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Always compare rest types as mutable #55793

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a6609d9
Always compare rest types as mutable
jakebailey Sep 20, 2023
88cc10e
Remove unused todo
jakebailey Sep 20, 2023
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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 @@ -20377,8 +20377,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const restIndex = sourceRestType || targetRestType ? paramCount - 1 : -1;

for (let i = 0; i < paramCount; i++) {
const sourceType = i === restIndex ? getRestTypeAtPosition(source, i) : tryGetTypeAtPosition(source, i);
const targetType = i === restIndex ? getRestTypeAtPosition(target, i) : tryGetTypeAtPosition(target, i);
const sourceType = i === restIndex ? getMutableArrayOrTupleType(getRestTypeAtPosition(source, i), /*forceVariadic*/ false) : tryGetTypeAtPosition(source, i);
const targetType = i === restIndex ? getMutableArrayOrTupleType(getRestTypeAtPosition(target, i), /*forceVariadic*/ false) : 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,
Expand Down Expand Up @@ -33195,11 +33195,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return getInferredTypes(context);
}

function getMutableArrayOrTupleType(type: Type) {
return type.flags & TypeFlags.Union ? mapType(type, getMutableArrayOrTupleType) :
// TODO(jakebailey): cache?
function getMutableArrayOrTupleType(type: Type, forceVariadic: boolean): Type {
return type.flags & TypeFlags.Union ? mapType(type, t => getMutableArrayOrTupleType(t, forceVariadic)) :
type.flags & TypeFlags.Any || isMutableArrayOrTuple(getBaseConstraintOfType(type) || type) ? type :
isTupleType(type) ? createTupleType(getElementTypes(type), type.target.elementFlags, /*readonly*/ false, type.target.labeledElementDeclarations) :
createTupleType([type], [ElementFlags.Variadic]);
forceVariadic ? createTupleType([type], [ElementFlags.Variadic]) : type;
}

function getSpreadArgumentType(args: readonly Expression[], index: number, argCount: number, restType: Type, context: InferenceContext | undefined, checkMode: CheckMode) {
Expand All @@ -33214,7 +33215,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
checkExpressionWithContextualType((arg as SpreadElement).expression, restType, context, checkMode);

if (isArrayLikeType(spreadType)) {
return getMutableArrayOrTupleType(spreadType);
return getMutableArrayOrTupleType(spreadType, /*forceVariadic*/ true);
}

return createArrayType(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg), inConstContext);
Expand Down
33 changes: 0 additions & 33 deletions tests/baselines/reference/contextualTupleTypeParameterReadonly.errors.txt
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This file was deleted.

2 changes: 0 additions & 2 deletions tests/baselines/reference/contextualTupleTypeParameterReadonly.js
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Expand Up @@ -15,7 +15,6 @@ eacher((a, b) => {
b;
});

// TODO: https://github.com/microsoft/TypeScript/issues/53255
eacher((...args) => {
const [a, b] = args;
a;
Expand All @@ -34,7 +33,6 @@ eacher(function (a, b) {
a;
b;
});
// TODO: https://github.com/microsoft/TypeScript/issues/53255
eacher(function () {
var args = [];
for (var _i = 0; _i < arguments.length; _i++) {
Expand Down
13 changes: 6 additions & 7 deletions tests/baselines/reference/contextualTupleTypeParameterReadonly.symbols
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Expand Up @@ -38,21 +38,20 @@ eacher((a, b) => {

});

// TODO: https://github.com/microsoft/TypeScript/issues/53255
eacher((...args) => {
>eacher : Symbol(eacher, Decl(contextualTupleTypeParameterReadonly.ts, 7, 5))
>args : Symbol(args, Decl(contextualTupleTypeParameterReadonly.ts, 15, 8))
>args : Symbol(args, Decl(contextualTupleTypeParameterReadonly.ts, 14, 8))

const [a, b] = args;
>a : Symbol(a, Decl(contextualTupleTypeParameterReadonly.ts, 16, 11))
>b : Symbol(b, Decl(contextualTupleTypeParameterReadonly.ts, 16, 13))
>args : Symbol(args, Decl(contextualTupleTypeParameterReadonly.ts, 15, 8))
>a : Symbol(a, Decl(contextualTupleTypeParameterReadonly.ts, 15, 11))
>b : Symbol(b, Decl(contextualTupleTypeParameterReadonly.ts, 15, 13))
>args : Symbol(args, Decl(contextualTupleTypeParameterReadonly.ts, 14, 8))

a;
>a : Symbol(a, Decl(contextualTupleTypeParameterReadonly.ts, 16, 11))
>a : Symbol(a, Decl(contextualTupleTypeParameterReadonly.ts, 15, 11))

b;
>b : Symbol(b, Decl(contextualTupleTypeParameterReadonly.ts, 16, 13))
>b : Symbol(b, Decl(contextualTupleTypeParameterReadonly.ts, 15, 13))

});

1 change: 0 additions & 1 deletion tests/baselines/reference/contextualTupleTypeParameterReadonly.types
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Expand Up @@ -45,7 +45,6 @@ eacher((a, b) => {

});

// TODO: https://github.com/microsoft/TypeScript/issues/53255
eacher((...args) => {
>eacher((...args) => { const [a, b] = args; a; b;}) : void
>eacher : (fn: (...args: readonly [1, "1"] | readonly [2, "2"]) => any) => void
Expand Down
1 change: 0 additions & 1 deletion tests/cases/compiler/contextualTupleTypeParameterReadonly.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,6 @@ eacher((a, b) => {
b;
});

// TODO: https://github.com/microsoft/TypeScript/issues/53255
eacher((...args) => {
const [a, b] = args;
a;
Expand Down