[PATCH] libstdc++: Compare keys and values separately in flat_map::operator==

[Patrick Palka]

Tested on x86_64-pc-linux-gnu, does this look OK for trunk/15?

-- >8 --

Instead of effectively doing a zipped comparison of the keys and values,
compare them separately to leverage the underlying containers' optimized
equality implementations.

libstdc++-v3/ChangeLog:

        * include/std/flat_map (_Flat_map_impl::operator==): Compare
        keys and values separately.
---
 libstdc++-v3/include/std/flat_map | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/std/flat_map 
b/libstdc++-v3/include/std/flat_map
index c0716d12412a..134307324190 100644
--- a/libstdc++-v3/include/std/flat_map
+++ b/libstdc++-v3/include/std/flat_map
@@ -873,7 +873,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       [[nodiscard]]
       friend bool
       operator==(const _Derived& __x, const _Derived& __y)
-      { return std::equal(__x.begin(), __x.end(), __y.begin(), __y.end()); }
+      {
+       return __x._M_cont.keys == __y._M_cont.keys
+         && __x._M_cont.values == __y._M_cont.values;
+      }
 
       template<typename _Up = value_type>
        [[nodiscard]]
-- 
2.50.0.rc0