external/boost: Adapt to clang-cl

Change-Id: Ib07e85bd1a157b6fa78f07a17f8cf5033b01bddf

external/boost/StaticLibrary_boostthread.mk

@@ -18,6 +18,26 @@ $(eval $(call gb_StaticLibrary_add_defs,boostthread,\
 	-DBOOST_ALL_NO_LIB \
 ))
 
+# Lots of the declarations in boost duplicated from windows.h when
+# BOOST_USE_WINDOWS_H is not defined (which appears to be the normal case) cause
+# warnings or even errors with Clang when windows.h is included too (e.g.,
+# "conflicting types for 'FileTimeToLocalFileTime'" between
+# C:/PROGRA~2/WI3CF2~1/8.1/include/um/fileapi.h and
+# workdir/UnpackedTarball/boost/boost/date_time/filetime_functions.hpp), for
+# which it appears easies to just define BOOST_USE_WINDOWS_H; also
+# -Winvalid-constexpr (e.g., reported from the constexpr definition of lowest()
+# in workdir/UnpackedTarball/boost/boost/chrono/duration.hpp, which uses
+# std::numeric_limits<>::max() from MSVC's standard library, where nothing is
+# marked constexpr) is apparently reported as an error by default:
+ifeq ($(OS),WNT)
+ifeq ($(COM_IS_CLANG),TRUE)
+$(eval $(call gb_StaticLibrary_add_defs,boostthread, \
+    -DBOOST_USE_WINDOWS_H \
+    -Wno-error=invalid-constexpr \
+))
+endif
+endif
+
 $(eval $(call gb_StaticLibrary_use_external,boostthread,boost_headers))
 
 $(eval $(call gb_StaticLibrary_set_generated_cxx_suffix,boostthread,cpp))

external/boost/UnpackedTarball_boost.mk

@@ -85,6 +85,8 @@ boost_patches += boost_1_59_0.multi_array.wshadow.patch
 # https://svn.boost.org/trac/boost/ticket/11501
 boost_patches += boost_1_59_0.property_tree.wreturn-type.patch
 
+boost_patches += clang-cl.patch.0
+
 $(eval $(call gb_UnpackedTarball_UnpackedTarball,boost))
 
 $(eval $(call gb_UnpackedTarball_set_tarball,boost,$(BOOST_TARBALL)))

external/boost/clang-cl.patch.0

+--- boost/config/compiler/clang.hpp
++++ boost/config/compiler/clang.hpp
+@@ -260,9 +260,7 @@
+ 
+ 
+ // Unused attribute:
+-#if defined(__GNUC__) && (__GNUC__ >= 4)
+ #  define BOOST_ATTRIBUTE_UNUSED __attribute__((unused))
+-#endif
+ 
+ #ifndef BOOST_COMPILER
+ #  define BOOST_COMPILER "Clang version " __clang_version__
+
+# workdir/UnpackedTarball/boost\boost/smart_ptr/detail/sp_counted_base_clang.hpp(29,1) :  error: cannot mangle this C11 atomic type yet
+# inline void atomic_increment( atomic_int_least32_t * pw )
+# ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+--- boost/smart_ptr/detail/sp_counted_base.hpp
++++ boost/smart_ptr/detail/sp_counted_base.hpp
+@@ -21,7 +21,7 @@
+ #include <boost/smart_ptr/detail/sp_has_sync.hpp>
+ 
+ #if defined( __clang__ ) && defined( __has_extension )
+-# if __has_extension( __c_atomic__ )
++# if __has_extension( __c_atomic__ ) && !defined _MSC_VER
+ #   define BOOST_SP_HAS_CLANG_C11_ATOMICS
+ # endif
+ #endif
+
+# C:/lo64/core/workdir/UnpackedTarball/boost/libs/thread/src/win32/thread.cpp(1006,36) :  error: dllimport cannot be applied to non-inline function definition
+#     BOOST_THREAD_DECL void __cdecl on_process_enter()
+#                                    ^
+--- boost/thread/detail/config.hpp
++++ boost/thread/detail/config.hpp
+@@ -396,7 +396,7 @@
+ #else //Use default
+ #   if defined(BOOST_THREAD_PLATFORM_WIN32)
+ #       if defined(BOOST_MSVC) || defined(BOOST_INTEL_WIN) \
+-      || defined(__MINGW32__) || defined(MINGW32) || defined(BOOST_MINGW32)
++      || defined(__MINGW32__) || defined(MINGW32) || defined(BOOST_MINGW32) || defined __clang__
+       //For compilers supporting auto-tss cleanup
+             //with Boost.Threads lib, use Boost.Threads lib
+ #           define BOOST_THREAD_USE_LIB