https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113976
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- E.g. --- gcc/cp/decl.cc.jj 2024-02-15 09:51:34.460065992 +0100 +++ gcc/cp/decl.cc 2024-02-19 18:20:23.423410659 +0100 @@ -15263,7 +15263,14 @@ grokdeclarator (const cp_declarator *dec /* Record constancy and volatility on the DECL itself . There's no need to do this when processing a template; we'll do this for the instantiated declaration based on the type of DECL. */ - if (!processing_template_decl) + if (!processing_template_decl + /* Don't do it for instantiated variable templates either, + cp_apply_type_quals_to_decl should have been called on it + already and might have have been overridden in cp_finish_decl + if initializer needs runtime initialization. */ + && (!VAR_P (decl) + || DECL_LANG_SPECIFIC (decl) == NULL + || !DECL_USE_TEMPLATE (decl))) cp_apply_type_quals_to_decl (type_quals, decl); return decl; fixes it, but it is just a random shot in the dark. I think we want to differentiate between freshly created VAR_DECL from the grokdeclarator vs. existing VAR_DECL grokdeclarator just looked up.