[Bug c++/87017] New: vector must have the same value as its allocator

["development at faf-ltd dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87017

            Bug ID: 87017
           Summary: vector must have the same value as its allocator
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: development@faf-ltd.com
  Target Milestone: ---

This MCVE compiles/runs with gcc 7.3, clang 6.0 and icc 18.0 [this is, what I
tested so far]:

#include <regex>
#include <string>
#include <iostream>

namespace FaF
{
  template <typename T>
  class Allocator
  {
    public:
      typedef T value_type;

      Allocator() throw() {}
      template <typename U> Allocator (const Allocator<U>&) throw() {}
      ~Allocator() throw() {}

      T* allocate (std::size_t num, const void* hint = 0)
      {
        (void) hint; (void) num;
        return  new ( T );
      }

      void deallocate (T* p, std::size_t num) { (void) num; (void) p; }
  };

  using string = std::basic_string<char, std::char_traits<char>,
Allocator<char>>;
  using smatch = std::match_results<FaF::string::const_iterator,
Allocator<FaF::string::const_iterator>>;

}

int main()
{
  FaF::smatch results {};
  std::cout << "OK\n";
}


gcc 8.2 complains here:
    FaF::smatch results {};
    ^--- vector must have the same value as its allocator

Changing it to std::smatch then it compiles.

Compiler options:
-O3 -std=c++17 -Werror -Wextra -Wold-style-cast -Wall

Live version: https://godbolt.org/z/8wI6YS