Ensure all default type params are mapped to some default even in circular scenarios

src/compiler/checker.ts

@@ -7663,16 +7663,18 @@ namespace ts {
                 // Map an unsatisfied type parameter with a default type.
                 // If a type parameter does not have a default type, or if the default type
                 // is a forward reference, the empty object type is used.
+                const baseDefaultType = getDefaultTypeArgumentType(isJavaScriptImplicitAny);
+                const cicrularityMapper = createTypeMapper(typeParameters!, map(typeParameters!, () => baseDefaultType));
                 for (let i = numTypeArguments; i < numTypeParameters; i++) {
-                    result[i] = getConstraintFromTypeParameter(typeParameters![i]) || getDefaultTypeArgumentType(isJavaScriptImplicitAny);
+                    result[i] = instantiateType(getConstraintFromTypeParameter(typeParameters![i]) || baseDefaultType, cicrularityMapper);
                 }
                 for (let i = numTypeArguments; i < numTypeParameters; i++) {
                     const mapper = createTypeMapper(typeParameters!, result);
                     let defaultType = getDefaultFromTypeParameter(typeParameters![i]);
                     if (isJavaScriptImplicitAny && defaultType && isTypeIdenticalTo(defaultType, emptyObjectType)) {
                         defaultType = anyType;
                     }
-                    result[i] = defaultType ? instantiateType(defaultType, mapper) : getDefaultTypeArgumentType(isJavaScriptImplicitAny);
+                    result[i] = defaultType ? instantiateType(defaultType, mapper) : baseDefaultType;
                 }
                 result.length = typeParameters!.length;
                 return result;

tests/baselines/reference/subclassThisTypeAssignable.js

@@ -0,0 +1,34 @@
+//// [subclassThisTypeAssignable.ts]
+interface Lifecycle<Attrs, State> {
+	oninit?(vnode: Vnode<Attrs, State>): number;
+	[_: number]: any;
+}
+
+interface Vnode<Attrs, State extends Lifecycle<Attrs, State> = Lifecycle<Attrs, State>> {
+	tag: Component<Attrs, State>;
+}
+
+interface Component<Attrs, State> {
+	view(this: State, vnode: Vnode<Attrs, State>): number;
+}
+
+interface ClassComponent<A> extends Lifecycle<A, ClassComponent<A>> {
+	oninit?(vnode: Vnode<A, this>): number;
+	view(vnode: Vnode<A, this>): number;
+}
+
+interface MyAttrs { id: number }
+class C implements ClassComponent<MyAttrs> {
+	view(v: Vnode<MyAttrs>) { return 0; }
+}
+
+const test8: ClassComponent<any> = new C();
+
+//// [subclassThisTypeAssignable.js]
+var C = /** @class */ (function () {
+    function C() {
+    }
+    C.prototype.view = function (v) { return 0; };
+    return C;
+}());
+var test8 = new C();

