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Improve how intersections are classified as weak types #60889
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50 changes: 50 additions & 0 deletions
50
tests/baselines/reference/weakTypeIntersections1.errors.txt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| weakTypeIntersections1.ts(11,7): error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo> & ThisType<{ x: string; }>'. | ||
| weakTypeIntersections1.ts(12,7): error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo>'. | ||
| weakTypeIntersections1.ts(13,7): error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo> & EmptyInterface'. | ||
| weakTypeIntersections1.ts(15,7): error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo> & Partial<Bar>'. | ||
| weakTypeIntersections1.ts(23,1): error TS2769: No overload matches this call. | ||
| Overload 1 of 2, '(arg: () => Foo & ThisType<Foo>): void', gave the following error. | ||
| Type 'number' is not assignable to type 'string'. | ||
| Overload 2 of 2, '(arg: Partial<Foo> & ThisType<Foo>): void', gave the following error. | ||
| Type '() => { a: number; }' has no properties in common with type 'Partial<Foo> & ThisType<Foo>'. | ||
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| ==== weakTypeIntersections1.ts (5 errors) ==== | ||
| interface EmptyInterface {} | ||
| interface EmptyInterface2 {} | ||
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| interface Foo { | ||
| a: string; | ||
| } | ||
| interface Bar { | ||
| b: string; | ||
| } | ||
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| const m1: Partial<Foo> & ThisType<{ x: string }> = () => null; // error | ||
| ~~ | ||
| !!! error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo> & ThisType<{ x: string; }>'. | ||
| const m2: Partial<Foo> = () => null; // error | ||
| ~~ | ||
| !!! error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo>'. | ||
| const m3: Partial<Foo> & EmptyInterface = () => null; // error | ||
| ~~ | ||
| !!! error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo> & EmptyInterface'. | ||
| const m4: EmptyInterface & EmptyInterface2 = () => null; // ok | ||
| const m5: Partial<Foo> & Partial<Bar> = () => null; // error | ||
| ~~ | ||
| !!! error TS2559: Type '() => null' has no properties in common with type 'Partial<Foo> & Partial<Bar>'. | ||
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| // https://github.com/microsoft/TypeScript/issues/56995 | ||
| declare function fun0(arg: () => Foo & ThisType<Foo>): void; | ||
| declare function fun0(arg: Partial<Foo> & ThisType<Foo>): void; | ||
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| fun0({ a: "1" }); // ok | ||
| fun0(() => ({ a: "1" })); // ok | ||
| fun0(() => ({ a: 1 })); // error | ||
| ~~~~ | ||
| !!! error TS2769: No overload matches this call. | ||
| !!! error TS2769: Overload 1 of 2, '(arg: () => Foo & ThisType<Foo>): void', gave the following error. | ||
| !!! error TS2769: Type 'number' is not assignable to type 'string'. | ||
| !!! error TS2769: Overload 2 of 2, '(arg: Partial<Foo> & ThisType<Foo>): void', gave the following error. | ||
| !!! error TS2769: Type '() => { a: number; }' has no properties in common with type 'Partial<Foo> & ThisType<Foo>'. | ||
| !!! related TS6500 weakTypeIntersections1.ts:5:3: The expected type comes from property 'a' which is declared here on type 'Foo & ThisType<Foo>' |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,80 @@ | ||
| //// [tests/cases/compiler/weakTypeIntersections1.ts] //// | ||
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| === weakTypeIntersections1.ts === | ||
| interface EmptyInterface {} | ||
| >EmptyInterface : Symbol(EmptyInterface, Decl(weakTypeIntersections1.ts, 0, 0)) | ||
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| interface EmptyInterface2 {} | ||
| >EmptyInterface2 : Symbol(EmptyInterface2, Decl(weakTypeIntersections1.ts, 0, 27)) | ||
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| interface Foo { | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
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| a: string; | ||
| >a : Symbol(Foo.a, Decl(weakTypeIntersections1.ts, 3, 15)) | ||
| } | ||
| interface Bar { | ||
| >Bar : Symbol(Bar, Decl(weakTypeIntersections1.ts, 5, 1)) | ||
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| b: string; | ||
| >b : Symbol(Bar.b, Decl(weakTypeIntersections1.ts, 6, 15)) | ||
| } | ||
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| const m1: Partial<Foo> & ThisType<{ x: string }> = () => null; // error | ||
| >m1 : Symbol(m1, Decl(weakTypeIntersections1.ts, 10, 5)) | ||
| >Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
| >ThisType : Symbol(ThisType, Decl(lib.es5.d.ts, --, --)) | ||
