Bug 1480834 - 5. Keep target flag when building for Android on Linux; r=glandium

Currently, when building for Android x86-64 on Linux x86-64, we drop the
'--target' flag, which causes the build to fail. This patch adds a check
for OS mismatch, so we keep the '--target' flag in this situation.

Differential Revision: https://phabricator.services.mozilla.com/D4483

build/moz.configure/toolchain.configure

@@ -352,6 +352,8 @@ def try_preprocess(compiler, language, source):
          _import='CPU_preprocessor_checks')
 @imports(_from='mozbuild.configure.constants',
          _import='kernel_preprocessor_checks')
+@imports(_from='mozbuild.configure.constants',
+         _import='OS_preprocessor_checks')
 @imports(_from='textwrap', _import='dedent')
 def get_compiler_info(compiler, language):
     '''Returns information about the given `compiler` (command line in the
@@ -408,6 +410,7 @@ def get_compiler_info(compiler, language):
     for name, preprocessor_checks in (
         ('CPU', CPU_preprocessor_checks),
         ('KERNEL', kernel_preprocessor_checks),
+        ('OS', OS_preprocessor_checks),
     ):
         for n, (value, condition) in enumerate(preprocessor_checks.iteritems()):
             check += dedent('''\
@@ -475,12 +478,15 @@ def get_compiler_info(compiler, language):
         cpu=data.get('CPU'),
         kernel=data.get('KERNEL'),
         endianness=data.get('ENDIANNESS'),
+        os=data.get('OS'),
         language='C++' if cplusplus else 'C',
         language_version=cplusplus if cplusplus else stdc_version,
     )
 
 
 @imports(_from='mozbuild.shellutil', _import='quote')
+@imports(_from='mozbuild.configure.constants',
+         _import='OS_preprocessor_checks')
 def check_compiler(compiler, language, target):
     info = get_compiler_info(compiler, language)
 
@@ -555,12 +561,21 @@ def check_compiler(compiler, language, target):
         if info.type == 'clang':
             append_flag('--target=%s' % target.toolchain)
 
+    # Add target flag when there is an OS mismatch (e.g. building for Android on
+    # Linux). However, only do this if the target OS is in our whitelist, to
+    # keep things the same on other platforms.
+    if target.os in OS_preprocessor_checks and (
+            not info.os or info.os != target.os):
+        if info.type == 'clang':
+            append_flag('--target=%s' % target.toolchain)
+
     return namespace(
         type=info.type,
         version=info.version,
         target_cpu=info.cpu,
         target_kernel=info.kernel,
         target_endianness=info.endianness,
+        target_os=info.os,
         flags=flags,
     )
 

python/mozbuild/mozbuild/configure/constants.py

@@ -106,3 +106,11 @@ kernel_preprocessor_checks = {
 }
 
 assert sorted(kernel_preprocessor_checks.keys()) == sorted(Kernel.POSSIBLE_VALUES)
+
+OS_preprocessor_checks = {
+    'Android': '__ANDROID__',
+}
+
+# We intentionally don't include all possible OSes in our checks, because we
+# only care about OS mismatches for specific target OSes.
+# assert sorted(OS_preprocessor_checks.keys()) == sorted(OS.POSSIBLE_VALUES)