, basePath: string, value: any): CompilerOptionsValue {
         if (isNullOrUndefined(value)) return undefined;
-        if (option.type === "list") {
+        if (option.type === "listOrElement" && !isArray(value)) return normalizeOptionValue(option.element, basePath, value);
+        else if (option.type === "list" || option.type === "listOrElement") {
             const listOption = option;
             if (listOption.element.isFilePath || !isString(listOption.element.type)) {
                 return filter(map(value, v => normalizeOptionValue(listOption.element, basePath, v)), v => listOption.listPreserveFalsyValues ? true : !!v) as CompilerOptionsValue;
             }
             return value;
         }
-        if(option.type === "listOrElement"){
-            if (option.element.type === "string"){
-                return normalizeNonListOptionValue(option, basePath, value);
-            }
-            else{
-                const listOption = option;
-                if (listOption.element.isFilePath || !isString(listOption.element.type)) {
-                    return filter(map(value, v => normalizeOptionValue(listOption.element, basePath, v)), v => listOption.listPreserveFalsyValues ? true : !!v) as CompilerOptionsValue;
-                }
-                return value;
-            }
-        }
         else if (!isString(option.type)) {
             return option.type.get(isString(value) ? value.toLowerCase() : value);
         }
@@ -3830,15 +3823,12 @@ namespace ts {
                 return typeof value === "number" ? value : "";
             case "boolean":
                 return typeof value === "boolean" ? value : "";
+            case "listOrElement":
+                if (!isArray(value)) return getOptionValueWithEmptyStrings(value, option.element);
+                // fall through to list
             case "list":
                 const elementType = option.element;
                 return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, elementType)) : "";
-            case "listOrElement":
-                if(option.element.type === "string"){
-                    return "";
-                }
-                const typeOfElement = option.element;
-                return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, typeOfElement)) : "";
             default:
                 return forEachEntry(option.type, (optionEnumValue, optionStringValue) => {
                     if (optionEnumValue === value) {
@@ -3849,7 +3839,7 @@ namespace ts {
     }
 
 
-    function getDefaultValueForOption(option: CommandLineOption) {
+    function getDefaultValueForOption(option: CommandLineOption): {} {
         switch (option.type) {
             case "number":
                 return 1;
@@ -3861,11 +3851,7 @@ namespace ts {
             case "list":
                 return [];
             case "listOrElement":
-                if (option.element.type === "string"){
-                    const defaultValue = option.defaultValueDescription;
-                    return option.isFilePath ? `./${defaultValue && typeof defaultValue === "string" ? defaultValue : ""}` : "";
-                }
-                return [];
+                return getDefaultValueForOption(option.element);
             case "object":
                 return {};
             default:
diff --git a/src/testRunner/unittests/config/configurationExtension.ts b/src/testRunner/unittests/config/configurationExtension.ts
index 058c21d907140..230c70f95887e 100644
--- a/src/testRunner/unittests/config/configurationExtension.ts
+++ b/src/testRunner/unittests/config/configurationExtension.ts
@@ -202,6 +202,7 @@ namespace ts {
                             module: null, // eslint-disable-line no-null/no-null
                             noImplicitAny: false
                         },
+                        extends: "./extendsArrayFirst",
                         include: ["../supplemental.*"]
                     }),
                     "dev/configs/extendsArrayFourth.json": JSON.stringify({
@@ -217,7 +218,7 @@ namespace ts {
                         files: [],
                     }),
                     "dev/extendsArrayFails.json": JSON.stringify({
-                        extends: [""],
+                        extends: ["./missingFile"],
                         compilerOptions: {
                             types: []
                         }
@@ -414,7 +415,7 @@ namespace ts {
 
                 testFailure("can report missing configurations", "extendsArrayFails.json", [{
                     code: 6053,
-                    messageText: `File '' not found.`
+                    messageText: `File './missingFile' not found.`
                 }]);
 
                 testFailure("can error when 'extends' is not a string or Array2", "extendsArrayFails2.json", [{
diff --git a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
index 2699cc20660c0..4c3dafa862b84 100644
--- a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
+++ b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
@@ -633,7 +633,7 @@ export function someFn() { }`),
                 const project3Config: File = {
                     path: "/a/b/project3.tsconfig.json",
                     content: JSON.stringify({
-                        extends: ["./extendsCnfig1.tsconfig.json", "./extendsConfig2.tsconfig.json", "./extendsConfig3.tsconfig.json"],
+                        extends: ["./extendsConfig1.tsconfig.json", "./extendsConfig2.tsconfig.json", "./extendsConfig3.tsconfig.json"],
                         compilerOptions: {
                             composite: false,
                         },
diff --git a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
index 7db2e2c1c0fb8..3cf8f534f9ac4 100644
--- a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
+++ b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
@@ -46,7 +46,7 @@ let k = 0;
 {"compilerOptions":{"noImplicitAny":true}}
 
 //// [/a/b/project3.tsconfig.json]
-{"extends":["./extendsCnfig1.tsconfig.json","./extendsConfig2.tsconfig.json","./extendsConfig3.tsconfig.json"],"compilerOptions":{"composite":false},"files":["/a/b/other.ts"]}
+{"extends":["./extendsConfig1.tsconfig.json","./extendsConfig2.tsconfig.json","./extendsConfig3.tsconfig.json"],"compilerOptions":{"composite":false},"files":["/a/b/other.ts"]}
 
 
 /a/lib/tsc.js -b -w -v project1.tsconfig.json project2.tsconfig.json project3.tsconfig.json
@@ -69,9 +69,7 @@ Output::
 
 [12:01:03 AM] Project 'project3.tsconfig.json' is up to date because newest input 'other.ts' is older than output 'other.js'
 
-error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
-
-[12:01:04 AM] Found 1 error. Watching for file changes.
+[12:01:04 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -125,8 +123,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -293,8 +291,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -371,9 +369,7 @@ Output::
 
 [12:01:25 AM] Building project '/a/b/project2.tsconfig.json'...
 
-error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
-
-[12:01:36 AM] Found 1 error. Watching for file changes.
+[12:01:36 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -407,8 +403,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -479,9 +475,7 @@ Output::
 
 [12:01:42 AM] Building project '/a/b/project2.tsconfig.json'...
 
-error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
-
-[12:01:53 AM] Found 1 error. Watching for file changes.
+[12:01:53 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -515,8 +509,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -586,9 +580,7 @@ Output::
 
 [12:01:59 AM] Building project '/a/b/project2.tsconfig.json'...
 
-error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
-
-[12:02:12 AM] Found 1 error. Watching for file changes.
+[12:02:12 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -630,8 +622,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -707,8 +699,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -786,9 +778,7 @@ Output::
 
 [12:02:34 AM] Building project '/a/b/project2.tsconfig.json'...
 
-error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
-
-[12:02:48 AM] Found 1 error. Watching for file changes.
+[12:02:48 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -826,8 +816,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -869,22 +859,24 @@ Output::
 
 [12:02:54 AM] Building project '/a/b/project3.tsconfig.json'...
 
-error TS5083: Cannot read file '/a/b/extendsCnfig1.tsconfig.json'.
-
-[12:02:55 AM] Found 1 error. Watching for file changes.
+[12:02:59 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/a/b/other.ts"]
-Program options: {"strictNullChecks":true,"noImplicitAny":true,"composite":false,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
+Program options: {"composite":false,"strictNullChecks":true,"noImplicitAny":true,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
 /a/b/other.ts
 
-No cached semantic diagnostics in the builder::
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/a/b/other.ts
 
-No shapes updated in the builder::
+Shape signatures in builder refreshed for::
+/a/lib/lib.d.ts (used version)
+/a/b/other.ts (used version)
 
 WatchedFiles::
 /a/b/project1.tsconfig.json:
@@ -901,8 +893,8 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
-/a/b/extendscnfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsCnfig1.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig3.tsconfig.json:
@@ -918,6 +910,7 @@ FsWatchesRecursive::
 
 exitCode:: ExitStatus.undefined
 
+//// [/a/b/other.js] file written with same contents
 
 Change:: Modify project 3
 
@@ -928,13 +921,13 @@ Input::
 
 Output::
 >> Screen clear
-[12:02:59 AM] File change detected. Starting incremental compilation...
+[12:03:03 AM] File change detected. Starting incremental compilation...
 
-[12:03:00 AM] Project 'project3.tsconfig.json' is out of date because output file 'project3.tsconfig.tsbuildinfo' does not exist
+[12:03:04 AM] Project 'project3.tsconfig.json' is out of date because output file 'project3.tsconfig.tsbuildinfo' does not exist
 
-[12:03:01 AM] Building project '/a/b/project3.tsconfig.json'...
+[12:03:05 AM] Building project '/a/b/project3.tsconfig.json'...
 
-[12:03:30 AM] Found 0 errors. Watching for file changes.
+[12:03:34 AM] Found 0 errors. Watching for file changes.
 
 
 
@@ -956,7 +949,6 @@ Semantic diagnostics in builder refreshed for::
 /a/b/other2.ts
 
 Shape signatures in builder refreshed for::
-/a/lib/lib.d.ts (used version)
 /a/b/commonfile1.ts (computed .d.ts)
 /a/b/commonfile2.ts (computed .d.ts)
 /a/b/other.ts (computed .d.ts)
@@ -977,12 +969,12 @@ WatchedFiles::
   {"fileName":"/a/b/other.ts","pollingInterval":250}
 /a/b/project3.tsconfig.json:
   {"fileName":"/a/b/project3.tsconfig.json","pollingInterval":250}
+/a/b/extendsconfig1.tsconfig.json:
+  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 /a/b/extendsconfig2.tsconfig.json:
   {"fileName":"/a/b/extendsConfig2.tsconfig.json","pollingInterval":250}
 /a/b/other2.ts:
   {"fileName":"/a/b/other2.ts","pollingInterval":250}
-/a/b/extendsconfig1.tsconfig.json:
-  {"fileName":"/a/b/extendsConfig1.tsconfig.json","pollingInterval":250}
 
 FsWatches::
 

From 77f9b508b9d9ff8360a2fe04a5f558ee7816ef60 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 29 Aug 2022 11:25:40 -0700
Subject: [PATCH 04/12] Changes for pr comments

---
 src/compiler/builder.ts                       |  1 +
 src/compiler/commandLineParser.ts             | 55 +++++++++----------
 src/executeCommandLine/executeCommandLine.ts  | 14 ++---
 src/services/getEditsForFileRename.ts         |  1 +
 src/testRunner/unittests/config/showConfig.ts | 18 +-----
 5 files changed, 32 insertions(+), 57 deletions(-)

diff --git a/src/compiler/builder.ts b/src/compiler/builder.ts
index 6177713582859..33744091866d3 100644
--- a/src/compiler/builder.ts
+++ b/src/compiler/builder.ts
@@ -994,6 +994,7 @@ namespace ts {
 
     function convertToReusableCompilerOptionValue(option: CommandLineOption | undefined, value: CompilerOptionsValue, relativeToBuildInfo: (path: string) => string) {
         if (option) {
+            Debug.assert(option.type !== "listOrElement");
             if (option.type === "list") {
                 const values = value as readonly (string | number)[];
                 if (option.element.isFilePath && values.length) {
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 811d760e7c07f..04986e4e2aeb1 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1732,17 +1732,7 @@ namespace ts {
                         }
                         break;
                     case "listOrElement":
-                        if(opt.element.type === "string"){
-                            options[opt.name] = validateJsonOptionValue(opt, args[i] || "", errors);
-                            i++;
-                        }
-                        else{
-                            const result = parseListTypeOption(opt, args[i], errors);
-                            options[opt.name] = result || [];
-                            if (result) {
-                                i++;
-                            }
-                        }
+                        Debug.fail();
                         break;
                     // If not a primitive, the possible types are specified in what is effectively a map of options.
                     default:
@@ -2252,8 +2242,11 @@ namespace ts {
                     if (!isDoubleQuotedString(valueExpression)) {
                         errors.push(createDiagnosticForNodeInSourceFile(sourceFile, valueExpression, Diagnostics.String_literal_with_double_quotes_expected));
                     }
-                    reportInvalidOptionValue(option && (isString(option.type) && option.type !== "string")&& (option.type !== "listOrElement" || option.element.type !== "string"));
+                    reportInvalidOptionValue(option && (isString(option.type) && option.type !== "string") && (option.type !== "listOrElement" || (isString(option.element.type) && option.element.type !== "string")));
                     const text = (valueExpression as StringLiteral).text;
+                    if (option) {
+                        Debug.assert(option.type !== "listOrElement" || option.element.type === "string", "Only string or array of string is handled for now");
+                    }
                     if (option && !isString(option.type)) {
                         const customOption = option as CommandLineOptionOfCustomType;
                         // Validate custom option type
@@ -2512,6 +2505,7 @@ namespace ts {
                 const value = options[name] as CompilerOptionsValue;
                 const optionDefinition = optionsNameMap.get(name.toLowerCase());
                 if (optionDefinition) {
+                    Debug.assert(optionDefinition.type !== "listOrElement");
                     const customTypeMap = getCustomTypeMapOfCommandLineOption(optionDefinition);
                     if (!customTypeMap) {
                         // There is no map associated with this compiler option then use the value as-is
@@ -2696,7 +2690,7 @@ namespace ts {
                 if(option.element.type === "string"){
                     return toAbsolutePath(value as string);
                 }
-                else{
+                else {
                     const values = value as readonly (string | number)[];
                     if (option.element.isFilePath && values.length) {
                         return values.map(toAbsolutePath);
@@ -2985,12 +2979,12 @@ namespace ts {
     }
 
