[gcc r16-7546] libstdc++: Fix up submdspan std exports

[Jakub Jelinek]

https://gcc.gnu.org/g:f037fdeb95bb2b179d79ef634ced1b488560975a

commit r16-7546-gf037fdeb95bb2b179d79ef634ced1b488560975a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Feb 17 11:37:52 2026 +0100

    libstdc++: Fix up submdspan std exports
    
    On Mon, Feb 16, 2026 at 01:34:50PM +0100, Tomasz Kamiński wrote:
    > This patch implements LWG 4491, addressing C++26 NB comments.
    >
    > libstdc++-v3/ChangeLog:
    >
    >       * include/std/mdspan (std::submdspan_extents): Rename to...
    >       (std::subextents): Rename of submdspan_extents.
    >       (std::submdspan_canonicalize_slices): Rename to...
    >       (std::canonical_slices):
    
    This broke
    +FAIL: g++.dg/modules/compile-std1.C -std=c++26 (test for excess errors)
    +FAIL: g++.dg/modules/compile-std1.C module-cmi std (gcm.cache/std.gcm)
    +FAIL: g++.dg/modules/compile-std1.C module-cmi std.compat (gcm.cache/std.compat.gcm)
    on all targets.
    
    The following patch fixes it.
    
    2026-02-17  Jakub Jelinek  <jakub@redhat.com>
    
            * src/c++23/std.cc.in (std::submdspan_canonicalize_slices,
            std::submdspan_extents): Remove exports.
            (std::canonical_slices, std::subextents): New exports.

Diff:
---
 libstdc++-v3/src/c++23/std.cc.in | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in
index bcaa0cb51b60..514ac5939fef 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -1915,8 +1915,8 @@ export namespace std
   using std::full_extent_t;
   using std::full_extent;
   using std::submdspan_mapping_result;
-  using std::submdspan_canonicalize_slices;
-  using std::submdspan_extents;
+  using std::canonical_slices;
+  using std::subextents;
   using std::submdspan;
 #endif
 }