win: Pass /W4 in front of all the -wd flags.

This should fix many many -Wunused-parameter warnings in self-host builds on
Windows after r255382.  cl.exe doesn't care about the order of /W4 and
/wd flags, but clang-cl currently does (just like -Wno-foo -Wall order
matters for clang).  We might want to change how clang-cl behaves in
the future, but until then this change makes self-host builds much more
silent.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256315 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index d583d0ee95c669f57b459fef9ebeaf9b17c9daab..4c5ffe2f7b28e78094fa3da23ba55314be8eab16 100644 (file)
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -338,7 +338,10 @@ if( MSVC )
 
   # Enable warnings
   if (LLVM_ENABLE_WARNINGS)
-    append("/W4" msvc_warning_flags)
+    # Put /W4 in front of all the -we flags. cl.exe doesn't care, but for
+    # clang-cl having /W4 after the -we flags will re-enable the warnings
+    # disabled by -we.
+    set(msvc_warning_flags "/W4 ${msvc_warning_flags}")
     # CMake appends /W3 by default, and having /W3 followed by /W4 will result in 
     # cl : Command line warning D9025 : overriding '/W3' with '/W4'.  Since this is
     # a command line warning and not a compiler warning, it cannot be suppressed except