     interface ExtendsResult {
-        options: CompilerOptions,
-        watchOptions?: WatchOptions,
-        include?: string[],
-        exclude?: string[],
-        files?: string[],
-        compileOnSave?: boolean,
+        options: CompilerOptions;
+        watchOptions?: WatchOptions;
+        include?: string[];
+        exclude?: string[];
+        files?: string[];
+        compileOnSave?: boolean;
         extendedSourceFiles?: Set<string>
     }
     /**
@@ -3030,22 +3024,22 @@ namespace ts {
             // copy the resolution stack so it is never reused between branches in potential diamond-problem scenarios.
             resolutionStack = resolutionStack.concat([resolvedPath]);
             const result: ExtendsResult = { options:{} };
-            if(isString(ownConfig.extendedConfigPath)){
+            if (isString(ownConfig.extendedConfigPath)) {
                 applyExtendedConfig(result, ownConfig.extendedConfigPath);
             }
-            else{
+            else {
                 ownConfig.extendedConfigPath.forEach(extendedConfigPath => applyExtendedConfig(result, extendedConfigPath));
             }
-            if(!ownConfig.raw.include && result.include) ownConfig.raw.include = result.include;
-            if(!ownConfig.raw.exclude && result.exclude) ownConfig.raw.exclude = result.exclude;
-            if(!ownConfig.raw.files && result.files) ownConfig.raw.files = result.files;
+            if (!ownConfig.raw.include && result.include) ownConfig.raw.include = result.include;
+            if (!ownConfig.raw.exclude && result.exclude) ownConfig.raw.exclude = result.exclude;
+            if (!ownConfig.raw.files && result.files) ownConfig.raw.files = result.files;
             if (ownConfig.raw.compileOnSave === undefined && result.compileOnSave) ownConfig.raw.compileOnSave = result.compileOnSave;
             if (sourceFile && result.extendedSourceFiles) sourceFile.extendedSourceFiles = arrayFrom(result.extendedSourceFiles.keys());
 
             ownConfig.options = assign(result.options, ownConfig.options);
-            ownConfig.watchOptions = ownConfig.watchOptions && result.watchOptions?
-            assign(result.watchOptions, ownConfig.watchOptions) :
-            ownConfig.watchOptions || result.watchOptions;
+            ownConfig.watchOptions = ownConfig.watchOptions && result.watchOptions ?
+                assign(result.watchOptions, ownConfig.watchOptions) :
+                ownConfig.watchOptions || result.watchOptions;
         }
         return ownConfig;
 
@@ -3130,7 +3124,7 @@ namespace ts {
         const options = getDefaultCompilerOptions(configFileName);
         let typeAcquisition: TypeAcquisition | undefined, typingOptionstypeAcquisition: TypeAcquisition | undefined;
         let watchOptions: WatchOptions | undefined;
-        let extendedConfigPath: string[] | undefined;
+        let extendedConfigPath: string | string[] | undefined;
         let rootCompilerOptions: PropertyName[] | undefined;
 
         const optionsIterator: JsonConversionNotifier = {
@@ -3160,16 +3154,17 @@ namespace ts {
                         case "extends":
                             const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
                             if (isString(value)) {
-                                extendedConfigPath = append (extendedConfigPath, getExtendsConfigPath(
+                                extendedConfigPath = getExtendsConfigPath(
                                     value,
                                     host,
                                     newBase,
                                     errors,
                                     (message, arg0) =>
                                         createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
-                                ));
+                                );
                             }
                             else {
+                                extendedConfigPath = [];
                                 for (const fileName of value as unknown[]) {
                                     if (isString(fileName)) {
                                         extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(
diff --git a/src/executeCommandLine/executeCommandLine.ts b/src/executeCommandLine/executeCommandLine.ts
index 13d1292442169..7c5277a64e3db 100644
--- a/src/executeCommandLine/executeCommandLine.ts
+++ b/src/executeCommandLine/executeCommandLine.ts
@@ -163,7 +163,8 @@ namespace ts {
         const defaultValueDescription =
             typeof option.defaultValueDescription === "object"
                 ? getDiagnosticText(option.defaultValueDescription)
-                : formatDefaultValue(
+                : Debug.assert(option.type !== "listOrElement");
+                    formatDefaultValue(
                       option.defaultValueDescription,
                       option.type === "list" ? option.element.type : option.type
                   );
@@ -276,6 +277,7 @@ namespace ts {
             };
 
             function getValueType(option: CommandLineOption) {
+                Debug.assert(option.type !== "listOrElement");
                 switch (option.type) {
                     case "string":
                     case "number":
@@ -297,16 +299,8 @@ namespace ts {
                         possibleValues = option.type;
                         break;
                     case "list":
-                        // TODO: check infinite loop
-                        possibleValues = getPossibleValues(option.element);
-                        break;
                     case "listOrElement":
-                        if (option.element.type === "string"){
-                            possibleValues = option.type;
-                        }
-                        else {
-                            possibleValues = getPossibleValues(option.element);
-                        }
+                        possibleValues = getPossibleValues(option.element);
                         break;
                     case "object":
                         possibleValues = "";
diff --git a/src/services/getEditsForFileRename.ts b/src/services/getEditsForFileRename.ts
index 5120560da4cee..8cb4872dbfd35 100644
--- a/src/services/getEditsForFileRename.ts
+++ b/src/services/getEditsForFileRename.ts
@@ -73,6 +73,7 @@ namespace ts {
                 case "compilerOptions":
                     forEachProperty(property.initializer, (property, propertyName) => {
                         const option = getOptionFromName(propertyName);
+                        Debug.assert(option?.type !== "listOrElement");
                         if (option && (option.isFilePath || option.type === "list" && option.element.isFilePath)) {
                             updatePaths(property);
                         }
diff --git a/src/testRunner/unittests/config/showConfig.ts b/src/testRunner/unittests/config/showConfig.ts
index 8a18303a71764..28830c558bd79 100644
--- a/src/testRunner/unittests/config/showConfig.ts
+++ b/src/testRunner/unittests/config/showConfig.ts
@@ -146,23 +146,7 @@ namespace ts {
                     break;
                 }
                 case "listOrElement": {
-                    if (option.isTSConfigOnly) {
-                        args = ["-p", "tsconfig.json"];
-                        if(option.element.type === "string"){
-                            optionValue = { [option.name]: "someString" };
-                        }
-                        else{
-                            optionValue = { [option.name]: [] };
-                        }
-                    }
-                    else {
-                        if(option.element.type === "string"){
-                            args = [`--${option.name}`, "someString"];
-                        }
-                        else{
-                            args = [`--${option.name}`];
-                        }
-                    }
+                    Debug.fail();
                     break;
                 }
                 case "string": {

From f85c7720fd2a504818d1cf03944d0474754c2c22 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 28 Nov 2022 10:50:22 -0800
Subject: [PATCH 05/12] Fixed formatting and edited a test

---
 src/compiler/builder.ts                       |   2 +-
 src/compiler/commandLineParser.ts             | 372 +++++++++---------
 src/executeCommandLine/executeCommandLine.ts  |  76 ++--
 src/services/getEditsForFileRename.ts         |  38 +-
 .../config/configurationExtension.ts          |  86 ++--
 src/testRunner/unittests/config/showConfig.ts |   8 +-
 .../unittests/tsbuildWatch/programUpdates.ts  |  77 ++--
 .../works-with-extended-source-files.js       |  68 +---
 8 files changed, 340 insertions(+), 387 deletions(-)

diff --git a/src/compiler/builder.ts b/src/compiler/builder.ts
index 5dc915d152e7e..5f06711031448 100644
--- a/src/compiler/builder.ts
+++ b/src/compiler/builder.ts
@@ -1116,7 +1116,7 @@ function getBuildInfo(state: BuilderProgramState, getCanonicalFileName: GetCanon
 
 function convertToReusableCompilerOptionValue(option: CommandLineOption | undefined, value: CompilerOptionsValue, relativeToBuildInfo: (path: string) => string) {
     if (option) {
-            Debug.assert(option.type !== "listOrElement");
+        Debug.assert(option.type !== "listOrElement");
         if (option.type === "list") {
             const values = value as readonly (string | number)[];
             if (option.element.isFilePath && values.length) {
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index e72ad522cedd3..4853e3b876bbf 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1751,9 +1751,9 @@ function parseOptionValue(
                         i++;
                     }
                     break;
-                    case "listOrElement":
-                        Debug.fail("listOrElement not supported here");
-                        break;
+                case "listOrElement":
+                    Debug.fail("listOrElement not supported here");
+                    break;
                 // If not a primitive, the possible types are specified in what is effectively a map of options.
                 default:
                     options[opt.name] = parseCustomTypeOption(opt as CommandLineOptionOfCustomType, args[i], errors);
@@ -1994,91 +1994,91 @@ function getCommandLineTypeAcquisitionMap() {
     return commandLineTypeAcquisitionMapCache || (commandLineTypeAcquisitionMapCache = commandLineOptionsToMap(typeAcquisitionDeclarations));
 }
 
