[Bug c++/71267] [C++14] recursive metafunction won't compile: no type named 'type'
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71267 Andrew Pinski changed: What|Removed |Added Keywords||rejects-valid Status|UNCONFIRMED |NEW Last reconfirmed||2016-05-25 Summary|recursive metafunction |[C++14] recursive |won't compile: no type |metafunction won't compile: |named 'type'|no type named 'type' Ever confirmed|0 |1 --- Comment #1 from Andrew Pinski --- Here is a reduced such that we don't depend on any headers: template struct tt{}; template struct typelist {}; // specialization of typelist for std::integral_constant<>s #ifdef WORKS template struct integer_typelist {}; #else template using integer_typelist = typelist...>; #endif // helper metafunction to generate typelist<> of integral_constant<>s by // specifying a Start, End, and Step value template struct make_integer_list_impl; // specialization for: Start < End template struct make_integer_list_impl, true> { typedef typename make_integer_list_impl< Start+Step, End, Step, integer_typelist >::type type; }; // specialization for: Start >= End (terminate the recursion) template struct make_integer_list_impl, false> { using type = integer_typelist; }; // helper alias template template using make_integer_typelist = typename make_integer_list_impl>::type; int main() { // typelist< // std::integral_constant, // std::integral_constant, // std::integral_constant, // std::integral_constant, // std::integral_constant // > using t2 = make_integer_typelist<0, 13, 3>; } - CUT If we change integer_typelist to a template struct instead of an using alias, it works.
[Bug c++/71267] [C++14] recursive metafunction won't compile: no type named 'type'
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71267 Andrew Pinski changed: What|Removed |Added Known to fail||10.3.0, 11.1.0 Known to work||11.2.0 --- Comment #2 from Andrew Pinski --- Looks fixed in GCC 11.2.0 and GCC12+.
[Bug c++/71267] [C++14] recursive metafunction won't compile: no type named 'type'
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71267 --- Comment #3 from Jonathan Wakely --- Accepted since r12-1094 and r11-8714: c++: argument pack with expansion [PR86355] This testcase revealed that we were using PACK_EXPANSION_EXTRA_ARGS a lot more than necessary; use_pack_expansion_extra_args_p meant to use it in the case of corresponding arguments in different argument packs differing in whether they are pack expansions, but it was mistakenly also returning true for the case of a single argument pack containing both expansion and non-expansion elements. Surprisingly, just disabling that didn't lead to any regressions in the testsuite; it seems other changes have prevented us getting to this point for code that used to exercise it. So this patch limits the check to arguments in the same position in the packs, and asserts that we never actually see a mismatch. PR c++/86355 gcc/cp/ChangeLog: * pt.c (use_pack_expansion_extra_args_p): Don't compare args from the same argument pack. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/alias-decl-variadic2.C: New test.