tests/baselines/reference/subclassThisTypeAssignable.symbols

@@ -0,0 +1,92 @@
+=== tests/cases/compiler/subclassThisTypeAssignable.ts ===
+interface Lifecycle<Attrs, State> {
+>Lifecycle : Symbol(Lifecycle, Decl(subclassThisTypeAssignable.ts, 0, 0))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 0, 20))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 0, 26))
+
+	oninit?(vnode: Vnode<Attrs, State>): number;
+>oninit : Symbol(Lifecycle.oninit, Decl(subclassThisTypeAssignable.ts, 0, 35))
+>vnode : Symbol(vnode, Decl(subclassThisTypeAssignable.ts, 1, 9))
+>Vnode : Symbol(Vnode, Decl(subclassThisTypeAssignable.ts, 3, 1))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 0, 20))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 0, 26))
+
+	[_: number]: any;
+>_ : Symbol(_, Decl(subclassThisTypeAssignable.ts, 2, 2))
+}
+
+interface Vnode<Attrs, State extends Lifecycle<Attrs, State> = Lifecycle<Attrs, State>> {
+>Vnode : Symbol(Vnode, Decl(subclassThisTypeAssignable.ts, 3, 1))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 5, 16))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 5, 22))
+>Lifecycle : Symbol(Lifecycle, Decl(subclassThisTypeAssignable.ts, 0, 0))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 5, 16))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 5, 22))
+>Lifecycle : Symbol(Lifecycle, Decl(subclassThisTypeAssignable.ts, 0, 0))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 5, 16))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 5, 22))
+
+	tag: Component<Attrs, State>;
+>tag : Symbol(Vnode.tag, Decl(subclassThisTypeAssignable.ts, 5, 89))
+>Component : Symbol(Component, Decl(subclassThisTypeAssignable.ts, 7, 1))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 5, 16))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 5, 22))
+}
+
+interface Component<Attrs, State> {
+>Component : Symbol(Component, Decl(subclassThisTypeAssignable.ts, 7, 1))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 9, 20))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 9, 26))
+
+	view(this: State, vnode: Vnode<Attrs, State>): number;
+>view : Symbol(Component.view, Decl(subclassThisTypeAssignable.ts, 9, 35))
+>this : Symbol(this, Decl(subclassThisTypeAssignable.ts, 10, 6))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 9, 26))
+>vnode : Symbol(vnode, Decl(subclassThisTypeAssignable.ts, 10, 18))
+>Vnode : Symbol(Vnode, Decl(subclassThisTypeAssignable.ts, 3, 1))
+>Attrs : Symbol(Attrs, Decl(subclassThisTypeAssignable.ts, 9, 20))
+>State : Symbol(State, Decl(subclassThisTypeAssignable.ts, 9, 26))
+}
+
+interface ClassComponent<A> extends Lifecycle<A, ClassComponent<A>> {
+>ClassComponent : Symbol(ClassComponent, Decl(subclassThisTypeAssignable.ts, 11, 1))
+>A : Symbol(A, Decl(subclassThisTypeAssignable.ts, 13, 25))
+>Lifecycle : Symbol(Lifecycle, Decl(subclassThisTypeAssignable.ts, 0, 0))
+>A : Symbol(A, Decl(subclassThisTypeAssignable.ts, 13, 25))
+>ClassComponent : Symbol(ClassComponent, Decl(subclassThisTypeAssignable.ts, 11, 1))
+>A : Symbol(A, Decl(subclassThisTypeAssignable.ts, 13, 25))
+
+	oninit?(vnode: Vnode<A, this>): number;
+>oninit : Symbol(ClassComponent.oninit, Decl(subclassThisTypeAssignable.ts, 13, 69))
+>vnode : Symbol(vnode, Decl(subclassThisTypeAssignable.ts, 14, 9))
+>Vnode : Symbol(Vnode, Decl(subclassThisTypeAssignable.ts, 3, 1))
+>A : Symbol(A, Decl(subclassThisTypeAssignable.ts, 13, 25))
+
+	view(vnode: Vnode<A, this>): number;
+>view : Symbol(ClassComponent.view, Decl(subclassThisTypeAssignable.ts, 14, 40))
+>vnode : Symbol(vnode, Decl(subclassThisTypeAssignable.ts, 15, 6))
+>Vnode : Symbol(Vnode, Decl(subclassThisTypeAssignable.ts, 3, 1))
+>A : Symbol(A, Decl(subclassThisTypeAssignable.ts, 13, 25))
+}
+
+interface MyAttrs { id: number }
+>MyAttrs : Symbol(MyAttrs, Decl(subclassThisTypeAssignable.ts, 16, 1))
+>id : Symbol(MyAttrs.id, Decl(subclassThisTypeAssignable.ts, 18, 19))
+
+class C implements ClassComponent<MyAttrs> {
+>C : Symbol(C, Decl(subclassThisTypeAssignable.ts, 18, 32))
+>ClassComponent : Symbol(ClassComponent, Decl(subclassThisTypeAssignable.ts, 11, 1))
+>MyAttrs : Symbol(MyAttrs, Decl(subclassThisTypeAssignable.ts, 16, 1))
+
+	view(v: Vnode<MyAttrs>) { return 0; }
+>view : Symbol(C.view, Decl(subclassThisTypeAssignable.ts, 19, 44))
+>v : Symbol(v, Decl(subclassThisTypeAssignable.ts, 20, 6))
+>Vnode : Symbol(Vnode, Decl(subclassThisTypeAssignable.ts, 3, 1))
+>MyAttrs : Symbol(MyAttrs, Decl(subclassThisTypeAssignable.ts, 16, 1))
+}
+
+const test8: ClassComponent<any> = new C();
+>test8 : Symbol(test8, Decl(subclassThisTypeAssignable.ts, 23, 5))
+>ClassComponent : Symbol(ClassComponent, Decl(subclassThisTypeAssignable.ts, 11, 1))
+>C : Symbol(C, Decl(subclassThisTypeAssignable.ts, 18, 32))
+

