Add missing arity check on second inference pass (microsoft#29386)

Author: weswigham

src/compiler/checker.ts

@@ -20422,6 +20422,12 @@ namespace ts {
                         if (inferenceContext) {
                             const typeArgumentTypes = inferTypeArguments(node, candidate, args, excludeArgument, inferenceContext);
                             checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration));
+                            // If the original signature has a generic rest type, instantiation may produce a
+                            // signature with different arity and we need to perform another arity check.
+                            if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) {
+                                candidateForArgumentArityError = checkCandidate;
+                                continue;
+                            }
                         }
                         if (!checkApplicableSignature(node, args, checkCandidate, relation, excludeArgument, /*reportErrors*/ false)) {
                             // Give preference to error candidates that have no rest parameters (as they are more specific)

tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.errors.txt

@@ -0,0 +1,15 @@
+error TS2318: Cannot find global type 'IterableIterator'.
+tests/cases/compiler/spreadOfParamsFromGeneratorMakesRequiredParams.ts(6,1): error TS2554: Expected 2 arguments, but got 1.
+
+
+!!! error TS2318: Cannot find global type 'IterableIterator'.
+==== tests/cases/compiler/spreadOfParamsFromGeneratorMakesRequiredParams.ts (1 errors) ====
+    declare function call<Fn extends (...args: any[]) => any>(
+        fn: Fn,
+        ...args: Parameters<Fn>
+    ): any;
+    
+    call(function* (a: 'a') { }); // error, 2nd argument required
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2554: Expected 2 arguments, but got 1.
+!!! related TS6210 tests/cases/compiler/spreadOfParamsFromGeneratorMakesRequiredParams.ts:3:5: An argument for 'args' was not provided.

tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.js

@@ -0,0 +1,39 @@
+//// [spreadOfParamsFromGeneratorMakesRequiredParams.ts]
+declare function call<Fn extends (...args: any[]) => any>(
+    fn: Fn,
+    ...args: Parameters<Fn>
+): any;
+
+call(function* (a: 'a') { }); // error, 2nd argument required
+
+//// [spreadOfParamsFromGeneratorMakesRequiredParams.js]
+var __generator = (this && this.__generator) || function (thisArg, body) {
+    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
+    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
+    function verb(n) { return function (v) { return step([n, v]); }; }
+    function step(op) {
+        if (f) throw new TypeError("Generator is already executing.");
+        while (_) try {
+            if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
+            if (y = 0, t) op = [op[0] & 2, t.value];
+            switch (op[0]) {
+                case 0: case 1: t = op; break;
+                case 4: _.label++; return { value: op[1], done: false };
+                case 5: _.label++; y = op[1]; op = [0]; continue;
+                case 7: op = _.ops.pop(); _.trys.pop(); continue;
+                default:
+                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
+                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
+                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
+                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
+                    if (t[2]) _.ops.pop();
+                    _.trys.pop(); continue;
+            }
+            op = body.call(thisArg, _);
+        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
+        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
+    }
+};
+call(function (a) { return __generator(this, function (_a) {
+    return [2 /*return*/];
+}); }); // error, 2nd argument required

tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.symbols

@@ -0,0 +1,21 @@
+=== tests/cases/compiler/spreadOfParamsFromGeneratorMakesRequiredParams.ts ===
+declare function call<Fn extends (...args: any[]) => any>(
+>call : Symbol(call, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 0))
+>Fn : Symbol(Fn, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 22))
+>args : Symbol(args, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 34))
+
+    fn: Fn,
+>fn : Symbol(fn, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 58))
+>Fn : Symbol(Fn, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 22))
+
+    ...args: Parameters<Fn>
+>args : Symbol(args, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 1, 11))
+>Parameters : Symbol(Parameters, Decl(lib.es5.d.ts, --, --))
+>Fn : Symbol(Fn, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 22))
+
+): any;
+
+call(function* (a: 'a') { }); // error, 2nd argument required
+>call : Symbol(call, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 0, 0))
+>a : Symbol(a, Decl(spreadOfParamsFromGeneratorMakesRequiredParams.ts, 5, 16))
+

tests/baselines/reference/spreadOfParamsFromGeneratorMakesRequiredParams.types

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/spreadOfParamsFromGeneratorMakesRequiredParams.ts ===
+declare function call<Fn extends (...args: any[]) => any>(
+>call : <Fn extends (...args: any[]) => any>(fn: Fn, ...args: Parameters<Fn>) => any
+>args : any[]
+
+    fn: Fn,
+>fn : Fn
+
+    ...args: Parameters<Fn>
+>args : Parameters<Fn>
+
+): any;
+
+call(function* (a: 'a') { }); // error, 2nd argument required
+>call(function* (a: 'a') { }) : any
+>call : <Fn extends (...args: any[]) => any>(fn: Fn, ...args: Parameters<Fn>) => any
+>function* (a: 'a') { } : (a: "a") => {}
+>a : "a"
+

tests/cases/compiler/spreadOfParamsFromGeneratorMakesRequiredParams.ts

@@ -0,0 +1,6 @@
+declare function call<Fn extends (...args: any[]) => any>(
+    fn: Fn,
+    ...args: Parameters<Fn>
+): any;
+
+call(function* (a: 'a') { }); // error, 2nd argument required