bpo-14527: fix (some) _ctypes liffi build problems

Makefile.pre.in

@@ -305,6 +305,7 @@ IO_OBJS= \
 ##########################################################################
 
 LIBFFI_INCLUDEDIR= @LIBFFI_INCLUDEDIR@
+LIBFFI_LIBDIR= @LIBFFI_LIBDIR@
 
 ##########################################################################
 # Parser

Misc/NEWS.d/next/Build/2020-05-28-10-39-11.bpo-14527.OavBJT.rst

@@ -0,0 +1 @@
+Fix issues with building python with a non-system version of libffi.

configure

@@ -660,6 +660,7 @@ DFLAGS
 DTRACE
 TCLTK_LIBS
 TCLTK_INCLUDES
+LIBFFI_LIBDIR
 LIBFFI_INCLUDEDIR
 PKG_CONFIG_LIBDIR
 PKG_CONFIG_PATH
@@ -10632,11 +10633,14 @@ fi
 
 if test "$with_system_ffi" = "yes" && test -n "$PKG_CONFIG" then
  LIBFFI_INCLUDEDIR="`"$PKG_CONFIG" libffi --cflags-only-I 2>/dev/null | sed -e 's/^-I//;s/ *$//'`"
+ LIBFFI_LIBDIR="`"$PKG_CONFIG" libffi --libs-only-L 2>/dev/null | sed -e 's/^-L//;s/ *$//'`"
 else
  LIBFFI_INCLUDEDIR=""
+ LIBFFI_LIBDIR=""
 fi
 
 
+
 # Check for use of the system libmpdec library
 {$as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-system-libmpdec" >&5
 $as_echo_n "checking for --with-system-libmpdec... " >&6}

configure.ac

@@ -3097,10 +3097,13 @@ fi
 
 if test "$with_system_ffi" = "yes" && test -n "$PKG_CONFIG" then
  LIBFFI_INCLUDEDIR="`"$PKG_CONFIG" libffi --cflags-only-I 2>/dev/null | sed -e 's/^-I//;s/ *$//'`"
+ LIBFFI_LIBDIR="`"$PKG_CONFIG" libffi --libs-only-L 2>/dev/null | sed -e 's/^-L//;s/ *$//'`"
 else
  LIBFFI_INCLUDEDIR=""
+ LIBFFI_LIBDIR=""
 fi
 AC_SUBST(LIBFFI_INCLUDEDIR)
+AC_SUBST(LIBFFI_LIBDIR)
 
 # Check for use of the system libmpdec library
 AC_MSG_CHECKING(for --with-system-libmpdec)

setup.py

@@ -2236,7 +2236,9 @@ def detect_ctypes(self):
  libraries=['m']))
 
  ffi_inc = sysconfig.get_config_var("LIBFFI_INCLUDEDIR")
- ffi_lib = None
+
+ # Potential names of the library (e.g. libNAME.{so,dylib})
+ ffi_libname_candidates = ('ffi', 'ffi_pic')
 
  ffi_inc_dirs = self.inc_dirs.copy()
  if MACOS:
@@ -2246,7 +2248,7 @@ def detect_ctypes(self):
  if os.path.exists(ffi_in_sdk):
  ext.extra_compile_args.append("-DUSING_APPLE_OS_LIBFFI=1")
  ffi_inc = ffi_in_sdk
-ffi_lib = 'ffi'
+ffi_libname_candidates = ('ffi',)
  else:
  # OS X 10.5 comes with libffi.dylib; the include files are
  # in /usr/include/ffi
@@ -2261,10 +2263,21 @@ def detect_ctypes(self):
  if not os.path.exists(ffi_h):
  ffi_inc = None
  print('Header file{} does not exist'.format(ffi_h))
- if ffi_lib is None and ffi_inc:
- for lib_name in ('ffi', 'ffi_pic'):
- if (self.compiler.find_library_file(self.lib_dirs, lib_name)):
+
+ ffi_lib = None
+ # Then we probably also need to figure out the path to the
+ # library too.
+ if ffi_inc:
+ # A list containing nothing or the directory from the
+ # configure script.
+ maybe_ffi_libdir = [d for d in [sysconfig.get_config_var("LIBFFI_LIBDIR")]
+ if os.path.isdir(d)]
+
+ for lib_name in ffi_libname_candidates:
+ fullpath = self.compiler.find_library_file(self.lib_dirs + maybe_ffi_libdir, lib_name)
+ if fullpath:
  ffi_lib = lib_name
+ ffi_libdir = os.path.normpath(os.path.dirname(fullpath))
  break
 
  if ffi_inc and ffi_lib:
@@ -2278,6 +2291,8 @@ def detect_ctypes(self):
 
  ext.include_dirs.append(ffi_inc)
  ext.libraries.append(ffi_lib)
+ if ffi_libdir not in self.lib_dirs:
+ ext.library_dirs.append(ffi_libdir)
  self.use_system_libffi = True
 
  if sysconfig.get_config_var('HAVE_LIBDL'):