clang: Suppress a -Wstring-conversion warnings in nspr, gyp edition.

nss.gyp

 # 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.
 
 {
   'variables': {
     'conditions': [
       ['OS=="ios"', {
         'exclude_nss_root_certs%': 0,
         'exclude_nss_libpkix%': 0,
@@ skipping 235 matching lines @@
           },
           # TODO(wtc): suppress C4244 and C4554 in prdtoa.c.
           'msvs_disabled_warnings': [4018, 4244, 4554, 4267,],
           'variables': {
             'clang_warning_flags': [
               # nspr passes "const char*" through "void*".
               '-Wno-incompatible-pointer-types',
               # nspr passes "int*" through "unsigned int*".
               '-Wno-pointer-sign',
             ],
+            'clang_warning_flags_unset': [
+              # nspr uses assert(!"foo") instead of assert(false && "foo").

[wtc, 2014/12/01 19:05:11]

PR_ASSERT(!"foo") can be replaced with PR_NOT_REACHED("foo"). I will fix these
in this way in the NSPR upstream.

PR_NOT_REACHED is defined as
http://mxr.mozilla.org/nspr/ident?i=PR_NOT_REACHED

The definition doesn't use the !"foo" construct.

Are you sure the compiler won't warn about assert(false && "foo")? I will need
to use that construct in one place, where the NSPR file defines its own
assertion macro.

+              '-Wstring-conversion',
+            ],
           },
           'conditions': [
             ['OS=="mac" or OS=="ios"', {
               'defines': [
                 'XP_UNIX',
                 'DARWIN',
                 'XP_MACOSX',
                 '_PR_PTHREADS',
                 'HAVE_BSD_FLOCK',
                 'HAVE_CRT_EXTERNS_H',
@@ skipping 1016 matching lines @@
                 # mpi_x86_asm.c contains MSVC inline assembly code.
                 'nss/lib/freebl/mpi/mpi_x86_asm.c',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }