Propagate wildcard types in non-homomorphic mapped types (#41622)

* Propagate wildcard types in non-homomorphic mapped types * Add regression test * Accept new baselines * Accept new baselines
2026-05-23 07:07:09 -05:00 · 2020-12-01 13:57:00 -08:00
parent d57954345b
commit 4782c74b75
8 changed files with 71 additions and 7 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15276,7 +15276,9 @@ namespace ts {
                    });
                }
            }
-            return instantiateAnonymousType(type, mapper);
+            // If the constraint type of the instantiation is the wildcard type, return the wildcard type.
+            const result = <MappedType>instantiateAnonymousType(type, mapper);
+            return getConstraintTypeFromMappedType(result) === wildcardType ? wildcardType : result;
        }

        function getModifiedReadonlyState(state: boolean, modifiers: MappedTypeModifiers) {
--- a/tests/baselines/reference/conditionalTypes2.errors.txt
+++ b/tests/baselines/reference/conditionalTypes2.errors.txt
@@ -326,4 +326,10 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
    declare function gg<T>(f: (x: Foo3<T>) => void): void;
    type Foo3<T> = T extends number ? { n: T } : { x: T };
    gg(ff);
+    
+    // Repro from #41613
+    
+    type Wat<K extends string> = { x: { y: 0, z: 1 } } extends { x: { [P in K]: 0 } } ? true : false;
+     
+    type Huh = Wat<"y">;  // true
    
--- a/tests/baselines/reference/conditionalTypes2.js
+++ b/tests/baselines/reference/conditionalTypes2.js
@@ -237,6 +237,12 @@ declare function ff(x: Foo3<string>): void;
 declare function gg<T>(f: (x: Foo3<T>) => void): void;
 type Foo3<T> = T extends number ? { n: T } : { x: T };
 gg(ff);
+
+// Repro from #41613
+
+type Wat<K extends string> = { x: { y: 0, z: 1 } } extends { x: { [P in K]: 0 } } ? true : false;
+ 
+type Huh = Wat<"y">;  // true


 //// [conditionalTypes2.js]
@@ -477,3 +483,14 @@ declare type Foo3<T> = T extends number ? {
 } : {
    x: T;
 };
+declare type Wat<K extends string> = {
+    x: {
+        y: 0;
+        z: 1;
+    };
+} extends {
+    x: {
+        [P in K]: 0;
+    };
+} ? true : false;
+declare type Huh = Wat<"y">;
--- a/tests/baselines/reference/conditionalTypes2.symbols
+++ b/tests/baselines/reference/conditionalTypes2.symbols
@@ -841,3 +841,19 @@ gg(ff);
 >gg : Symbol(gg, Decl(conditionalTypes2.ts, 234, 43))
 >ff : Symbol(ff, Decl(conditionalTypes2.ts, 230, 2))

+// Repro from #41613
+
+type Wat<K extends string> = { x: { y: 0, z: 1 } } extends { x: { [P in K]: 0 } } ? true : false;
+>Wat : Symbol(Wat, Decl(conditionalTypes2.ts, 237, 7))
+>K : Symbol(K, Decl(conditionalTypes2.ts, 241, 9))
+>x : Symbol(x, Decl(conditionalTypes2.ts, 241, 30))
+>y : Symbol(y, Decl(conditionalTypes2.ts, 241, 35))
+>z : Symbol(z, Decl(conditionalTypes2.ts, 241, 41))
+>x : Symbol(x, Decl(conditionalTypes2.ts, 241, 60))
+>P : Symbol(P, Decl(conditionalTypes2.ts, 241, 67))
+>K : Symbol(K, Decl(conditionalTypes2.ts, 241, 9))
+ 
+type Huh = Wat<"y">;  // true
+>Huh : Symbol(Huh, Decl(conditionalTypes2.ts, 241, 97))
+>Wat : Symbol(Wat, Decl(conditionalTypes2.ts, 237, 7))
+
--- a/tests/baselines/reference/conditionalTypes2.types
+++ b/tests/baselines/reference/conditionalTypes2.types
@@ -527,3 +527,17 @@ gg(ff);
 >gg : <T>(f: (x: Foo3<T>) => void) => void
 >ff : (x: { x: string; }) => void