-    const extendsOptionDeclaration: CommandLineOptionOfListType = {
+const extendsOptionDeclaration: CommandLineOptionOfListType = {
+    name: "extends",
+    type: "listOrElement",
+    element: {
         name: "extends",
-        type: "listOrElement",
-        element: {
-            name: "extends",
-            type: "string"
-        },
-        category: Diagnostics.File_Management,
-    };
-    let _tsconfigRootOptions: TsConfigOnlyOption;
-    function getTsconfigRootOptionsMap() {
-        if (_tsconfigRootOptions === undefined) {
-            _tsconfigRootOptions = {
-                name: undefined!, // should never be needed since this is root
-                type: "object",
-                elementOptions: commandLineOptionsToMap([
-                    {
-                        name: "compilerOptions",
-                        type: "object",
-                        elementOptions: getCommandLineCompilerOptionsMap(),
-                        extraKeyDiagnostics: compilerOptionsDidYouMeanDiagnostics,
-                    },
-                    {
-                        name: "watchOptions",
-                        type: "object",
-                        elementOptions: getCommandLineWatchOptionsMap(),
-                        extraKeyDiagnostics: watchOptionsDidYouMeanDiagnostics,
-                    },
-                    {
-                        name: "typingOptions",
-                        type: "object",
-                        elementOptions: getCommandLineTypeAcquisitionMap(),
-                        extraKeyDiagnostics: typeAcquisitionDidYouMeanDiagnostics,
-                    },
-                    {
-                        name: "typeAcquisition",
-                        type: "object",
-                        elementOptions: getCommandLineTypeAcquisitionMap(),
-                        extraKeyDiagnostics: typeAcquisitionDidYouMeanDiagnostics
-                    },
-                    extendsOptionDeclaration,
-                    {
+        type: "string"
+    },
+    category: Diagnostics.File_Management,
+};
+let _tsconfigRootOptions: TsConfigOnlyOption;
+function getTsconfigRootOptionsMap() {
+    if (_tsconfigRootOptions === undefined) {
+        _tsconfigRootOptions = {
+            name: undefined!, // should never be needed since this is root
+            type: "object",
+            elementOptions: commandLineOptionsToMap([
+                {
+                    name: "compilerOptions",
+                    type: "object",
+                    elementOptions: getCommandLineCompilerOptionsMap(),
+                    extraKeyDiagnostics: compilerOptionsDidYouMeanDiagnostics,
+                },
+                {
+                    name: "watchOptions",
+                    type: "object",
+                    elementOptions: getCommandLineWatchOptionsMap(),
+                    extraKeyDiagnostics: watchOptionsDidYouMeanDiagnostics,
+                },
+                {
+                    name: "typingOptions",
+                    type: "object",
+                    elementOptions: getCommandLineTypeAcquisitionMap(),
+                    extraKeyDiagnostics: typeAcquisitionDidYouMeanDiagnostics,
+                },
+                {
+                    name: "typeAcquisition",
+                    type: "object",
+                    elementOptions: getCommandLineTypeAcquisitionMap(),
+                    extraKeyDiagnostics: typeAcquisitionDidYouMeanDiagnostics
+                },
+                extendsOptionDeclaration,
+                {
+                    name: "references",
+                    type: "list",
+                    element: {
                         name: "references",
-                        type: "list",
-                        element: {
-                            name: "references",
-                            type: "object"
-                        },
-                        category: Diagnostics.Projects,
+                        type: "object"
                     },
-                    {
+                    category: Diagnostics.Projects,
+                },
+                {
+                    name: "files",
+                    type: "list",
+                    element: {
                         name: "files",
-                        type: "list",
-                        element: {
-                            name: "files",
-                            type: "string"
-                        },
-                        category: Diagnostics.File_Management,
+                        type: "string"
                     },
-                    {
+                    category: Diagnostics.File_Management,
+                },
+                {
+                    name: "include",
+                    type: "list",
+                    element: {
                         name: "include",
-                        type: "list",
-                        element: {
-                            name: "include",
-                            type: "string"
-                        },
-                        category: Diagnostics.File_Management,
-                        defaultValueDescription: Diagnostics.if_files_is_specified_otherwise_Asterisk_Asterisk_Slash_Asterisk
+                        type: "string"
                     },
-                    {
+                    category: Diagnostics.File_Management,
+                    defaultValueDescription: Diagnostics.if_files_is_specified_otherwise_Asterisk_Asterisk_Slash_Asterisk
+                },
+                {
+                    name: "exclude",
+                    type: "list",
+                    element: {
                         name: "exclude",
-                        type: "list",
-                        element: {
-                            name: "exclude",
-                            type: "string"
-                        },
-                        category: Diagnostics.File_Management,
-                        defaultValueDescription: Diagnostics.node_modules_bower_components_jspm_packages_plus_the_value_of_outDir_if_one_is_specified
+                        type: "string"
                     },
-                    compileOnSaveCommandLineOption
-                ])
-            };
-        }
-        return _tsconfigRootOptions;
+                    category: Diagnostics.File_Management,
+                    defaultValueDescription: Diagnostics.node_modules_bower_components_jspm_packages_plus_the_value_of_outDir_if_one_is_specified
+                },
+                compileOnSaveCommandLineOption
+            ])
+        };
     }
+    return _tsconfigRootOptions;
+}
 
 /** @internal */
 export interface JsonConversionNotifier {
@@ -2529,7 +2529,7 @@ function serializeOptionBaseObject(
             const value = options[name] as CompilerOptionsValue;
             const optionDefinition = optionsNameMap.get(name.toLowerCase());
             if (optionDefinition) {
-                    Debug.assert(optionDefinition.type !== "listOrElement");
+                Debug.assert(optionDefinition.type !== "listOrElement");
                 const customTypeMap = getCustomTypeMapOfCommandLineOption(optionDefinition);
                 if (!customTypeMap) {
                     // There is no map associated with this compiler option then use the value as-is
@@ -3002,15 +3002,15 @@ function isSuccessfulParsedTsconfig(value: ParsedTsconfig) {
     return !!value.options;
 }
 
-    interface ExtendsResult {
-        options: CompilerOptions;
-        watchOptions?: WatchOptions;
-        include?: string[];
-        exclude?: string[];
-        files?: string[];
-        compileOnSave?: boolean;
-        extendedSourceFiles?: Set<string>
-    }
+interface ExtendsResult {
+    options: CompilerOptions;
+    watchOptions?: WatchOptions;
+    include?: string[];
+    exclude?: string[];
+    files?: string[];
+    compileOnSave?: boolean;
+    extendedSourceFiles?: Set<string>
+}
 /**
  * This *just* extracts options/include/exclude/files out of a config file.
  * It does *not* resolve the included files.
@@ -3037,63 +3037,63 @@ function parseConfig(
         parseOwnConfigOfJson(json, host, basePath, configFileName, errors) :
         parseOwnConfigOfJsonSourceFile(sourceFile!, host, basePath, configFileName, errors);
 
-        if (ownConfig.options?.paths) {
-            // If we end up needing to resolve relative paths from 'paths' relative to
-            // the config file location, we'll need to know where that config file was.
-            // Since 'paths' can be inherited from an extended config in another directory,
-            // we wouldn't know which directory to use unless we store it here.
-            ownConfig.options.pathsBasePath = basePath;
-        }
-        if (ownConfig.extendedConfigPath) {
-            // copy the resolution stack so it is never reused between branches in potential diamond-problem scenarios.
-            resolutionStack = resolutionStack.concat([resolvedPath]);
-            const result: ExtendsResult = { options:{} };
-            if (isString(ownConfig.extendedConfigPath)) {
-                applyExtendedConfig(result, ownConfig.extendedConfigPath);
-            }
-            else {
-                ownConfig.extendedConfigPath.forEach(extendedConfigPath => applyExtendedConfig(result, extendedConfigPath));
-            }
-            if (!ownConfig.raw.include && result.include) ownConfig.raw.include = result.include;
-            if (!ownConfig.raw.exclude && result.exclude) ownConfig.raw.exclude = result.exclude;
-            if (!ownConfig.raw.files && result.files) ownConfig.raw.files = result.files;
-            if (ownConfig.raw.compileOnSave === undefined && result.compileOnSave) ownConfig.raw.compileOnSave = result.compileOnSave;
-            if (sourceFile && result.extendedSourceFiles) sourceFile.extendedSourceFiles = arrayFrom(result.extendedSourceFiles.keys());
-
-            ownConfig.options = assign(result.options, ownConfig.options);
-            ownConfig.watchOptions = ownConfig.watchOptions && result.watchOptions ?
-                assign(result.watchOptions, ownConfig.watchOptions) :
-                ownConfig.watchOptions || result.watchOptions;
-        }
-        return ownConfig;
-
-        function applyExtendedConfig(result: ExtendsResult, extendedConfigPath: string){
-            const extendedConfig = getExtendedConfig(sourceFile, extendedConfigPath, host, resolutionStack, errors, extendedConfigCache, result);
-            if (extendedConfig && isSuccessfulParsedTsconfig(extendedConfig)) {
-                const extendsRaw = extendedConfig.raw;
-                let relativeDifference: string | undefined ;
-                const setPropertyInResultIfNotUndefined = (propertyName: "include" | "exclude" | "files") => {
-                    if (extendsRaw[propertyName]) {
-                        result[propertyName] = map(extendsRaw[propertyName], (path: string) => isRootedDiskPath(path) ? path : combinePaths(
-                            relativeDifference ||= convertToRelativePath(getDirectoryPath(extendedConfigPath), basePath, createGetCanonicalFileName(host.useCaseSensitiveFileNames)),
-                            path
-                        ));
-                    }
-                };
-                setPropertyInResultIfNotUndefined("include");
-                setPropertyInResultIfNotUndefined("exclude");
-                setPropertyInResultIfNotUndefined("files");
-                if (extendsRaw.compileOnSave !== undefined) {
-                    result.compileOnSave = extendsRaw.compileOnSave;
+    if (ownConfig.options?.paths) {
+        // If we end up needing to resolve relative paths from 'paths' relative to
+        // the config file location, we'll need to know where that config file was.
+        // Since 'paths' can be inherited from an extended config in another directory,
+        // we wouldn't know which directory to use unless we store it here.
+        ownConfig.options.pathsBasePath = basePath;
+    }
+    if (ownConfig.extendedConfigPath) {
+        // copy the resolution stack so it is never reused between branches in potential diamond-problem scenarios.
+        resolutionStack = resolutionStack.concat([resolvedPath]);
+        const result: ExtendsResult = { options:{} };
+        if (isString(ownConfig.extendedConfigPath)) {
+            applyExtendedConfig(result, ownConfig.extendedConfigPath);
+        }
+        else {
+            ownConfig.extendedConfigPath.forEach(extendedConfigPath => applyExtendedConfig(result, extendedConfigPath));
+        }
+        if (!ownConfig.raw.include && result.include) ownConfig.raw.include = result.include;
+        if (!ownConfig.raw.exclude && result.exclude) ownConfig.raw.exclude = result.exclude;
+        if (!ownConfig.raw.files && result.files) ownConfig.raw.files = result.files;
+        if (ownConfig.raw.compileOnSave === undefined && result.compileOnSave) ownConfig.raw.compileOnSave = result.compileOnSave;
+        if (sourceFile && result.extendedSourceFiles) sourceFile.extendedSourceFiles = arrayFrom(result.extendedSourceFiles.keys());
+
+        ownConfig.options = assign(result.options, ownConfig.options);
+        ownConfig.watchOptions = ownConfig.watchOptions && result.watchOptions ?
+            assign(result.watchOptions, ownConfig.watchOptions) :
+            ownConfig.watchOptions || result.watchOptions;
+        }
+    return ownConfig;
+
+    function applyExtendedConfig(result: ExtendsResult, extendedConfigPath: string){
+        const extendedConfig = getExtendedConfig(sourceFile, extendedConfigPath, host, resolutionStack, errors, extendedConfigCache, result);
+        if (extendedConfig && isSuccessfulParsedTsconfig(extendedConfig)) {
+            const extendsRaw = extendedConfig.raw;
+            let relativeDifference: string | undefined ;
+            const setPropertyInResultIfNotUndefined = (propertyName: "include" | "exclude" | "files") => {
+                if (extendsRaw[propertyName]) {
+                    result[propertyName] = map(extendsRaw[propertyName], (path: string) => isRootedDiskPath(path) ? path : combinePaths(
+                        relativeDifference ||= convertToRelativePath(getDirectoryPath(extendedConfigPath), basePath, createGetCanonicalFileName(host.useCaseSensitiveFileNames)),
+                        path
+                    ));
                 }
-                assign(result.options, extendedConfig.options);
-                result.watchOptions = result.watchOptions && extendedConfig.watchOptions ?
-                    assign({}, result.watchOptions, extendedConfig.watchOptions) :
-                    result.watchOptions || extendedConfig.watchOptions;
-                // TODO extend type typeAcquisition
+            };
+            setPropertyInResultIfNotUndefined("include");
+            setPropertyInResultIfNotUndefined("exclude");
+            setPropertyInResultIfNotUndefined("files");
+            if (extendsRaw.compileOnSave !== undefined) {
+                result.compileOnSave = extendsRaw.compileOnSave;
             }
+            assign(result.options, extendedConfig.options);
+            result.watchOptions = result.watchOptions && extendedConfig.watchOptions ?
+                assign({}, result.watchOptions, extendedConfig.watchOptions) :
+                result.watchOptions || extendedConfig.watchOptions;
+            // TODO extend type typeAcquisition
         }
     }
+}
 
 function parseOwnConfigOfJson(
     json: any,
@@ -3120,22 +3120,22 @@ function parseOwnConfigOfJson(
         }
         else {
             const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
-                if (isString(json.extends)) {
-                    extendedConfigPath = getExtendsConfigPath(json.extends, host, newBase, errors, createCompilerDiagnostic);
+            if (isString(json.extends)) {
+                extendedConfigPath = getExtendsConfigPath(json.extends, host, newBase, errors, createCompilerDiagnostic);
+            }
+            else {
+                extendedConfigPath = [];
+                for (const fileName of json.extends as unknown[]) {
+                    if (isString(fileName)) {
+                        extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(fileName, host, newBase, errors, createCompilerDiagnostic));
                 }
-                else {
-                    extendedConfigPath = [];
-                    for (const fileName of json.extends as unknown[]) {
-                        if (isString(fileName)) {
-                            extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(fileName, host, newBase, errors, createCompilerDiagnostic));
-                    }
-                        else {
-                            errors.push(createCompilerDiagnostic(Diagnostics.Compiler_option_0_requires_a_value_of_type_1, "extends", getCompilerOptionValueTypeString(extendsOptionDeclaration.element)));
-                        }
+                    else {
+                        errors.push(createCompilerDiagnostic(Diagnostics.Compiler_option_0_requires_a_value_of_type_1, "extends", getCompilerOptionValueTypeString(extendsOptionDeclaration.element)));
                     }
                 }
             }
         }
+    }
     return { raw: json, options, watchOptions, typeAcquisition, extendedConfigPath };
 }
 
