[Bug c++/60437] [C++11] Bogus "error: no matching function for call to 'X::X(<brace-enclosed initializer list>)'"

[neoncat6 at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60437

--- Comment #4 from Foo Bar <neoncat6 at outlook dot com> ---
Seems like I found same issue on gcc 9.1.1.... Both MSVC 2019 and clang 9 can
compile this source without any error.

#include <iostream>
#include <vector>

class Abc {
public:
        Abc(std::initializer_list<int> il = {}) : vec(il) {}

        std::vector<int> vec;
};

int main(void) {
        Abc abc{ 1, 2, 3, 4 };

        for (auto num : abc.vec)
                std::cout << num << std::endl;

        return 0;
}

Error message:
$ g++ -Wall -std=c++11 il_def_arg.cpp 
il_def_arg.cpp: In function ‘int main()’:
il_def_arg.cpp:12:22: error: no matching function for call to
‘Abc::Abc(<brace-enclosed initializer list>)’
   12 |  Abc abc{ 1, 2, 3, 4 };
      |                      ^
il_def_arg.cpp:6:2: note: candidate: ‘Abc::Abc(std::initializer_list<int>)’
    6 |  Abc(std::initializer_list<int> il = {}) : vec(il) {}
      |  ^~~
il_def_arg.cpp:6:2: note:   candidate expects 1 argument, 4 provided
il_def_arg.cpp:4:7: note: candidate: ‘Abc::Abc(const Abc&)’
    4 | class Abc {
      |       ^~~
il_def_arg.cpp:4:7: note:   candidate expects 1 argument, 4 provided
il_def_arg.cpp:4:7: note: candidate: ‘Abc::Abc(Abc&&)’
il_def_arg.cpp:4:7: note:   candidate expects 1 argument, 4 provided