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Use strict variance checks for strict subtype checks unconditionally #48123

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949daee
Use strict variance checks for strict subtype checks unconditionally
weswigham Mar 4, 2022
afb0126
Merge branch 'main' into strict-subtype-no-bivariance
weswigham Mar 23, 2022
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13 changes: 7 additions & 6 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -17818,7 +17818,7 @@ namespace ts {
target: Signature,
ignoreReturnTypes: boolean): boolean {
return compareSignaturesRelated(source, target, ignoreReturnTypes ? SignatureCheckMode.IgnoreReturnTypes : 0, /*reportErrors*/ false,
/*errorReporter*/ undefined, /*errorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined) !== Ternary.False;
/*errorReporter*/ undefined, /*errorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined, assignableRelation) !== Ternary.False;
}

type ErrorReporter = (message: DiagnosticMessage, arg0?: string, arg1?: string) => void;
Expand All @@ -17842,7 +17842,8 @@ namespace ts {
errorReporter: ErrorReporter | undefined,
incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined,
compareTypes: TypeComparer,
reportUnreliableMarkers: TypeMapper | undefined): Ternary {
reportUnreliableMarkers: TypeMapper | undefined,
relation: typeof strictSubtypeRelation): Ternary {
// TODO (drosen): De-duplicate code between related functions.
if (source === target) {
return Ternary.True;
Expand Down Expand Up @@ -17872,8 +17873,8 @@ namespace ts {
}

const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown;
const strictVariance = !(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration &&
kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor;
const strictVariance = relation === strictSubtypeRelation || (!(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration &&
kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor);
let result = Ternary.True;

const sourceThisType = getThisTypeOfSignature(source);
Expand Down Expand Up @@ -17913,7 +17914,7 @@ namespace ts {
const callbacks = sourceSig && targetSig && !getTypePredicateOfSignature(sourceSig) && !getTypePredicateOfSignature(targetSig) &&
(getFalsyFlags(sourceType) & TypeFlags.Nullable) === (getFalsyFlags(targetType) & TypeFlags.Nullable);
let related = callbacks ?
compareSignaturesRelated(targetSig, sourceSig, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) :
compareSignaturesRelated(targetSig, sourceSig, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers, relation) :
!(checkMode & SignatureCheckMode.Callback) && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors);
// With strict arity, (x: number | undefined) => void is a subtype of (x?: number | undefined) => void
if (related && checkMode & SignatureCheckMode.StrictArity && i >= getMinArgumentCount(source) && i < getMinArgumentCount(target) && compareTypes(sourceType, targetType, /*reportErrors*/ false)) {
Expand Down Expand Up @@ -20327,7 +20328,7 @@ namespace ts {
*/
function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, incompatibleReporter: (source: Type, target: Type) => void): Ternary {
return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target,
relation === strictSubtypeRelation ? SignatureCheckMode.StrictArity : 0, reportErrors, reportError, incompatibleReporter, isRelatedToWorker, makeFunctionTypeMapper(reportUnreliableMarkers));
relation === strictSubtypeRelation ? SignatureCheckMode.StrictArity : 0, reportErrors, reportError, incompatibleReporter, isRelatedToWorker, makeFunctionTypeMapper(reportUnreliableMarkers), relation);
}

function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary {
Expand Down
4 changes: 2 additions & 2 deletions tests/baselines/reference/arrayLiteralWithMultipleBestCommonTypes.types
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Expand Up @@ -36,8 +36,8 @@ var cs = [a, b, c]; // { x: number; y?: number };[]
>c : { x: number; a?: number; }

var ds = [(x: Object) => 1, (x: string) => 2]; // { (x:Object) => number }[]
>ds : ((x: Object) => number)[]
>[(x: Object) => 1, (x: string) => 2] : ((x: Object) => number)[]
>ds : ((x: string) => number)[]
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This is a pretty big correctness improvement, so we should document it as a breaking change

>[(x: Object) => 1, (x: string) => 2] : ((x: string) => number)[]
>(x: Object) => 1 : (x: Object) => number
>x : Object
>1 : 1
Expand Down
14 changes: 7 additions & 7 deletions tests/baselines/reference/arrayOfFunctionTypes3.types
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Expand Up @@ -50,28 +50,28 @@ var c: { (x: number): number; (x: any): any; };
>x : any

var z = [a, b, c];
>z : { (x: number): number; (x: any): any; }[]
>[a, b, c] : { (x: number): number; (x: any): any; }[]
>z : ({ (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; })[]
>[a, b, c] : ({ (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; })[]
>a : { (x: number): number; (x: string): string; }
>b : { (x: number): number; (x: string): string; }
>c : { (x: number): number; (x: any): any; }

var r4 = z[0];
>r4 : { (x: number): number; (x: any): any; }
>z[0] : { (x: number): number; (x: any): any; }
>z : { (x: number): number; (x: any): any; }[]
>r4 : { (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; }
>z[0] : { (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; }
>z : ({ (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; })[]
>0 : 0

