android: Support “unified headers” with GCC build

Previously, the __ANDROID_API__ macro was provided by
<android/api-level.h>. With unified headers (expected to become the
default in the next NDK release and the sole option in the subsequent
release), this macro is not set properly by headers. When building with
Clang, the standalone toolchain’s clang and clang++ wrappers set the
macro properly. GCC isn’t accounted for in this way, so the build system
must assume the responsibility of setting it.

This change fishes the value of __ANDROID_API__ out of the standalone
toolchain’s clang wrapper and sets the android_api_level GYP variable
appropriately. From there, it will be picked up by common.gypi in
mini_chromium and used to define __ANDROID_API__.

This updates mini_chromium to 62e6015f633dd4acb1610db15a064889315cadaa
which understands this new GYP variable.

62e6015f633d android: Support “unified headers” with GCC build

https://android.googlesource.com/platform/ndk/+/master/docs/UnifiedHeaders.md
https://android.googlesource.com/platform/ndk/+/ndk-r14/CHANGELOG.md

Bug: crashpad:30
Change-Id: I33e66eba8394e32ced8dca80c8226b85e0e786f3
Reviewed-on: https://chromium-review.googlesource.com/458021
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Scott Graham <scottmg@chromium.org>

DEPS

@@ -38,7 +38,7 @@ deps = {
 
   'crashpad/third_party/mini_chromium/mini_chromium':
       Var('chromium_git') + '/chromium/mini_chromium@' +
-      '9e0d322ae9f87acbe17c4ced025319b4964bf0b7',
+      '62e6015f633dd4acb1610db15a064889315cadaa',
   'crashpad/third_party/zlib/zlib':
       Var('chromium_git') + '/chromium/src/third_party/zlib@' +
       '13dc246a58e4b72104d35f9b1809af95221ebda7',

build/gyp_crashpad_android.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# coding: utf-8
 
 # Copyright 2017 The Crashpad Authors. All rights reserved.
 #
@@ -18,6 +19,7 @@ import argparse
 import glob
 import gyp_crashpad
 import os
+import re
 import subprocess
 import sys
 
@@ -31,7 +33,7 @@ def main(args):
                       default='clang',
                       choices=('clang', 'gcc'),
                       help='The compiler to use, clang by default')
-  (parsed, extra_args) = parser.parse_known_args(args)
+  (parsed, extra_command_line_args) = parser.parse_known_args(args)
 
   NDK_ERROR=(
       'NDK must be a valid standalone NDK toolchain.\n' +
@@ -55,8 +57,11 @@ def main(args):
 
   ndk_bin_dir = os.path.join(parsed.ndk, 'bin')
 
+  clang_path = os.path.join(ndk_bin_dir, 'clang')
+  extra_args = []
+
   if parsed.compiler == 'clang':
-    os.environ['CC_target'] = os.path.join(ndk_bin_dir, 'clang')
+    os.environ['CC_target'] = clang_path
     os.environ['CXX_target'] = os.path.join(ndk_bin_dir, 'clang++')
   elif parsed.compiler == 'gcc':
     os.environ['CC_target'] = os.path.join(ndk_bin_dir,
@@ -64,6 +69,27 @@ def main(args):
     os.environ['CXX_target'] = os.path.join(ndk_bin_dir,
                                             '%s-g++' % arch_triplet)
 
+    # Unlike the Clang build, when using GCC with “unified headers,”
+    # __ANDROID_API__ isn’t set automatically and must be pushed in to the
+    # build. Fish the correct value out of the Clang wrapper script. If unified
+    # headers are not being used, the Clang wrapper won’t mention
+    # __ANDROID_API__, but the standalone toolchain’s <android/api-level.h> will
+    # #define it for both Clang and GCC.
+    #
+    # Unified headers are the way of the future, according to
+    # https://android.googlesource.com/platform/ndk/+/ndk-r14/CHANGELOG.md and
+    # https://android.googlesource.com/platform/ndk/+/master/docs/UnifiedHeaders.md.
+    with open(clang_path, 'r') as file:
+      clang_script_contents = file.read()
+    matches = re.finditer(r'\s-D__ANDROID_API__=([\d]+)\s',
+                          clang_script_contents)
+    match = next(matches, None)
+    if match:
+      android_api = int(match.group(1))
+      extra_args.extend(['-D', 'android_api_level=%d' % android_api])
+      if next(matches, None):
+        raise AssertionError('__ANDROID_API__ defined too many times')
+
   for tool in ('ar', 'nm', 'readelf'):
     os.environ['%s_target' % tool.upper()] = (
         os.path.join(ndk_bin_dir, '%s-%s' % (arch_triplet, tool)))
@@ -72,7 +98,9 @@ def main(args):
       ['-D', 'OS=android',
        '-D', 'target_arch=%s' % arch,
        '-D', 'clang=%d' % (1 if parsed.compiler == 'clang' else 0),
-       '-f', 'ninja-android'] + extra_args)
+       '-f', 'ninja-android'] +
+      extra_args +
+      extra_command_line_args)
 
 
 if __name__ == '__main__':