https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65579
Paolo Carlini <paolo.carlini at oracle dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |paolo.carlini at oracle dot com --- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> --- Hi Martin. Are you still actively working on this? Because something implementing as trivially as the below what Jason suggested on the mailing list already appears to pass testing, shouldn't be *that* far from an actual fix... Index: decl.c =================================================================== --- decl.c (revision 253091) +++ decl.c (working copy) @@ -12348,7 +12348,11 @@ /* Set constexpr flag on vars (functions got it in grokfndecl). */ if (constexpr_p && VAR_P (decl)) - DECL_DECLARED_CONSTEXPR_P (decl) = true; + { + DECL_DECLARED_CONSTEXPR_P (decl) = true; + if (!processing_template_decl) + complete_type (TREE_TYPE (decl)); + } /* Record constancy and volatility on the DECL itself . There's no need to do this when processing a template; we'll do this