Re-apply "Fix cmake check for futimens when deploying to earlier macOS releases."

ributzka · ributzka · commit c0fc219bd52d · 2017-08-29T00:34:56.000Z
This fixes an issue with the use of LLVM_PARALLEL_LINK_JOBS. Original commit message: macOS 10.13 added a new API (futimens). This API is only available on macOS 10.13 and later, but the cmake check we have in place only tests if the symbol is present and ignores the availability attribute. Luckily we have new warning for this and by making this warning an error the cmake check will return the correct result. See also rdar://problem/33992750. Differential Revision: https://reviews.llvm.org/D37027 llvm-svn: 311965
diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
@@ -8,6 +8,7 @@ include(CheckIncludeFileCXX)
 include(CheckLibraryExists)
 include(CheckSymbolExists)
 include(CheckFunctionExists)
+include(CheckCCompilerFlag)
 include(CheckCXXSourceCompiles)
 include(TestBigEndian)
 
@@ -179,6 +180,14 @@ check_symbol_exists(arc4random "stdlib.h" HAVE_DECL_ARC4RANDOM)
 find_package(Backtrace)
 set(HAVE_BACKTRACE ${Backtrace_FOUND})
 set(BACKTRACE_HEADER ${Backtrace_HEADER})
+
+# Prevent check_symbol_exists from using API that is not supported for a given
+# deployment target.
+check_c_compiler_flag("-Werror=unguarded-availability-new" "C_SUPPORTS_WERROR_UNGUARDED_AVAILABILITY_NEW")
+if(C_SUPPORTS_WERROR_UNGUARDED_AVAILABILITY_NEW)
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unguarded-availability-new")
+endif()
+
 check_symbol_exists(_Unwind_Backtrace "unwind.h" HAVE__UNWIND_BACKTRACE)
 check_symbol_exists(getpagesize unistd.h HAVE_GETPAGESIZE)
 check_symbol_exists(sysconf unistd.h HAVE_SYSCONF)
diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -383,6 +383,7 @@ elseif( LLVM_COMPILER_IS_GCC_COMPATIBLE )
   append_if(LLVM_ENABLE_WERROR "-Werror" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
   append_if(LLVM_ENABLE_WERROR "-Wno-error" CMAKE_REQUIRED_FLAGS)
   add_flag_if_supported("-Werror=date-time" WERROR_DATE_TIME)
+  add_flag_if_supported("-Werror=unguarded-availability-new" WERROR_UNGUARDED_AVAILABILITY_NEW)
   if (LLVM_ENABLE_CXX1Y)
     check_cxx_compiler_flag("-std=c++1y" CXX_SUPPORTS_CXX1Y)
     append_if(CXX_SUPPORTS_CXX1Y "-std=c++1y" CMAKE_CXX_FLAGS)
