Fix libffi recipe, and build + runtime linker errors when compiling on WSL (#1744)

* Fix libffi linker errors when compiling on WSL

Optional use of lld (LLVM's linker), and include a python37 bugfix.
https://clang.llvm.org/docs/Toolchain.html
https://lld.llvm.org/
https://bz-attachments.freebsd.org/attachment.cgi?id=200526

* Remove lld unsupported fix-cortex-a8 from LDFLAGS

android/ndk#313
android/ndk#766
https://developer.android.com/ndk/guides/standalone_toolchain

* Fix libffi recipe, runtime libffi linker errors.

Libtool didnt like the space after --sysroot, replaced with =

* CRAs - Check for lld before using it.

Changed hardcoded cpu count to cpu_count().
Added comment to python patch.
Made remove-fix-cortex-a8.patch conditional on lld.
Moved LDFLAGS change to get_recipe_env() so its not libffi specific
within python.py.

Author: Aralox

pythonforandroid/archs.py

@@ -86,7 +86,7 @@ def get_env(self, with_flags_in_cc=True, clang=False):
                                          self.ctx.python_recipe.version[0:3])
                                     )
 
-        env['LDFLAGS'] += '--sysroot {} '.format(self.ctx.ndk_platform)
+        env['LDFLAGS'] += '--sysroot={} '.format(self.ctx.ndk_platform)
 
         env["CXXFLAGS"] = env["CFLAGS"]
 

pythonforandroid/python.py

@@ -170,6 +170,14 @@ def get_recipe_env(self, arch=None, with_flags_in_cc=True):
 
         env['SYSROOT'] = sysroot
 
+        if sh.which('lld') is not None:
+            # Note: The -L. is to fix a bug in python 3.7.
+            # https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234409
+            env["LDFLAGS"] += ' -L. -fuse-ld=lld'
+        else:
+            logger.warning('lld not found, linking without it. ' +
+                           'Consider installing lld if linker errors occur.')
+
         return env
 
     def set_libs_flags(self, env, arch):

pythonforandroid/recipes/libffi/__init__.py

@@ -1,8 +1,8 @@
 from os.path import exists, join
+from multiprocessing import cpu_count
 from pythonforandroid.recipe import Recipe
-from pythonforandroid.logger import info, shprint
+from pythonforandroid.logger import shprint
 from pythonforandroid.util import current_directory, ensure_dir
-from glob import glob
 import sh
 
 
@@ -37,46 +37,10 @@ def build_arch(self, arch):
                     '--prefix=' + self.get_build_dir(arch.arch),
                     '--disable-builddir',
                     '--enable-shared', _env=env)
-            # '--with-sysroot={}'.format(self.ctx.ndk_platform),
-            # '--target={}'.format(arch.toolchain_prefix),
 
-            # ndk 15 introduces unified headers required --sysroot and
-            # -isysroot for libraries and headers. libtool's head explodes
-            # trying to weave them into it's own magic. The result is a link
-            # failure trying to link libc. We call make to compile the bits
-            # and manually link...
+            shprint(sh.make, '-j', str(cpu_count()), 'libffi.la', _env=env)
 
-            try:
-                shprint(sh.make, '-j5', 'libffi.la', _env=env)
-            except sh.ErrorReturnCode_2:
-                info("make libffi.la failed as expected")
-            cc = sh.Command(env['CC'].split()[0])
-            cflags = env['CC'].split()[1:]
             host_build = self.get_build_dir(arch.arch)
-
-            arch_flags = ''
-            if '-march=' in env['CFLAGS']:
-                arch_flags = '-march={}'.format(env['CFLAGS'].split('-march=')[1])
-
-            src_arch = arch.command_prefix.split('-')[0]
-            if src_arch == 'x86_64':
-                # libffi has not specific arch files for x86_64...so...using
-                # the ones from x86 which seems to build fine...
-                src_arch = 'x86'
-
-            cflags.extend(arch_flags.split())
-            cflags.extend(['-shared', '-fPIC', '-DPIC'])
-            cflags.extend(glob(join(host_build, 'src/.libs/*.o')))
-            cflags.extend(glob(join(host_build, 'src', src_arch, '.libs/*.o')))
-
-            ldflags = env['LDFLAGS'].split()
-            cflags.extend(ldflags)
-            cflags.extend(['-Wl,-soname', '-Wl,libffi.so', '-o',
-                           '.libs/libffi.so'])
-
-            with current_directory(host_build):
-                shprint(cc, *cflags, _env=env)
-
             ensure_dir(self.ctx.get_libs_dir(arch.arch))
             shprint(sh.cp,
                     join(host_build, '.libs', 'libffi.so'),

pythonforandroid/recipes/python3/__init__.py

@@ -1,3 +1,4 @@
+import sh
 from pythonforandroid.python import GuestPythonRecipe
 from pythonforandroid.recipe import Recipe
 
@@ -23,6 +24,9 @@ class Python3Recipe(GuestPythonRecipe):
 
     patches = ["patches/fix-ctypes-util-find-library.patch"]
 
+    if sh.which('lld') is not None:
+        patches = patches + ["patches/remove-fix-cortex-a8.patch"]
+
     depends = ['hostpython3', 'sqlite3', 'openssl', 'libffi']
     conflicts = ['python3crystax', 'python2', 'python2legacy']
 

pythonforandroid/recipes/python3/patches/remove-fix-cortex-a8.patch

@@ -0,0 +1,14 @@
+This patch removes --fix-cortex-a8 from the linker flags in order to support linking
+with lld, as lld does not support this flag (https://github.com/android-ndk/ndk/issues/766).
+diff --git a/configure b/configure
+--- a/configure
++++ b/configure
+@@ -5671,7 +5671,7 @@ $as_echo_n "checking for the Android arm ABI... " >&6; }
+ $as_echo "$_arm_arch" >&6; }
+   if test "$_arm_arch" = 7; then
+     BASECFLAGS="${BASECFLAGS} -mfloat-abi=softfp -mfpu=vfpv3-d16"
+-    LDFLAGS="${LDFLAGS} -march=armv7-a -Wl,--fix-cortex-a8"
++    LDFLAGS="${LDFLAGS} -march=armv7-a"
+   fi
+ else
+   { $as_echo "$as_me:${as_lineno-$LINENO}: result: not Android" >&5