[Vim/YCM] Calculate system library paths based on Clang++ binary path.

tools/vim/chromium.ycm_extra_conf.py

Index: tools/vim/chromium.ycm_extra_conf.py
diff --git a/tools/vim/chromium.ycm_extra_conf.py b/tools/vim/chromium.ycm_extra_conf.py
index 76fce6761164f7f6aa976c93899f4ca1aeb6e049..091a5ac5503368ed08a5e33e2df9b2d52c025e64 100644
--- a/tools/vim/chromium.ycm_extra_conf.py
+++ b/tools/vim/chromium.ycm_extra_conf.py
@@ -44,17 +44,23 @@ import subprocess
 import sys
 
 
-def SystemIncludeDirectoryFlags():
+def SystemIncludeDirectoryFlags(clang_binary, clang_flags):
   """Determines compile flags to include the system include directories.
 
   Use as a workaround for https://github.com/Valloric/YouCompleteMe/issues/303
 
+  Args:
+    clang_binary: (String) Path to clang binary.
+    clang_flags: (List of Strings) List of additional flags to clang. It may
+      affect the choice of system include directories if -stdlib= is specified.
+
   Returns:
     (List of Strings) Compile flags to append.
   """
+  all_flags = ['-v', '-E', '-x', 'c++'] + clang_flags + ['-']
   try:
     with open(os.devnull, 'rb') as DEVNULL:
-      output = subprocess.check_output(['clang', '-v', '-E', '-x', 'c++', '-'],
+      output = subprocess.check_output([clang_binary] + all_flags,
                                        stdin=DEVNULL, stderr=subprocess.STDOUT)
   except:
     return []
@@ -69,18 +75,14 @@ def SystemIncludeDirectoryFlags():
       flags.append(path)
   return flags
 
-
-_system_include_flags = SystemIncludeDirectoryFlags()
-
 # Flags from YCM's default config.
-flags = [
-'-DUSE_CLANG_COMPLETER',
-'-std=c++11',
-'-x',
-'c++',
+_default_flags = [
+  '-DUSE_CLANG_COMPLETER',
+  '-std=c++11',
+  '-x',
+  'c++',
 ]
 
-
 def PathExists(*args):
   return os.path.exists(os.path.join(*args))
 
@@ -208,6 +210,10 @@ def GetClangCommandFromNinjaForFilename(chrome_root, filename):
         continue
       chrome_flags.append(flag)
 
+  clang_path = clang_line.split(' ')[0]

[eroman, 2015/05/18 17:56:42]

This is too simplistic, the "path" may contain spaces.

For instance when using goma, my line starts with:

/usr/local/google/home/ericroman/goma/gomacc
../../third_party/llvm-build/Release+Asserts/bin/clang++

So there is at the very least going to be a space before clang++

How about instead taking clang path as everything from the start of the line up
until (and including) "clang++" ?

[asanka, 2015/05/18 19:36:48]

That's also a no-go due to the gomacc wrapper not liking the stdin source used
by SystemIncludeDirectoryFlags. I've updated the code to use shlex (so as not to
be confused by embedded whitespace), and looking at the first two tokens for a
Clang like command.

Let me know if we should be more general than this.

+  if clang_path.endswith('clang++'):
+    chrome_flags += SystemIncludeDirectoryFlags(clang_path, chrome_flags)
+
   return chrome_flags
 
 
@@ -225,7 +231,7 @@ def FlagsForFile(filename):
   chrome_root = FindChromeSrcFromFilename(filename)
   chrome_flags = GetClangCommandFromNinjaForFilename(chrome_root,
                                                      filename)
-  final_flags = flags + chrome_flags + _system_include_flags
+  final_flags = _default_flags + chrome_flags
 
   return {
     'flags': final_flags,