Add warning when set "alias" in low level annontated field

[nix010]

Change Summary

Add warning message when user setup annotated field with alias kwarg at low level. #7828.

Related issue number

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @adriangb

[codspeed-hq]

CodSpeed Performance Report

Merging #9170 will not alter performance

_{Comparing nix010:7828-add-warning-on-low-level-alias-in-annotated-field (fc394c5) with main (7501231)}

Summary

✅ 13 untouched benchmarks

[nix010]

please review.

[dmontagu]

Suggested change

	if hasattr(ann_type, '__args__'):
	for anno_arg in ann_type.__args__:
	if _typing_extra.is_annotated(anno_arg):
	for anno_type_arg in _typing_extra.get_args(anno_arg):
	if isinstance(anno_type_arg, FieldInfo) and anno_type_arg.alias is not None:
	warnings.warn(
	f'Field "{ann_name}" has `alias` should be set at higher level to have affect',
	UserWarning,
	)
	break
	break
	for anno_arg in getattr(ann_type, '__args__', ()):
	if not _typing_extra.is_annotated(anno_arg):
	continue
	for anno_type_arg in _typing_extra.get_args(anno_arg):
	if isinstance(anno_type_arg, FieldInfo) and anno_type_arg.alias is not None:
	warnings.warn(
	f'Field "{ann_name}" has `alias` should be set at higher level to have affect',
	UserWarning,
	)
	break

Note: I removed the second break, and it seems to me like including it is problematic — if there are multiple annotated args it looks to me like it won't hit them.

I would prefer if we broke this out into a separate function (private in this module) to get this check moved out-of-line instead of making this method bigger and more complicated than it already is. (In that case, the break can just become return). And if it makes sense to change the code in a different way than suggested above after moving it into its own function, that's fine.

[nix010]

@dmontagu Thank for the suggestions.
As my understand and please correct me if i'm wrong, warning on the first annotated args that has alias set or on all annotated args that have it is the same things !?.

[sydney-runkle]

@nix010,

Thanks for your work on this.

I think we want to warn for each argument where it's a problem, which is what @dmontagu is pointing out.

I agree with his suggestions above! Feel free to ping me when you've made the changes, and I can do a second review!