[gcc r16-7320] libstdc++: Fix some -Wpedantic warnings in regex tests

[Jonathan Wakely]

https://gcc.gnu.org/g:1be41ad752945b0ed5c26aa134a30c145a29afd0

commit r16-7320-g1be41ad752945b0ed5c26aa134a30c145a29afd0
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Feb 2 13:10:50 2026 +0000

    libstdc++: Fix some -Wpedantic warnings in regex tests
    
    These tests can be run as C++11, so should use a string literal with the
    static assertions.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/28_regex/algorithms/regex_match/multiline.cc: Add
            string to static_assert.
            * testsuite/28_regex/sub_match/lwg3204.cc: Likewise.
    
    Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

Diff:
---
 libstdc++-v3/testsuite/28_regex/algorithms/regex_match/multiline.cc | 4 ++--
 libstdc++-v3/testsuite/28_regex/sub_match/lwg3204.cc                | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/multiline.cc b/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/multiline.cc
index f4b3cf03a225..090fd0955cc8 100644
--- a/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/multiline.cc
+++ b/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/multiline.cc
@@ -3,8 +3,8 @@
 #include <testsuite_hooks.h>
 
 #if __cplusplus >= 201703L || !defined __STRICT_ANSI__
-static_assert( std::regex_constants::multiline == std::regex::multiline );
-static_assert( std::regex_constants::__multiline == std::regex::multiline );
+static_assert( std::regex_constants::multiline == std::regex::multiline, "" );
+static_assert( std::regex_constants::__multiline == std::regex::multiline, "" );
 #else
 namespace test { constexpr int multiline = 0; }
 namespace check {
diff --git a/libstdc++-v3/testsuite/28_regex/sub_match/lwg3204.cc b/libstdc++-v3/testsuite/28_regex/sub_match/lwg3204.cc
index 58ef0df58a14..d95aed367876 100644
--- a/libstdc++-v3/testsuite/28_regex/sub_match/lwg3204.cc
+++ b/libstdc++-v3/testsuite/28_regex/sub_match/lwg3204.cc
@@ -33,6 +33,8 @@ struct iter
 };
 
 using CS = std::csub_match;
-static_assert( noexcept(std::declval<CS&>().swap(std::declval<CS&>())) );
+static_assert( noexcept(std::declval<CS&>().swap(std::declval<CS&>())),
+	       "std::csub_match::swap is nothrow" );
 using IS = std::sub_match<iter>;
-static_assert( ! noexcept(std::declval<IS&>().swap(std::declval<IS&>())) );
+static_assert( ! noexcept(std::declval<IS&>().swap(std::declval<IS&>())),
+	       "std::sub_match<I>::swap is potentially throwing" );