fix: Pick up optional/readonly from mapped types

Resolves TypeStrong#1509

Author: Gerrit0

src/lib/converter/symbols.ts

@@ -324,7 +324,7 @@ function convertFunctionOrMethod(
 
     if (declarations.length && isMethod) {
         // All method signatures must have the same modifier flags.
-        setModifiers(declarations[0], reflection);
+        setModifiers(symbol, declarations[0], reflection);
 
         assert(parentSymbol, "Tried to convert a method without a parent.");
         if (
@@ -375,7 +375,7 @@ function convertClassOrInterface(
         .getDeclarations()
         ?.find((d) => ts.isClassDeclaration(d) || ts.isFunctionDeclaration(d));
     if (classDeclaration) {
-        setModifiers(classDeclaration, reflection);
+        setModifiers(symbol, classDeclaration, reflection);
 
         // Classes can have static props
         const staticType = context.checker.getTypeOfSymbolAtLocation(
@@ -421,7 +421,7 @@ function convertClassOrInterface(
             .map((sig, i) => {
                 // Modifiers are the same for all constructors
                 if (sig.declaration && i === 0) {
-                    setModifiers(sig.declaration, constructMember);
+                    setModifiers(symbol, sig.declaration, constructMember);
                 }
                 const sigRef = createSignature(
                     constructContext,
@@ -574,7 +574,7 @@ function convertProperty(
             ts.isParameter(declaration))
     ) {
         parameterType = declaration.type;
-        setModifiers(declaration, reflection);
+        setModifiers(symbol, declaration, reflection);
         const parentSymbol = context.project.getSymbolFromReflection(
             context.scope
         );
@@ -614,7 +614,7 @@ function convertArrowAsMethod(
         symbol,
         exportSymbol
     );
-    setModifiers(arrow.parent as ts.PropertyDeclaration, reflection);
+    setModifiers(symbol, arrow.parent as ts.PropertyDeclaration, reflection);
     const rc = context.withScope(reflection);
 
     const signature = context.checker.getSignatureFromDeclaration(arrow);
@@ -771,7 +771,7 @@ function convertVariable(
         typeNode ?? type
     );
 
-    setModifiers(declaration, reflection);
+    setModifiers(symbol, declaration, reflection);
 
     // Does anyone care about this? I doubt it...
     if (
@@ -806,7 +806,7 @@ function convertVariableAsFunction(
         symbol,
         exportSymbol
     );
-    setModifiers(declaration ?? symbol.valueDeclaration, reflection);
+    setModifiers(symbol, declaration ?? symbol.valueDeclaration, reflection);
     // Does anyone care about this? I doubt it...
     if (
         declaration &&
@@ -892,7 +892,11 @@ function isInherited(context: Context, symbol: ts.Symbol) {
     );
 }
 
-function setModifiers(declaration: ts.Declaration, reflection: Reflection) {
+function setModifiers(
+    symbol: ts.Symbol,
+    declaration: ts.Declaration,
+    reflection: Reflection
+) {
     const modifiers = ts.getCombinedModifierFlags(declaration);
     // Note: We only set this flag if the modifier is present because we allow
     // fake "private" or "protected" members via @private and @protected
@@ -907,11 +911,12 @@ function setModifiers(declaration: ts.Declaration, reflection: Reflection) {
     }
     reflection.setFlag(
         ReflectionFlag.Optional,
-        !!(declaration as any).questionToken
+        hasAllFlags(symbol.flags, ts.SymbolFlags.Optional)
     );
     reflection.setFlag(
         ReflectionFlag.Readonly,
-        hasAllFlags(modifiers, ts.ModifierFlags.Readonly)
+        hasAllFlags(symbol.checkFlags ?? 0, ts.CheckFlags.Readonly) ||
+            hasAllFlags(modifiers, ts.ModifierFlags.Readonly)
     );
     reflection.setFlag(
         ReflectionFlag.Abstract,

src/lib/ts-internal.ts

@@ -5,15 +5,48 @@ import * as ts from "typescript";
  */
 declare module "typescript" {
     interface Node {
-        // https://github.com/microsoft/TypeScript/blob/v4.1.3/src/compiler/types.ts#L847
+        // https://github.com/microsoft/TypeScript/blob/v4.1.5/src/compiler/types.ts#L847
         symbol?: ts.Symbol;
     }
 
+    interface Symbol {
+        // https://github.com/microsoft/TypeScript/blob/v4.1.5/src/compiler/types.ts#L4734-L4737
+        checkFlags?: CheckFlags;
+    }
+
     interface TypeChecker {
-        // https://github.com/microsoft/TypeScript/blob/v4.1.3/src/compiler/types.ts#L4145
+        // https://github.com/microsoft/TypeScript/blob/v4.1.5/src/compiler/types.ts#L4145
         // https://github.com/microsoft/TypeScript/issues/42118
         getTypePredicateOfSignature(
             signature: ts.Signature
         ): ts.TypePredicate | undefined;
     }
+
+    // https://github.com/microsoft/TypeScript/blob/v4.1.5/src/compiler/types.ts#L4707-L4732
+    /* @internal */
+    export const enum CheckFlags {
+        Instantiated = 1 << 0, // Instantiated symbol
+        SyntheticProperty = 1 << 1, // Property in union or intersection type
+        SyntheticMethod = 1 << 2, // Method in union or intersection type
+        Readonly = 1 << 3, // Readonly transient symbol
+        ReadPartial = 1 << 4, // Synthetic property present in some but not all constituents
+        WritePartial = 1 << 5, // Synthetic property present in some but only satisfied by an index signature in others
+        HasNonUniformType = 1 << 6, // Synthetic property with non-uniform type in constituents
+        HasLiteralType = 1 << 7, // Synthetic property with at least one literal type in constituents
+        ContainsPublic = 1 << 8, // Synthetic property with public constituent(s)
+        ContainsProtected = 1 << 9, // Synthetic property with protected constituent(s)
+        ContainsPrivate = 1 << 10, // Synthetic property with private constituent(s)
+        ContainsStatic = 1 << 11, // Synthetic property with static constituent(s)
+        Late = 1 << 12, // Late-bound symbol for a computed property with a dynamic name
+        ReverseMapped = 1 << 13, // Property of reverse-inferred homomorphic mapped type
+        OptionalParameter = 1 << 14, // Optional parameter
+        RestParameter = 1 << 15, // Rest parameter
+        DeferredType = 1 << 16, // Calculation of the type of this symbol is deferred due to processing costs, should be fetched with `getTypeOfSymbolWithDeferredType`
+        HasNeverType = 1 << 17, // Synthetic property with at least one never type in constituents
+        Mapped = 1 << 18, // Property of mapped type
+        StripOptional = 1 << 19, // Strip optionality in mapped property
+        Synthetic = SyntheticProperty | SyntheticMethod,
+        Discriminant = HasNonUniformType | HasLiteralType,
+        Partial = ReadPartial | WritePartial,
+    }
 }

src/test/converter/class/class.ts

@@ -121,3 +121,12 @@ export class Ts38PrivateFields {
     /** Docs */
     #foo = 1;
 }
+
+export namespace GH1509 {
+    export interface Foo {
+        foo: number;
+    }
+
+    export interface PartialFoo extends Partial<Foo> {}
+    export interface ReadonlyFoo extends Readonly<Partial<Foo>> {}
+}