Disable the gcc 12 warning about dllimport in directory.hpp.

The warnings suppressed in header.hpp can be force-enabled by the user,
so disable the buggy warning in directory.hpp instead. Also make the
workaround more specific to MinGW.

Author: Lastique

include/boost/filesystem/detail/header.hpp

@@ -44,12 +44,6 @@
 // unused function 'foo'
 #pragma GCC diagnostic ignored "-Wunused-function"
 
-#if (__GNUC__ == 12)
-// 'function' redeclared without dllimport attribute: previous dllimport ignored
-// MinGW-w64 bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106395
-#pragma GCC diagnostic ignored "-Wattributes"
-#endif
-
 #if defined(__clang__)
 // template argument uses unnamed type
 #pragma clang diagnostic ignored "-Wunnamed-type-template-args"

include/boost/filesystem/directory.hpp

@@ -35,6 +35,13 @@
 
 #include <boost/filesystem/detail/header.hpp> // must be the last #include
 
+#if defined(__MINGW32__) && defined(BOOST_GCC) && (__GNUC__ == 12)
+#pragma GCC diagnostic push
+// 'function' redeclared without dllimport attribute: previous dllimport ignored
+// MinGW-w64 bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106395
+#pragma GCC diagnostic ignored "-Wattributes"
+#endif
+
 //--------------------------------------------------------------------------------------//
 
 namespace boost {
@@ -1034,6 +1041,10 @@ struct range_const_iterator< boost::filesystem::recursive_directory_iterator, vo
 
 } // namespace boost
 
+#if defined(__MINGW32__) && defined(BOOST_GCC) && (__GNUC__ == 12)
+#pragma GCC diagnostic pop
+#endif
+
 #include <boost/filesystem/detail/footer.hpp>
 
 #endif // BOOST_FILESYSTEM_DIRECTORY_HPP