Merge pull request #8713 from Microsoft/generic-inherited-default-constructor

Generic inherited default constructor

Author: sandersn

src/compiler/checker.ts

@@ -4579,12 +4579,7 @@ namespace ts {
         function getErasedSignature(signature: Signature): Signature {
             if (!signature.typeParameters) return signature;
             if (!signature.erasedSignatureCache) {
-                if (signature.target) {
-                    signature.erasedSignatureCache = instantiateSignature(getErasedSignature(signature.target), signature.mapper);
-                }
-                else {
-                    signature.erasedSignatureCache = instantiateSignature(signature, createTypeEraser(signature.typeParameters), /*eraseTypeParameters*/ true);
-                }
+                signature.erasedSignatureCache = instantiateSignature(signature, createTypeEraser(signature.typeParameters), /*eraseTypeParameters*/ true);
             }
             return signature.erasedSignatureCache;
         }

tests/baselines/reference/genericInheritedDefaultConstructors.js

@@ -0,0 +1,31 @@
+//// [genericInheritedDefaultConstructors.ts]
+// repro from #8166
+interface Constructor<T> {
+    new(...args: any[]): T;
+    prototype: T;
+}
+
+class A<U> { a: U; }
+class B<V> extends A<V> { b: V; }
+var c:Constructor<B<boolean>> = B; // shouldn't error here
+
+
+//// [genericInheritedDefaultConstructors.js]
+var __extends = (this && this.__extends) || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+};
+var A = (function () {
+    function A() {
+    }
+    return A;
+}());
+var B = (function (_super) {
+    __extends(B, _super);
+    function B() {
+        _super.apply(this, arguments);
+    }
+    return B;
+}(A));
+var c = B; // shouldn't error here

tests/baselines/reference/genericInheritedDefaultConstructors.symbols

@@ -0,0 +1,35 @@
+=== tests/cases/compiler/genericInheritedDefaultConstructors.ts ===
+// repro from #8166
+interface Constructor<T> {
+>Constructor : Symbol(Constructor, Decl(genericInheritedDefaultConstructors.ts, 0, 0))
+>T : Symbol(T, Decl(genericInheritedDefaultConstructors.ts, 1, 22))
+
+    new(...args: any[]): T;
+>args : Symbol(args, Decl(genericInheritedDefaultConstructors.ts, 2, 8))
+>T : Symbol(T, Decl(genericInheritedDefaultConstructors.ts, 1, 22))
+
+    prototype: T;
+>prototype : Symbol(Constructor.prototype, Decl(genericInheritedDefaultConstructors.ts, 2, 27))
+>T : Symbol(T, Decl(genericInheritedDefaultConstructors.ts, 1, 22))
+}
+
+class A<U> { a: U; }
+>A : Symbol(A, Decl(genericInheritedDefaultConstructors.ts, 4, 1))
+>U : Symbol(U, Decl(genericInheritedDefaultConstructors.ts, 6, 8))
+>a : Symbol(A.a, Decl(genericInheritedDefaultConstructors.ts, 6, 12))
+>U : Symbol(U, Decl(genericInheritedDefaultConstructors.ts, 6, 8))
+
+class B<V> extends A<V> { b: V; }
+>B : Symbol(B, Decl(genericInheritedDefaultConstructors.ts, 6, 20))
+>V : Symbol(V, Decl(genericInheritedDefaultConstructors.ts, 7, 8))
+>A : Symbol(A, Decl(genericInheritedDefaultConstructors.ts, 4, 1))
+>V : Symbol(V, Decl(genericInheritedDefaultConstructors.ts, 7, 8))
+>b : Symbol(B.b, Decl(genericInheritedDefaultConstructors.ts, 7, 25))
+>V : Symbol(V, Decl(genericInheritedDefaultConstructors.ts, 7, 8))
+
+var c:Constructor<B<boolean>> = B; // shouldn't error here
+>c : Symbol(c, Decl(genericInheritedDefaultConstructors.ts, 8, 3))
+>Constructor : Symbol(Constructor, Decl(genericInheritedDefaultConstructors.ts, 0, 0))
+>B : Symbol(B, Decl(genericInheritedDefaultConstructors.ts, 6, 20))
+>B : Symbol(B, Decl(genericInheritedDefaultConstructors.ts, 6, 20))
+

tests/baselines/reference/genericInheritedDefaultConstructors.types

@@ -0,0 +1,35 @@
+=== tests/cases/compiler/genericInheritedDefaultConstructors.ts ===
+// repro from #8166
+interface Constructor<T> {
+>Constructor : Constructor<T>
+>T : T
+
+    new(...args: any[]): T;
+>args : any[]
+>T : T
+
+    prototype: T;
+>prototype : T
+>T : T
+}
+
+class A<U> { a: U; }
+>A : A<U>
+>U : U
+>a : U
+>U : U
+
+class B<V> extends A<V> { b: V; }
+>B : B<V>
+>V : V
+>A : A<V>
+>V : V
+>b : V
+>V : V
+
+var c:Constructor<B<boolean>> = B; // shouldn't error here
+>c : Constructor<B<boolean>>
+>Constructor : Constructor<T>
+>B : B<V>
+>B : typeof B
+

tests/cases/compiler/genericInheritedDefaultConstructors.ts

@@ -0,0 +1,9 @@
+// repro from #8166
+interface Constructor<T> {
+    new(...args: any[]): T;
+    prototype: T;
+}
+
+class A<U> { a: U; }
+class B<V> extends A<V> { b: V; }
+var c:Constructor<B<boolean>> = B; // shouldn't error here