CMake: react to python version changes

The new FindPython-based variant of the CMake scripts caches information
about the chosen Python version that can become stale. For example,
suppose I configure a simple pybind11-based project as follows

```
cmake -S . -B build -GNinja -DPython_ROOT=<path to python 3.8>
```

which will generate `my_extension.cpython-38-x86_64-linux-gnu.so`.
A subsequent change to the python version like

```
cmake -S . -B build -GNinja -DPython_ROOT=<path to python 3.9>
```

does not update all necessary build system information. In particular,
the compiled file is still called
`my_extension.cpython-38-x86_64-linux-gnu.so`.

This commit fixes the problem by detecting changes in
`Python_EXECUTABLE` and re-running Python as needed.

Note that the previous way of detecting Python does not seem to be
affected, it always specifies the right suffix.
This commit is contained in:
Wenzel Jakob 2021-09-24 13:03:57 +02:00
parent 6ad3f874a7
commit 409be8336f

View File

@ -82,6 +82,15 @@ if(NOT DEFINED ${_Python}_EXECUTABLE)
endif() endif()
if(NOT ${_Python}_EXECUTABLE STREQUAL PYTHON_EXECUTABLE_LAST)
# Detect changes to the Python version/binary in subsequent CMake runs, and refresh config if needed
unset(PYTHON_IS_DEBUG CACHE)
unset(PYTHON_MODULE_EXTENSION CACHE)
set(PYTHON_EXECUTABLE_LAST
"${${_Python}_EXECUTABLE}"
CACHE INTERNAL "Python executable during the last CMake run")
endif()
if(NOT DEFINED PYTHON_IS_DEBUG) if(NOT DEFINED PYTHON_IS_DEBUG)
# Debug check - see https://stackoverflow.com/questions/646518/python-how-to-detect-debug-Interpreter # Debug check - see https://stackoverflow.com/questions/646518/python-how-to-detect-debug-Interpreter
execute_process( execute_process(