Use comparability for discriminant properties when narrowing types for a default switch clause (#61211)

2025-12-10 00:20:22 -06:00 · 2025-10-30 15:20:13 +01:00 · 2025-10-30 15:20:13 +01:00 · 6fd2874d0d
commit 6fd2874d0d
parent 2a90a739c1
4 changed files with 540 additions and 1 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@ -29739,7 +29739,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
            if (!hasDefaultClause) {
                return caseType;
            }
-            const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, t.flags & TypeFlags.Undefined ? undefinedType : getRegularTypeOfLiteralType(extractUnitType(t)))));
+            const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, t.flags & TypeFlags.Undefined ? undefinedType : getRegularTypeOfLiteralType(extractUnitType(t)), (t1, t2) => isUnitType(t1) && areTypesComparable(t1, t2))));
            return caseType.flags & TypeFlags.Never ? defaultType : getUnionType([caseType, defaultType]);
        }

--- a/tests/baselines/reference/discriminatedUnionTypes4.symbols
+++ b/tests/baselines/reference/discriminatedUnionTypes4.symbols
@ -0,0 +1,180 @@
+//// [tests/cases/conformance/types/union/discriminatedUnionTypes4.ts] ////
+
+=== discriminatedUnionTypes4.ts ===
+// https://github.com/microsoft/TypeScript/issues/61207
+
+enum AnimalType {
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+
+  cat = "cat",
+>cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+
+  dog = "dog",
+>dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+}
+
+type Animal =
+>Animal : Symbol(Animal, Decl(discriminatedUnionTypes4.ts, 5, 1))
+
+  | {
+      type: `${AnimalType.cat}`;
+>type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+
+      meow: string;
+>meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+    }
+  | {
+      type: `${AnimalType.dog}`;
+>type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 12, 5))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+
+      bark: string;
+>bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+
+    };
+
+function check(p: never) {
+>check : Symbol(check, Decl(discriminatedUnionTypes4.ts, 15, 6))
+>p : Symbol(p, Decl(discriminatedUnionTypes4.ts, 17, 15))
+
+  throw new Error("Error!");
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+}
+
+function action1(animal: Animal) {
+>action1 : Symbol(action1, Decl(discriminatedUnionTypes4.ts, 19, 1))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 21, 17))
+>Animal : Symbol(Animal, Decl(discriminatedUnionTypes4.ts, 5, 1))
+
+  if (animal.type === AnimalType.cat) {
+>animal.type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5), Decl(discriminatedUnionTypes4.ts, 12, 5))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 21, 17))
+>type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5), Decl(discriminatedUnionTypes4.ts, 12, 5))
+>AnimalType.cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+
+    console.log(animal.meow);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>animal.meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 21, 17))
+>meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+
+  } else if (animal.type === AnimalType.dog) {
+>animal.type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 12, 5))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 21, 17))
+>type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 12, 5))
+>AnimalType.dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+
+    console.log(animal.bark);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>animal.bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 21, 17))
+>bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+
+  } else {
+    check(animal);
+>check : Symbol(check, Decl(discriminatedUnionTypes4.ts, 15, 6))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 21, 17))
+  }
+}
+
+function action2(animal: Animal) {
+>action2 : Symbol(action2, Decl(discriminatedUnionTypes4.ts, 29, 1))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 31, 17))
