https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68586
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |mpolacek at gcc dot gnu.org
--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This passes with trunk with -std=c++03, because the difference comes from
maybe_constant_value in convert_nontype_argument:
6260 /* In C++11, integral or enumeration non-type template arguments can be
6261 arbitrary constant expressions. Pointer and pointer to
6262 member arguments can be general constant expressions that evaluate
6263 to a null value, but otherwise still need to be of a specific form.
*/
6264 if (cxx_dialect >= cxx11)
6265 {
6266 if (TREE_CODE (expr) == PTRMEM_CST)
6267 /* A PTRMEM_CST is already constant, and a valid template
6268 argument for a parameter of pointer to member type, we just
want
6269 to leave it in that form rather than lower it to a
6270 CONSTRUCTOR. */;
6271 else if (INTEGRAL_OR_ENUMERATION_TYPE_P (type))
6272 expr = maybe_constant_value (expr);
gcc-5 compiles this testcase fine even with -std=c++11 though. It looks as if
the difference is that for const_decl 'x' gcc-6's maybe_constant_value returns
"1" (integer_cst) while gcc-5's maybe_constant_value returns "1" (enumeral_type
E).
