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Don't relate unmatched parameter positions in signatures (#41308)

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* Don't relate unmatched parameter positions in signatures

* Add regression test

* Accept new baselines
This commit is contained in:
Anders Hejlsberg
2020-10-28 11:55:32 -07:00
committed by GitHub
parent 3eed4a61d1
commit bd27bd8d47
5 changed files with 82 additions and 28 deletions
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58
src/compiler/checker.ts
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@@ -16156,36 +16156,38 @@ namespace ts {
const restIndex = sourceRestType || targetRestType ? paramCount - 1 : -1;
for (let i = 0; i < paramCount; i++) {
const sourceType = i === restIndex ? getRestTypeAtPosition(source, i) : getTypeAtPosition(source, i);
const targetType = i === restIndex ? getRestTypeAtPosition(target, i) : getTypeAtPosition(target, i);
// In order to ensure that any generic type Foo<T> is at least co-variant with respect to T no matter
// how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions,
// they naturally relate only contra-variantly). However, if the source and target parameters both have
// function types with a single call signature, we know we are relating two callback parameters. In
// that case it is sufficient to only relate the parameters of the signatures co-variantly because,
// similar to return values, callback parameters are output positions. This means that a Promise<T>,
// where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant)
// with respect to T.
const sourceSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(sourceType));
const targetSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(targetType));
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) :
!(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)) {
related = Ternary.False;
}
if (!related) {
if (reportErrors) {
errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible,
unescapeLeadingUnderscores(getParameterNameAtPosition(source, i)),
unescapeLeadingUnderscores(getParameterNameAtPosition(target, i)));
const sourceType = i === restIndex ? getRestTypeAtPosition(source, i) : tryGetTypeAtPosition(source, i);
const targetType = i === restIndex ? getRestTypeAtPosition(target, i) : tryGetTypeAtPosition(target, i);
if (sourceType && targetType) {
// In order to ensure that any generic type Foo<T> is at least co-variant with respect to T no matter
// how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions,
// they naturally relate only contra-variantly). However, if the source and target parameters both have
// function types with a single call signature, we know we are relating two callback parameters. In
// that case it is sufficient to only relate the parameters of the signatures co-variantly because,
// similar to return values, callback parameters are output positions. This means that a Promise<T>,
// where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant)
// with respect to T.
const sourceSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(sourceType));
const targetSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(targetType));
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) :
!(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)) {
related = Ternary.False;
}
return Ternary.False;
if (!related) {
if (reportErrors) {
errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible,
unescapeLeadingUnderscores(getParameterNameAtPosition(source, i)),
unescapeLeadingUnderscores(getParameterNameAtPosition(target, i)));
}
return Ternary.False;
}
result &= related;
}
result &= related;
}
if (!(checkMode & SignatureCheckMode.IgnoreReturnTypes)) {

13
tests/baselines/reference/unmatchedParameterPositions.js Normal file
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@@ -0,0 +1,13 @@
//// [unmatchedParameterPositions.ts]
// Repros from #40251
declare let s: (...items: never[]) => never[];
let t1: () => unknown[] = s;
let t2: (...args: []) => unknown[] = s;
//// [unmatchedParameterPositions.js]
"use strict";
// Repros from #40251
var t1 = s;
var t2 = s;

16
tests/baselines/reference/unmatchedParameterPositions.symbols Normal file
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@@ -0,0 +1,16 @@
=== tests/cases/compiler/unmatchedParameterPositions.ts ===
// Repros from #40251
declare let s: (...items: never[]) => never[];
>s : Symbol(s, Decl(unmatchedParameterPositions.ts, 2, 11))
>items : Symbol(items, Decl(unmatchedParameterPositions.ts, 2, 16))
let t1: () => unknown[] = s;
>t1 : Symbol(t1, Decl(unmatchedParameterPositions.ts, 3, 3))
>s : Symbol(s, Decl(unmatchedParameterPositions.ts, 2, 11))
let t2: (...args: []) => unknown[] = s;
>t2 : Symbol(t2, Decl(unmatchedParameterPositions.ts, 4, 3))
>args : Symbol(args, Decl(unmatchedParameterPositions.ts, 4, 9))
>s : Symbol(s, Decl(unmatchedParameterPositions.ts, 2, 11))

16
tests/baselines/reference/unmatchedParameterPositions.types Normal file
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@@ -0,0 +1,16 @@
=== tests/cases/compiler/unmatchedParameterPositions.ts ===
// Repros from #40251
declare let s: (...items: never[]) => never[];
>s : (...items: never[]) => never[]
>items : never[]
let t1: () => unknown[] = s;
>t1 : () => unknown[]
>s : (...items: never[]) => never[]
let t2: (...args: []) => unknown[] = s;
>t2 : () => unknown[]
>args : []
>s : (...items: never[]) => never[]

7
tests/cases/compiler/unmatchedParameterPositions.ts Normal file
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@@ -0,0 +1,7 @@
// @strict: true
// Repros from #40251
declare let s: (...items: never[]) => never[];
let t1: () => unknown[] = s;
let t2: (...args: []) => unknown[] = s;