Disable -Wmicrosoft-cast on clang-cl.

There's no easy / clean way to make it not fire, so disabling globally.
It's also pretty harmless (on other systems we'd use reinterpret_cast),
so why bother.

modules/UseCorrade.cmake

@@ -213,6 +213,12 @@ elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" OR CMAKE_CXX_SIMULATE_ID STREQUAL "
         "_CRT_SECURE_NO_WARNINGS" "_SCL_SECURE_NO_WARNINGS")
 endif()
 
+if(CORRADE_TARGET_CLANG_CL)
+    list(APPEND CORRADE_PEDANTIC_COMPILER_OPTIONS
+        # See Utility::Directory::libraryLocation() for details
+        "-Wno-microsoft-cast")
+endif()
+
 # Compiler flags to undo horrible crimes done by windows.h, common for both
 # MSVC and MinGW
 if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" OR CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC" OR MINGW)

src/Corrade/Utility/Debug.cpp

@@ -282,14 +282,21 @@ bool Debug::isTty(std::ostream* const output) {
        ANSI colors enabled */
     #elif defined(CORRADE_UTILITY_USE_ANSI_COLORS) || defined(CORRADE_TARGET_UNIX)
     return
-        /* Windows RT projects have C4996 treated as error by default. WHY */
-        #ifdef _MSC_VER
+        /* Windows RT projects have C4996 treated as error by default. WHY.
+           Also, clang-cl doesn't understand warning IDs yet, so using its own
+           warning suppression right now. */
+        #ifdef CORRADE_TARGET_CLANG_CL
+        #pragma clang diagnostic push
+        #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+        #elif defined(CORRADE_TARGET_MSVC)
         #pragma warning(push)
         #pragma warning(disable: 4996)
         #endif
         ((output == &std::cout && isatty(1)) ||
          (output == &std::cerr && isatty(2)))
-        #ifdef _MSC_VER
+        #ifdef CORRADE_TARGET_CLANG_CL
+        #pragma clang diagnostic pop
+        #elif defined(CORRADE_TARGET_MSVC)
         #pragma warning(pop)
         #endif
         #ifdef CORRADE_TARGET_APPLE

src/Corrade/Utility/Directory.h

@@ -303,6 +303,11 @@ struct FunctionPointer {
 };
 
 }
+/* Unfortunately, on MSVC (and clang-cl), the const void* overload is picked
+   instead, as MSVC implements implicit cast from function pointers to void*
+   (while GCC doesn't). On clang-cl it prints a -Wmicrosoft-cast warning and there's no way to make it go to this overload first without using a
+   template, so the warning is disabled globally in UseCorrade.cmake. More
+   info here: https://bugs.chromium.org/p/chromium/issues/detail?id=550065 */
 CORRADE_UTILITY_EXPORT std::string libraryLocation(Implementation::FunctionPointer address);
 #endif
 #endif