[Bug c++/84082] [7/8 Regression] ICE with broken template function definition

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84082

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
build_functional_cast here creates CAST_EXPR with NULL TREE_TYPE as well as
TREE_OPERAND (, 0) and cp_parser_constant_expression ->
potential_rvalue_constant_expression -> potential_constant_expression_1 is
called on it and doesn't handle that case:
      return (RECUR (TREE_OPERAND (t, 0),
                     TREE_CODE (TREE_TYPE (t)) != REFERENCE_TYPE));