+// Repro from #41613
+
+type Wat<K extends string> = { x: { y: 0, z: 1 } } extends { x: { [P in K]: 0 } } ? true : false;
+>Wat : Wat<K>
+>x : { y: 0; z: 1; }
+>y : 0
+>z : 1
+>x : { [P in K]: 0; }
+>true : true
+>false : false
+ 
+type Huh = Wat<"y">;  // true
+>Huh : true
+
--- a/tests/baselines/reference/recursiveMappedTypes.errors.txt
+++ b/tests/baselines/reference/recursiveMappedTypes.errors.txt
@@ -6,10 +6,11 @@ tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(11,6): error TS2456
 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(12,11): error TS2313: Type parameter 'K' has a circular constraint.
 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(20,19): error TS2589: Type instantiation is excessively deep and possibly infinite.
 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(66,25): error TS2313: Type parameter 'P' has a circular constraint.
-tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(79,1): error TS2615: Type of property '"each"' circularly references itself in mapped type '{ type: never; minimum_count: never; maximum_count: never; collapsable?: never; each: never; }'.
+tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(73,5): error TS2502: '"each"' is referenced directly or indirectly in its own type annotation.
+tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(73,13): error TS2615: Type of property '"each"' circularly references itself in mapped type '{ [P in keyof ListWidget]: undefined extends ListWidget[P] ? never : P; }'.


-==== tests/cases/conformance/types/mapped/recursiveMappedTypes.ts (9 errors) ====
+==== tests/cases/conformance/types/mapped/recursiveMappedTypes.ts (10 errors) ====
    // Recursive mapped types simply appear empty
    
    type Recurse = {
@@ -93,7 +94,7 @@ tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(79,1): error TS2615
    type Child<T> = { [P in NonOptionalKeys<T>]: T[P] }
                            ~~~~~~~~~~~~~~~~~~
 !!! error TS2313: Type parameter 'P' has a circular constraint.
-!!! related TS2751 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts:79:1: Circularity originates in type at this location.
+!!! related TS2751 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts:73:13: Circularity originates in type at this location.
    
    export interface ListWidget {
        "type": "list",
@@ -101,12 +102,14 @@ tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(79,1): error TS2615
        "maximum_count": number,
        "collapsable"?: boolean, //default to false, means all expanded
        "each": Child<ListWidget>;
+        ~~~~~~
+!!! error TS2502: '"each"' is referenced directly or indirectly in its own type annotation.
+                ~~~~~~~~~~~~~~~~~
+!!! error TS2615: Type of property '"each"' circularly references itself in mapped type '{ [P in keyof ListWidget]: undefined extends ListWidget[P] ? never : P; }'.
    }
    
    type ListChild = Child<ListWidget>
    
    declare let x: ListChild;
    x.type;
-    ~~~~~~
-!!! error TS2615: Type of property '"each"' circularly references itself in mapped type '{ type: never; minimum_count: never; maximum_count: never; collapsable?: never; each: never; }'.
    
--- a/tests/baselines/reference/recursiveMappedTypes.types
+++ b/tests/baselines/reference/recursiveMappedTypes.types
@@ -119,7 +119,7 @@ export interface ListWidget {
 >"collapsable" : boolean

    "each": Child<ListWidget>;
->"each" : Child<ListWidget>
+>"each" : any
 }

 type ListChild = Child<ListWidget>
--- a/tests/cases/conformance/types/conditional/conditionalTypes2.ts
+++ b/tests/cases/conformance/types/conditional/conditionalTypes2.ts
@@ -239,3 +239,9 @@ declare function ff(x: Foo3<string>): void;
 declare function gg<T>(f: (x: Foo3<T>) => void): void;
 type Foo3<T> = T extends number ? { n: T } : { x: T };
 gg(ff);
+
+// Repro from #41613
+
+type Wat<K extends string> = { x: { y: 0, z: 1 } } extends { x: { [P in K]: 0 } } ? true : false;
+ 
+type Huh = Wat<"y">;  // true