Fix isolated declarations to not flag function expressions in call arguments #62125
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Function expressions used as arguments to function calls were incorrectly being flagged for needing explicit return type annotations with
--isolatedDeclarations
, even when they are not directly exported.Issue
Consider this common pattern with libraries like MobX:
Previously, this would generate errors for both the variable declarations AND the function expressions:
Solution
The function expressions themselves should not be flagged since they are arguments to function calls, not directly exported declarations. Only the variables should require type annotations.
This PR modifies
reportInferenceFallback
insrc/compiler/transformers/declarations.ts
to skip isolated declaration error reporting for function expressions and arrow functions that are direct arguments to call expressions.Result
After the fix, the same code now correctly shows only variable-level errors:
This prevents
ts-fix
and other code transformation tools from inserting unnecessary return type annotations on function expressions that don't need them.Fixes #62085.
💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.