@@ -3175,37 +3175,37 @@ function parseOwnConfigOfJsonSourceFile(
             currentOption[option.name] = normalizeOptionValue(option, basePath, value);
         },
         onSetValidOptionKeyValueInRoot(key: string, _keyNode: PropertyName, value: CompilerOptionsValue, valueNode: Expression) {
-                switch (key) {
-                    case "extends":
-                        const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
-                            if (isString(value)) {
-                            extendedConfigPath = getExtendsConfigPath(
-                                value,
-                                host,
-                                newBase,
-                                errors,
-                                (message, arg0) =>
-                                    createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
-                            );
-                            }
-                            else {
-                                extendedConfigPath = [];
-                                for (let index = 0; index < (value as unknown[]).length; index++) {
-                                    const fileName = (value as unknown[])[index];
-                                    if (isString(fileName)) {
-                                        extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(
-                                            fileName,
-                                            host,
-                                            newBase,
-                                            errors,
-                                            (message, arg0) =>
-                                                createDiagnosticForNodeInSourceFile(sourceFile, (valueNode as ArrayLiteralExpression).elements[index], message, arg0)
-                                        ));
-                                    }
+            switch (key) {
+                case "extends":
+                    const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
+                        if (isString(value)) {
+                        extendedConfigPath = getExtendsConfigPath(
+                            value,
+                            host,
+                            newBase,
+                            errors,
+                            (message, arg0) =>
+                                createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
+                        );
+                        }
+                        else {
+                            extendedConfigPath = [];
+                            for (let index = 0; index < (value as unknown[]).length; index++) {
+                                const fileName = (value as unknown[])[index];
+                                if (isString(fileName)) {
+                                    extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(
+                                        fileName,
+                                        host,
+                                        newBase,
+                                        errors,
+                                        (message, arg0) =>
+                                            createDiagnosticForNodeInSourceFile(sourceFile, (valueNode as ArrayLiteralExpression).elements[index], message, arg0)
+                                    ));
                                 }
                             }
-                        return;
-                }
+                        }
+                    return;
+            }
         },
         onSetUnknownOptionKeyValueInRoot(key: string, keyNode: PropertyName, _value: CompilerOptionsValue, _valueNode: Expression) {
             if (key === "excludes") {
@@ -3846,9 +3846,9 @@ function getOptionValueWithEmptyStrings(value: any, option: CommandLineOption):
             return typeof value === "number" ? value : "";
         case "boolean":
             return typeof value === "boolean" ? value : "";
-            case "listOrElement":
-                if (!isArray(value)) return getOptionValueWithEmptyStrings(value, option.element);
-                // fall through to list
+        case "listOrElement":
+            if (!isArray(value)) return getOptionValueWithEmptyStrings(value, option.element);
+            // fall through to list
         case "list":
             const elementType = option.element;
             return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, elementType)) : "";
@@ -3873,8 +3873,8 @@ function getDefaultValueForOption(option: CommandLineOption): {} {
             return option.isFilePath ? `./${defaultValue && typeof defaultValue === "string" ? defaultValue : ""}` : "";
         case "list":
             return [];
-            case "listOrElement":
-                return getDefaultValueForOption(option.element);
+        case "listOrElement":
+            return getDefaultValueForOption(option.element);
         case "object":
             return {};
         default:
diff --git a/src/executeCommandLine/executeCommandLine.ts b/src/executeCommandLine/executeCommandLine.ts
index 06f01d1463067..4c45f09da7507 100644
--- a/src/executeCommandLine/executeCommandLine.ts
+++ b/src/executeCommandLine/executeCommandLine.ts
@@ -177,16 +177,16 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
     // name and description
     const name = getDisplayNameTextOfOption(option);
 
-        // value type and possible value
-        const valueCandidates = getValueCandidate(option);
-        const defaultValueDescription =
-            typeof option.defaultValueDescription === "object"
-                ? getDiagnosticText(option.defaultValueDescription)
-                : formatDefaultValue(
-                    option.defaultValueDescription,
-                    option.type === "list" || option.type === "listOrElement" ? option.element.type : option.type
-                );
-        const terminalWidth = sys.getWidthOfTerminal?.() ?? 0;
+    // value type and possible value
+    const valueCandidates = getValueCandidate(option);
+    const defaultValueDescription =
+        typeof option.defaultValueDescription === "object"
+            ? getDiagnosticText(option.defaultValueDescription)
+            : formatDefaultValue(
+                option.defaultValueDescription,
+                option.type === "list" || option.type === "listOrElement" ? option.element.type : option.type
+            );
+    const terminalWidth = sys.getWidthOfTerminal?.() ?? 0;
 
     // Note: child_process might return `terminalWidth` as undefined.
     if (terminalWidth >= 80) {
@@ -295,7 +295,7 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
         };
 
         function getValueType(option: CommandLineOption) {
-                Debug.assert(option.type !== "listOrElement");
+            Debug.assert(option.type !== "listOrElement");
             switch (option.type) {
                 case "string":
                 case "number":
@@ -308,34 +308,34 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
             }
         }
 
-            function getPossibleValues(option: CommandLineOption) {
-                let possibleValues: string;
-                switch (option.type) {
-                    case "string":
-                    case "number":
-                    case "boolean":
-                        possibleValues = option.type;
-                        break;
-                    case "list":
-                    case "listOrElement":
-                        possibleValues = getPossibleValues(option.element);
-                        break;
-                    case "object":
-                        possibleValues = "";
-                        break;
-                    default:
-                        // ESMap<string, number | string>
-                        // Group synonyms: es6/es2015
-                        const inverted: { [value: string]: string[] } = {};
-                        option.type.forEach((value, name) => {
-                            (inverted[value] ||= []).push(name);
-                        });
-                        return getEntries(inverted)
-                            .map(([, synonyms]) => synonyms.join("/"))
-                            .join(", ");
-                }
-                return possibleValues;
+        function getPossibleValues(option: CommandLineOption) {
+            let possibleValues: string;
+            switch (option.type) {
+                case "string":
+                case "number":
+                case "boolean":
+                    possibleValues = option.type;
+                    break;
+                case "list":
+                case "listOrElement":
+                    possibleValues = getPossibleValues(option.element);
+                    break;
+                case "object":
+                    possibleValues = "";
+                    break;
+                default:
+                    // ESMap<string, number | string>
+                    // Group synonyms: es6/es2015
+                    const inverted: { [value: string]: string[] } = {};
+                    option.type.forEach((value, name) => {
+                        (inverted[value] ||= []).push(name);
+                    });
+                    return getEntries(inverted)
+                        .map(([, synonyms]) => synonyms.join("/"))
+                        .join(", ");
             }
+            return possibleValues;
+        }
         }
     }
 
diff --git a/src/services/getEditsForFileRename.ts b/src/services/getEditsForFileRename.ts
index 522f23b2963ba..2580db97c452f 100644
--- a/src/services/getEditsForFileRename.ts
+++ b/src/services/getEditsForFileRename.ts
@@ -87,25 +87,25 @@ function updateTsconfigFiles(program: Program, changeTracker: textChanges.Change
                 }
                 return;
             }
-                case "compilerOptions":
-                    forEachProperty(property.initializer, (property, propertyName) => {
-                        const option = getOptionFromName(propertyName);
-                        Debug.assert(option?.type !== "listOrElement");
-                        if (option && (option.isFilePath || option.type === "list" && option.element.isFilePath)) {
-                            updatePaths(property);
-                        }
-                        else if (propertyName === "paths") {
-                            forEachProperty(property.initializer, (pathsProperty) => {
-                                if (!isArrayLiteralExpression(pathsProperty.initializer)) return;
-                                for (const e of pathsProperty.initializer.elements) {
-                                    tryUpdateString(e);
-                                }
-                            });
-                        }
-                    });
-                    return;
-            }
-        });
+            case "compilerOptions":
+                forEachProperty(property.initializer, (property, propertyName) => {
+                    const option = getOptionFromName(propertyName);
+                    Debug.assert(option?.type !== "listOrElement");
+                    if (option && (option.isFilePath || option.type === "list" && option.element.isFilePath)) {
+                        updatePaths(property);
+                    }
+                    else if (propertyName === "paths") {
+                        forEachProperty(property.initializer, (pathsProperty) => {
+                            if (!isArrayLiteralExpression(pathsProperty.initializer)) return;
+                            for (const e of pathsProperty.initializer.elements) {
+                                tryUpdateString(e);
+                            }
+                        });
+                    }
+                });
+                return;
+        }
+    });
 
     function updatePaths(property: PropertyAssignment): boolean {
         const elements = isArrayLiteralExpression(property.initializer) ? property.initializer.elements : [property.initializer];
diff --git a/src/testRunner/unittests/config/configurationExtension.ts b/src/testRunner/unittests/config/configurationExtension.ts
index da2c8b5689ee5..8677621a6e514 100644
--- a/src/testRunner/unittests/config/configurationExtension.ts
+++ b/src/testRunner/unittests/config/configurationExtension.ts
@@ -378,54 +378,54 @@ describe("unittests:: config:: configurationExtension", () => {
                 testSuccess("can lookup via an implicit tsconfig in a package-relative directory with extension", "tsconfig.extendsBoxImpliedPath.json", { strict: true }, [ts.combinePaths(basePath, "main.ts")]);
             });
 
-                it("adds extendedSourceFiles only once", () => {
-                    const sourceFile = ts.readJsonConfigFile("configs/fourth.json", (path) => host.readFile(path));
-                    const dir = ts.combinePaths(basePath, "configs");
-                    const expected = [
-                        ts.combinePaths(dir, "third.json"),
-                        ts.combinePaths(dir, "second.json"),
-                        ts.combinePaths(dir, "base.json"),
-                    ];
-                    ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "fourth.json");
-                    assert.deepEqual(sourceFile.extendedSourceFiles, expected);
-                    ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "fourth.json");
-                    assert.deepEqual(sourceFile.extendedSourceFiles, expected);
-                });
+            it("adds extendedSourceFiles only once", () => {
+                const sourceFile = ts.readJsonConfigFile("configs/fourth.json", (path) => host.readFile(path));
+                const dir = ts.combinePaths(basePath, "configs");
+                const expected = [
+                    ts.combinePaths(dir, "third.json"),
+                    ts.combinePaths(dir, "second.json"),
+                    ts.combinePaths(dir, "base.json"),
+                ];
+                ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "fourth.json");
+                assert.deepEqual(sourceFile.extendedSourceFiles, expected);
+                ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "fourth.json");
+                assert.deepEqual(sourceFile.extendedSourceFiles, expected);
             });
+        });
 
-            describe(testName, () => {
-                it("adds extendedSourceFiles from an array only once", () => {
-                    const sourceFile = ts.readJsonConfigFile("configs/extendsArrayFifth.json", (path) => host.readFile(path));
-                    const dir = ts.combinePaths(basePath, "configs");
-                    const expected = [
-                        ts.combinePaths(dir, "extendsArrayFirst.json"),
-                        ts.combinePaths(dir, "extendsArraySecond.json"),
-                        ts.combinePaths(dir, "extendsArrayThird.json"),
-                        ts.combinePaths(dir, "extendsArrayFourth.json"),
-                    ];
-                    ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "extendsArrayFifth.json");
-                    assert.deepEqual(sourceFile.extendedSourceFiles, expected);
-                    ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "extendsArrayFifth.json");
-                    assert.deepEqual(sourceFile.extendedSourceFiles, expected);
-                });
+        describe(testName, () => {
+            it("adds extendedSourceFiles from an array only once", () => {
+                const sourceFile = ts.readJsonConfigFile("configs/extendsArrayFifth.json", (path) => host.readFile(path));
+                const dir = ts.combinePaths(basePath, "configs");
+                const expected = [
+                    ts.combinePaths(dir, "extendsArrayFirst.json"),
+                    ts.combinePaths(dir, "extendsArraySecond.json"),
+                    ts.combinePaths(dir, "extendsArrayThird.json"),
+                    ts.combinePaths(dir, "extendsArrayFourth.json"),
+                ];
+                ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "extendsArrayFifth.json");
+                assert.deepEqual(sourceFile.extendedSourceFiles, expected);
+                ts.parseJsonSourceFileConfigFileContent(sourceFile, host, dir, {}, "extendsArrayFifth.json");
+                assert.deepEqual(sourceFile.extendedSourceFiles, expected);
+            });
 
