clang: setup correct configuration in gnu mode

Modules/Compiler/Clang-CXX.cmake

@@ -1,7 +1,7 @@
 include(Compiler/Clang)
 __compiler_clang(CXX)
 
-if(NOT "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
+if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
   set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 endif()
 
@@ -10,7 +10,8 @@ if(APPLE AND NOT appleClangPolicy STREQUAL NEW)
   return()
 endif()
 
-if(NOT "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
+
+if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
   if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 2.1)
     set(CMAKE_CXX98_STANDARD_COMPILE_OPTION "-std=c++98")
     set(CMAKE_CXX98_EXTENSION_COMPILE_OPTION "-std=gnu++98")
@@ -56,6 +57,14 @@ if(NOT "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
 
   unset(_clang_version_std17)
 
+  if("x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
+    # This clang++ is missing some features because of MSVC compatibility.
+    unset(CMAKE_CXX11_STANDARD__HAS_FULL_SUPPORT)
+    unset(CMAKE_CXX14_STANDARD__HAS_FULL_SUPPORT)
+    unset(CMAKE_CXX17_STANDARD__HAS_FULL_SUPPORT)
+    unset(CMAKE_CXX20_STANDARD__HAS_FULL_SUPPORT)
+  endif()
+
   __compiler_check_default_language_standard(CXX 2.1 98)
 elseif(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 3.9
     AND CMAKE_CXX_SIMULATE_VERSION VERSION_GREATER_EQUAL 19.0)

Modules/Platform/Windows-Clang.cmake

@@ -8,13 +8,120 @@ if(__WINDOWS_CLANG)
 endif()
 set(__WINDOWS_CLANG 1)
 
