Drop unnecessary type arguments in the isolated declarations quick fix #59665
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This is the TypeNode representation of a ReferenceType that includes the minimal number of typeArguments that are still semantically equivalent to the full type. Also use this functionality in the isolatedDeclaration autofixer to fix microsoft#58449
These are the cases where our heuristic makes some compromise that isn't what we would have preferred, but add the unit tests as a way of documenting the current behavior.
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Co-authored-by: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Also, mark typeToMinimizedReferenceType as `@internal`.
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OK, I switched to the more idiomatic way of creating a new AST node, rather than trying to mutate anything. PTAL |
src/services/codefixes/helpers.ts
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| const genericType = type as GenericType; | ||
| if (genericType.typeArguments) { | ||
| const cutoff = endOfRequiredTypeParameters(checker, genericType); | ||
| if (cutoff !== undefined && typeNode.typeArguments) { |
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cutoff can't be undefined; should this instead be a check that skips this block if the length is different than the existing node?
| description: "Add annotation of type 'MyIterator<number>'", | ||
| index: 0, | ||
| newFileContent: | ||
| `interface MyIterator<T, TReturn = any, TNext = undefined> {} |
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Do we have tests for generators elsewhere? I seem to recall us auto-adding type long type annotations for those...
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Sure, I can add a case with Generator.
For reasons I don't fully understand, Generator<T> and Iterator<T> get generated with the full 3 type arguments, whereas Iterable<T> and IterableIterator<T> are special cased inside the TypeChecker to omit the extra arguments when unnecessary.
The special casing inside typeReferenceToTypeNode:
// Maybe we should do this for more types, but for now we only elide type arguments that are
// identical to their associated type parameters' defaults for `Iterable`, `IterableIterator`,
// `AsyncIterable`, and `AsyncIterableIterator` to provide backwards-compatible .d.ts emit due
// to each now having three type parameters instead of only one.
if (
isReferenceToType(type, getGlobalIterableType(/*reportErrors*/ false)) ||
isReferenceToType(type, getGlobalIterableIteratorType(/*reportErrors*/ false)) ||
isReferenceToType(type, getGlobalAsyncIterableType(/*reportErrors*/ false)) ||
isReferenceToType(type, getGlobalAsyncIterableIteratorType(/*reportErrors*/ false))
) {
if (
!type.node || !isTypeReferenceNode(type.node) || !type.node.typeArguments ||
type.node.typeArguments.length < typeParameterCount
) {
while (typeParameterCount > 0) {
const typeArgument = typeArguments[typeParameterCount - 1];
const typeParameter = type.target.typeParameters[typeParameterCount - 1];
const defaultType = getDefaultFromTypeParameter(typeParameter);
if (!defaultType || !isTypeIdenticalTo(typeArgument, defaultType)) {
break;
}
typeParameterCount--;
}
}
}
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Makes sense. Thanks for the context.
Also include test cases with the global `Generator` and `Iterator` which, unlike `Iterable` and `IterableIterator`, are not special cased in the type system and were previously always generated with 3 type arguments.
| description: "Add return type 'Generator<number>'", | ||
| index: 0, | ||
| newFileContent: | ||
| `export function foo(x: Generator<number>): Generator<number> { |
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To be clear I was meaning to write function *foo() { } here and then see what happens.
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Ah, OK, added.
It's not technically related to the rest of this PR since it gets inferred a precise return that needs all 3 type arguments, but it's a good case to include in the test suite anyway.
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Any advice on who would make a good secondary reviewer? |
tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports52-gerenrics-oversimplification.ts
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tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports52-gerenrics-oversimplification.ts
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tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports52-gerenrics-oversimplification.ts
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…gerenrics-oversimplification.ts Fix typo Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Simplify loop Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
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Tested locally with main and it merges and passes cleanly. |
Drops unnecessary type arguments in the isolated declarations quick fix by repeatedly trying to resolve a resulting reference type with a prefix of the full type arguments until finding the minimal number of arguments that work.
Fixes #58449
(I'm sure that the code at present isn't using the proper APIs, but I'd appreciate feedback)