-                testSuccess("can overwrite top-level compilerOptions", "configs/extendsArrayFifth.json", {
-                    allowJs: true,
-                    noImplicitAny: false,
-                    strictNullChecks: false,
-                    module: ts.ModuleKind.System
-                }, []);
+            testSuccess("can overwrite top-level compilerOptions", "configs/extendsArrayFifth.json", {
+                allowJs: true,
+                noImplicitAny: false,
+                strictNullChecks: false,
+                module: ts.ModuleKind.System
+            }, []);
 
-                testFailure("can report missing configurations", "extendsArrayFails.json", [{
-                    code: 6053,
-                    messageText: `File './missingFile' not found.`
-                }]);
+            testFailure("can report missing configurations", "extendsArrayFails.json", [{
+                code: 6053,
+                messageText: `File './missingFile' not found.`
+            }]);
 
-                testFailure("can error when 'extends' is not a string or Array2", "extendsArrayFails2.json", [{
-                    code: 5024,
-                    messageText: `Compiler option 'extends' requires a value of type string.`
-                }]);
-            });
+            testFailure("can error when 'extends' is not a string or Array2", "extendsArrayFails2.json", [{
+                code: 5024,
+                messageText: `Compiler option 'extends' requires a value of type string.`
+            }]);
         });
     });
+});
 
diff --git a/src/testRunner/unittests/config/showConfig.ts b/src/testRunner/unittests/config/showConfig.ts
index 5c81a9451296f..a815ec7d7750c 100644
--- a/src/testRunner/unittests/config/showConfig.ts
+++ b/src/testRunner/unittests/config/showConfig.ts
@@ -147,10 +147,10 @@ describe("unittests:: config:: showConfig", () => {
                 }
                 break;
             }
-                case "listOrElement": {
-                    ts.Debug.fail();
-                    break;
-                }
+            case "listOrElement": {
+                ts.Debug.fail();
+                break;
+            }
             case "string": {
                 if (option.isTSConfigOnly) {
                     args = ["-p", "tsconfig.json"];
diff --git a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
index 2cecfdc689aab..21b395b20710c 100644
--- a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
+++ b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
@@ -618,44 +618,44 @@ export function someFn() { }`),
                     files: [otherFile.path]
                 })
             };
-                const otherFile2: File = {
-                    path: "/a/b/other2.ts",
-                    content: "let k = 0;",
-                };
-                const extendsConfigFile1: File = {
-                    path: "/a/b/extendsConfig1.tsconfig.json",
-                    content: JSON.stringify({
-                        compilerOptions: {
-                            composite: true,
-                        }
-                    })
-                };
-                const extendsConfigFile2: File = {
-                    path: "/a/b/extendsConfig2.tsconfig.json",
-                    content: JSON.stringify({
-                        compilerOptions: {
-                            strictNullChecks: false,
-                        }
-                    })
-                };
-                const extendsConfigFile3: File = {
-                    path: "/a/b/extendsConfig3.tsconfig.json",
-                    content: JSON.stringify({
-                        compilerOptions: {
-                            noImplicitAny: true,
-                        }
-                    })
-                };
-                const project3Config: File = {
-                    path: "/a/b/project3.tsconfig.json",
-                    content: JSON.stringify({
-                        extends: ["./extendsConfig1.tsconfig.json", "./extendsConfig2.tsconfig.json", "./extendsConfig3.tsconfig.json"],
-                        compilerOptions: {
-                            composite: false,
-                        },
-                        files: [otherFile2.path]
-                    })
-                };
+            const otherFile2: File = {
+                path: "/a/b/other2.ts",
+                content: "let k = 0;",
+            };
+            const extendsConfigFile1: File = {
+                path: "/a/b/extendsConfig1.tsconfig.json",
+                content: JSON.stringify({
+                    compilerOptions: {
+                        composite: true,
+                    }
+                })
+            };
+            const extendsConfigFile2: File = {
+                path: "/a/b/extendsConfig2.tsconfig.json",
+                content: JSON.stringify({
+                    compilerOptions: {
+                        strictNullChecks: false,
+                    }
+                })
+            };
+            const extendsConfigFile3: File = {
+                path: "/a/b/extendsConfig3.tsconfig.json",
+                content: JSON.stringify({
+                    compilerOptions: {
+                        noImplicitAny: true,
+                    }
+                })
+            };
+            const project3Config: File = {
+                path: "/a/b/project3.tsconfig.json",
+                content: JSON.stringify({
+                    extends: ["./extendsConfig1.tsconfig.json", "./extendsConfig2.tsconfig.json", "./extendsConfig3.tsconfig.json"],
+                    compilerOptions: {
+                        composite: false,
+                    },
+                    files: [otherFile2.path]
+                })
+            };
             return createWatchedSystem([
                 libFile,
                 alphaExtendedConfigFile, project1Config, commonFile1, commonFile2,
@@ -727,6 +727,7 @@ export function someFn() { }`),
                 caption: "Modify project 3",
                 change: sys => sys.writeFile("/a/b/project3.tsconfig.json", JSON.stringify({
                     extends: ["./extendsConfig1.tsconfig.json", "./extendsConfig2.tsconfig.json"],
+                    compilerOptions: { composite: false },
                     files: ["/a/b/other2.ts"]
                 })),
                 timeouts: sys => { // Build project3
diff --git a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
index e33f0ae70a6d0..38aa01cf7af96 100644
--- a/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
+++ b/tests/baselines/reference/tsbuildWatch/programUpdates/works-with-extended-source-files.js
@@ -1014,23 +1014,25 @@ Change:: Modify project 3
 
 Input::
 //// [/a/b/project3.tsconfig.json]
-{"extends":["./extendsConfig1.tsconfig.json","./extendsConfig2.tsconfig.json"],"files":["/a/b/other2.ts"]}
+{"extends":["./extendsConfig1.tsconfig.json","./extendsConfig2.tsconfig.json"],"compilerOptions":{"composite":false},"files":["/a/b/other2.ts"]}
 
 
 Output::
 >> Screen clear
 [12:03:06 AM] File change detected. Starting incremental compilation...
 
-[12:03:07 AM] Project 'project3.tsconfig.json' is out of date because output file 'project3.tsconfig.tsbuildinfo' does not exist
+[12:03:07 AM] Project 'project3.tsconfig.json' is out of date because output 'other2.js' is older than input 'project3.tsconfig.json'
 
 [12:03:08 AM] Building project '/a/b/project3.tsconfig.json'...
 
-[12:03:16 AM] Found 0 errors. Watching for file changes.
+[12:03:09 AM] Updating unchanged output timestamps of project '/a/b/project3.tsconfig.json'...
+
+[12:03:11 AM] Found 0 errors. Watching for file changes.
 
 
 
 Program root files: ["/a/b/other2.ts"]
-Program options: {"composite":true,"strictNullChecks":true,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
+Program options: {"composite":false,"strictNullChecks":true,"watch":true,"configFilePath":"/a/b/project3.tsconfig.json"}
 Program structureReused: Not
 Program files::
 /a/lib/lib.d.ts
@@ -1072,57 +1074,7 @@ FsWatchesRecursive::
 
 exitCode:: ExitStatus.undefined
 
-//// [/a/b/other2.d.ts]
-declare let k: number;
-
-
-//// [/a/b/project3.tsconfig.tsbuildinfo]
-{"program":{"fileNames":["../lib/lib.d.ts","./other2.ts"],"fileInfos":[{"version":"-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }","affectsGlobalScope":true},{"version":"2287258045-let k = 0;","signature":"3820390125-declare let k: number;\n","affectsGlobalScope":true}],"options":{"composite":true,"strictNullChecks":true},"referencedMap":[],"exportedModulesMap":[],"semanticDiagnosticsPerFile":[2,1],"latestChangedDtsFile":"./other2.d.ts"},"version":"FakeTSVersion"}
-
-//// [/a/b/project3.tsconfig.tsbuildinfo.readable.baseline.txt]
-{
-  "program": {
-    "fileNames": [
-      "../lib/lib.d.ts",
-      "./other2.ts"
-    ],
-    "fileInfos": {
-      "../lib/lib.d.ts": {
-        "original": {
-          "version": "-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }",
-          "affectsGlobalScope": true
-        },
-        "version": "-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }",
-        "signature": "-7698705165-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }",
-        "affectsGlobalScope": true
-      },
-      "./other2.ts": {
-        "original": {
-          "version": "2287258045-let k = 0;",
-          "signature": "3820390125-declare let k: number;\n",
-          "affectsGlobalScope": true
-        },
-        "version": "2287258045-let k = 0;",
-        "signature": "3820390125-declare let k: number;\n",
-        "affectsGlobalScope": true
-      }
-    },
-    "options": {
-      "composite": true,
-      "strictNullChecks": true
-    },
-    "referencedMap": {},
-    "exportedModulesMap": {},
-    "semanticDiagnosticsPerFile": [
-      "./other2.ts",
-      "../lib/lib.d.ts"
-    ],
-    "latestChangedDtsFile": "./other2.d.ts"
-  },
-  "version": "FakeTSVersion",
-  "size": 780
-}
-
+//// [/a/b/other2.js] file changed its modified time
 
 Change:: Delete extendedConfigFile2 and report error
 
@@ -1131,13 +1083,13 @@ Input::
 
 Output::
 >> Screen clear
-[12:03:18 AM] File change detected. Starting incremental compilation...
+[12:03:13 AM] File change detected. Starting incremental compilation...
 
-[12:03:19 AM] Project 'project3.tsconfig.json' is up to date because newest input 'other2.ts' is older than output 'project3.tsconfig.tsbuildinfo'
+[12:03:14 AM] Project 'project3.tsconfig.json' is up to date because newest input 'other2.ts' is older than output 'other2.js'
 
 error TS5083: Cannot read file '/a/b/extendsConfig2.tsconfig.json'.
 
-[12:03:20 AM] Found 1 error. Watching for file changes.
+[12:03:15 AM] Found 1 error. Watching for file changes.
 
 
 

From de792204620386e0db524ecf1db59d60de998f69 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 28 Nov 2022 15:42:21 -0800
Subject: [PATCH 06/12] Resolved errors after a merge conflict

---
 src/compiler/commandLineParser.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 1e0c2c6ecd7c7..52f2241133321 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -3377,7 +3377,7 @@ function getExtendedConfig(
     host: ParseConfigHost,
     resolutionStack: string[],
     errors: Push<Diagnostic>,
-    extendedConfigCache: ESMap<string, ExtendedConfigCacheEntry> | undefined,
+    extendedConfigCache: Map<string, ExtendedConfigCacheEntry> | undefined,
         result: ExtendsResult
 ): ParsedTsconfig | undefined {
     const path = host.useCaseSensitiveFileNames ? extendedConfigPath : toFileNameLowerCase(extendedConfigPath);

From 1b36b57ccff236af22bcd8bb2a77a0933430ac44 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 28 Nov 2022 16:46:35 -0800
Subject: [PATCH 07/12] Added "string | list" type implentation

---
 src/compiler/commandLineParser.ts             | 56 ++++++++++++++-----
 src/compiler/types.ts                         |  4 +-
 src/executeCommandLine/executeCommandLine.ts  |  4 ++
 src/harness/harnessIO.ts                      |  1 +
 src/testRunner/unittests/config/showConfig.ts | 19 +++++++
 5 files changed, 68 insertions(+), 16 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 52f2241133321..a67a6dcb6b5f6 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -103,6 +103,7 @@ import {
     returnTrue,
     ScriptTarget,
     startsWith,
+    stringContains,
     StringLiteral,
     SyntaxKind,
     sys,
@@ -1658,11 +1659,14 @@ export function parseCustomTypeOption(opt: CommandLineOptionOfCustomType, value:
 }
 
