[Bug c++/111087] New: -Wnonnull issued for std::array of zero size when under C++20

[adam.f.badura at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111087

            Bug ID: 111087
           Summary: -Wnonnull issued for std::array of zero size when
                    under C++20
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: adam.f.badura at gmail dot com
  Target Milestone: ---

At least for GCC 10.2 and 12.2, when using -std=c++20 I'm getting unexpected
-Wnonnull in the following (simplified) case:

  #include <algorithm>
  #include <array>
  #include <string_view>

  const std::array<std::string_view, 0> tags{};

  bool hasTag(const char* const tag)
  {
    const auto result = std::lower_bound(tags.begin(), tags. End(), tag);
    return result != tags.end() && result->compare(tag) == 0;
  }

See it on Compiler Explorer: https://godbolt.org/z/rGenGef7n.

It seems to be associated with the 0 size of the array since as soon as I
change it to 1 (or more) the warning goes away. Same if I drop the -std=c++20
(for 12.2 - with 10.2 it will not work due to <string_view>).