Fix swapping TypeVars with defaults. #19448
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
randolf-scholz
commented
Jul 15, 2025
Comment on lines
+251
to
+254
| if isinstance(expanded, TypeVarType): | ||
| expanded.default = expanded.default.accept(self) | ||
| else: | ||
| repl = expanded |
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maybe more readable if done the other way round?
expanded = repl.accept(self)
if not isinstance(expanded, TypeVarType):
repl = expanded
else:
expanded.default = expanded.default.accept(self)
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testTypeVarDefaultsSwapMy idea is that we should only return the result of
repl = repl.accept(self)if that result is no longer aTypeVarType, because if we are simply permuting the type variables, then this will be incorrect.