https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68669
--- Comment #7 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- (In reply to Manuel López-Ibáñez from comment #6) > Perhaps you need to try with -Wunused-const-variable ? There may be some > problem with TREE_READONLY (decl). There is no -Wunused-const-variable in gcc-5.