René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Cygwin build fails due to use of Windows-only functions in _tkagg.cpp","articleBody":"### Bug summary\r\n\r\nWhen the build gets to https://github.com/matplotlib/matplotlib/blob/main/src/_tkagg.cpp#L262-L273 on Cygwin, the build fails with a few `goto crosses initialization` warnings, which are easy to fix (closed by #23051), and two `error: ‘PyErr_SetFromWindowsErr’ was not declared in this scope`, which are less easy to fix.\r\n\r\n### Code for reproduction\r\n\r\n```python\r\npip install matplotlib\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\n```con\r\n...\r\nlots of compiler command lines and some warnings (`array subscript has type 'char'`)\r\n...\r\n          gcc ...  -I/usr/include/python3.8 -c src/_tkagg.cpp -o build/temp.cygwin-3.3.4-x86_64-3.8/matplotlib.backends._tkagg/src/_tkagg.o -fvisibility=hidden -flto\r\n          src/_tkagg.cpp: In function ‘void load_tkinter_funcs()’:\r\n          src/_tkagg.cpp:263:9: error: ‘PyErr_SetFromWindowsErr’ was not declared in this scope\r\n            263 |         PyErr_SetFromWindowsErr(0);\r\n                |         ^~~~~~~~~~~~~~~~~~~~~~~\r\n          src/_tkagg.cpp:271:9: error: ‘PyErr_SetFromWindowsErr’ was not declared in this scope\r\n            271 |         PyErr_SetFromWindowsErr(0);\r\n                |         ^~~~~~~~~~~~~~~~~~~~~~~\r\n          src/_tkagg.cpp:283:1: error: jump to label ‘exit’\r\n            283 | exit:\r\n                | ^~~~\r\n          src/_tkagg.cpp:272:14: note:   from here\r\n            272 |         goto exit;\r\n                |              ^~~~\r\n          src/_tkagg.cpp:274:26: note:   crosses initialization of ‘bool tk_ok’\r\n            274 |     bool tcl_ok = false, tk_ok = false;\r\n                |                          ^~~~~\r\n          src/_tkagg.cpp:274:10: note:   crosses initialization of ‘bool tcl_ok’\r\n            274 |     bool tcl_ok = false, tk_ok = false;\r\n                |          ^~~~~~\r\n          src/_tkagg.cpp:283:1: error: jump to label ‘exit’\r\n            283 | exit:\r\n                | ^~~~\r\n          src/_tkagg.cpp:268:14: note:   from here\r\n            268 |         goto exit;\r\n                |              ^~~~\r\n          src/_tkagg.cpp:274:26: note:   crosses initialization of ‘bool tk_ok’\r\n            274 |     bool tcl_ok = false, tk_ok = false;\r\n                |                          ^~~~~\r\n          src/_tkagg.cpp:274:10: note:   crosses initialization of ‘bool tcl_ok’\r\n            274 |     bool tcl_ok = false, tk_ok = false;\r\n                |          ^~~~~~\r\n          src/_tkagg.cpp:283:1: error: jump to label ‘exit’\r\n            283 | exit:\r\n                | ^~~~\r\n          src/_tkagg.cpp:264:14: note:   from here\r\n            264 |         goto exit;\r\n                |              ^~~~\r\n          src/_tkagg.cpp:274:26: note:   crosses initialization of ‘bool tk_ok’\r\n            274 |     bool tcl_ok = false, tk_ok = false;\r\n                |                          ^~~~~\r\n          src/_tkagg.cpp:274:10: note:   crosses initialization of ‘bool tcl_ok’\r\n            274 |     bool tcl_ok = false, tk_ok = false;\r\n                |          ^~~~~~\r\n          error: command '/usr/bin/gcc' failed with exit code 1\r\n...\r\npip reminds me this is not pip's fault\r\n ```\r\n\r\n### Expected outcome\r\n\r\n```con\r\n...\r\nSuccessfully installed collected packages: matplotlib\r\n```\r\n\r\n### Additional information\r\n\r\nCygwin 3.3.4\r\nGCC 11.2.0\r\nPython 3.8.12\r\n\r\nI've installed matplotlib in earlier versions.  #17415 rather suggests that Cygwin builds worked at that time, and probably made using the default backend somewhat easier.  #22445 seems to be where the `PyErr_SetFromWindowsErr` calls came in.\r\n\r\nI've attempted to create a dummy `PyErr_SetFromWindowsErr` on Cygwin, but, given the number of failures in the test suite, I probably didn't do it right.\r\n\r\n### Operating system\r\n\r\nCygwin 3.3.4 on Windows 10\r\n\r\n### Matplotlib Version\r\n\r\n3.5.2\r\n\r\n### Matplotlib Backend\r\n\r\nTkAgg\r\n\r\n### Python version\r\n\r\n3.8.12\r\n\r\n### Jupyter version\r\n\r\nN/A\r\n\r\n### Installation\r\n\r\npip","author":{"url":"https://github.com/DWesl","@type":"Person","name":"DWesl"},"datePublished":"2022-05-06T22:08:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/22997/matplotlib/issues/22997"}