[Bug c++/121705] [16 Regression] When using import std, formatting std::chrono::year_month_day will cause compilation failure

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121705

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This does fix it, but probably shouldn't be needed:

-- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -3415,3 +3415,7 @@ export namespace std
   }
   using std::hash;
 }
+
+export namespace std::__format {
+  using std::__format::operator==;
+}