[gcc r16-7662] libstdc++: Do not check exception at compile-time for mdspan::at for cow string.

[Tomasz Kaminski]

https://gcc.gnu.org/g:4ae4340c202c2945189d32af64d8c11c5a1f07eb

commit r16-7662-g4ae4340c202c2945189d32af64d8c11c5a1f07eb
Author: Tomasz Kamiński <tkaminsk@redhat.com>
Date:   Tue Feb 24 17:54:11 2026 +0100

    libstdc++: Do not check exception at compile-time for mdspan::at for cow string.
    
    Do not test the exception at compile time if _GLIBCXX_USE_CXX11_ABI
    is not set, i.e. standard exceptions types are not supported.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/23_containers/mdspan/at.cc: Updated test.

Diff:
---
 libstdc++-v3/testsuite/23_containers/mdspan/at.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/at.cc b/libstdc++-v3/testsuite/23_containers/mdspan/at.cc
index 4e659f572754..d9edce464add 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/at.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/at.cc
@@ -89,6 +89,12 @@ template<typename Int, bool ValidForPacks, bool ValidForArrays>
       }
     };
 
+#if !_GLIBCXX_USE_CXX11_ABI
+    if consteval {
+      return true;
+    }
+#endif
+
     verify_throw(-1, 0, 0);
     verify_throw(0, -3, 0);
     verify_throw(0, 0, -5);