[Bug c++/87322] New: [GCC 8.1+] GCC fails to parse captured lambda of 2nd inner lambda if the captured lambda has "," (having 2 arguments)

[hotguest1 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87322

            Bug ID: 87322
           Summary: [GCC 8.1+] GCC fails to parse captured lambda of 2nd
                    inner lambda if the captured lambda has "," (having 2
                    arguments)
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hotguest1 at hotmail dot com
  Target Milestone: ---

Compiler thinks ',' in
inner_func2 =  [] (auto a, auto b) { return a + b; }
is capture separation.


////////////////////////////////////////////////////////////
Reproducing code: https://godbolt.org/z/3h1ByQ
////////////////////////////////////////////////////////////
#include <array>
#include <algorithm>

int main()
{
  constexpr std::array<std::array<double,2>,3> my_mat { 
     { { 1., 1. },
       { 1., 1. },
       { 1., 1. }, }
  };

  std::for_each(my_mat.begin(), my_mat.end(), [
      inner_func =  [] (auto a, auto b) { return a + b; } ](auto& row) {
    std::for_each(row.begin(), row.end(), [&,
      inner_func2 =  [] (auto a, auto b) { return a + b; } ]
      (const double&) {
        return;
    });
  }); 

}

////////////////////////////////////////////////////////////
Error:
////////////////////////////////////////////////////////////
<source>: In instantiation of 'main()::<lambda(auto:3&)> [with auto:3 = const
std::array<double, 2>]':

/opt/compiler-explorer/gcc-8.1.0/include/c++/8.1.0/bits/stl_algo.h:3882:5:  
required from '_Funct std::for_each(_IIter, _IIter, _Funct) [with _IIter =
const std::array<double, 2>*; _Funct = main()::<lambda(auto:3&)>]'

<source>:19:4:   required from here

<source>:15:58: internal compiler error: Segmentation fault

       inner_func2 =  [] (auto a, auto b) { return a + b; } ]

                                                          ^

Please submit a full bug report,

with preprocessed source if appropriate.

See <https://gcc.gnu.org/bugs/> for instructions.

Compiler returned: 1