Retain None (unreachable) when typemap is None with type(x) is Foo check
#18486
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
hauntsaninja
approved these changes
Jan 26, 2025
Comment on lines
+5917
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5921
| if all(m is None for m in list_maps): | ||
| return None | ||
| result_map = {} | ||
| for d in list_maps: | ||
| if d is not None: |
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Suggested change
| if all(m is None for m in list_maps): | |
| return None | |
| result_map = {} | |
| for d in list_maps: | |
| if d is not None: | |
| result_map = None | |
| for d in list_maps: | |
| if d is not None: | |
| if result_map is None: | |
| result_map = {} |
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I'd keep my version if you don't mind: this part isn't hot (only reachable when we actually have some type(x) <op> Something checks), and I find it more explicit/slightly easier to follow. This shouldn't have any measurable performance impact.
x612skm
pushed a commit
to x612skm/mypy-dev
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Feb 24, 2025
…check (python#18486) Fixes python#18428. Prevents rewriting `None` ("unreachable") typemaps as empty dicts ("nothing to infer")
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Fixes #18428.
Prevents rewriting
None("unreachable") typemaps as empty dicts ("nothing to infer")