var r5 = r4(''); // any not string
>r5 : any
>r4('') : any
>r4 : { (x: number): number; (x: any): any; }
>r4 : { (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; }
>'' : ""

var r5b = r4(1);
>r5b : number
>r4(1) : number
>r4 : { (x: number): number; (x: any): any; }
>r4 : { (x: number): number; (x: string): string; } | { (x: number): number; (x: any): any; }
>1 : 1

var a2: { <T>(x: T): number; (x: string): string;};
Expand Down
18 changes: 6 additions & 12 deletions tests/baselines/reference/bestChoiceType.symbols
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Expand Up @@ -2,14 +2,12 @@
// Repro from #10041

(''.match(/ /) || []).map(s => s.toLowerCase());
>(''.match(/ /) || []).map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
>(''.match(/ /) || []).map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>''.match : Symbol(String.match, Decl(lib.es5.d.ts, --, --))
>match : Symbol(String.match, Decl(lib.es5.d.ts, --, --))
>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 2, 26))
>s.toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 2, 26))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))

// Similar cases

Expand All @@ -27,13 +25,11 @@ function f1() {

let z = y.map(s => s.toLowerCase());
>z : Symbol(z, Decl(bestChoiceType.ts, 9, 7))
>y.map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
>y.map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>y : Symbol(y, Decl(bestChoiceType.ts, 8, 7))
>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 9, 18))
>s.toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 9, 18))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
}

function f2() {
Expand All @@ -51,12 +47,10 @@ function f2() {

let z = y.map(s => s.toLowerCase());
>z : Symbol(z, Decl(bestChoiceType.ts, 15, 7))
>y.map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
>y.map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>y : Symbol(y, Decl(bestChoiceType.ts, 14, 7))
>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 15, 18))
>s.toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
>s : Symbol(s, Decl(bestChoiceType.ts, 15, 18))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
}

74 changes: 37 additions & 37 deletions tests/baselines/reference/bestChoiceType.types
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Expand Up @@ -2,23 +2,23 @@
// Repro from #10041

(''.match(/ /) || []).map(s => s.toLowerCase());
>(''.match(/ /) || []).map(s => s.toLowerCase()) : string[]
>(''.match(/ /) || []).map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>(''.match(/ /) || []) : RegExpMatchArray
>''.match(/ /) || [] : RegExpMatchArray
>(''.match(/ /) || []).map(s => s.toLowerCase()) : any[]
>(''.match(/ /) || []).map : (<U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]) | (<U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[])
>(''.match(/ /) || []) : RegExpMatchArray | never[]
>''.match(/ /) || [] : RegExpMatchArray | never[]
>''.match(/ /) : RegExpMatchArray | null
>''.match : (regexp: string | RegExp) => RegExpMatchArray | null
>'' : ""
>match : (regexp: string | RegExp) => RegExpMatchArray | null
>/ / : RegExp
>[] : never[]
>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>s => s.toLowerCase() : (s: string) => string
>s : string
>s.toLowerCase() : string
>s.toLowerCase : () => string
>s : string
>toLowerCase : () => string
>map : (<U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]) | (<U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[])
>s => s.toLowerCase() : (s: any) => any
>s : any
>s.toLowerCase() : any
>s.toLowerCase : any
>s : any
>toLowerCase : any

// Similar cases

Expand All @@ -34,23 +34,23 @@ function f1() {
>/ / : RegExp

let y = x || [];
>y : RegExpMatchArray
>x || [] : RegExpMatchArray
>y : RegExpMatchArray | never[]
>x || [] : RegExpMatchArray | never[]
>x : RegExpMatchArray | null
>[] : never[]

let z = y.map(s => s.toLowerCase());
>z : string[]
>y.map(s => s.toLowerCase()) : string[]
>y.map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>y : RegExpMatchArray
>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>s => s.toLowerCase() : (s: string) => string
>s : string
>s.toLowerCase() : string
>s.toLowerCase : () => string
>s : string
>toLowerCase : () => string
>z : any[]
>y.map(s => s.toLowerCase()) : any[]
>y.map : (<U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]) | (<U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[])
>y : RegExpMatchArray | never[]
>map : (<U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]) | (<U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[])
>s => s.toLowerCase() : (s: any) => any
>s : any
>s.toLowerCase() : any
>s.toLowerCase : any
>s : any
>toLowerCase : any
}

function f2() {
Expand All @@ -65,23 +65,23 @@ function f2() {
>/ / : RegExp

let y = x ? x : [];
>y : RegExpMatchArray
>x ? x : [] : RegExpMatchArray
>y : RegExpMatchArray | never[]
>x ? x : [] : RegExpMatchArray | never[]
>x : RegExpMatchArray | null
>x : RegExpMatchArray
>[] : never[]

