Drop unnecessary type arguments in the isolated declarations quick fix by blickly · Pull Request #59665 · microsoft/TypeScript

blickly · 2024-08-17T03:47:34Z

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)

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.

src/compiler/types.ts

src/services/codefixes/helpers.ts

src/compiler/types.ts

Co-authored-by: Jake Bailey <5341706+jakebailey@users.noreply.github.com>

Also, mark typeToMinimizedReferenceType as `@internal`.

blickly · 2024-08-20T16:52:37Z

OK, I switched to the more idiomatic way of creating a new AST node, rather than trying to mutate anything. PTAL

jakebailey · 2024-08-20T16:56:29Z

src/services/codefixes/helpers.ts

+        const genericType = type as GenericType;
+        if (genericType.typeArguments) {
+            const cutoff = endOfRequiredTypeParameters(checker, genericType);
+            if (cutoff !== undefined && typeNode.typeArguments) {


cutoff can't be undefined; should this instead be a check that skips this block if the length is different than the existing node?

Good catch. Done.

jakebailey · 2024-08-20T16:58:20Z

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports50-generics-with-default.ts

+    description: "Add annotation of type 'MyIterator<number>'",
+    index: 0,
+    newFileContent:
+`interface MyIterator<T, TReturn = any, TNext = undefined> {}


Do we have tests for generators elsewhere? I seem to recall us auto-adding type long type annotations for those...

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--; } } }

That was a part of #58243.

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.

jakebailey · 2024-08-20T20:51:59Z

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports54-generator-generics.ts

+    description: "Add return type 'Generator<number>'",
+    index: 0,
+    newFileContent:
+`export function foo(x: Generator<number>): Generator<number> {


To be clear I was meaning to write function *foo() { } here and then see what happens.

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.

jakebailey

LGTM I think, but would be good to get a couple of other eyes on it.

blickly · 2024-08-28T20:48:36Z

Any advice on who would make a good secondary reviewer?

src/services/codefixes/helpers.ts

tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports52-gerenrics-oversimplification.ts

…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>

jakebailey · 2024-09-16T17:27:20Z

Tested locally with main and it merges and passes cleanly.

blickly added 3 commits August 16, 2024 19:11

Create a few (failing) test cases of microsoft#58449

dd29423

Add a few more test cases of the "negative" cases

b0bc68f

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.

typescript-bot added the For Backlog Bug PRs that fix a backlog bug label Aug 17, 2024

jakebailey reviewed Aug 17, 2024

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jakebailey reviewed Aug 19, 2024

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First fixes based on code review feedback

de61d6d

blickly force-pushed the dont-suggest-default-generics branch from f4eea52 to de61d6d Compare August 19, 2024 16:35

blickly and others added 4 commits August 19, 2024 09:41

Update src/compiler/types.ts

b0b1e02

Co-authored-by: Jake Bailey <5341706+jakebailey@users.noreply.github.com>

Fix unused import

943761b

Also, mark typeToMinimizedReferenceType as `@internal`.

Run dprint to fix formatting

d53552f

Use factory methods to create new AST node instead of mutating

77ac42f

jakebailey reviewed Aug 20, 2024

View reviewed changes

Avoid updating nodes when unnecessary

71c092a

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.

jakebailey reviewed Aug 20, 2024

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Add example case with a inferred generator return

14deb8e

jakebailey requested review from andrewbranch and weswigham August 20, 2024 22:25

jakebailey approved these changes Aug 20, 2024

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sandersn requested changes Aug 29, 2024

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blickly and others added 3 commits August 29, 2024 14:49

Update tests/cases/fourslash/codeFixMissingTypeAnnotationOnExports52-…

a603aa2

…gerenrics-oversimplification.ts Fix typo Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>

Update src/services/codefixes/helpers.ts

4e21657

Simplify loop Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>

Fix typo in filename

cd0cd4e

blickly force-pushed the dont-suggest-default-generics branch from ee3d89e to cd0cd4e Compare August 29, 2024 22:06

sandersn approved these changes Sep 16, 2024

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jakebailey merged commit 8230bc6 into microsoft:main Sep 16, 2024

blickly mentioned this pull request Feb 17, 2025

[isolatedDecalaration] Quick fix for isolatedDeclarations drops trailing unknown in generics instantiation #61208

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sandersn removed this from PR Backlog Apr 22, 2025

microsoft locked as resolved and limited conversation to collaborators Oct 16, 2025

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blickly commented Aug 17, 2024

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blickly commented Aug 28, 2024

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