+>Animal : Symbol(Animal, Decl(discriminatedUnionTypes4.ts, 5, 1))
+
+  switch (animal.type) {
+>animal.type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5), Decl(discriminatedUnionTypes4.ts, 12, 5))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 31, 17))
+>type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5), Decl(discriminatedUnionTypes4.ts, 12, 5))
+
+    case `${AnimalType.cat}`:
+>AnimalType.cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+
+      console.log(animal.meow);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>animal.meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 31, 17))
+>meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+
+      break;
+    case `${AnimalType.dog}`:
+>AnimalType.dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+
+      console.log(animal.bark);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>animal.bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 31, 17))
+>bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+
+      break;
+    default:
+      check(animal);
+>check : Symbol(check, Decl(discriminatedUnionTypes4.ts, 15, 6))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 31, 17))
+  }
+}
+
+function action3(animal: Animal) {
+>action3 : Symbol(action3, Decl(discriminatedUnionTypes4.ts, 42, 1))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 44, 17))
+>Animal : Symbol(Animal, Decl(discriminatedUnionTypes4.ts, 5, 1))
+
+  switch (animal.type) {
+>animal.type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5), Decl(discriminatedUnionTypes4.ts, 12, 5))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 44, 17))
+>type : Symbol(type, Decl(discriminatedUnionTypes4.ts, 8, 5), Decl(discriminatedUnionTypes4.ts, 12, 5))
+
+    case AnimalType.cat:
+>AnimalType.cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>cat : Symbol(AnimalType.cat, Decl(discriminatedUnionTypes4.ts, 2, 17))
+
+      console.log(animal.meow);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>animal.meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 44, 17))
+>meow : Symbol(meow, Decl(discriminatedUnionTypes4.ts, 9, 32))
+
+      break;
+    case AnimalType.dog:
+>AnimalType.dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+>AnimalType : Symbol(AnimalType, Decl(discriminatedUnionTypes4.ts, 0, 0))
+>dog : Symbol(AnimalType.dog, Decl(discriminatedUnionTypes4.ts, 3, 14))
+
+      console.log(animal.bark);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>animal.bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 44, 17))
+>bark : Symbol(bark, Decl(discriminatedUnionTypes4.ts, 13, 32))
+
+      break;
+    default:
+      check(animal);
+>check : Symbol(check, Decl(discriminatedUnionTypes4.ts, 15, 6))
+>animal : Symbol(animal, Decl(discriminatedUnionTypes4.ts, 44, 17))
+  }
+}
+
--- a/tests/baselines/reference/discriminatedUnionTypes4.types
+++ b/tests/baselines/reference/discriminatedUnionTypes4.types
@ -0,0 +1,300 @@
+//// [tests/cases/conformance/types/union/discriminatedUnionTypes4.ts] ////
+
+=== discriminatedUnionTypes4.ts ===
+// https://github.com/microsoft/TypeScript/issues/61207
+
+enum AnimalType {
+>AnimalType : AnimalType
+>           : ^^^^^^^^^^
+
+  cat = "cat",
+>cat : AnimalType.cat
+>    : ^^^^^^^^^^^^^^
+>"cat" : "cat"
+>      : ^^^^^
+
+  dog = "dog",
+>dog : AnimalType.dog
+>    : ^^^^^^^^^^^^^^
+>"dog" : "dog"
+>      : ^^^^^
+}
+
+type Animal =
+>Animal : Animal
+>       : ^^^^^^
+
+  | {
+      type: `${AnimalType.cat}`;
+>type : "cat"
+>     : ^^^^^
+>AnimalType : any
+>           : ^^^
+
+      meow: string;
+>meow : string
+>     : ^^^^^^
+    }
+  | {
+      type: `${AnimalType.dog}`;
+>type : "dog"
+>     : ^^^^^
+>AnimalType : any
+>           : ^^^
+
+      bark: string;
+>bark : string
+>     : ^^^^^^
+
+    };
+
+function check(p: never) {
+>check : (p: never) => void
+>      : ^ ^^     ^^^^^^^^^
+>p : never
+>  : ^^^^^
+
+  throw new Error("Error!");
+>new Error("Error!") : Error
+>                    : ^^^^^
+>Error : ErrorConstructor
+>      : ^^^^^^^^^^^^^^^^
+>"Error!" : "Error!"
