[committed] libstdc++: Fix module std export for std::extents

[Jonathan Wakely]

libstdc++-v3/ChangeLog:

        * src/c++23/std.cc.in: Fix export for std::extents.
---

Lightly tested x86_64-linux. Pushed to trunk.

 libstdc++-v3/src/c++23/std.cc.in | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in
index 0df27cd7e7da..73316d168c94 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -1834,10 +1834,13 @@ export namespace std
 }
 
 // <mdspan>
+#if __glibcxx_mdspan
+export namespace std
 {
   using std::extents;
   // FIXME layout_*, default_accessor and mdspan
 }
+#endif
 
 // 20.2 <memory>
 export namespace std
-- 
2.49.0