 /** @internal */
-export function parseListTypeOption(opt: CommandLineOptionOfListType, value = "", errors: Push<Diagnostic>): (string | number)[] | undefined {
+export function parseListTypeOption(opt: CommandLineOptionOfListType, value = "", errors: Push<Diagnostic>): string | (string | number)[] | undefined {
     value = trimString(value);
     if (startsWith(value, "-")) {
         return undefined;
     }
+    if (opt.type === "string | list" && !stringContains(value, ",")) {
+        return validateJsonOptionValue(opt, value, errors);
+    }
     if (value === "") {
         return [];
     }
@@ -1672,6 +1676,10 @@ export function parseListTypeOption(opt: CommandLineOptionOfListType, value = ""
             return mapDefined(values, v => validateJsonOptionValue(opt.element, parseInt(v), errors));
         case "string":
             return mapDefined(values, v => validateJsonOptionValue(opt.element, v || "", errors));
+        case "boolean":
+        case "object":
+        case "string | list":
+            return Debug.fail(`List of ${opt.element.type} is not yet supported.`);
         default:
             return mapDefined(values, v => parseCustomTypeOption(opt.element as CommandLineOptionOfCustomType, v, errors));
     }
@@ -1843,6 +1851,7 @@ function parseOptionValue(
                     options[opt.name] = validateJsonOptionValue(opt, args[i] || "", errors);
                     i++;
                     break;
+                case "string | list":
                 case "list":
                     const result = parseListTypeOption(opt, args[i], errors);
                     options[opt.name] = result || [];
@@ -2362,7 +2371,7 @@ export function convertToObjectWorker(
                 if (!isDoubleQuotedString(valueExpression)) {
                     errors.push(createDiagnosticForNodeInSourceFile(sourceFile, valueExpression, Diagnostics.String_literal_with_double_quotes_expected));
                 }
-                reportInvalidOptionValue(option && isString(option.type) && option.type !== "string" && (option.type !== "listOrElement" || (isString(option.element.type) && option.element.type !== "string")));
+                reportInvalidOptionValue(option && isString(option.type) && option.type !== "string" && (option.type !== "listOrElement" || (isString(option.element.type) && option.element.type !== "string")) && option.type !== "string | list");
                 const text = (valueExpression as StringLiteral).text;
                     if (option) {
                         Debug.assert(option.type !== "listOrElement" || option.element.type === "string", "Only string or array of string is handled for now");
@@ -2394,7 +2403,7 @@ export function convertToObjectWorker(
                 return validateValue(-Number(((valueExpression as PrefixUnaryExpression).operand as NumericLiteral).text));
 
             case SyntaxKind.ObjectLiteralExpression:
-                reportInvalidOptionValue(option && option.type !== "object" && (option.type !== "listOrElement" || option.element.type !== "object"));
+                reportInvalidOptionValue(option && option.type !== "object" && (option.type !== "listOrElement" || option.element.type !== "object") && option.type !== "string | list");
                 const objectLiteralExpression = valueExpression as ObjectLiteralExpression;
 
                 // Currently having element option declaration in the tsconfig with type "object"
@@ -2472,6 +2481,9 @@ function isCompilerOptionsValue(option: CommandLineOption | undefined, value: an
         if (option.type === "listOrElement") {
             return isArray(value) || isCompilerOptionsValue(option.element, value);
         }
+        if (option.type === "string | list") {
+            return typeof value === "string" || isArray(value);
+        }
         const expectedType = isString(option.type) ? option.type : "string";
         return typeof value === expectedType;
     }
@@ -2576,15 +2588,29 @@ function matchesSpecs(path: string, includeSpecs: readonly string[] | undefined,
 }
 
 function getCustomTypeMapOfCommandLineOption(optionDefinition: CommandLineOption): Map<string, string | number> | undefined {
-    if (optionDefinition.type === "string" || optionDefinition.type === "number" || optionDefinition.type === "boolean" || optionDefinition.type === "object") {
-        // this is of a type CommandLineOptionOfPrimitiveType
-        return undefined;
-    }
-    else if (optionDefinition.type === "list" || optionDefinition.type === "listOrElement") {
-        return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
-    }
-    else {
-        return optionDefinition.type;
+    // if (optionDefinition.type === "string" || optionDefinition.type === "number" || optionDefinition.type === "boolean" || optionDefinition.type === "object") {
+    //     // this is of a type CommandLineOptionOfPrimitiveType
+    //     return undefined;
+    // }
+    // else if (optionDefinition.type === "list" || optionDefinition.type === "listOrElement") {
+    //     return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
+    // }
+    // else {
+    //     return optionDefinition.type;
+    // }
+    switch (optionDefinition.type) {
+        case "string":
+        case "number":
+        case "boolean":
+        case "object":
+        case "string | list":
+            // this is of a type CommandLineOptionOfPrimitiveType
+            return undefined;
+        case "list":
+        case "listOrElement":
+            return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
+        default:
+            return optionDefinition.type;
     }
 }
 
@@ -3495,7 +3521,7 @@ function convertOptionsFromJson(optionsNameMap: Map<string, CommandLineOption>,
 export function convertJsonOption(opt: CommandLineOption, value: any, basePath: string, errors: Push<Diagnostic>): CompilerOptionsValue {
     if (isCompilerOptionsValue(opt, value)) {
         const optType = opt.type;
-        if (optType === "list" && isArray(value)) {
+        if ((optType === "list" || opt.type === "string | list") && isArray(value)) {
             return convertJsonOptionOfListType(opt, value, basePath, errors);
         }
         else if (optType === "listOrElement") {
@@ -3503,7 +3529,7 @@ export function convertJsonOption(opt: CommandLineOption, value: any, basePath:
                 convertJsonOptionOfListType(opt, value, basePath, errors) :
                 convertJsonOption(opt.element, value, basePath, errors);
         }
-        else if (!isString(optType)) {
+        else if (!isString(opt.type)) {
             return convertJsonOptionOfCustomType(opt as CommandLineOptionOfCustomType, value as string, errors);
         }
         const validatedValue = validateJsonOptionValue(opt, value, errors);
@@ -3949,6 +3975,7 @@ function getOptionValueWithEmptyStrings(value: any, option: CommandLineOption):
             if (!isArray(value)) return getOptionValueWithEmptyStrings(value, option.element);
             // fall through to list
         case "list":
+        case "string | list":
             const elementType = option.element;
             return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, elementType)) : "";
         default:
@@ -3968,6 +3995,7 @@ function getDefaultValueForOption(option: CommandLineOption): {} {
         case "boolean":
             return true;
         case "string":
+        case "string | list":
             const defaultValue = option.defaultValueDescription;
             return option.isFilePath ? `./${defaultValue && typeof defaultValue === "string" ? defaultValue : ""}` : "";
         case "list":
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index f9788f96bcbac..4ef984c08321d 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6960,7 +6960,7 @@ export interface CreateProgramOptions {
 /** @internal */
 export interface CommandLineOptionBase {
     name: string;
-    type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | Map<string, number | string> ;    // a value of a primitive type, or an object literal mapping named values to actual values
+    type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | "string | list" | Map<string, number | string> ;    // a value of a primitive type, or an object literal mapping named values to actual values
     isFilePath?: boolean;                                   // True if option value is a path or fileName
     shortName?: string;                                     // A short mnemonic for convenience - for instance, 'h' can be used in place of 'help'
     description?: DiagnosticMessage;                        // The message describing what the command line switch does.
@@ -7030,7 +7030,7 @@ export interface TsConfigOnlyOption extends CommandLineOptionBase {
 
 /** @internal */
 export interface CommandLineOptionOfListType extends CommandLineOptionBase {
-    type: "list" | "listOrElement";
+    type: "list" | "listOrElement" | "string | list";
     element: CommandLineOptionOfCustomType | CommandLineOptionOfStringType | CommandLineOptionOfNumberType | CommandLineOptionOfBooleanType | TsConfigOnlyOption;
     listPreserveFalsyValues?: boolean;
 }
diff --git a/src/executeCommandLine/executeCommandLine.ts b/src/executeCommandLine/executeCommandLine.ts
index 5a2936d8640cf..c2eb86ddbf0e7 100644
--- a/src/executeCommandLine/executeCommandLine.ts
+++ b/src/executeCommandLine/executeCommandLine.ts
@@ -372,6 +372,7 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
                 case "boolean":
                     return getDiagnosticText(Diagnostics.type_Colon);
                 case "list":
+                case "string | list":
                     return getDiagnosticText(Diagnostics.one_or_more_Colon);
                 default:
                     return getDiagnosticText(Diagnostics.one_of_Colon);
@@ -390,6 +391,9 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
                 case "listOrElement":
                     possibleValues = getPossibleValues(option.element);
                     break;
+                case "string | list":
+                    possibleValues = "string";
+                    break;
                 case "object":
                     possibleValues = "";
                     break;
diff --git a/src/harness/harnessIO.ts b/src/harness/harnessIO.ts
index 642e4990385b3..5c1098e3ea681 100644
--- a/src/harness/harnessIO.ts
+++ b/src/harness/harnessIO.ts
@@ -380,6 +380,7 @@ export namespace Compiler {
             }
             // If not a primitive, the possible types are specified in what is effectively a map of options.
             case "list":
+            case "string | list":
                 return ts.parseListTypeOption(option, value, errors);
             default:
                 return ts.parseCustomTypeOption(option as ts.CommandLineOptionOfCustomType, value, errors);
diff --git a/src/testRunner/unittests/config/showConfig.ts b/src/testRunner/unittests/config/showConfig.ts
index a815ec7d7750c..5b8cfc9564fad 100644
--- a/src/testRunner/unittests/config/showConfig.ts
+++ b/src/testRunner/unittests/config/showConfig.ts
@@ -126,6 +126,24 @@ describe("unittests:: config:: showConfig", () => {
         if (option.name === "project") return;
         let args: string[];
         let optionValue: object | undefined;
+        if (option.type === "string | list") {
+            if (option.isTSConfigOnly) {
+                showTSConfigCorrectly(
+                    `Shows tsconfig for single option/${option.name}WithStringValue`,
+                    ["-p", "tsconfig.json"],
+                    isCompilerOptions ?
+                        { compilerOptions: { [option.name]: "someString" } } :
+                        { watchOptions: { [option.name]: "someString" } }
+                );
+            }
+            else {
+                showTSConfigCorrectly(
+                    `Shows tsconfig for single option/${option.name}WithStringValue`,
+                    [`--${option.name}`, "someString"],
+                        /*configJson*/ undefined,
+                );
+            }
+        }
         switch (option.type) {
             case "boolean": {
                 if (option.isTSConfigOnly) {
@@ -137,6 +155,7 @@ describe("unittests:: config:: showConfig", () => {
                 }
                 break;
             }
+            case "string | list":
             case "list": {
                 if (option.isTSConfigOnly) {
                     args = ["-p", "tsconfig.json"];

From 7a214bdbad6e7c36991ec836ef1c9eacbfa2a64a Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Tue, 29 Nov 2022 11:47:00 -0800
Subject: [PATCH 08/12] Removed string | list type implementation

---
 src/compiler/commandLineParser.ts             | 17 +++++------------
 src/compiler/types.ts                         |  4 ++--
 src/executeCommandLine/executeCommandLine.ts  |  4 ----
 src/harness/harnessIO.ts                      |  2 +-
 src/testRunner/unittests/config/showConfig.ts | 19 -------------------
 5 files changed, 8 insertions(+), 38 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index a67a6dcb6b5f6..06bb6d24c1103 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1664,7 +1664,7 @@ export function parseListTypeOption(opt: CommandLineOptionOfListType, value = ""
     if (startsWith(value, "-")) {
         return undefined;
     }
-    if (opt.type === "string | list" && !stringContains(value, ",")) {
+    if (opt.type === "listOrElement" && !stringContains(value, ",")) {
         return validateJsonOptionValue(opt, value, errors);
     }
     if (value === "") {
@@ -1678,7 +1678,7 @@ export function parseListTypeOption(opt: CommandLineOptionOfListType, value = ""
             return mapDefined(values, v => validateJsonOptionValue(opt.element, v || "", errors));
         case "boolean":
         case "object":
-        case "string | list":
+        case "listOrElement":
             return Debug.fail(`List of ${opt.element.type} is not yet supported.`);
         default:
             return mapDefined(values, v => parseCustomTypeOption(opt.element as CommandLineOptionOfCustomType, v, errors));
@@ -1851,7 +1851,6 @@ function parseOptionValue(
                     options[opt.name] = validateJsonOptionValue(opt, args[i] || "", errors);
                     i++;
                     break;
-                case "string | list":
                 case "list":
                     const result = parseListTypeOption(opt, args[i], errors);
                     options[opt.name] = result || [];
@@ -2371,7 +2370,7 @@ export function convertToObjectWorker(
                 if (!isDoubleQuotedString(valueExpression)) {
                     errors.push(createDiagnosticForNodeInSourceFile(sourceFile, valueExpression, Diagnostics.String_literal_with_double_quotes_expected));
                 }
-                reportInvalidOptionValue(option && isString(option.type) && option.type !== "string" && (option.type !== "listOrElement" || (isString(option.element.type) && option.element.type !== "string")) && option.type !== "string | list");
+                reportInvalidOptionValue(option && isString(option.type) && option.type !== "string" && (option.type !== "listOrElement" || (isString(option.element.type) && option.element.type !== "string")));
                 const text = (valueExpression as StringLiteral).text;
                     if (option) {
                         Debug.assert(option.type !== "listOrElement" || option.element.type === "string", "Only string or array of string is handled for now");
@@ -2403,7 +2402,7 @@ export function convertToObjectWorker(
                 return validateValue(-Number(((valueExpression as PrefixUnaryExpression).operand as NumericLiteral).text));
 
             case SyntaxKind.ObjectLiteralExpression:
-                reportInvalidOptionValue(option && option.type !== "object" && (option.type !== "listOrElement" || option.element.type !== "object") && option.type !== "string | list");
+                reportInvalidOptionValue(option && option.type !== "object" && (option.type !== "listOrElement" || option.element.type !== "object"));
                 const objectLiteralExpression = valueExpression as ObjectLiteralExpression;
 
