Hi Brad, Thanks for the quick and helpful response!
I've had a quick education on CMake variable scoping, and now realise that the cached PYTHON_LIBRARY variable, which contains either the user-specified library or the found release library, becomes eclipsed by a local PYTHON_LIBRARY variable, set in SELECT_LIBRARY_CONFIGURATIONS() when FindPythonLibs is run, and in multi-configuration builds the variable becomes a list containing: "optimized;PYTHON_LIBRARY_RELEASE;debug;PYTHON_LIBRARY_DEBUG". This would not be a problem except that FindPythonLibs assigns it to PYTHON_LIBRARY_RELEASE, which then feeds into the new PYTHON_LIBRARY list. So I've attached an improved fix, which is much simpler: it determines whether PYTHON_LIBRARY is a list and extracts the optimized library out of it. It would be nice if it were more elegant or a standard function were available to do this as needed elsewhere. The obvious question is whether our re-running of find_package(PythonLibs) is bad practice... It comes about because one CMakeLists does a first check on whether python is available, then another builds SWIG interfaces using it. OTOH the way the PYTHON_LIBRARY variable is manipulated is quite unexpected, however I imagine there are a lot of behaviours in these scripts which you're stuck with for legacy reasons... Regards, Richard -----Original Message----- From: Brad King [mailto:brad.k...@kitware.com] Sent: Friday, 1 April 2016 2:38 a.m. To: Richard Christie Cc: cmake-developers@cmake.org Subject: Re: [cmake-developers] Fix for FindPythonLibs with multiple configurations Hi Richard, > The attached patch fixes this nesting issue. Thanks for working on this. Please look at revising this to avoid exposing the _ANYCONFIG variable. Use a "_Python_..." internal variable that is unset, or find another way to do it without the variable, such as `(PYTHON_RELEASE_LIBRARY OR PYTHON_DEBUG_LIBRARY)`. > idiom for dealing with pre-specified multi-configuration libraries I don't think our find modules ever consider the possibility of pre-specified multi-config libraries. Each cache entry is meant to hold a single find_library result and the module puts them together. The leaking across multiple calls was not intentional. Therefore this is not a concern for me. Thanks, -Brad
0001-Fix-re-running-FindPythonLibs-for-multi-config.patch
Description: 0001-Fix-re-running-FindPythonLibs-for-multi-config.patch
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