https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39159
--- Comment #7 from Martin Sebor <msebor at gcc dot gnu.org> --- I'm not an expert in this area but the approach seems reasonable to me. I didn't test it in 5.x but with 6.0, it doesn't make a difference because simple_cst_equal() cannot compare TREE_LISTs. Using attribute_value_equal() instead does work. >From a user's point of view, though, it would be helpful if the diagnostic included the names of the "new" attributes that are being ignored, and pointed to the location of the previous "old" declaration that the current one conflicts with. The former should be a matter of concatenating the names of the new attributes into a string and making that part of the warning. The latter can be done by calling: inform (DECL_SOURCE_LOCATION (TYPE_FIELDS (*anode)), "previous declaration here"); To get the patch reviewed and ultimately approved, you should rebase it to the current trunk, add tests and ChangeLog entries, and post it to gcc-patches.