tests/baselines/reference/subclassThisTypeAssignable.types

@@ -0,0 +1,49 @@
+=== tests/cases/compiler/subclassThisTypeAssignable.ts ===
+interface Lifecycle<Attrs, State> {
+	oninit?(vnode: Vnode<Attrs, State>): number;
+>oninit : (vnode: Vnode<Attrs, State>) => number
+>vnode : Vnode<Attrs, State>
+
+	[_: number]: any;
+>_ : number
+}
+
+interface Vnode<Attrs, State extends Lifecycle<Attrs, State> = Lifecycle<Attrs, State>> {
+	tag: Component<Attrs, State>;
+>tag : Component<Attrs, State>
+}
+
+interface Component<Attrs, State> {
+	view(this: State, vnode: Vnode<Attrs, State>): number;
+>view : (this: State, vnode: Vnode<Attrs, State>) => number
+>this : State
+>vnode : Vnode<Attrs, State>
+}
+
+interface ClassComponent<A> extends Lifecycle<A, ClassComponent<A>> {
+	oninit?(vnode: Vnode<A, this>): number;
+>oninit : (vnode: Vnode<A, this>) => number
+>vnode : Vnode<A, this>
+
+	view(vnode: Vnode<A, this>): number;
+>view : (vnode: Vnode<A, this>) => number
+>vnode : Vnode<A, this>
+}
+
+interface MyAttrs { id: number }
+>id : number
+
+class C implements ClassComponent<MyAttrs> {
+>C : C
+
+	view(v: Vnode<MyAttrs>) { return 0; }
+>view : (v: Vnode<MyAttrs, Lifecycle<MyAttrs, Lifecycle<{}, {}>>>) => number
+>v : Vnode<MyAttrs, Lifecycle<MyAttrs, Lifecycle<{}, {}>>>
+>0 : 0
+}
+
+const test8: ClassComponent<any> = new C();
+>test8 : ClassComponent<any>
+>new C() : C
+>C : typeof C
+

tests/cases/compiler/subclassThisTypeAssignable.ts

@@ -0,0 +1,24 @@
+interface Lifecycle<Attrs, State> {
+	oninit?(vnode: Vnode<Attrs, State>): number;
+	[_: number]: any;
+}
+
+interface Vnode<Attrs, State extends Lifecycle<Attrs, State> = Lifecycle<Attrs, State>> {
+	tag: Component<Attrs, State>;
+}
+
+interface Component<Attrs, State> {
+	view(this: State, vnode: Vnode<Attrs, State>): number;
+}
+
+interface ClassComponent<A> extends Lifecycle<A, ClassComponent<A>> {
+	oninit?(vnode: Vnode<A, this>): number;
+	view(vnode: Vnode<A, this>): number;
+}
+
+interface MyAttrs { id: number }
+class C implements ClassComponent<MyAttrs> {
+	view(v: Vnode<MyAttrs>) { return 0; }
+}
+
+const test8: ClassComponent<any> = new C();