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Diffstat (limited to 'docs/userguide/ext_modules.rst')
| -rw-r--r-- | docs/userguide/ext_modules.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/docs/userguide/ext_modules.rst b/docs/userguide/ext_modules.rst index 0467f4ec..9f19e8c7 100644 --- a/docs/userguide/ext_modules.rst +++ b/docs/userguide/ext_modules.rst @@ -84,6 +84,26 @@ compiler and linker options from various sources: .. Ignoring AR, ARFLAGS, RANLIB here because they are used by the (obsolete?) build_clib, not build_ext. +Specifically, if the environment variables ``CC``, ``CPP``, ``CXX``, and ``LDSHARED`` +are set, they will be used instead of the ``sysconfig`` variables of the same names. + +The compiler options appear in the command line in the following order: + +.. Reference: "compiler_so" and distutils.ccompiler.gen_preprocess_options, CCompiler.compile, UnixCCompiler._compile + +* first, the options provided by the ``sysconfig`` variable ``CFLAGS``, +* then, the options provided by the environment variables ``CFLAGS`` and ``CPPFLAGS``, +* then, the options provided by the ``sysconfig`` variable ``CCSHARED``, +* finally, a ``-I`` option for each element of ``Extension.include_dirs``. + +The linker options appear in the command line in the following order: + +.. Reference: "linker_so" and CCompiler.link + +* first, the options provided by environment variables and ``sysconfig`` variables, +* then, a ``-L`` option for each element of ``Extension.library_dirs``, +* finally, a linker-specific option like ``-Wl,-rpath`` for each element of ``Extension.runtime_library_dirs``. + The resulting command line is then processed by the compiler and linker. According to the GCC manual sections on `directory options`_ and `environment variables`_, the C/C++ compiler searches for files named in |