Instantiate constraint with default upon comparison

src/compiler/checker.ts

@@ -24369,7 +24369,7 @@ namespace ts {
             const constraintType = getConstraintOfTypeParameter(typeParameter);
             const defaultType = getDefaultFromTypeParameter(typeParameter);
             if (constraintType && defaultType) {
-                checkTypeAssignableTo(defaultType, getTypeWithThisArgument(constraintType, defaultType), node.default, Diagnostics.Type_0_does_not_satisfy_the_constraint_1);
+                checkTypeAssignableTo(defaultType, getTypeWithThisArgument(instantiateType(constraintType, makeUnaryTypeMapper(typeParameter, defaultType)), defaultType), node.default, Diagnostics.Type_0_does_not_satisfy_the_constraint_1);
             }
             if (produceDiagnostics) {
                 checkTypeNameIsReserved(node.name, Diagnostics.Type_parameter_name_cannot_be_0);

tests/baselines/reference/typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.js

@@ -0,0 +1,42 @@
+//// [typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts]
+// tricky interface
+interface Settable<T, V> {
+    set(value: V): T;
+}
+
+// implement
+class Identity<V> implements Settable<Identity<V>, V> {
+    readonly item: V;
+    constructor(value: V) {
+        this.item = value;
+    }
+    public set(value: V): Identity<V> {
+        return new Identity<V>(value);
+    }
+}
+
+// generic parameter default
+interface Test1<V, T extends Settable<T, V> = Identity<V>> { };
+let test1: Test1<number>;
+
+// not generic parameter default
+interface Test2Base<V, T extends Settable<T, V>> { };
+type Test2<V> = Test2Base<V, Identity<V>>;
+let test2: Test2<number>;
+
+
+//// [typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.js]
+// implement
+var Identity = /** @class */ (function () {
+    function Identity(value) {
+        this.item = value;
+    }
+    Identity.prototype.set = function (value) {
+        return new Identity(value);
+    };
+    return Identity;
+}());
+;
+var test1;
+;
+var test2;

tests/baselines/reference/typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.symbols

@@ -0,0 +1,87 @@
+=== tests/cases/compiler/typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts ===
+// tricky interface
+interface Settable<T, V> {
+>Settable : Symbol(Settable, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 0, 0))
+>T : Symbol(T, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 1, 19))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 1, 21))
+
+    set(value: V): T;
+>set : Symbol(Settable.set, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 1, 26))
+>value : Symbol(value, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 2, 8))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 1, 21))
+>T : Symbol(T, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 1, 19))
+}
+
+// implement
+class Identity<V> implements Settable<Identity<V>, V> {
+>Identity : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+>Settable : Symbol(Settable, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 0, 0))
+>Identity : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+
+    readonly item: V;
+>item : Symbol(Identity.item, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 55))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+
+    constructor(value: V) {
+>value : Symbol(value, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 8, 16))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+
+        this.item = value;
+>this.item : Symbol(Identity.item, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 55))
+>this : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>item : Symbol(Identity.item, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 55))
+>value : Symbol(value, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 8, 16))
+    }
+    public set(value: V): Identity<V> {
+>set : Symbol(Identity.set, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 10, 5))
+>value : Symbol(value, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 11, 15))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+>Identity : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+
+        return new Identity<V>(value);
+>Identity : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 6, 15))
+>value : Symbol(value, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 11, 15))
+    }
+}
+
+// generic parameter default
+interface Test1<V, T extends Settable<T, V> = Identity<V>> { };
+>Test1 : Symbol(Test1, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 14, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 17, 16))
+>T : Symbol(T, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 17, 18))
+>Settable : Symbol(Settable, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 0, 0))
+>T : Symbol(T, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 17, 18))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 17, 16))
+>Identity : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 17, 16))
+
+let test1: Test1<number>;
+>test1 : Symbol(test1, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 18, 3))
+>Test1 : Symbol(Test1, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 14, 1))
+
+// not generic parameter default
+interface Test2Base<V, T extends Settable<T, V>> { };
+>Test2Base : Symbol(Test2Base, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 18, 25))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 21, 20))
+>T : Symbol(T, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 21, 22))
+>Settable : Symbol(Settable, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 0, 0))
+>T : Symbol(T, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 21, 22))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 21, 20))
+
+type Test2<V> = Test2Base<V, Identity<V>>;
+>Test2 : Symbol(Test2, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 21, 53))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 22, 11))
+>Test2Base : Symbol(Test2Base, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 18, 25))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 22, 11))
+>Identity : Symbol(Identity, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 3, 1))
+>V : Symbol(V, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 22, 11))
+
+let test2: Test2<number>;
+>test2 : Symbol(test2, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 23, 3))
+>Test2 : Symbol(Test2, Decl(typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts, 21, 53))
+

tests/baselines/reference/typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.types

@@ -0,0 +1,49 @@
+=== tests/cases/compiler/typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts ===
+// tricky interface
+interface Settable<T, V> {
+    set(value: V): T;
+>set : (value: V) => T
+>value : V
+}
+
+// implement
+class Identity<V> implements Settable<Identity<V>, V> {
+>Identity : Identity<V>
+
+    readonly item: V;
+>item : V
+
+    constructor(value: V) {
+>value : V
+
+        this.item = value;
+>this.item = value : V
+>this.item : V
+>this : this
+>item : V
+>value : V
+    }
+    public set(value: V): Identity<V> {
+>set : (value: V) => Identity<V>
+>value : V
+
+        return new Identity<V>(value);
+>new Identity<V>(value) : Identity<V>
+>Identity : typeof Identity
+>value : V
+    }
+}
+
+// generic parameter default
+interface Test1<V, T extends Settable<T, V> = Identity<V>> { };
+let test1: Test1<number>;
+>test1 : Test1<number, Identity<number>>
+
+// not generic parameter default
+interface Test2Base<V, T extends Settable<T, V>> { };
+type Test2<V> = Test2Base<V, Identity<V>>;
+>Test2 : Test2Base<V, Identity<V>>
+
+let test2: Test2<number>;
+>test2 : Test2Base<number, Identity<number>>
+

tests/cases/compiler/typePartameterConstraintInstantiatedWithDefaultWhenCheckingDefault.ts

@@ -0,0 +1,24 @@
+// tricky interface
+interface Settable<T, V> {
+    set(value: V): T;
+}
+
+// implement
+class Identity<V> implements Settable<Identity<V>, V> {
+    readonly item: V;
+    constructor(value: V) {
+        this.item = value;
+    }
+    public set(value: V): Identity<V> {
+        return new Identity<V>(value);
+    }
+}
+
+// generic parameter default
+interface Test1<V, T extends Settable<T, V> = Identity<V>> { };
+let test1: Test1<number>;
+
+// not generic parameter default
+interface Test2Base<V, T extends Settable<T, V>> { };
+type Test2<V> = Test2Base<V, Identity<V>>;
+let test2: Test2<number>;