[Bug c++/96330] Constexpr variables cannot be used in the template context.

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96330

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Tried
--- gcc/cp/pt.c.jj      2020-07-27 10:38:19.000000000 +0200
+++ gcc/cp/pt.c 2020-07-27 17:25:09.748240198 +0200
@@ -16838,14 +16838,17 @@ tsubst_copy (tree t, tree args, tsubst_f
     case TEMPLATE_ID_EXPR:
       {
        /* Substituted template arguments */
-       tree fn = TREE_OPERAND (t, 0);
+       tree expr = TREE_OPERAND (t, 0);
        tree targs = TREE_OPERAND (t, 1);

-       fn = tsubst_copy (fn, args, complain, in_decl);
+       expr = tsubst_copy (expr, args, complain, in_decl);
        if (targs)
          targs = tsubst_template_args (targs, args, complain, in_decl);

-       return lookup_template_function (fn, targs);
+        if (variable_template_p (expr))
+         return lookup_and_finish_template_variable (expr, targs, complain);
+       else
+         return lookup_template_function (expr, targs);
       }

     case TREE_LIST:
but that just means an ICE elsewhere.