[Bug c++/67238] New: [C++11][C++14]cc1plus crash for nested decltype expression in parameter pack in trailing return type when '-g' enabled

["webrown.cpp at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67238

            Bug ID: 67238
           Summary: [C++11][C++14]cc1plus crash for nested decltype
                    expression in parameter pack in trailing return type
                    when '-g' enabled
           Product: gcc
           Version: 5.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: frankhb1989 at gmail dot com
                CC: webrown.cpp at gmail dot com
  Target Milestone: ---
                CC: webrown.cpp at gmail dot com

g++ -v
...
gcc version 5.2.0 (Rev3, Built by MSYS2 project)

Case:
//a.cc
template<class F, class... A>
void
g(F&&, A&&...)
{}

template<class... A>
auto
h(A&&... a) -> decltype(g(0, g<decltype(a)>(a)...))
{
        return g([]{}, a...); // Crash if any error here.
}

int
main()
{
        h();
}

g++ a.cc -std=c++11 -g1

The frontend crashes, and no diagnostics shown for this particular case on my
machine. Otherwise there may be segfault. Same for -std=c++14, but '-g0' seems
to be OK.

BTW, it seems that nested decltype expression in trailing return types are
often buggy playing with lambdas. Should there be any other reports?