+>         : ^^^^^^^^
+}
+
+function action1(animal: Animal) {
+>action1 : (animal: Animal) => void
+>        : ^      ^^      ^^^^^^^^^
+>animal : Animal
+>       : ^^^^^^
+
+  if (animal.type === AnimalType.cat) {
+>animal.type === AnimalType.cat : boolean
+>                               : ^^^^^^^
+>animal.type : "cat" | "dog"
+>            : ^^^^^^^^^^^^^
+>animal : Animal
+>       : ^^^^^^
+>type : "cat" | "dog"
+>     : ^^^^^^^^^^^^^
+>AnimalType.cat : AnimalType.cat
+>               : ^^^^^^^^^^^^^^
+>AnimalType : typeof AnimalType
+>           : ^^^^^^^^^^^^^^^^^
+>cat : AnimalType.cat
+>    : ^^^^^^^^^^^^^^
+
+    console.log(animal.meow);
+>console.log(animal.meow) : void
+>                         : ^^^^
+>console.log : (...data: any[]) => void
+>            : ^^^^    ^^     ^^^^^    
+>console : Console
+>        : ^^^^^^^
+>log : (...data: any[]) => void
+>    : ^^^^    ^^     ^^^^^    
+>animal.meow : string
+>            : ^^^^^^
+>animal : { type: `${AnimalType.cat}`; meow: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>meow : string
+>     : ^^^^^^
+
+  } else if (animal.type === AnimalType.dog) {
+>animal.type === AnimalType.dog : boolean
+>                               : ^^^^^^^
+>animal.type : "dog"
+>            : ^^^^^
+>animal : { type: `${AnimalType.dog}`; bark: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>type : "dog"
+>     : ^^^^^
+>AnimalType.dog : AnimalType.dog
+>               : ^^^^^^^^^^^^^^
+>AnimalType : typeof AnimalType
+>           : ^^^^^^^^^^^^^^^^^
+>dog : AnimalType.dog
+>    : ^^^^^^^^^^^^^^
+
+    console.log(animal.bark);
+>console.log(animal.bark) : void
+>                         : ^^^^
+>console.log : (...data: any[]) => void
+>            : ^^^^    ^^     ^^^^^    
+>console : Console
+>        : ^^^^^^^
+>log : (...data: any[]) => void
+>    : ^^^^    ^^     ^^^^^    
+>animal.bark : string
+>            : ^^^^^^
+>animal : { type: `${AnimalType.dog}`; bark: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>bark : string
+>     : ^^^^^^
+
+  } else {
+    check(animal);
+>check(animal) : void
+>              : ^^^^
+>check : (p: never) => void
+>      : ^ ^^     ^^^^^^^^^
+>animal : never
+>       : ^^^^^
+  }
+}
+
+function action2(animal: Animal) {
+>action2 : (animal: Animal) => void
+>        : ^      ^^      ^^^^^^^^^
+>animal : Animal
+>       : ^^^^^^
+
+  switch (animal.type) {
+>animal.type : "cat" | "dog"
+>            : ^^^^^^^^^^^^^
+>animal : Animal
+>       : ^^^^^^
+>type : "cat" | "dog"
+>     : ^^^^^^^^^^^^^
+
+    case `${AnimalType.cat}`:
+>`${AnimalType.cat}` : "cat"
+>                    : ^^^^^
+>AnimalType.cat : AnimalType.cat
+>               : ^^^^^^^^^^^^^^
+>AnimalType : typeof AnimalType
+>           : ^^^^^^^^^^^^^^^^^
+>cat : AnimalType.cat
+>    : ^^^^^^^^^^^^^^
+
+      console.log(animal.meow);
+>console.log(animal.meow) : void
+>                         : ^^^^
+>console.log : (...data: any[]) => void
+>            : ^^^^    ^^     ^^^^^    
+>console : Console
+>        : ^^^^^^^
+>log : (...data: any[]) => void
+>    : ^^^^    ^^     ^^^^^    
+>animal.meow : string
+>            : ^^^^^^
+>animal : { type: `${AnimalType.cat}`; meow: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>meow : string
+>     : ^^^^^^
+
+      break;
+    case `${AnimalType.dog}`:
+>`${AnimalType.dog}` : "dog"
+>                    : ^^^^^
+>AnimalType.dog : AnimalType.dog
+>               : ^^^^^^^^^^^^^^
+>AnimalType : typeof AnimalType
+>           : ^^^^^^^^^^^^^^^^^
+>dog : AnimalType.dog
+>    : ^^^^^^^^^^^^^^
+
+      console.log(animal.bark);
+>console.log(animal.bark) : void
+>                         : ^^^^
