[gcc r16-7486] libstdc++: Don't test for __unused on Glibc targets

[Jonathan Wakely]

https://gcc.gnu.org/g:1a0b276f69f535244cf8d0983db2ebbc537de536

commit r16-7486-g1a0b276f69f535244cf8d0983db2ebbc537de536
Author: Xi Ruoyao <xry111@xry111.site>
Date:   Thu Feb 12 18:46:05 2026 +0000

    libstdc++: Don't test for __unused on Glibc targets
    
    x86_64 glibc has started to use it since the 2.43 release, but is
    expected to fix it before the 2.44 release.
    
    Link: https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=b9579342c68b#patch67
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/17_intro/badnames.cc (__unused): Do not define.
            * testsuite/17_intro/names.cc [glibc == 2.43] (__unused): Undef.
    
    Co-authored-by: Jonathan Wakely <jwakely@redhat.com>

Diff:
---
 libstdc++-v3/testsuite/17_intro/badnames.cc | 2 +-
 libstdc++-v3/testsuite/17_intro/names.cc    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/testsuite/17_intro/badnames.cc b/libstdc++-v3/testsuite/17_intro/badnames.cc
index ff590fcdf4d9..de4d94faf14c 100644
--- a/libstdc++-v3/testsuite/17_intro/badnames.cc
+++ b/libstdc++-v3/testsuite/17_intro/badnames.cc
@@ -67,7 +67,7 @@
 
 // BSD adds:
 #define __used		__used is a BADNAME
-#define __unused	__unused is a BADNAME
+        // __unused	(glibc uses this so can't test here)
         // __inline	(glibc uses this so can't test here)
         // _Complex	(glibc uses this so can't test here)
 #define __istype	__istype is a BADNAME
diff --git a/libstdc++-v3/testsuite/17_intro/names.cc b/libstdc++-v3/testsuite/17_intro/names.cc
index 106acfa641b8..404cc93e9630 100644
--- a/libstdc++-v3/testsuite/17_intro/names.cc
+++ b/libstdc++-v3/testsuite/17_intro/names.cc
@@ -303,7 +303,7 @@
 #if defined (__linux__) || defined (__gnu_hurd__)
 #if __has_include(<features.h>)
 #include <features.h>
-#if __GLIBC__ == 2 && __GLIBC_MINOR__ < 19
+#if __GLIBC__ == 2 && (__GLIBC_MINOR__ < 19 || __GLIBC_MINOR__ == 43)
 // Glibc defines this prior to 2.19
 #undef __unused
 #endif