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pybind / pybind11

Seamless operability between C++11 and Python
https://pybind11.readthedocs.io/
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Disable force-linking with release python311.dll in Debug mode on Windows #4824

Closed andreigh closed 10 months ago

andreigh commented 10 months ago

Description

Compiling Pytorch in Debug mode on Windows gave:

LINK : fatal error LNK1104: cannot open file 'python311.lib'

After investigations I found that the files that include pybind11.h include Python.h with the _DEBUG symbol undef'd, thus triggering the #pragma lib("python311.lib"), which conflicted with the already linked (by CMake) python311_d.lib.

I removed the code changed by this PR, everything compiled successfully (only the Debug python lib is linked now).

This is with the latest VS2022, so I think the workaround is not needed anymore.

Suggested changelog entry:

henryiii commented 10 months ago

All Windows CI fails with LINK : fatal error LNK1104: cannot open file 'python310_d.lib'

andreigh commented 10 months ago

An idea would be to use find_package(PythonLibs 3.0) like in Pytorch, which would fill in PYTHON_LIBRARIES:

optimized;C:/ProgramData/miniconda3/envs/pytorch/libs/python311.lib;debug;C:/Program Files/Python311/libs/python311_d.lib

and then, depending on CMAKE_BUILD_TYPE, use the specific library. But that's quite a big change.

So I am thinking reverting this PR and defining Py_DEBUG in Pytorch if _DEBUG is defined, so the workaround code doesn't get called.

henryiii commented 10 months ago

PythonLibs has been deprecated since CMake 3.12, and has been removed (sort of) in CMake 3.27.

depending on CMAKE_BUILD_TYPE, use the specific library

This is complicated, due to multiconfiguation generators (like VSCode!) not using CMAKE_BUILD_TYPE.