[Bug c++/85214] [7/8 Regression] ICE on valid C++17 code on x86_64-linux-gnu: in tsubst_copy, at cp/pt.c:14562

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85214

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-04-06
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org
   Target Milestone|---                         |7.4
            Summary|ICE on valid C++17 code on  |[7/8 Regression] ICE on
                   |x86_64-linux-gnu: in        |valid C++17 code on
                   |tsubst_copy, at             |x86_64-linux-gnu: in
                   |cp/pt.c:14562               |tsubst_copy, at
                   |                            |cp/pt.c:14562
     Ever confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced testcase:
typedef int a;
namespace b {
template <typename c, c d> struct e { static constexpr c f = d; constexpr
operator int() { return f; } };
typedef e<bool, false> g;
template <typename, typename> struct h : g {};
template <typename...> class k;
template <typename c, typename l> constexpr bool m = h<c, l>::f;
template <a> struct n;
template <typename> struct aa;
template <long, typename> struct C;
template <long ab, typename c> using o = typename C<ab, c>::q;
template <typename c, c> struct p {};
template <typename, typename = n<0>> struct F;
template <typename c, a... r> struct F<c, n<r...>> { typedef p<c, r...> ae; };
template <typename c, c> using t = typename F<c>::ae;
template <a... r> using w = p<a, r...>;
template <a ad> using af = t<a, ad>;
template <typename... ag> struct aa<k<ag...>> : e<long, sizeof...(ag)> {};
template <typename c> constexpr a ah = aa<c>::f;
template <typename ai, typename... aj> struct C<0, k<ai, aj...>> { typedef ai
q; };
}
template <typename ak, a... s> void al(ak am, b::w<s...>) { int{(am(b::e<a,
s>{}), 0)...}; }
template <int an, typename ak> void al(ak am) { al(am, b::af<an>()); }
void ao() {
  using ap = b::k<double>;
  const a aq = b::ah<ap>;
  al<aq>([](auto i) {
    using ar = b::o<i, ap>;
    al<aq>([](auto j) { using as = b::o<j, ap>; if constexpr (b::m<ar, as>) ;
});
  });
}

Started to ICE with r239338 when if constexpr has been introduced.