+macro(__windows_compiler_clang_gnu lang)
+  set(CMAKE_LIBRARY_PATH_FLAG "-L")
+  set(CMAKE_LINK_LIBRARY_FLAG "-l")
+
+  set(CMAKE_IMPORT_LIBRARY_PREFIX "")
+  set(CMAKE_SHARED_LIBRARY_PREFIX "")
+  set(CMAKE_SHARED_MODULE_PREFIX  "")
+  set(CMAKE_STATIC_LIBRARY_PREFIX "")
+  set(CMAKE_EXECUTABLE_SUFFIX     ".exe")
+  set(CMAKE_IMPORT_LIBRARY_SUFFIX ".lib")
+  set(CMAKE_SHARED_LIBRARY_SUFFIX ".dll")
+  set(CMAKE_SHARED_MODULE_SUFFIX  ".dll")
+  set(CMAKE_STATIC_LIBRARY_SUFFIX ".lib")
+  set(CMAKE_DEPFILE_FLAGS_${lang} "-MD -MT <OBJECT> -MF <DEPFILE>")
+
+  set(CMAKE_FIND_LIBRARY_PREFIXES "lib" "")
+  set(CMAKE_FIND_LIBRARY_SUFFIXES ".dll" ".dll.a" ".a" ".lib")
+  set(CMAKE_SUPPORT_WINDOWS_EXPORT_ALL_SYMBOLS 1)
+  set (CMAKE_LINK_DEF_FILE_FLAG "-Xlinker /DEF:")
+
+  if("${CMAKE_${lang}_SIMULATE_VERSION}" MATCHES "^([0-9]+)\\.([0-9]+)")
+    math(EXPR MSVC_VERSION "${CMAKE_MATCH_1}*100 + ${CMAKE_MATCH_2}")
+  endif()
+
+  # No -fPIC on Windows
+  set(CMAKE_${lang}_COMPILE_OPTIONS_PIC "")
+  set(CMAKE_${lang}_COMPILE_OPTIONS_PIE "")
+  set(_CMAKE_${lang}_PIE_MAY_BE_SUPPORTED_BY_LINKER NO)
+  set(CMAKE_${lang}_LINK_OPTIONS_PIE "")
+  set(CMAKE_${lang}_LINK_OPTIONS_NO_PIE "")
+  set(CMAKE_SHARED_LIBRARY_${lang}_FLAGS "")
+
+  set(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_OBJECTS 1)
+  set(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_LIBRARIES 1)
+  set(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_INCLUDES 1)
+
+  # Create archiving rules to support large object file lists for static libraries.
+  set(CMAKE_${lang}_ARCHIVE_CREATE "<CMAKE_AR> qc <TARGET> <LINK_FLAGS> <OBJECTS>")
+  set(CMAKE_${lang}_ARCHIVE_APPEND "<CMAKE_AR> q  <TARGET> <LINK_FLAGS> <OBJECTS>")
+  set(CMAKE_${lang}_ARCHIVE_FINISH "<CMAKE_RANLIB> <TARGET>")
+  set(CMAKE_${lang}_CREATE_SHARED_LIBRARY
+    "<CMAKE_${lang}_COMPILER> -nostartfiles -nostdlib <CMAKE_SHARED_LIBRARY_${lang}_FLAGS> <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS> -o <TARGET> ${CMAKE_GNULD_IMAGE_VERSION} -Xlinker /implib:<TARGET_IMPLIB> -Xlinker /pdb:<TARGET_PDB> -Xlinker /version:<TARGET_VERSION_MAJOR>.<TARGET_VERSION_MINOR> <OBJECTS> <LINK_LIBRARIES>")
+  set(CMAKE_${lang}_CREATE_SHARED_MODULE ${CMAKE_${lang}_CREATE_SHARED_LIBRARY})
+  set(CMAKE_${lang}_LINK_EXECUTABLE
+    "<CMAKE_${lang}_COMPILER> -nostartfiles -nostdlib <FLAGS> <CMAKE_${lang}_LINK_FLAGS> <LINK_FLAGS> <OBJECTS>  -o <TARGET> -Xlinker /implib:<TARGET_IMPLIB> -Xlinker /pdb:<TARGET_PDB> -Xlinker /version:<TARGET_VERSION_MAJOR>.<TARGET_VERSION_MINOR> ${CMAKE_GNULD_IMAGE_VERSION} <LINK_LIBRARIES>")
+
+  set(CMAKE_${lang}_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreaded         -Xclang -flto-visibility-public-std -D_MT -Xclang --dependent-lib=libcmt)
+  set(CMAKE_${lang}_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreadedDLL      -D_DLL -D_MT -Xclang --dependent-lib=msvcrt)
+  set(CMAKE_${lang}_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreadedDebug    -D_DEBUG -Xclang -flto-visibility-public-std -D_MT -Xclang --dependent-lib=libcmtd)
+  set(CMAKE_${lang}_COMPILE_OPTIONS_MSVC_RUNTIME_LIBRARY_MultiThreadedDebugDLL -D_DEBUG -D_DLL -D_MT -Xclang --dependent-lib=msvcrtd)
+
+  if(CMAKE_MSVC_RUNTIME_LIBRARY_DEFAULT)
+    set(__ADDED_FLAGS "")
+    set(__ADDED_FLAGS_DEBUG "")
+  else()
+    set(__ADDED_FLAGS_DEBUG "-D_DEBUG -D_DLL -D_MT -Xclang --dependent-lib=msvcrtd")
+    set(__ADDED_FLAGS "-D_DLL -D_MT -Xclang --dependent-lib=msvcrt")
+  endif()
+
+  string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -g -Xclang -gcodeview -O0 ${__ADDED_FLAGS_DEBUG}")
+  string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -Os -DNDEBUG ${__ADDED_FLAGS}")
+  string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O3 -DNDEBUG ${__ADDED_FLAGS}")
+  string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -O2 -g -DNDEBUG -Xclang -gcodeview ${__ADDED_FLAGS}")
+  set(CMAKE_INCLUDE_SYSTEM_FLAG_${lang} "-isystem ")
+
+  unset(__ADDED_FLAGS)
+  unset(__ADDED_FLAGS_DEBUG)
+  string(TOLOWER "${CMAKE_BUILD_TYPE}" BUILD_TYPE_LOWER)
+  set(CMAKE_${lang}_STANDARD_LIBRARIES_INIT "-lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 -loldnames")
+
+  enable_language(RC)
+endmacro()
+
 if("x${CMAKE_C_SIMULATE_ID}" STREQUAL "xMSVC"
     OR "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
-  include(Platform/Windows-MSVC)
-  macro(__windows_compiler_clang lang)
-    set(_COMPILE_${lang} "${_COMPILE_${lang}_MSVC}")
-    __windows_compiler_msvc(${lang})
-  endmacro()
+
+  if ( DEFINED CMAKE_C_COMPILER_ID AND DEFINED CMAKE_CXX_COMPILER_ID
+       AND NOT "x${CMAKE_C_COMPILER_ID}" STREQUAL "x${CMAKE_CXX_COMPILER_ID}")
+    message(FATAL_ERROR "The current configuration mixes Clang and MSVC or "
+            "some other CL compatible compiler tool. This is not supported. "
+            "Use either clang or MSVC as both C and C++ compilers.")
+  endif()
+
+  if ( DEFINED CMAKE_C_COMPILER_FRONTEND_VARIANT AND DEFINED CMAKE_CXX_COMPILER_FRONTEND_VARIANT
+       AND NOT "x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}")
+    message(FATAL_ERROR "The current configuration uses the Clang compiler "
+            "tool with mixed frontend variants, both the GNU and in MSVC CL "
+            "like variants. This is not supported. Use either clang/clang++ "
+            "or clang-cl as both C and C++ compilers.")
+  endif()
+
+  if ( "x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC" OR "x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC" )
+    include(Platform/Windows-MSVC)
+
+    macro(__windows_compiler_clang lang)
+      set(_COMPILE_${lang} "${_COMPILE_${lang}_MSVC}")
+      __windows_compiler_msvc(${lang})
+    endmacro()
+  else()
+    cmake_policy(GET CMP0091 __WINDOWS_CLANG_CMP0091)
+    if(__WINDOWS_CLANG_CMP0091 STREQUAL "NEW")
+      set(CMAKE_MSVC_RUNTIME_LIBRARY_DEFAULT "MultiThreaded$<$<CONFIG:Debug>:Debug>DLL")
+    else()
+      set(CMAKE_MSVC_RUNTIME_LIBRARY_DEFAULT "")
+    endif()
+    unset(__WINDOWS_CLANG_CMP0091)
+
+    set(CMAKE_BUILD_TYPE_INIT Debug)
+
+    macro(__windows_compiler_clang lang)
+      __windows_compiler_clang_gnu(${lang})
+    endmacro()
+  endif()
+
 else()
   include(Platform/Windows-GNU)
   macro(__windows_compiler_clang lang)