[build] Port options to support win-clang

build/standalone.gypi

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@@ skipping 928 matching lines @@
               }],
               ['v8_target_arch=="x64"', {
                 'MinimumRequiredVersion': '5.02',  # Server 2003.
                 'TargetMachine': '17',  # x64
               }, {
                 'MinimumRequiredVersion': '5.01',  # XP.
                 'TargetMachine': '1',  # ia32
               }],
             ],
           },
+          'conditions': [
+            ['clang==1', {
+              'VCCLCompilerTool': {
+                'AdditionalOptions': [
+                  # Don't warn about unused function parameters.
+                  # (This is also used on other platforms.)
+                  '-Wno-unused-parameter',
+                  # Don't warn about the "struct foo f = {0};" initialization
+                  # pattern.
+                  '-Wno-missing-field-initializers',
+
+                  # Many files use intrinsics without including this header.
+                  # TODO(hans): Fix those files, or move this to sub-GYPs.
+                  '/FIIntrin.h',
+
+                  # TODO(hans): Make this list shorter eventually, http://crbug.com/504657
+                  '-Wno-microsoft-enum-value',  # http://crbug.com/505296
+                  '-Wno-unknown-pragmas',  # http://crbug.com/505314
+                  '-Wno-microsoft-cast',  # http://crbug.com/550065
+
+                  '-fmsc-version=1900',

[Nico, 2016/04/14 13:54:12]

1900 means msvc2015. If you're still on 2013, you might want 1800 here

[Michael Achenbach, 2016/04/14 14:03:42]

Yea - but no point in supporting also 2013 with clang as we never supported
win-clang...

[Nico, 2016/04/14 14:48:06]

In general, I feel you'll have fewest problems if the version here matches the
versions of the MSVC headers you're using. If you're using the 2015 headers,
this _must_ be 1900 since clang-cl in 2013 mode can't parse the 2015 headers. If
you're using clang-cl in 2015 mode with the 2013 headers, then that might work,
but you're using a configuration that as far as I know nobody else uses.

+                ],
+              },
+            }],
+          ],
         },
       },
     }],  # OS=="win"
     ['OS=="mac"', {
       'xcode_settings': {
         'SDKROOT': 'macosx',
         'SYMROOT': '<(DEPTH)/xcodebuild',
       },
       'target_defaults': {
         'xcode_settings': {
@@ skipping 445 matching lines @@
               '-fsanitize=cfi-vcall',
               '-fsanitize=cfi-derived-cast',
               '-fsanitize=cfi-unrelated-cast',
             ],
           }],
         ],
       },
     }],
   ],
 }