Reuse single errored signature candidate as resolved signature

[Andarist]

fixes #61500

[Copilot]

Pull Request Overview

This PR enhances overload resolution by reusing a single errored signature candidate as the resolved signature and updates tests and baselines accordingly.

• Adjust overload failure logic in checker.ts to prefer a lone errored candidate
• Add new fourslash tests for failed inference in context-sensitive arguments
• Update numerous baseline reference files to reflect the new signature resolution behavior

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/compiler/checker.ts	Adjust candidate selection to reuse a single errored signature
tests/cases/fourslash/quickInfoFailedInferenceWithContextSensitiveArg2.ts	Add quickInfo test for second context-sensitive failure scenario
tests/cases/fourslash/quickInfoFailedInferenceWithContextSensitiveArg1.ts	Add quickInfo test for first context-sensitive failure scenario
tests/cases/fourslash/completionsFailedInferenceWithContextSensitiveArg1.ts	Add completion test for context-sensitive inference failure
tests/cases/conformance/types/typeRelationships/typeInference/contextualSignatureInstantiation.ts	Update test to use baz signature reuse with explicit b2
tests/baselines/reference/promiseTry.types	Update expected return type for Promise.try
tests/baselines/reference/promisePermutations3.types	Update expected IPromise chaining result
tests/baselines/reference/partiallyAnnotatedFunctionInferenceError.types	Revise expected inference error outputs
tests/baselines/reference/genericCallWithFunctionTypedArguments5.types	Correct expected return type from function-typed argument calls
tests/baselines/reference/generatorTypeCheck62.types	Update expected strategy generator signature
tests/baselines/reference/contextualSignatureInstantiation.types	Reflect new baz return types and renamed b2
tests/baselines/reference/contextualSignatureInstantiation.symbols	Update symbol declarations for b2 and d vars
tests/baselines/reference/contextualSignatureInstantiation.js	Adjust JS baseline for b2 and d variable initializations
tests/baselines/reference/contextualSignatureInstantiation.errors.txt	Update error messages and variable names from b to b2

[Andarist]

This looks bad but this call errors so I think it's a fair game that the returned type changes - as it doesn't quite matter anyway.

The reason it got changed is simple - this got inferred from the implicit any assigned to t2 and t3. The same was always inferred here internally. It's just the final assigned signature was the one computed by inferSignatureInstantiationForOverloadFailure and that ignores context--sensitive arguments.

All of the changes in baselines can be attributed to the same thing. It's just any here is, of course, extra suspicious.

Maybe this could be "improved" but given this callback has more parameters than the contextual signature - the contextual signature is not selected so it can't assign "better" types to t2 and t3. This gets ignored in getContextualCallSignature based on the isAritySmaller check.

[Andarist]

why the change here? it's because now the previous calls are able to change the assigned type to b (by not ignoring generic functions we infer string/number instead of unknown). So the contextual return type here changed from string | number to string and that introduced the error. But that never was the intention of this test case anyway - so I just separated this to decouple this from CFA type changes