[gcc r14-5966] Fix '23_containers/span/at.cc' for '-fno-exceptions' configurations

[gcc r14-5966] Fix '23_containers/span/at.cc' for '-fno-exceptions' configurations

[Thomas Schwinge]

https://gcc.gnu.org/g:762b428815d4e762abdff5c1ffc1e9aa60da7870

commit r14-5966-g762b428815d4e762abdff5c1ffc1e9aa60da7870
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Tue Nov 28 17:30:13 2023 +0100

    Fix '23_containers/span/at.cc' for '-fno-exceptions' configurations
    
    Added in recent commit 1fa85dcf656e2f2c7e483c9ed3c2680bf7db6858
    "libstdc++: Add std::span::at for C++26 (P2821R5)", the test case already
    does use '#if __cpp_exceptions', but failed to correspondingly guard the
    'dg-warning' directives, resulting in:
    
        FAIL: 23_containers/span/at.cc  -std=gnu++26  (test for warnings, line 15)
        FAIL: 23_containers/span/at.cc  -std=gnu++26  (test for warnings, line 26)
        PASS: 23_containers/span/at.cc  -std=gnu++26 (test for excess errors)
        PASS: 23_containers/span/at.cc  -std=gnu++26 execution test
    
            libstdc++-v3/
            * testsuite/23_containers/span/at.cc: Fix for '-fno-exceptions'
            configurations.

Diff:
---
 libstdc++-v3/testsuite/23_containers/span/at.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/testsuite/23_containers/span/at.cc b/libstdc++-v3/testsuite/23_containers/span/at.cc
index dc4d8e3e8eb..6f6fc396bc7 100644
--- a/libstdc++-v3/testsuite/23_containers/span/at.cc
+++ b/libstdc++-v3/testsuite/23_containers/span/at.cc
@@ -12,7 +12,7 @@ test_at()
   VERIFY(s.at(2) == 2);
 #if __cpp_exceptions
   try {
-    s.at(4); // { dg-warning "ignoring return value" }
+    s.at(4); // { dg-warning "ignoring return value" "" { target exceptions_enabled } }
     VERIFY(false);
   } catch (const std::out_of_range&) {
   }
@@ -23,7 +23,7 @@ test_at()
   VERIFY(s2.at(1) == 2);
 #if __cpp_exceptions
   try {
-    s2.at(2); // { dg-warning "ignoring return value" }
+    s2.at(2); // { dg-warning "ignoring return value" "" { target exceptions_enabled } }
     VERIFY(false);
   } catch (const std::out_of_range&) {
   }