| >x : Symbol(x, Decl(weakTypeIntersections1.ts, 10, 35)) | ||
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| const m2: Partial<Foo> = () => null; // error | ||
| >m2 : Symbol(m2, Decl(weakTypeIntersections1.ts, 11, 5)) | ||
| >Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
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| const m3: Partial<Foo> & EmptyInterface = () => null; // error | ||
| >m3 : Symbol(m3, Decl(weakTypeIntersections1.ts, 12, 5)) | ||
| >Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
| >EmptyInterface : Symbol(EmptyInterface, Decl(weakTypeIntersections1.ts, 0, 0)) | ||
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| const m4: EmptyInterface & EmptyInterface2 = () => null; // ok | ||
| >m4 : Symbol(m4, Decl(weakTypeIntersections1.ts, 13, 5)) | ||
| >EmptyInterface : Symbol(EmptyInterface, Decl(weakTypeIntersections1.ts, 0, 0)) | ||
| >EmptyInterface2 : Symbol(EmptyInterface2, Decl(weakTypeIntersections1.ts, 0, 27)) | ||
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| const m5: Partial<Foo> & Partial<Bar> = () => null; // error | ||
| >m5 : Symbol(m5, Decl(weakTypeIntersections1.ts, 14, 5)) | ||
| >Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
| >Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --)) | ||
| >Bar : Symbol(Bar, Decl(weakTypeIntersections1.ts, 5, 1)) | ||
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| // https://github.com/microsoft/TypeScript/issues/56995 | ||
| declare function fun0(arg: () => Foo & ThisType<Foo>): void; | ||
| >fun0 : Symbol(fun0, Decl(weakTypeIntersections1.ts, 14, 51), Decl(weakTypeIntersections1.ts, 17, 60)) | ||
| >arg : Symbol(arg, Decl(weakTypeIntersections1.ts, 17, 22)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
| >ThisType : Symbol(ThisType, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
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| declare function fun0(arg: Partial<Foo> & ThisType<Foo>): void; | ||
| >fun0 : Symbol(fun0, Decl(weakTypeIntersections1.ts, 14, 51), Decl(weakTypeIntersections1.ts, 17, 60)) | ||
| >arg : Symbol(arg, Decl(weakTypeIntersections1.ts, 18, 22)) | ||
| >Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
| >ThisType : Symbol(ThisType, Decl(lib.es5.d.ts, --, --)) | ||
| >Foo : Symbol(Foo, Decl(weakTypeIntersections1.ts, 1, 28)) | ||
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| fun0({ a: "1" }); // ok | ||
| >fun0 : Symbol(fun0, Decl(weakTypeIntersections1.ts, 14, 51), Decl(weakTypeIntersections1.ts, 17, 60)) | ||
| >a : Symbol(a, Decl(weakTypeIntersections1.ts, 20, 6)) | ||
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| fun0(() => ({ a: "1" })); // ok | ||
| >fun0 : Symbol(fun0, Decl(weakTypeIntersections1.ts, 14, 51), Decl(weakTypeIntersections1.ts, 17, 60)) | ||
| >a : Symbol(a, Decl(weakTypeIntersections1.ts, 21, 13)) | ||
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| fun0(() => ({ a: 1 })); // error | ||
| >fun0 : Symbol(fun0, Decl(weakTypeIntersections1.ts, 14, 51), Decl(weakTypeIntersections1.ts, 17, 60)) | ||
| >a : Symbol(a, Decl(weakTypeIntersections1.ts, 22, 13)) | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,106 @@ | ||
| //// [tests/cases/compiler/weakTypeIntersections1.ts] //// | ||
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| === weakTypeIntersections1.ts === | ||
| interface EmptyInterface {} | ||
| interface EmptyInterface2 {} | ||
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| interface Foo { | ||
| a: string; | ||
| >a : string | ||
| > : ^^^^^^ | ||
| } | ||
| interface Bar { | ||
| b: string; | ||
| >b : string | ||
| > : ^^^^^^ | ||
| } | ||
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| const m1: Partial<Foo> & ThisType<{ x: string }> = () => null; // error | ||
| >m1 : Partial<Foo> & ThisType<{ x: string; }> | ||
| > : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^ | ||
| >x : string | ||
| > : ^^^^^^ | ||
| >() => null : () => null | ||
| > : ^^^^^^^^^^ | ||
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| const m2: Partial<Foo> = () => null; // error | ||
| >m2 : Partial<Foo> | ||
| > : ^^^^^^^^^^^^ | ||
| >() => null : () => null | ||
| > : ^^^^^^^^^^ | ||
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| const m3: Partial<Foo> & EmptyInterface = () => null; // error | ||
| >m3 : Partial<Foo> & EmptyInterface | ||
| > : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| >() => null : () => null | ||
| > : ^^^^^^^^^^ | ||
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| const m4: EmptyInterface & EmptyInterface2 = () => null; // ok | ||
| >m4 : EmptyInterface & EmptyInterface2 | ||
| > : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| >() => null : () => null | ||
| > : ^^^^^^^^^^ | ||
