Fix crash on typevar with forward ref used in other module #20334
+105
−9
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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
Nov 30, 2025
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Fixes #20326
Type variables with forward references in upper bound are known to be problematic. Existing mechanisms to work with them implicitly assumed that they are used in the same module where they are defined, which is not necessarily the case for "old-style" type variables that can be imported.
Note that the simplification I made in
semanal_typeargs.pywould be probably sufficient to fix this, but that would be papering over the real issue, so I am making a bit more principled fix.