Early error out if the 'msvs' is specified in GYP_GENERATORS

build/gyp_chromium

 #!/usr/bin/env python
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script is wrapper for Chromium that adds some support for how GYP
 # is invoked by Chromium beyond what can be done in the gclient hooks.
 
 import glob
@@ skipping 257 matching lines @@
   # list.
   if sys.platform not in ('darwin',):
     args.append('--no-circular-check')
 
   # We explicitly don't support the make gyp generator (crbug.com/348686). Be
   # nice and fail here, rather than choking in gyp.
   if re.search(r'(^|,|\s)make($|,|\s)', os.environ.get('GYP_GENERATORS', '')):
     print 'Error: make gyp generator not supported (check GYP_GENERATORS).'
     sys.exit(1)
 
+  # We explicitly don't support the native msvs gyp generator. Be nice and
+  # fail here, rather than generating broken projects.
+  if re.search(r'(^|,|\s)msvs($|,|\s)', os.environ.get('GYP_GENERATORS', '')):
+    print 'Error: msvs gyp generator not supported (check GYP_GENERATORS).'
+    print 'Did you mean to use the `msvs-ninja` generator?'
+    sys.exit(1)
+
   # If CHROMIUM_GYP_SYNTAX_CHECK is set to 1, it will invoke gyp with --check
   # to enfore syntax checking.
   syntax_check = os.environ.get('CHROMIUM_GYP_SYNTAX_CHECK')
   if syntax_check and int(syntax_check):
     args.append('--check')
 
   supplemental_includes = GetSupplementalFiles()
   gyp_vars_dict = GetGypVars(supplemental_includes)
 
   # TODO(dmikurube): Remove these checks and messages after a while.
@@ skipping 31 matching lines @@
 
   if not use_analyzer:
     vs2013_runtime_dll_dirs = vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
     if vs2013_runtime_dll_dirs:
       x64_runtime, x86_runtime = vs2013_runtime_dll_dirs
       vs_toolchain.CopyVsRuntimeDlls(
         os.path.join(chrome_src, GetOutputDirectory()),
         (x86_runtime, x64_runtime))
 
   sys.exit(gyp_rc)