[gcc r16-2608] libsdc++: Test using range_format::map as format_kind.

[Tomasz Kaminski]

https://gcc.gnu.org/g:689ee39f7bbb632a9ca7d1dc18192bd1921e54a8

commit r16-2608-g689ee39f7bbb632a9ca7d1dc18192bd1921e54a8
Author: Tomasz Kamiński <tkaminsk@redhat.com>
Date:   Tue Jul 29 14:59:35 2025 +0200

    libsdc++: Test using range_format::map as format_kind.
    
    This adderess TODO from the test file.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/std/format/ranges/format_kind.cc: New test.
    
    Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>

Diff:
---
 libstdc++-v3/testsuite/std/format/ranges/format_kind.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/testsuite/std/format/ranges/format_kind.cc b/libstdc++-v3/testsuite/std/format/ranges/format_kind.cc
index 14b9ff20c218..1450fbaebc59 100644
--- a/libstdc++-v3/testsuite/std/format/ranges/format_kind.cc
+++ b/libstdc++-v3/testsuite/std/format/ranges/format_kind.cc
@@ -75,7 +75,9 @@ void test_override()
   CustFormat<int, std::range_format::set> setf{1, 2, 3};
   VERIFY( std::format("{}", setf) == "{1, 2, 3}" );
 
-  // TODO test map once formatter for pair is implenented
+  CustFormat<std::pair<int, int>, std::range_format::map> mapf
+  {{1, 11}, {2, 22}, {3, 33}};
+  VERIFY( std::format("{}", mapf) == "{1: 11, 2: 22, 3: 33}" );
 
   CustFormat<char, std::range_format::string> stringf{'a', 'b', 'c', 'd'};
   VERIFY( std::format("{}", stringf) == "abcd" );