Add option to disable __deallocate #warning

[kastiglione]

Summary

From r229162:

Visual Studio's SAL extension uses a macro named __deallocate. This
macro is used pervasively

Using -Werror when building for Windows can force the use of -Wno-#warnings
specifically because of this __deallocate #warning. Instead of forcing
builds to disable all #warnings, this option allows libc++ to be built
without this particular warning, while leaving other #warnings enabled.

[compnerd]

There is another header, __undef_min_max, please apply the same behavior there. This patch, as is, only does it partially, which I don't think is ideal.

include/__undef___deallocate

16

I don't think that we should do this partially. Id rather have the behavior be identical across MSVC and not-MSVC. Please move this above the _MSC_VER check.

[kastiglione]

Handle min/max; Cover MSVC too

[compnerd]

SVN r275172.

CMakeLists.txt

 option(LIBCXX_HAS_MUSL_LIBC "Build libc++ with support for the Musl C library" OFF)
 option(LIBCXX_HAS_PTHREAD_API "Ignore auto-detection and force use of pthread API" OFF)
 
 # Misc options ----------------------------------------------------------------
 # FIXME: Turn -pedantic back ON. It is currently off because it warns
 # about #include_next which is used everywhere.
 option(LIBCXX_ENABLE_PEDANTIC "Compile with pedantic enabled." OFF)
 option(LIBCXX_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
+option(LIBCXX_DISABLE_MACRO_CONFLICT_WARNINGS "Disable #warnings about conflicting macros." OFF)
 
 option(LIBCXX_GENERATE_COVERAGE "Enable generating code coverage." OFF)
 set(LIBCXX_COVERAGE_LIBRARY "" CACHE STRING
     "The Profile-rt library used to build with code coverage")
 
 # Don't allow a user to accidentally overwrite the system libc++ installation on Darwin.
 # If the user specifies -DCMAKE_INSTALL_PREFIX=/usr the install rules for libc++
 # will not be generated and a warning will be issued.

 else()
   # TODO(EricWF) Remove this. We shouldn't be suppressing errors when -Werror is
   # added elsewhere.
   add_compile_flags_if_supported(-Wno-error)
 endif()
 if (LIBCXX_ENABLE_PEDANTIC)
   add_compile_flags_if_supported(-pedantic)
 endif()
+if (LIBCXX_DISABLE_MACRO_CONFLICT_WARNINGS)
+  add_definitions(-D_LIBCPP_DISABLE_MACRO_CONFLICT_WARNINGS)
+endif()
 
 # Exception flags =============================================================
 if (LIBCXX_ENABLE_EXCEPTIONS)
   # Catches C++ exceptions only and tells the compiler to assume that extern C
   # functions never throw a C++ exception.
   add_compile_flags_if_supported(-EHsc)
 else()
   add_definitions(-D_LIBCPP_NO_EXCEPTIONS)

include/__undef___deallocate

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifdef __deallocate
+#if !defined(_LIBCPP_DISABLE_MACRO_CONFLICT_WARNINGS)
 #if defined(_MSC_VER) && !defined(__clang__)
 _LIBCPP_WARNING("macro __deallocate is incompatible with C++.  #undefining __deallocate")
 #else
 #warning: macro __deallocate is incompatible with C++.  #undefining __deallocate
 #endif
+#endif
 #undef __deallocate
 #endif

include/__undef_min_max

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifdef min
+#if !defined(_LIBCPP_DISABLE_MACRO_CONFLICT_WARNINGS)
 #if defined(_MSC_VER) && ! defined(__clang__)
 _LIBCPP_WARNING("macro min is incompatible with C++.  Try #define NOMINMAX "
                 "before any Windows header. #undefing min")
 #else
 #warning: macro min is incompatible with C++.  #undefing min
 #endif
+#endif
 #undef min
 #endif
 
 #ifdef max
+#if !defined(_LIBCPP_DISABLE_MACRO_CONFLICT_WARNINGS)
 #if defined(_MSC_VER) && ! defined(__clang__)
 _LIBCPP_WARNING("macro max is incompatible with C++.  Try #define NOMINMAX "
                 "before any Windows header. #undefing max")
 #else
 #warning: macro max is incompatible with C++.  #undefing max
 #endif
+#endif
 #undef max
 #endif