don't try to link _ctypes with a ffi_convenience library

[doko42]

BPO	21277
Nosy	@Yhg1s, @doko42, @zware

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2016-06-04.23:39:08.788>
created_at = <Date 2014-04-16.22:44:26.206>
labels = ['build']
title = "don't try to link _ctypes with a ffi_convenience library"
updated_at = <Date 2016-06-04.23:39:08.787>
user = 'https://github.com/doko42'

bugs.python.org fields:

activity = <Date 2016-06-04.23:39:08.787>
actor = 'doko'
assignee = 'none'
closed = True
closed_date = <Date 2016-06-04.23:39:08.788>
closer = 'doko'
components = ['Build']
creation = <Date 2014-04-16.22:44:26.206>
creator = 'doko'
dependencies = []
files = []
hgrepos = []
issue_num = 21277
keywords = []
message_count = 5.0
messages = ['216614', '216627', '216787', '258557', '267347']
nosy_count = 4.0
nosy_names = ['twouters', 'doko', 'python-dev', 'zach.ware']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue21277'
versions = ['Python 3.5', 'Python 3.6']

[doko42]

the ffi_convenience library was once built and installed with oldish GCC versions. Either remove it completely from the search path, or search for the standard libffi system library.

--- a/setup.py
+++ b/setup.py
@@ -1939,7 +1939,7 @@
                         break
         ffi_lib = None
         if ffi_inc is not None:
-            for lib_name in ('ffi_convenience', 'ffi_pic', 'ffi'):
+            for lib_name in ('ffi', 'ffi_convenience', 'ffi_pic', 'ffi'):
                 if (self.compiler.find_library_file(lib_dirs, lib_name)):
                     ffi_lib = lib_name
                     break

[doko42]

the list of libs should be just: ('ffi', 'ffi_pic')

[Yhg1s]

I don't understand the story with ffi_convenience here. Perhaps someone else on python-dev remembers what it was for and whether we need it for any platforms, still?

[zware]

It's not easy to find anything with a google search for 'ffi_convenience' that's not this issue. I did find doko's patch to GCC to not install libffi_convenience, which included a comment from the author of libffi saying he didn't recommend that GCC install libffi_convenience in the first place[1].

For the record, bpo-1464444 is the issue that added the line in question in the first place.

[1] https://www.sourceware.org/ml/libffi-discuss/2013/msg00125.html

[python-dev]

New changeset 0a8509023c09 by doko in branch 'default':

• Issue bpo-21277: Don't try to link _ctypes with a ffi_convenience library.
  https://hg.python.org/cpython/rev/0a8509023c09