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| const m5: Partial<Foo> & Partial<Bar> = () => null; // error | ||
| >m5 : Partial<Foo> & Partial<Bar> | ||
| > : ^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| >() => null : () => null | ||
| > : ^^^^^^^^^^ | ||
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| // https://github.com/microsoft/TypeScript/issues/56995 | ||
| declare function fun0(arg: () => Foo & ThisType<Foo>): void; | ||
| >fun0 : { (arg: () => Foo & ThisType<Foo>): void; (arg: Partial<Foo> & ThisType<Foo>): void; } | ||
| > : ^^^ ^^ ^^^ ^^^ ^^ ^^^ ^^^ | ||
| >arg : () => Foo & ThisType<Foo> | ||
| > : ^^^^^^ | ||
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| declare function fun0(arg: Partial<Foo> & ThisType<Foo>): void; | ||
| >fun0 : { (arg: () => Foo & ThisType<Foo>): void; (arg: Partial<Foo> & ThisType<Foo>): void; } | ||
| > : ^^^ ^^ ^^^ ^^^ ^^ ^^^ ^^^ | ||
| >arg : Partial<Foo> & ThisType<Foo> | ||
| > : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
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| fun0({ a: "1" }); // ok | ||
| >fun0({ a: "1" }) : void | ||
| > : ^^^^ | ||
| >fun0 : { (arg: () => Foo & ThisType<Foo>): void; (arg: Partial<Foo> & ThisType<Foo>): void; } | ||
| > : ^^^ ^^ ^^^ ^^^ ^^ ^^^ ^^^ | ||
| >{ a: "1" } : { a: string; } | ||
| > : ^^^^^^^^^^^^^^ | ||
| >a : string | ||
| > : ^^^^^^ | ||
| >"1" : "1" | ||
| > : ^^^ | ||
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| fun0(() => ({ a: "1" })); // ok | ||
| >fun0(() => ({ a: "1" })) : void | ||
| > : ^^^^ | ||
| >fun0 : { (arg: () => Foo & ThisType<Foo>): void; (arg: Partial<Foo> & ThisType<Foo>): void; } | ||
| > : ^^^ ^^ ^^^ ^^^ ^^ ^^^ ^^^ | ||
| >() => ({ a: "1" }) : () => { a: string; } | ||
| > : ^^^^^^^^^^^^^^^^^^^^ | ||
| >({ a: "1" }) : { a: string; } | ||
| > : ^^^^^^^^^^^^^^ | ||
| >{ a: "1" } : { a: string; } | ||
| > : ^^^^^^^^^^^^^^ | ||
| >a : string | ||
| > : ^^^^^^ | ||
| >"1" : "1" | ||
| > : ^^^ | ||
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| fun0(() => ({ a: 1 })); // error | ||
| >fun0(() => ({ a: 1 })) : void | ||
| > : ^^^^ | ||
| >fun0 : { (arg: () => Foo & ThisType<Foo>): void; (arg: Partial<Foo> & ThisType<Foo>): void; } | ||
| > : ^^^ ^^ ^^^ ^^^ ^^ ^^^ ^^^ | ||
| >() => ({ a: 1 }) : () => { a: number; } | ||
| > : ^^^^^^^^^^^^^^^^^^^^ | ||
| >({ a: 1 }) : { a: number; } | ||
| > : ^^^^^^^^^^^^^^ | ||
| >{ a: 1 } : { a: number; } | ||
| > : ^^^^^^^^^^^^^^ | ||
| >a : number | ||
| > : ^^^^^^ | ||
| >1 : 1 | ||
| > : ^ | ||
|
|
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,26 @@ | ||
| // @strict: true | ||
| // @noEmit: true | ||
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| interface EmptyInterface {} | ||
| interface EmptyInterface2 {} | ||
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| interface Foo { | ||
| a: string; | ||
| } | ||
| interface Bar { | ||
| b: string; | ||
| } | ||
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| const m1: Partial<Foo> & ThisType<{ x: string }> = () => null; // error | ||
| const m2: Partial<Foo> = () => null; // error | ||
| const m3: Partial<Foo> & EmptyInterface = () => null; // error | ||
| const m4: EmptyInterface & EmptyInterface2 = () => null; // ok | ||
| const m5: Partial<Foo> & Partial<Bar> = () => null; // error | ||
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| // https://github.com/microsoft/TypeScript/issues/56995 | ||
| declare function fun0(arg: () => Foo & ThisType<Foo>): void; | ||
| declare function fun0(arg: Partial<Foo> & ThisType<Foo>): void; | ||
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| fun0({ a: "1" }); // ok | ||
| fun0(() => ({ a: "1" })); // ok | ||
| fun0(() => ({ a: 1 })); // error |
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The idea behind the fix is that an empty object type should not be considered to be weak on its own. That's comes from the pre-existing requirement for weak types:
However, when it's intersected with a weak type that should not make it, out of a sudden, non-weak. The new logic still maintains the invariant that an intersection of many empty interfaces is not considered to be weak (it should obey the same rules as a single empty interface).
All of that doesn't change the definition put in the existing code comment:
Actually, the old behavior wasn't enforcing those rules for intersections precisely enough. The proposed adjustment is closer to checking the intersection as a single type with a flat list of properties instead of checking separate types and combining those results "blindly". I think it's more accurate to do it this way because for most purposes an intersection shouldn't be distinguishable from the same type with a "flattened" list of properties.