                 // Currently having element option declaration in the tsconfig with type "object"
@@ -2481,9 +2480,6 @@ function isCompilerOptionsValue(option: CommandLineOption | undefined, value: an
         if (option.type === "listOrElement") {
             return isArray(value) || isCompilerOptionsValue(option.element, value);
         }
-        if (option.type === "string | list") {
-            return typeof value === "string" || isArray(value);
-        }
         const expectedType = isString(option.type) ? option.type : "string";
         return typeof value === expectedType;
     }
@@ -2603,7 +2599,6 @@ function getCustomTypeMapOfCommandLineOption(optionDefinition: CommandLineOption
         case "number":
         case "boolean":
         case "object":
-        case "string | list":
             // this is of a type CommandLineOptionOfPrimitiveType
             return undefined;
         case "list":
@@ -3521,7 +3516,7 @@ function convertOptionsFromJson(optionsNameMap: Map<string, CommandLineOption>,
 export function convertJsonOption(opt: CommandLineOption, value: any, basePath: string, errors: Push<Diagnostic>): CompilerOptionsValue {
     if (isCompilerOptionsValue(opt, value)) {
         const optType = opt.type;
-        if ((optType === "list" || opt.type === "string | list") && isArray(value)) {
+        if ((optType === "list") && isArray(value)) {
             return convertJsonOptionOfListType(opt, value, basePath, errors);
         }
         else if (optType === "listOrElement") {
@@ -3975,7 +3970,6 @@ function getOptionValueWithEmptyStrings(value: any, option: CommandLineOption):
             if (!isArray(value)) return getOptionValueWithEmptyStrings(value, option.element);
             // fall through to list
         case "list":
-        case "string | list":
             const elementType = option.element;
             return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, elementType)) : "";
         default:
@@ -3995,7 +3989,6 @@ function getDefaultValueForOption(option: CommandLineOption): {} {
         case "boolean":
             return true;
         case "string":
-        case "string | list":
             const defaultValue = option.defaultValueDescription;
             return option.isFilePath ? `./${defaultValue && typeof defaultValue === "string" ? defaultValue : ""}` : "";
         case "list":
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 4ef984c08321d..f9788f96bcbac 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6960,7 +6960,7 @@ export interface CreateProgramOptions {
 /** @internal */
 export interface CommandLineOptionBase {
     name: string;
-    type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | "string | list" | Map<string, number | string> ;    // a value of a primitive type, or an object literal mapping named values to actual values
+    type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | Map<string, number | string> ;    // a value of a primitive type, or an object literal mapping named values to actual values
     isFilePath?: boolean;                                   // True if option value is a path or fileName
     shortName?: string;                                     // A short mnemonic for convenience - for instance, 'h' can be used in place of 'help'
     description?: DiagnosticMessage;                        // The message describing what the command line switch does.
@@ -7030,7 +7030,7 @@ export interface TsConfigOnlyOption extends CommandLineOptionBase {
 
 /** @internal */
 export interface CommandLineOptionOfListType extends CommandLineOptionBase {
-    type: "list" | "listOrElement" | "string | list";
+    type: "list" | "listOrElement";
     element: CommandLineOptionOfCustomType | CommandLineOptionOfStringType | CommandLineOptionOfNumberType | CommandLineOptionOfBooleanType | TsConfigOnlyOption;
     listPreserveFalsyValues?: boolean;
 }
diff --git a/src/executeCommandLine/executeCommandLine.ts b/src/executeCommandLine/executeCommandLine.ts
index c2eb86ddbf0e7..5a2936d8640cf 100644
--- a/src/executeCommandLine/executeCommandLine.ts
+++ b/src/executeCommandLine/executeCommandLine.ts
@@ -372,7 +372,6 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
                 case "boolean":
                     return getDiagnosticText(Diagnostics.type_Colon);
                 case "list":
-                case "string | list":
                     return getDiagnosticText(Diagnostics.one_or_more_Colon);
                 default:
                     return getDiagnosticText(Diagnostics.one_of_Colon);
@@ -391,9 +390,6 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
                 case "listOrElement":
                     possibleValues = getPossibleValues(option.element);
                     break;
-                case "string | list":
-                    possibleValues = "string";
-                    break;
                 case "object":
                     possibleValues = "";
                     break;
diff --git a/src/harness/harnessIO.ts b/src/harness/harnessIO.ts
index 5c1098e3ea681..4dcfcbca99faa 100644
--- a/src/harness/harnessIO.ts
+++ b/src/harness/harnessIO.ts
@@ -380,7 +380,7 @@ export namespace Compiler {
             }
             // If not a primitive, the possible types are specified in what is effectively a map of options.
             case "list":
-            case "string | list":
+            case "listOrElement":
                 return ts.parseListTypeOption(option, value, errors);
             default:
                 return ts.parseCustomTypeOption(option as ts.CommandLineOptionOfCustomType, value, errors);
diff --git a/src/testRunner/unittests/config/showConfig.ts b/src/testRunner/unittests/config/showConfig.ts
index 5b8cfc9564fad..a815ec7d7750c 100644
--- a/src/testRunner/unittests/config/showConfig.ts
+++ b/src/testRunner/unittests/config/showConfig.ts
@@ -126,24 +126,6 @@ describe("unittests:: config:: showConfig", () => {
         if (option.name === "project") return;
         let args: string[];
         let optionValue: object | undefined;
-        if (option.type === "string | list") {
-            if (option.isTSConfigOnly) {
-                showTSConfigCorrectly(
-                    `Shows tsconfig for single option/${option.name}WithStringValue`,
-                    ["-p", "tsconfig.json"],
-                    isCompilerOptions ?
-                        { compilerOptions: { [option.name]: "someString" } } :
-                        { watchOptions: { [option.name]: "someString" } }
-                );
-            }
-            else {
-                showTSConfigCorrectly(
-                    `Shows tsconfig for single option/${option.name}WithStringValue`,
-                    [`--${option.name}`, "someString"],
-                        /*configJson*/ undefined,
-                );
-            }
-        }
         switch (option.type) {
             case "boolean": {
                 if (option.isTSConfigOnly) {
@@ -155,7 +137,6 @@ describe("unittests:: config:: showConfig", () => {
                 }
                 break;
             }
-            case "string | list":
             case "list": {
                 if (option.isTSConfigOnly) {
                     args = ["-p", "tsconfig.json"];

From bb0ae2f165a53d872c90e731b5eef2abbb072a95 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Tue, 29 Nov 2022 14:04:15 -0800
Subject: [PATCH 09/12] Fixed formatting

---
 src/compiler/commandLineParser.ts            | 74 +++++++++-----------
 src/compiler/types.ts                        |  2 +-
 src/executeCommandLine/executeCommandLine.ts |  2 +-
 src/services/getEditsForFileRename.ts        |  3 +-
 4 files changed, 35 insertions(+), 46 deletions(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 06bb6d24c1103..394768cb704fa 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -2372,9 +2372,9 @@ export function convertToObjectWorker(
                 }
                 reportInvalidOptionValue(option && isString(option.type) && option.type !== "string" && (option.type !== "listOrElement" || (isString(option.element.type) && option.element.type !== "string")));
                 const text = (valueExpression as StringLiteral).text;
-                    if (option) {
-                        Debug.assert(option.type !== "listOrElement" || option.element.type === "string", "Only string or array of string is handled for now");
-                    }
+                if (option) {
+                    Debug.assert(option.type !== "listOrElement" || option.element.type === "string", "Only string or array of string is handled for now");
+                }
                 if (option && !isString(option.type)) {
                     const customOption = option as CommandLineOptionOfCustomType;
                     // Validate custom option type
@@ -2584,16 +2584,6 @@ function matchesSpecs(path: string, includeSpecs: readonly string[] | undefined,
 }
 
 function getCustomTypeMapOfCommandLineOption(optionDefinition: CommandLineOption): Map<string, string | number> | undefined {
-    // if (optionDefinition.type === "string" || optionDefinition.type === "number" || optionDefinition.type === "boolean" || optionDefinition.type === "object") {
-    //     // this is of a type CommandLineOptionOfPrimitiveType
-    //     return undefined;
-    // }
-    // else if (optionDefinition.type === "list" || optionDefinition.type === "listOrElement") {
-    //     return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
-    // }
-    // else {
-    //     return optionDefinition.type;
-    // }
     switch (optionDefinition.type) {
         case "string":
         case "number":
@@ -3298,33 +3288,33 @@ function parseOwnConfigOfJsonSourceFile(
             switch (key) {
                 case "extends":
                     const newBase = configFileName ? directoryOfCombinedPath(configFileName, basePath) : basePath;
-                        if (isString(value)) {
-                        extendedConfigPath = getExtendsConfigPath(
-                            value,
-                            host,
-                            newBase,
-                            errors,
-                            (message, arg0) =>
-                                createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
-                        );
-                        }
-                        else {
-                            extendedConfigPath = [];
-                            for (let index = 0; index < (value as unknown[]).length; index++) {
-                                const fileName = (value as unknown[])[index];
-                                if (isString(fileName)) {
-                                    extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(
-                                        fileName,
-                                        host,
-                                        newBase,
-                                        errors,
-                                        (message, arg0) =>
-                                            createDiagnosticForNodeInSourceFile(sourceFile, (valueNode as ArrayLiteralExpression).elements[index], message, arg0)
-                                    ));
-                                }
+                    if (isString(value)) {
+                    extendedConfigPath = getExtendsConfigPath(
+                        value,
+                        host,
+                        newBase,
+                        errors,
+                        (message, arg0) =>
+                            createDiagnosticForNodeInSourceFile(sourceFile, valueNode, message, arg0)
+                    );
+                    }
+                    else {
+                        extendedConfigPath = [];
+                        for (let index = 0; index < (value as unknown[]).length; index++) {
+                            const fileName = (value as unknown[])[index];
+                            if (isString(fileName)) {
+                                extendedConfigPath = append(extendedConfigPath, getExtendsConfigPath(
+                                    fileName,
+                                    host,
+                                    newBase,
+                                    errors,
+                                    (message, arg0) =>
+                                        createDiagnosticForNodeInSourceFile(sourceFile, (valueNode as ArrayLiteralExpression).elements[index], message, arg0)
+                                ));
                             }
                         }
-                    return;
+                    }
+                return;
             }
         },
         onSetUnknownOptionKeyValueInRoot(key: string, keyNode: PropertyName, _value: CompilerOptionsValue, _valueNode: Expression) {
@@ -3399,7 +3389,7 @@ function getExtendedConfig(
     resolutionStack: string[],
     errors: Push<Diagnostic>,
     extendedConfigCache: Map<string, ExtendedConfigCacheEntry> | undefined,
-        result: ExtendsResult
+    result: ExtendsResult
 ): ParsedTsconfig | undefined {
     const path = host.useCaseSensitiveFileNames ? extendedConfigPath : toFileNameLowerCase(extendedConfigPath);
     let value: ExtendedConfigCacheEntry | undefined;
@@ -3422,10 +3412,10 @@ function getExtendedConfig(
         (result.extendedSourceFiles ??= new Set()).add(extendedResult.fileName);
         if (extendedResult.extendedSourceFiles) {
             for (const extenedSourceFile of extendedResult.extendedSourceFiles) {
-                    result.extendedSourceFiles.add(extenedSourceFile);
+                result.extendedSourceFiles.add(extenedSourceFile);
             }
         }
-        }
+    }
     if (extendedResult.parseDiagnostics.length) {
         errors.push(...extendedResult.parseDiagnostics);
         return undefined;
@@ -3538,7 +3528,7 @@ export function convertJsonOption(opt: CommandLineOption, value: any, basePath:
 function normalizeOptionValue(option: CommandLineOption, basePath: string, value: any): CompilerOptionsValue {
     if (isNullOrUndefined(value)) return undefined;
     if (option.type === "listOrElement" && !isArray(value)) return normalizeOptionValue(option.element, basePath, value);
-        else if (option.type === "list" || option.type === "listOrElement") {
+    else if (option.type === "list" || option.type === "listOrElement") {
         const listOption = option;
         if (listOption.element.isFilePath || !isString(listOption.element.type)) {
             return filter(map(value, v => normalizeOptionValue(listOption.element, basePath, v)), v => listOption.listPreserveFalsyValues ? true : !!v) as CompilerOptionsValue;
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index f9788f96bcbac..d603c0ab677c1 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6960,7 +6960,7 @@ export interface CreateProgramOptions {
 /** @internal */
 export interface CommandLineOptionBase {
     name: string;
-    type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | Map<string, number | string> ;    // a value of a primitive type, or an object literal mapping named values to actual values
+    type: "string" | "number" | "boolean" | "object" | "list" | "listOrElement" | Map<string, number | string>;    // a value of a primitive type, or an object literal mapping named values to actual values
     isFilePath?: boolean;                                   // True if option value is a path or fileName
     shortName?: string;                                     // A short mnemonic for convenience - for instance, 'h' can be used in place of 'help'
     description?: DiagnosticMessage;                        // The message describing what the command line switch does.
diff --git a/src/executeCommandLine/executeCommandLine.ts b/src/executeCommandLine/executeCommandLine.ts
index 5a2936d8640cf..0853f9c6916f4 100644
--- a/src/executeCommandLine/executeCommandLine.ts
+++ b/src/executeCommandLine/executeCommandLine.ts
@@ -406,8 +406,8 @@ function generateOptionOutput(sys: System, option: CommandLineOption, rightAlign
             }
             return possibleValues;
         }
-        }
     }
+}
 
