bpo-14527: fix (some) _ctypes liffi build problems #20451
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Worked for my setup. Before following this commit, I had set PKG_CONFIG_PATH, LD_LIBRARY_PATH, LD_RUN_PATH and LIBRARY_PATH point towards the appropriate locations. ./configure did set correctly LIBFFI_INCLUDEDIR using pkgconfig Still couldn't build module _ctypes This commit solved my issue. |
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This patch seems correct to me. |
| if ffi_inc is not None: | ||
| for lib_name in ('ffi', 'ffi_pic'): | ||
| if (self.compiler.find_library_file(self.lib_dirs, lib_name)): | ||
| fullpath = self.compiler.find_library_file(self.lib_dirs + ffi_libdir, lib_name) |
pmp-p
Nov 22, 2020
Contributor
Why use setup.py heuristics to find libname when you could just let pkgconfig gives the right hint for compilation host/target with pkg-config libffi --libs-only-l like you did with LIBFFI_LIBDIR and LIBFFI_INCLUDEDIR ?
rupertnash
Dec 2, 2020
Author
That is a reasonable question.
The true answer is that while making my changes I tried to keep them as small as practical.
However when I came here to respond, I notice that this library search checks for libffi and libffi_pic, whether or not pkg-config is available on the compilation host.
If we simply create a new configure variable with say:
LIBFFI_LIBNAME="`"$PKG_CONFIG" libffi --libs-only-l 2> /dev/null | sed -e 's/^-l//;s/ *$//'`"
then we will lose the ability to find libffi_pic.{so,a} if there's no pkg-config.
We could set a default like LIBFFI_LIBNAME="ffi ffi_pic" and then have setup.py split it's value on space before looping much as now...
My feeling is to stick as we are, but happy to defer to core team
pmp-p
Dec 5, 2020
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Contributor
whether or not pkg-config is available on the compilation host.
maybe if pkg-config is here then use it fully else use old way ( and good luck for cross compilation setup.py will pick anything in /usr instead of sysroot in most cases ).
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my 3.9.1 android/wasm (with HAVE_FFI_PREP_CLOSURE_LOC and ffi git on wasm ) CI is quite happy with that patch, it looks like a good step forward into cross-compilation to me |
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Dear devs - I had forgotten about this PR until I had to rebuild python yesterday on a machine with libffi in a non-standard location. Due to some major changes in setup.py around libffi, I've basically had to re-implement my patch. I've done this and force-pushed this branch. (Old commits https://github.com/rupertnash/cpython/tree/fix-ffi-build-old) I would appreciate your comments again and I will have a bit of time in the next week or two to actually get this merged |
Fundamentally, the problem appears to be that configure uses pkgconfig to find the libffi include directory, while setup.py's detect_ctypes only uses the global list of library directories.
I have made an attempt at fixing this by having configure produce the directory containing libffi (
LIBFFI_LIBDIR) and setup.py use this. However I've hardly any experience with autotools, so I would be very happy to be corrected if this is no use at all.https://bugs.python.org/issue14527