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Merge pull request #17767 from tycho01/15768-generic-numeric-index-error

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loosen number index check, fixes #15768
This commit is contained in:
Anders Hejlsberg 2017-08-14 19:02:06 +02:00 committed by GitHub
parent 543e0affff 4268e13cde
commit a1cbeb2eca
5 changed files with 22 additions and 7 deletions
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11
src/compiler/checker.ts
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@ -18761,13 +18761,10 @@ namespace ts {
if (isTypeAssignableTo(indexType, getIndexType(objectType))) {
return type;
}
// Check if we're indexing with a numeric type and the object type is a generic
// type with a constraint that has a numeric index signature.
if (maybeTypeOfKind(objectType, TypeFlags.TypeVariable) && isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) {
const constraint = getBaseConstraintOfType(objectType);
if (constraint && getIndexInfoOfType(constraint, IndexKind.Number)) {
return type;
}
// Check if we're indexing with a numeric type and if either object or index types
// is a generic type with a constraint that has a numeric index signature.
if (getIndexInfoOfType(getApparentType(objectType), IndexKind.Number) && isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) {
return type;
}
error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(objectType));
return type;

5
tests/baselines/reference/genericNumberIndex.js Normal file
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@ -0,0 +1,5 @@
//// [genericNumberIndex.ts]
type X<I extends number> = ['a'][I];
//// [genericNumberIndex.js]

6
tests/baselines/reference/genericNumberIndex.symbols Normal file
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@ -0,0 +1,6 @@
=== tests/cases/compiler/genericNumberIndex.ts ===
type X<I extends number> = ['a'][I];
>X : Symbol(X, Decl(genericNumberIndex.ts, 0, 0))
>I : Symbol(I, Decl(genericNumberIndex.ts, 0, 7))
>I : Symbol(I, Decl(genericNumberIndex.ts, 0, 7))

6
tests/baselines/reference/genericNumberIndex.types Normal file
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@ -0,0 +1,6 @@
=== tests/cases/compiler/genericNumberIndex.ts ===
type X<I extends number> = ['a'][I];
>X : ["a"][I]
>I : I
>I : I

1
tests/cases/compiler/genericNumberIndex.ts Normal file
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@ -0,0 +1 @@
type X<I extends number> = ['a'][I];