From ef2c6368876722cfcd5f090e57fbf5f5fa104a78 Mon Sep 17 00:00:00 2001
From: Rupert Nash <r.nash@epcc.ed.ac.uk>
Date: Mon, 22 Mar 2021 16:18:59 +0000
Subject: [PATCH 1/2] fix for _ctypes liffi build problems bpo-14527

---
 Makefile.pre.in |  1 +
 configure       |  4 ++++
 configure.ac    |  3 +++
 setup.py        | 25 ++++++++++++++++++++-----
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 6655edafeb1ecf..8c044e031c0d7c 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -305,6 +305,7 @@ IO_OBJS=	\
 ##########################################################################
 
 LIBFFI_INCLUDEDIR=	@LIBFFI_INCLUDEDIR@
+LIBFFI_LIBDIR=		@LIBFFI_LIBDIR@
 
 ##########################################################################
 # Parser
diff --git a/configure b/configure
index 2ddca079860625..8f0dd3688e1dcd 100755
--- a/configure
+++ b/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; }
diff --git a/configure.ac b/configure.ac
index 4c3c80f74d215b..f7adeb016ee098 100644
--- a/configure.ac
+++ b/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)
diff --git a/setup.py b/setup.py
index 80deacce8de48c..a05e3d8f10a83e 100644
--- a/setup.py
+++ b/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'):

From 8fe5428e48519d5fc5daac0dc197786b366a34e3 Mon Sep 17 00:00:00 2001
From: Rupert Nash <r.nash@epcc.ed.ac.uk>
Date: Tue, 23 Mar 2021 15:02:07 +0000
Subject: [PATCH 2/2] add NEWS entry

---
 Misc/NEWS.d/next/Build/2020-05-28-10-39-11.bpo-14527.OavBJT.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Build/2020-05-28-10-39-11.bpo-14527.OavBJT.rst

diff --git a/Misc/NEWS.d/next/Build/2020-05-28-10-39-11.bpo-14527.OavBJT.rst b/Misc/NEWS.d/next/Build/2020-05-28-10-39-11.bpo-14527.OavBJT.rst
new file mode 100644
index 00000000000000..8f04902c7cb270
--- /dev/null
+++ b/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.