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[mypyc] Fix crash on nested function in a method of a non-native class - #22237
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Fixes mypyc/mypyc#1225. Fixes mypyc/mypyc#1205. Compiling a method of a non-native class that contains a nested function or a lambda crashed with an internal error: ```python from mypy_extensions import mypyc_attr @mypyc_attr(native_class=False) class C: def f(self) -> Callable[[], C]: return lambda: self # AssertionError ``` Methods of non-native classes are compiled to callable classes, like nested functions. If a method contains a nested function or a lambda, the method creates an environment object, which holds the variables captured by the nested function (`self` above) and the nested function objects. When adding these to the environment, the IR builder treated the method like a nested function and looked for the environment via the callable class, but only nested functions set it up there. Now the method's own environment is used, as in other functions that aren't nested.
p-sawicki
approved these changes
Oct 20, 2026
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Fixes mypyc/mypyc#1225. Fixes mypyc/mypyc#1205.
Compiling a method of a non-native class that contains a nested function or a lambda crashed with an internal error:
Methods of non-native classes are compiled to callable classes, like nested functions. If a method contains a nested function or a lambda, the method creates an environment object, which holds the variables captured by the nested function (
selfabove) and the nested function objects. When adding these to the environment, the IR builder treated the method like a nested function and looked for the environment via the callable class, but only nested functions set it up there. Now the method's own environment is used, as in other functions that aren't nested.