[Bug c++/95317] New: [7 regression] ICE on valid C++14 code, in tsubst_copy, at cp/pt.c:15649

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95317

            Bug ID: 95317
           Summary: [7 regression] ICE on valid C++14 code, in
                    tsubst_copy, at cp/pt.c:15649
           Product: gcc
           Version: 9.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fxcoudert at gcc dot gnu.org
  Target Milestone: ---

ICE on valid C++14 code:

$ cat b.C
#include <iostream>

template <int I>
struct num
{
    enum { value = I };
};

#define VALUEOFNUM(x) std::remove_reference_t<decltype(x)>::value


template <typename TYPE>
void foo()
{
    auto test = [&](auto i)
    {
        enum { VALUE = VALUEOFNUM(i) };
        std::cout << VALUE;
    };

    test(num<0>());
    test(num<1>());
}

int main()
{
    foo<void>();
}

$ g++-9 b.C 
b.C: In instantiation of 'void foo() [with TYPE = void]':
b.C:27:15:   required from here
b.C:18:22: internal compiler error: in tsubst_copy, at cp/pt.c:15649
   18 |         std::cout << VALUE;
      |                      ^~~~~
libbacktrace could not find executable to open
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://github.com/Homebrew/homebrew-core/issues> for instructions.



Works fine with GCC up to version 6, but regresses at 7 and later.