[Bug c++/96188] New: -Wstringop-overflow false positive

[derek.mauro at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96188

            Bug ID: 96188
           Summary: -Wstringop-overflow false positive
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: derek.mauro at gmail dot com
  Target Milestone: ---

This is strange issue that started appearing in gcc 10.1. It also seems to
require -O3 and -std=gnu++11 (gnu++14 etc appear unaffected).

Godbolt demo: https://godbolt.org/z/W8MWbz

Test case copy/pasted below.

Use -Werror -Wstringop-overflow -std=gnu++11 -O3

#include <string>
#include <vector>

bool b;

void F() {
  static bool b2 = b;
  for (const int fx : {0}) {
    struct Expectation {
      std::string out;
    };

    std::vector<Expectation> expect = {
        {std::string()},
        {std::string()},
        {std::string()},
    };
    if (b2) {
      expect.push_back({std::string()});
    }

  }
}