 function generateGroupOptionOutput(sys: System, optionsList: readonly CommandLineOption[]) {
     let maxLength = 0;
diff --git a/src/services/getEditsForFileRename.ts b/src/services/getEditsForFileRename.ts
index deee8f9b9fc73..e8722ce5e76e5 100644
--- a/src/services/getEditsForFileRename.ts
+++ b/src/services/getEditsForFileRename.ts
@@ -120,8 +120,7 @@ function updateTsconfigFiles(program: Program, changeTracker: textChanges.Change
                 if (foundExactMatch || propertyName !== "include" || !isArrayLiteralExpression(property.initializer)) return;
                 const includes = mapDefined(property.initializer.elements, e => isStringLiteral(e) ? e.text : undefined);
                 if (includes.length === 0) return;
-                const matchers = getFileMatcherPatterns(
-                    configDir, /*excludes*/[], includes, useCaseSensitiveFileNames, currentDirectory);
+                const matchers = getFileMatcherPatterns(configDir, /*excludes*/[], includes, useCaseSensitiveFileNames, currentDirectory);
                 // If there isn't some include for this, add a new one.
                 if (getRegexFromPattern(Debug.checkDefined(matchers.includeFilePattern), useCaseSensitiveFileNames).test(oldFileOrDirPath) &&
                     !getRegexFromPattern(Debug.checkDefined(matchers.includeFilePattern), useCaseSensitiveFileNames).test(newFileOrDirPath)) {

From ef8bd6e191f62b56e64e8fb5382b6112b377149e Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Mon, 12 Dec 2022 14:01:11 -0800
Subject: [PATCH 10/12] Added compiler test

---
 .../configFileExtendsAsList.errors.txt        | 31 +++++++++++++++++++
 .../reference/configFileExtendsAsList.js      | 25 +++++++++++++++
 .../reference/configFileExtendsAsList.symbols | 13 ++++++++
 .../reference/configFileExtendsAsList.types   | 14 +++++++++
 .../cases/compiler/configFileExtendsAsList.ts | 23 ++++++++++++++
 5 files changed, 106 insertions(+)
 create mode 100644 tests/baselines/reference/configFileExtendsAsList.errors.txt
 create mode 100644 tests/baselines/reference/configFileExtendsAsList.js
 create mode 100644 tests/baselines/reference/configFileExtendsAsList.symbols
 create mode 100644 tests/baselines/reference/configFileExtendsAsList.types
 create mode 100644 tests/cases/compiler/configFileExtendsAsList.ts

diff --git a/tests/baselines/reference/configFileExtendsAsList.errors.txt b/tests/baselines/reference/configFileExtendsAsList.errors.txt
new file mode 100644
index 0000000000000..1accde5ea2632
--- /dev/null
+++ b/tests/baselines/reference/configFileExtendsAsList.errors.txt
@@ -0,0 +1,31 @@
+/index.ts(1,12): error TS7006: Parameter 'x' implicitly has an 'any' type.
+/index.ts(3,1): error TS2454: Variable 'y' is used before being assigned.
+
+
+==== /tsconfig.json (0 errors) ====
+    {
+        "extends": ["./tsconfig1.json", "./tsconfig2.json"]
+    }
+    
+==== /tsconfig1.json (0 errors) ====
+    {
+        "compilerOptions": {
+            "strictNullChecks": true
+        }
+    }
+    
+==== /tsconfig2.json (0 errors) ====
+    {
+        "compilerOptions": {
+            "noImplicitAny": true
+        }
+    }
+    
+==== /index.ts (2 errors) ====
+    function f(x) { } // noImplicitAny error
+               ~
+!!! error TS7006: Parameter 'x' implicitly has an 'any' type.
+    let y: string;
+    y.toLowerCase(); // strictNullChecks error
+    ~
+!!! error TS2454: Variable 'y' is used before being assigned.
\ No newline at end of file
diff --git a/tests/baselines/reference/configFileExtendsAsList.js b/tests/baselines/reference/configFileExtendsAsList.js
new file mode 100644
index 0000000000000..e805b7a293656
--- /dev/null
+++ b/tests/baselines/reference/configFileExtendsAsList.js
@@ -0,0 +1,25 @@
+//// [tests/cases/compiler/configFileExtendsAsList.ts] ////
+
+//// [tsconfig1.json]
+{
+    "compilerOptions": {
+        "strictNullChecks": true
+    }
+}
+
+//// [tsconfig2.json]
+{
+    "compilerOptions": {
+        "noImplicitAny": true
+    }
+}
+
+//// [index.ts]
+function f(x) { } // noImplicitAny error
+let y: string;
+y.toLowerCase(); // strictNullChecks error
+
+//// [index.js]
+function f(x) { } // noImplicitAny error
+var y;
+y.toLowerCase(); // strictNullChecks error
diff --git a/tests/baselines/reference/configFileExtendsAsList.symbols b/tests/baselines/reference/configFileExtendsAsList.symbols
new file mode 100644
index 0000000000000..97b24a733694e
--- /dev/null
+++ b/tests/baselines/reference/configFileExtendsAsList.symbols
@@ -0,0 +1,13 @@
+=== /index.ts ===
+function f(x) { } // noImplicitAny error
+>f : Symbol(f, Decl(index.ts, 0, 0))
+>x : Symbol(x, Decl(index.ts, 0, 11))
+
+let y: string;
+>y : Symbol(y, Decl(index.ts, 1, 3))
+
+y.toLowerCase(); // strictNullChecks error
+>y.toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
+>y : Symbol(y, Decl(index.ts, 1, 3))
+>toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
+
diff --git a/tests/baselines/reference/configFileExtendsAsList.types b/tests/baselines/reference/configFileExtendsAsList.types
new file mode 100644
index 0000000000000..dfa1eadf113be
--- /dev/null
+++ b/tests/baselines/reference/configFileExtendsAsList.types
@@ -0,0 +1,14 @@
+=== /index.ts ===
+function f(x) { } // noImplicitAny error
+>f : (x: any) => void
+>x : any
+
+let y: string;
+>y : string
+
+y.toLowerCase(); // strictNullChecks error
+>y.toLowerCase() : string
+>y.toLowerCase : () => string
+>y : string
+>toLowerCase : () => string
+
diff --git a/tests/cases/compiler/configFileExtendsAsList.ts b/tests/cases/compiler/configFileExtendsAsList.ts
new file mode 100644
index 0000000000000..8b6e1cf971544
--- /dev/null
+++ b/tests/cases/compiler/configFileExtendsAsList.ts
@@ -0,0 +1,23 @@
+// @Filename: /tsconfig1.json
+{
+    "compilerOptions": {
+        "strictNullChecks": true
+    }
+}
+
+// @Filename: /tsconfig2.json
+{
+    "compilerOptions": {
+        "noImplicitAny": true
+    }
+}
+
+// @Filename: /tsconfig.json
+{
+    "extends": ["./tsconfig1.json", "./tsconfig2.json"]
+}
+
+// @Filename: /index.ts
+function f(x) { } // noImplicitAny error
+let y: string;
+y.toLowerCase(); // strictNullChecks error
\ No newline at end of file

From e0d9de8d465dd745adc200c2656bf5f4bd84f303 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Tue, 13 Dec 2022 09:46:40 -0800
Subject: [PATCH 11/12] Resolving programUpdate errors

---
 src/testRunner/unittests/tsbuildWatch/programUpdates.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
index 87931c96e38ef..b4498d1f7e5f9 100644
--- a/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
+++ b/src/testRunner/unittests/tsbuildWatch/programUpdates.ts
@@ -730,7 +730,7 @@ export function someFn() { }`),
             },
             {
                 caption: "Modify extendsConfigFile2",
-                change: sys => sys.writeFile("/a/b/extendsConfig2.tsconfig.json", JSON.stringify({
+                edit: sys => sys.writeFile("/a/b/extendsConfig2.tsconfig.json", JSON.stringify({
                     compilerOptions: { strictNullChecks: true }
                 })),
                 timeouts: sys => { // Build project3
@@ -740,7 +740,7 @@ export function someFn() { }`),
             },
             {
                 caption: "Modify project 3",
-                change: sys => sys.writeFile("/a/b/project3.tsconfig.json", JSON.stringify({
+                edit: sys => sys.writeFile("/a/b/project3.tsconfig.json", JSON.stringify({
                     extends: ["./extendsConfig1.tsconfig.json", "./extendsConfig2.tsconfig.json"],
                     compilerOptions: { composite: false },
                     files: ["/a/b/other2.ts"]
@@ -752,7 +752,7 @@ export function someFn() { }`),
             },
             {
                 caption: "Delete extendedConfigFile2 and report error",
-                change: sys => sys.deleteFile("./extendsConfig2.tsconfig.json"),
+                edit: sys => sys.deleteFile("./extendsConfig2.tsconfig.json"),
                 timeouts: sys => { // Build project3
                     sys.checkTimeoutQueueLengthAndRun(1);
                     sys.checkTimeoutQueueLength(0);

From 7d6bdb630cba33a2389d5be956c21eeffe570b42 Mon Sep 17 00:00:00 2001
From: navya9singh <navyasingh@microsoft.com>
Date: Tue, 13 Dec 2022 10:50:46 -0800
Subject: [PATCH 12/12] Fixing commandLineParser error

---
 src/compiler/commandLineParser.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index d2b057b6e7c8a..97a09f716345e 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1678,7 +1678,6 @@ export function parseListTypeOption(opt: CommandLineOptionOfListType, value = ""
             return mapDefined(values, v => validateJsonOptionValue(opt.element, v || "", errors));
         case "boolean":
         case "object":
-        case "listOrElement":
             return Debug.fail(`List of ${opt.element.type} is not yet supported.`);
         default:
             return mapDefined(values, v => parseCustomTypeOption(opt.element as CommandLineOptionOfCustomType, v, errors));