[gtest] Detect warning flags using the positive spelling.

Some GCC versions will accept any warning flag name after a '-Wno-',
which would cause us to try to disable warnings with names GCC didn't
understand. This will silently succeed unless there is some other output
from GCC in which case we get weird cc1plus warnings about the warning
name being bogus.

There is still the issue that gtest sets warning flags for building
gtest-all.cc using weird 'add_definitions' and the fact that there is
a GCC version which warns on the variadic macro usage in gtest under
-pedantic, but has no flag analogous to Clang's
-Wgnu-zero-variadic-macro-argumnets to suppress this warning. I haven't
been able to come up with any good solution here. The closest is to turn
off -pedantic for those versions of GCC, but that seems really nasty.
For now, those versinos of GCC aren't warning clean. If anyone is broken
by this, I'll work on CMake logic to detect and disable -pedantic in
these cases.

llvm-svn: 291299

3 files changed, 7 insertions, 7 deletions

diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
index 0f1fc34ed28..4288cf4bdd0 100755
--- a/llvm/cmake/config-ix.cmake
+++ b/llvm/cmake/config-ix.cmake
@@ -316,9 +316,9 @@ else()
   endif()
 endif()
 
-check_cxx_compiler_flag("-Wno-variadic-macros" SUPPORTS_NO_VARIADIC_MACROS_FLAG)
-check_cxx_compiler_flag("-Wno-gnu-zero-variadic-macro-arguments"
-                        SUPPORTS_NO_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
+check_cxx_compiler_flag("-Wvariadic-macros" SUPPORTS_VARIADIC_MACROS_FLAG)
+check_cxx_compiler_flag("-Wgnu-zero-variadic-macro-arguments"
+                        SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
 
 set(USE_NO_MAYBE_UNINITIALIZED 0)
 set(USE_NO_UNINITIALIZED 0)
diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index 0eb16974517..56ba1479d7e 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -1011,11 +1011,11 @@ function(add_unittest test_suite test_name)
     list(APPEND LLVM_COMPILE_DEFINITIONS GTEST_HAS_PTHREAD=0)
   endif ()
 
-  if (SUPPORTS_NO_VARIADIC_MACROS_FLAG)
+  if (SUPPORTS_VARIADIC_MACROS_FLAG)
     list(APPEND LLVM_COMPILE_FLAGS "-Wno-variadic-macros")
   endif ()
   # Some parts of gtest rely on this GNU extension, don't warn on it.
-  if(SUPPORTS_NO_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
+  if(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
     list(APPEND LLVM_COMPILE_FLAGS "-Wno-gnu-zero-variadic-macro-arguments")
   endif()
 
diff --git a/llvm/utils/unittest/CMakeLists.txt b/llvm/utils/unittest/CMakeLists.txt
index dadca65b3ae..16a35451274 100644
--- a/llvm/utils/unittest/CMakeLists.txt
+++ b/llvm/utils/unittest/CMakeLists.txt
@@ -21,10 +21,10 @@ if(WIN32)
   add_definitions(-DGTEST_OS_WINDOWS=1)
 endif()
 
-if(SUPPORTS_NO_VARIADIC_MACROS_FLAG)
+if(SUPPORTS_VARIADIC_MACROS_FLAG)
   add_definitions("-Wno-variadic-macros")
 endif()
-if(SUPPORTS_NO_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
+if(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
   add_definitions("-Wno-gnu-zero-variadic-macro-arguments")
 endif()
 if(CXX_SUPPORTS_COVERED_SWITCH_DEFAULT_FLAG)