Allow redefinition of underscore functions (#10811) #85
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This PR causes mypy to not show an error if a function named _ is redefined, as a single underscore is often used as a name for a throwaway function. This handles the case where _ is used as an alias for gettext by differentiating between functions that are aliased as _ but defined with another name, and functions that are defined as _. Overwriting a function named _ is allowed, but overwriting a function named something else but aliased as _ is not allowed, which should prevent people from accidentally overwriting gettext after importing it. This also turns calling a function named _ directly into an error, as currently we keep track of the type of the first definition if there are multiple functions defined as _, instead of the type of the last definition, and functions are usually not meant to be called directly if they're named _.
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Diff from mypy_primer, showing the effect of this PR on open source code: ibis (https://github.com/ibis-project/ibis.git)
- version: 0.920+dev.10203a9ace35c0792b19565f97d8dacc97130c95
+ version: 0.920+dev.3ffdd88eaffea434989d061f6ee06bdf4632638b
- File "/tmp/mypy_primer/old_mypy/venv/bin/mypy", line 8, in <module>
+ File "/tmp/mypy_primer/new_mypy/venv/bin/mypy", line 8, in <module>
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/__main__.py", line 11, in console_entry
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/__main__.py", line 11, in console_entry
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/main.py", line 87, in main
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/main.py", line 87, in main
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/main.py", line 165, in run_build
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/main.py", line 165, in run_build
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 179, in build
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 179, in build
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 254, in _build
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 254, in _build
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 2698, in dispatch
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 2698, in dispatch
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 3022, in process_graph
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 3022, in process_graph
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 3120, in process_stale_scc
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 3120, in process_stale_scc
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 2166, in type_check_first_pass
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/build.py", line 2166, in type_check_first_pass
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checker.py", line 295, in check_first_pass
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checker.py", line 295, in check_first_pass
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checker.py", line 402, in accept
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checker.py", line 402, in accept
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/nodes.py", line 783, in accept
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/nodes.py", line 783, in accept
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checker.py", line 3640, in visit_decorator
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checker.py", line 3640, in visit_decorator
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 951, in check_call
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 951, in check_call
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 932, in check_call
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 932, in check_call
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 1044, in check_callable_call
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 1044, in check_callable_call
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 752, in apply_function_plugin
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/checkexpr.py", line 752, in apply_function_plugin
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/plugins/singledispatch.py", line 192, in call_singledispatch_function_after_register_argument
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/plugins/singledispatch.py", line 192, in call_singledispatch_function_after_register_argument
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/plugins/singledispatch.py", line 159, in register_function
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/plugins/singledispatch.py", line 159, in register_function
- File "/tmp/mypy_primer/old_mypy/venv/lib/python3.8/site-packages/mypy/plugins/singledispatch.py", line 33, in get_singledispatch_info
+ File "/tmp/mypy_primer/new_mypy/venv/lib/python3.8/site-packages/mypy/plugins/singledispatch.py", line 33, in get_singledispatch_info
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This PR causes mypy to not show an error if a function named _ is redefined,
as a single underscore is often used as a name for a throwaway function.
This handles the case where _ is used as an alias for gettext by differentiating
between functions that are aliased as _ but defined with another name,
and functions that are defined as _. Overwriting a function named _ is allowed,
but overwriting a function named something else but aliased as _ is not allowed,
which should prevent people from accidentally overwriting gettext after importing it.
This also turns calling a function named _ directly into an error, as currently we
keep track of the type of the first definition if there are multiple functions defined
as _, instead of the type of the last definition, and functions are usually not meant
to be called directly if they're named _.
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Description
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