From 2caf90637da971fee746e80a561f9a1196d68846 Mon Sep 17 00:00:00 2001
From: Strahinja Val Markovic <val@markovic.io>
Date: Sun, 17 Nov 2013 13:10:16 -0800
Subject: [PATCH] Better handling of bad flags from extra conf

---
 python/ycm/completers/cpp/flags.py            | 35 +++++++++++++++----
 python/ycm/completers/cpp/tests/flags_test.py | 27 ++++++++++++++
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/python/ycm/completers/cpp/flags.py b/python/ycm/completers/cpp/flags.py
index 39a830c4..5bbefa7c 100644
--- a/python/ycm/completers/cpp/flags.py
+++ b/python/ycm/completers/cpp/flags.py
@@ -28,6 +28,7 @@ NO_EXTRA_CONF_FILENAME_MESSAGE = ( 'No {0} file detected, so no compile flags '
   'DOCS *NOW*, DON\'T file a bug report.' ).format(
     extra_conf_store.YCM_EXTRA_CONF_FILENAME )
 
+INCLUDE_FLAGS = [ '-isystem', '-I', '-iquote', '--sysroot=' ]
 
 class Flags( object ):
   """Keeps track of the flags necessary to compile a file.
@@ -143,8 +144,13 @@ def _SanitizeFlags( flags ):
 def _RemoveUnusedFlags( flags, filename ):
   """Given an iterable object that produces strings (flags for Clang), removes
   the '-c' and '-o' options that Clang does not like to see when it's producing
-  completions for a file. Also removes the first flag in the list if it does not
-  start with a '-' (it's highly likely to be the compiler name/path)."""
+  completions for a file.
+
+  Also removes the first flag in the list if it does not
+  start with a '-' (it's highly likely to be the compiler name/path).
+
+  We also try to remove any stray filenames in the flags that aren't include
+  dirs."""
 
   new_flags = []
 
@@ -154,23 +160,40 @@ def _RemoveUnusedFlags( flags, filename ):
   if not flags[ 0 ].startswith( '-' ):
     flags = flags[ 1: ]
 
-  skip = False
+  skip_next = False
+  previous_flag_is_include = False
+  previous_flag_starts_with_dash = False
+  current_flag_starts_with_dash = False
   for flag in flags:
-    if skip:
-      skip = False
+    previous_flag_starts_with_dash = current_flag_starts_with_dash
+    current_flag_starts_with_dash = flag.startswith( '-' )
+    if skip_next:
+      skip_next = False
       continue
 
     if flag == '-c':
       continue
 
     if flag == '-o':
-      skip = True;
+      skip_next = True;
       continue
 
     if flag == filename or os.path.realpath( flag ) == filename:
       continue
 
+    # We want to make sure that we don't have any stray filenames in our flags;
+    # filenames that are part of include flags are ok, but others are not. This
+    # solves the case where we ask the compilation database for flags for
+    # "foo.cpp" when we are compiling "foo.h" because the comp db doesn't have
+    # flags for headers. The returned flags include "foo.cpp" and we need to
+    # remove that.
+    if ( not current_flag_starts_with_dash and
+          ( not previous_flag_starts_with_dash or
+            ( not previous_flag_is_include and '/' in flag ) ) ):
+      continue
+
     new_flags.append( flag )
+    previous_flag_is_include = flag in INCLUDE_FLAGS
   return new_flags
 
 
diff --git a/python/ycm/completers/cpp/tests/flags_test.py b/python/ycm/completers/cpp/tests/flags_test.py
index 5d7c6658..73826aa3 100644
--- a/python/ycm/completers/cpp/tests/flags_test.py
+++ b/python/ycm/completers/cpp/tests/flags_test.py
@@ -107,3 +107,30 @@ def RemoveUnusedFlags_RemoveFilename_test():
        flags._RemoveUnusedFlags(
          expected[ :1 ] + to_remove + expected[ -1: ], filename ) )
 
+
+def RemoveUnusedFlags_RemoveFlagWithoutPrecedingDashFlag_test():
+  expected = [ '-foo', '-x', 'c++', '-bar', 'include_dir' ]
+  to_remove = [ 'unrelated_file' ]
+  filename = 'file'
+
+  eq_( expected,
+       flags._RemoveUnusedFlags( expected + to_remove, filename ) )
+
+  eq_( expected,
+       flags._RemoveUnusedFlags( to_remove + expected, filename ) )
+
+
+def RemoveUnusedFlags_RemoveFilenameWithoutPrecedingInclude_test():
+  expected = [ '-I', '/foo/bar', '-isystem/zoo/goo' ]
+  to_remove = [ '/moo/boo' ]
+  filename = 'file'
+
+  eq_( expected,
+       flags._RemoveUnusedFlags( expected + to_remove, filename ) )
+
+  eq_( expected,
+       flags._RemoveUnusedFlags( to_remove + expected, filename ) )
+
+  eq_( expected + expected,
+       flags._RemoveUnusedFlags( expected + to_remove + expected, filename ) )
+