From 1581d48eeb2acd4b1471575aefe2b098e20ee6b3 Mon Sep 17 00:00:00 2001
From: Boris Staletic <boris.staletic@gmail.com>
Date: Mon, 3 Jul 2017 16:11:48 +0200
Subject: [PATCH] Windows style flags

---
 ycmd/completers/cpp/flags.py   | 12 ++++++++++--
 ycmd/tests/clang/flags_test.py | 11 +++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/ycmd/completers/cpp/flags.py b/ycmd/completers/cpp/flags.py
index e85e6093fb..79465dfb46 100644
--- a/ycmd/completers/cpp/flags.py
+++ b/ycmd/completers/cpp/flags.py
@@ -391,6 +391,11 @@ def _RemoveUnusedFlags( flags, filename ):
   previous_flag_is_include = False
   previous_flag_starts_with_dash = False
   current_flag_starts_with_dash = False
+  enable_windows_style_flags = False
+
+  for flag in flags:
+    if flag.startswith( '--driver-mode' ):
+      enable_windows_style_flags = ( flag == '--driver-mode=cl' )
 
   for flag in flags:
     previous_flag_starts_with_dash = current_flag_starts_with_dash
@@ -417,12 +422,15 @@ def _RemoveUnusedFlags( flags, filename ):
     # 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 ) ) ):
+         ( not previous_flag_starts_with_dash or
+           ( not previous_flag_is_include and '/' in flag ) ) and
+             ( not enable_windows_style_flags or
+               ( enable_windows_style_flags and os.path.exists( flag ) ) ) ):
       continue
 
     new_flags.append( flag )
     previous_flag_is_include = flag in INCLUDE_FLAGS
+
   return new_flags
 
 
diff --git a/ycmd/tests/clang/flags_test.py b/ycmd/tests/clang/flags_test.py
index f72c0a0073..1b51d7cdca 100644
--- a/ycmd/tests/clang/flags_test.py
+++ b/ycmd/tests/clang/flags_test.py
@@ -215,6 +215,17 @@ def RemoveUnusedFlags_RemoveFlagWithoutPrecedingDashFlag_test():
   eq_( expected,
        flags._RemoveUnusedFlags( expected[ :1 ] + to_remove + expected[ 1: ],
                                  filename ) )
+  expected = [ 'g++', '-foo', '--driver-mode=cl', '-xc++', '-bar',
+               'include_dir', '/foo' ]
+  to_remove = [ '..' ]
+  filename = 'file'
+
+  eq_( expected,
+       flags._RemoveUnusedFlags( expected + to_remove, filename ) )
+
+  eq_( expected,
+       flags._RemoveUnusedFlags( expected[ :1 ] + to_remove + expected[ 1: ],
+                                 filename ) )
 
 
 def RemoveUnusedFlags_Depfiles_test():