Fix substitution types of indexed access types of substitution types (#47791)

* Fix substitution types of indexed access types of substitution types

* Add tests

* Fix accidental unindentation

src/compiler/checker.ts

@@ -13506,7 +13506,7 @@ namespace ts {
 
         function getImpliedConstraint(type: Type, checkNode: TypeNode, extendsNode: TypeNode): Type | undefined {
             return isUnaryTupleTypeNode(checkNode) && isUnaryTupleTypeNode(extendsNode) ? getImpliedConstraint(type, (checkNode as TupleTypeNode).elements[0], (extendsNode as TupleTypeNode).elements[0]) :
-                getActualTypeVariable(getTypeFromTypeNode(checkNode)) === type ? getTypeFromTypeNode(extendsNode) :
+                getActualTypeVariable(getTypeFromTypeNode(checkNode)) === getActualTypeVariable(type) ? getTypeFromTypeNode(extendsNode) :
                 undefined;
         }
 

tests/baselines/reference/substitutionTypeForIndexedAccessType1.js

@@ -0,0 +1,8 @@
+//// [substitutionTypeForIndexedAccessType1.ts]
+type AddPropToObject<Obj extends object, Prop extends string> = Prop extends keyof Obj
+  ? Obj[Prop] extends unknown[]
+    ? [...Obj[Prop]]
+    : never
+  : never
+
+//// [substitutionTypeForIndexedAccessType1.js]

tests/baselines/reference/substitutionTypeForIndexedAccessType1.symbols

@@ -0,0 +1,18 @@
+=== tests/cases/compiler/substitutionTypeForIndexedAccessType1.ts ===
+type AddPropToObject<Obj extends object, Prop extends string> = Prop extends keyof Obj
+>AddPropToObject : Symbol(AddPropToObject, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 0))
+>Obj : Symbol(Obj, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 21))
+>Prop : Symbol(Prop, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 40))
+>Prop : Symbol(Prop, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 40))
+>Obj : Symbol(Obj, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 21))
+
+  ? Obj[Prop] extends unknown[]
+>Obj : Symbol(Obj, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 21))
+>Prop : Symbol(Prop, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 40))
+
+    ? [...Obj[Prop]]
+>Obj : Symbol(Obj, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 21))
+>Prop : Symbol(Prop, Decl(substitutionTypeForIndexedAccessType1.ts, 0, 40))
+
+    : never
+  : never

tests/baselines/reference/substitutionTypeForIndexedAccessType1.types

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/substitutionTypeForIndexedAccessType1.ts ===
+type AddPropToObject<Obj extends object, Prop extends string> = Prop extends keyof Obj
+>AddPropToObject : AddPropToObject<Obj, Prop>
+
+  ? Obj[Prop] extends unknown[]
+    ? [...Obj[Prop]]
+    : never
+  : never

tests/baselines/reference/substitutionTypeForIndexedAccessType2.js

@@ -0,0 +1,18 @@
+//// [substitutionTypeForIndexedAccessType2.ts]
+interface Foo {
+  foo: string|undefined
+}
+
+type Str<T extends string> = T
+
+type Bar<T> = 
+  T extends Foo
+    ? T['foo'] extends string
+      // Type 'T["foo"]' does not satisfy the constraint 'string'.
+      //  Type 'string | undefined' is not assignable to type 'string'.
+      //   Type 'undefined' is not assignable to type 'string'.(2344)
+      ? Str<T['foo']>
+      : never
+    : never
+
+//// [substitutionTypeForIndexedAccessType2.js]

tests/baselines/reference/substitutionTypeForIndexedAccessType2.symbols

@@ -0,0 +1,33 @@
+=== tests/cases/compiler/substitutionTypeForIndexedAccessType2.ts ===
+interface Foo {
+>Foo : Symbol(Foo, Decl(substitutionTypeForIndexedAccessType2.ts, 0, 0))
+
+  foo: string|undefined
+>foo : Symbol(Foo.foo, Decl(substitutionTypeForIndexedAccessType2.ts, 0, 15))
+}
+
+type Str<T extends string> = T
+>Str : Symbol(Str, Decl(substitutionTypeForIndexedAccessType2.ts, 2, 1))
+>T : Symbol(T, Decl(substitutionTypeForIndexedAccessType2.ts, 4, 9))
+>T : Symbol(T, Decl(substitutionTypeForIndexedAccessType2.ts, 4, 9))
+
+type Bar<T> = 
+>Bar : Symbol(Bar, Decl(substitutionTypeForIndexedAccessType2.ts, 4, 30))
+>T : Symbol(T, Decl(substitutionTypeForIndexedAccessType2.ts, 6, 9))
+
+  T extends Foo
+>T : Symbol(T, Decl(substitutionTypeForIndexedAccessType2.ts, 6, 9))
+>Foo : Symbol(Foo, Decl(substitutionTypeForIndexedAccessType2.ts, 0, 0))
+
+    ? T['foo'] extends string
+>T : Symbol(T, Decl(substitutionTypeForIndexedAccessType2.ts, 6, 9))
+
+      // Type 'T["foo"]' does not satisfy the constraint 'string'.
+      //  Type 'string | undefined' is not assignable to type 'string'.
+      //   Type 'undefined' is not assignable to type 'string'.(2344)
+      ? Str<T['foo']>
+>Str : Symbol(Str, Decl(substitutionTypeForIndexedAccessType2.ts, 2, 1))
+>T : Symbol(T, Decl(substitutionTypeForIndexedAccessType2.ts, 6, 9))
+
+      : never
+    : never

tests/baselines/reference/substitutionTypeForIndexedAccessType2.types

@@ -0,0 +1,20 @@
+=== tests/cases/compiler/substitutionTypeForIndexedAccessType2.ts ===
+interface Foo {
+  foo: string|undefined
+>foo : string
+}
+
+type Str<T extends string> = T
+>Str : T
+
+type Bar<T> = 
+>Bar : Bar<T>
+
+  T extends Foo
+    ? T['foo'] extends string
+      // Type 'T["foo"]' does not satisfy the constraint 'string'.
+      //  Type 'string | undefined' is not assignable to type 'string'.
+      //   Type 'undefined' is not assignable to type 'string'.(2344)
+      ? Str<T['foo']>
+      : never
+    : never

tests/cases/compiler/substitutionTypeForIndexedAccessType1.ts

@@ -0,0 +1,5 @@
+type AddPropToObject<Obj extends object, Prop extends string> = Prop extends keyof Obj
+  ? Obj[Prop] extends unknown[]
+    ? [...Obj[Prop]]
+    : never
+  : never

tests/cases/compiler/substitutionTypeForIndexedAccessType2.ts

@@ -0,0 +1,15 @@
+interface Foo {
+  foo: string|undefined
+}
+
+type Str<T extends string> = T
+
+type Bar<T> = 
+  T extends Foo
+    ? T['foo'] extends string
+      // Type 'T["foo"]' does not satisfy the constraint 'string'.
+      //  Type 'string | undefined' is not assignable to type 'string'.
+      //   Type 'undefined' is not assignable to type 'string'.(2344)
+      ? Str<T['foo']>
+      : never
+    : never