[gcc r16-2100] libstdc++: Set feature test macro for complete C++23 mdspan [PR107761].

[Tomasz Kaminski]

https://gcc.gnu.org/g:7b3b315e4803e248a9083e99acf6ef3a2b21a6ee

commit r16-2100-g7b3b315e4803e248a9083e99acf6ef3a2b21a6ee
Author: Luc Grosheintz <luc.grosheintz@gmail.com>
Date:   Tue Jul 8 10:24:27 2025 +0200

    libstdc++: Set feature test macro for complete C++23 mdspan [PR107761].
    
            PR libstdc++/107761
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/version.def (mdspan): Set to 202207 and remove
            no_stdname.
            * include/bits/version.h: Regenerate.
            * testsuite/23_containers/mdspan/version.cc: Test presence
            of feature test macro.
    
    Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
    Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>

Diff:
---
 libstdc++-v3/include/bits/version.def                  | 3 +--
 libstdc++-v3/include/bits/version.h                    | 3 ++-
 libstdc++-v3/testsuite/23_containers/mdspan/version.cc | 9 +++++++++
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index 64f8190d240b..f1015abdbfae 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1007,9 +1007,8 @@ ftms = {
 
 ftms = {
   name = mdspan;
-  no_stdname = true; // FIXME: remove
   values = {
-    v = 1; // FIXME: 202207
+    v = 202207;
     cxxmin = 23;
   };
 };
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 744246a9938a..80f6586372d3 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -1126,8 +1126,9 @@
 
 #if !defined(__cpp_lib_mdspan)
 # if (__cplusplus >= 202100L)
-#  define __glibcxx_mdspan 1L
+#  define __glibcxx_mdspan 202207L
 #  if defined(__glibcxx_want_all) || defined(__glibcxx_want_mdspan)
+#   define __cpp_lib_mdspan 202207L
 #  endif
 # endif
 #endif /* !defined(__cpp_lib_mdspan) && defined(__glibcxx_want_mdspan) */
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/version.cc b/libstdc++-v3/testsuite/23_containers/mdspan/version.cc
new file mode 100644
index 000000000000..106ee4010ee6
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/version.cc
@@ -0,0 +1,9 @@
+// { dg-do compile { target c++23 } }
+#include <mdspan>
+
+#ifndef __cpp_lib_mdspan
+#error "Feature test macro __cpp_lib_mdspan is missing for <mdspan>"
+#if __cpp_lib_mdspan < 202207
+#error "Feature test macro __cpp_lib_mdspan has the wrong value"
+#endif
+#endif