+>console.log : (...data: any[]) => void
+>            : ^^^^    ^^     ^^^^^    
+>console : Console
+>        : ^^^^^^^
+>log : (...data: any[]) => void
+>    : ^^^^    ^^     ^^^^^    
+>animal.bark : string
+>            : ^^^^^^
+>animal : { type: `${AnimalType.dog}`; bark: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>bark : string
+>     : ^^^^^^
+
+      break;
+    default:
+      check(animal);
+>check(animal) : void
+>              : ^^^^
+>check : (p: never) => void
+>      : ^ ^^     ^^^^^^^^^
+>animal : never
+>       : ^^^^^
+  }
+}
+
+function action3(animal: Animal) {
+>action3 : (animal: Animal) => void
+>        : ^      ^^      ^^^^^^^^^
+>animal : Animal
+>       : ^^^^^^
+
+  switch (animal.type) {
+>animal.type : "cat" | "dog"
+>            : ^^^^^^^^^^^^^
+>animal : Animal
+>       : ^^^^^^
+>type : "cat" | "dog"
+>     : ^^^^^^^^^^^^^
+
+    case AnimalType.cat:
+>AnimalType.cat : AnimalType.cat
+>               : ^^^^^^^^^^^^^^
+>AnimalType : typeof AnimalType
+>           : ^^^^^^^^^^^^^^^^^
+>cat : AnimalType.cat
+>    : ^^^^^^^^^^^^^^
+
+      console.log(animal.meow);
+>console.log(animal.meow) : void
+>                         : ^^^^
+>console.log : (...data: any[]) => void
+>            : ^^^^    ^^     ^^^^^    
+>console : Console
+>        : ^^^^^^^
+>log : (...data: any[]) => void
+>    : ^^^^    ^^     ^^^^^    
+>animal.meow : string
+>            : ^^^^^^
+>animal : { type: `${AnimalType.cat}`; meow: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>meow : string
+>     : ^^^^^^
+
+      break;
+    case AnimalType.dog:
+>AnimalType.dog : AnimalType.dog
+>               : ^^^^^^^^^^^^^^
+>AnimalType : typeof AnimalType
+>           : ^^^^^^^^^^^^^^^^^
+>dog : AnimalType.dog
+>    : ^^^^^^^^^^^^^^
+
+      console.log(animal.bark);
+>console.log(animal.bark) : void
+>                         : ^^^^
+>console.log : (...data: any[]) => void
+>            : ^^^^    ^^     ^^^^^    
+>console : Console
+>        : ^^^^^^^
+>log : (...data: any[]) => void
+>    : ^^^^    ^^     ^^^^^    
+>animal.bark : string
+>            : ^^^^^^
+>animal : { type: `${AnimalType.dog}`; bark: string; }
+>       : ^^^^^^^^                   ^^^^^^^^      ^^^
+>bark : string
+>     : ^^^^^^
+
+      break;
+    default:
+      check(animal);
+>check(animal) : void
+>              : ^^^^
+>check : (p: never) => void
+>      : ^ ^^     ^^^^^^^^^
+>animal : never
+>       : ^^^^^
+  }
+}
+
--- a/tests/cases/conformance/types/union/discriminatedUnionTypes4.ts
+++ b/tests/cases/conformance/types/union/discriminatedUnionTypes4.ts
@ -0,0 +1,59 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/61207
+
+enum AnimalType {
+  cat = "cat",
+  dog = "dog",
+}
+
+type Animal =
+  | {
+      type: `${AnimalType.cat}`;
+      meow: string;
+    }
+  | {
+      type: `${AnimalType.dog}`;
+      bark: string;
+    };
+
+function check(p: never) {
+  throw new Error("Error!");
+}
+
+function action1(animal: Animal) {
+  if (animal.type === AnimalType.cat) {
+    console.log(animal.meow);
+  } else if (animal.type === AnimalType.dog) {
+    console.log(animal.bark);
+  } else {
+    check(animal);
+  }
+}
+
+function action2(animal: Animal) {
+  switch (animal.type) {
+    case `${AnimalType.cat}`:
+      console.log(animal.meow);
+      break;
+    case `${AnimalType.dog}`:
+      console.log(animal.bark);
+      break;
+    default:
+      check(animal);
+  }
+}
+
+function action3(animal: Animal) {
+  switch (animal.type) {
+    case AnimalType.cat:
+      console.log(animal.meow);
+      break;
+    case AnimalType.dog:
+      console.log(animal.bark);
+      break;
+    default:
+      check(animal);
+  }
+}