let z = y.map(s => s.toLowerCase());
>z : string[]
>y.map(s => s.toLowerCase()) : string[]
>y.map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>y : RegExpMatchArray
>map : <U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]
>s => s.toLowerCase() : (s: string) => string
>s : string
>s.toLowerCase() : string
>s.toLowerCase : () => string
>s : string
>toLowerCase : () => string
>z : any[]
>y.map(s => s.toLowerCase()) : any[]
>y.map : (<U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]) | (<U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[])
>y : RegExpMatchArray | never[]
>map : (<U>(callbackfn: (value: string, index: number, array: string[]) => U, thisArg?: any) => U[]) | (<U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[])
>s => s.toLowerCase() : (s: any) => any
>s : any
>s.toLowerCase() : any
>s.toLowerCase : any
>s : any
>toLowerCase : any
}

4 changes: 2 additions & 2 deletions tests/baselines/reference/contextualTypingArrayOfLambdas.types
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Expand Up @@ -23,8 +23,8 @@ class C extends A {
}

var xs = [(x: A) => { }, (x: B) => { }, (x: C) => { }];
>xs : ((x: A) => void)[]
>[(x: A) => { }, (x: B) => { }, (x: C) => { }] : ((x: A) => void)[]
>xs : (((x: B) => void) | ((x: C) => void))[]
>[(x: A) => { }, (x: B) => { }, (x: C) => { }] : (((x: B) => void) | ((x: C) => void))[]
>(x: A) => { } : (x: A) => void
>x : A
>(x: B) => { } : (x: B) => void
Expand Down
6 changes: 3 additions & 3 deletions tests/baselines/reference/flatArrayNoExcessiveStackDepth.types
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Expand Up @@ -36,8 +36,8 @@ const repro_43249 = (value: unknown) => {
>"No" : "No"
}
const match = value.match(/anything/) || [];
>match : RegExpMatchArray
>value.match(/anything/) || [] : RegExpMatchArray
>match : RegExpMatchArray | never[]
>value.match(/anything/) || [] : RegExpMatchArray | never[]
>value.match(/anything/) : RegExpMatchArray | null
>value.match : { (regexp: string | RegExp): RegExpMatchArray | null; (matcher: { [Symbol.match](string: string): RegExpMatchArray | null; }): RegExpMatchArray | null; }
>value : string
Expand All @@ -48,7 +48,7 @@ const repro_43249 = (value: unknown) => {
const [, extracted] = match;
> : undefined
>extracted : string
>match : RegExpMatchArray
>match : RegExpMatchArray | never[]

};

Expand Down
2 changes: 1 addition & 1 deletion tests/baselines/reference/initializedDestructuringAssignmentTypes.types
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Expand Up @@ -3,7 +3,7 @@ const [, a = ''] = ''.match('') || [];
> : undefined
>a : string
>'' : ""
>''.match('') || [] : RegExpMatchArray
>''.match('') || [] : RegExpMatchArray | undefined[]
>''.match('') : RegExpMatchArray
>''.match : (regexp: string | RegExp) => RegExpMatchArray
>'' : ""
Expand Down
61 changes: 61 additions & 0 deletions tests/baselines/reference/strictSubtypeReduction.js
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@@ -0,0 +1,61 @@
//// [strictSubtypeReduction.ts]
// Repro from #41977

class S1 {
static f(a: number | string): void { }
}

class S2 {
static f(a: number): void { }
static g(a: number): void { }
}

function f(a: number): void { }
function g(a: number): void { }

// Declaring the following type aliases should have no effect

type T1 = typeof S2.g;
type T2 = typeof g;

// All should have type ((a: number) => void)[]

const y1 = [S1.f, f];
const y2 = [S1.f, g];
const y3 = [S1.f, S2.f];
const y4 = [S1.f, S2.g];

// All assignments should be errors in strict mode, but won't be without strict function types on

const x1: ((ctrl: number | string) => void)[] = y1;
const x2: ((ctrl: number | string) => void)[] = y2;
const x3: ((ctrl: number | string) => void)[] = y3;
const x4: ((ctrl: number | string) => void)[] = y4;

//// [strictSubtypeReduction.js]
// Repro from #41977
var S1 = /** @class */ (function () {
function S1() {
}
S1.f = function (a) { };
return S1;
}());
var S2 = /** @class */ (function () {
function S2() {
}
S2.f = function (a) { };
S2.g = function (a) { };
return S2;
}());
function f(a) { }
function g(a) { }
// All should have type ((a: number) => void)[]
var y1 = [S1.f, f];
var y2 = [S1.f, g];
var y3 = [S1.f, S2.f];
var y4 = [S1.f, S2.g];
// All assignments should be errors in strict mode, but won't be without strict function types on
var x1 = y1;
var x2 = y2;
var x3 = y3;
var x4 = y4;
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