[committed, v2] libstdc++: Test 17_intro/names.cc with -D_FORTIFY_SOURCE=2 [PR116210]

[Jonathan Wakely]

I removed the >= 2.35 check, because it was failing on a RHEL glibc 2.34
with the fortify changes backported. So let's just #undef u for anything
older than 2.41 instead.

Tested powerpc64le-linux (glibc-2.34-100.el9_4.3) and x86_64-linux
(glibc-2.39-22.fc40).

Pushed to trunk.

-- >8 --

Add a new testcase that repeats 17_intro/names.cc but with
_FORTIFY_SOURCE defined, to find problems in Glibc fortify wrappers like
https://sourceware.org/bugzilla/show_bug.cgi?id=32052 (which is fixed
now).

libstdc++-v3/ChangeLog:

	PR libstdc++/116210
	* testsuite/17_intro/names.cc (sz): Undef for versions of Glibc
	that use it in the fortify wrappers.
	* testsuite/17_intro/names_fortify.cc: New test.
---
 libstdc++-v3/testsuite/17_intro/names.cc         | 7 +++++++
 libstdc++-v3/testsuite/17_intro/names_fortify.cc | 6 ++++++
 2 files changed, 13 insertions(+)
 create mode 100644 libstdc++-v3/testsuite/17_intro/names_fortify.cc

diff --git a/libstdc++-v3/testsuite/17_intro/names.cc b/libstdc++-v3/testsuite/17_intro/names.cc
index bea2d19ecba..5deb310dc31 100644
--- a/libstdc++-v3/testsuite/17_intro/names.cc
+++ b/libstdc++-v3/testsuite/17_intro/names.cc
@@ -383,4 +383,11 @@
 #undef y
 #endif
 
+#if defined __GLIBC_PREREQ && defined _FORTIFY_SOURCE
+# if ! __GLIBC_PREREQ(2,41)
+// https://sourceware.org/bugzilla/show_bug.cgi?id=32052
+#  undef sz
+# endif
+#endif
+
 #include <bits/stdc++.h>
diff --git a/libstdc++-v3/testsuite/17_intro/names_fortify.cc b/libstdc++-v3/testsuite/17_intro/names_fortify.cc
new file mode 100644
index 00000000000..c975412074b
--- /dev/null
+++ b/libstdc++-v3/testsuite/17_intro/names_fortify.cc
@@ -0,0 +1,6 @@
+// { dg-do compile { target *-*-linux* } }
+// { dg-add-options no_pch }
+
+#define _FORTIFY_SOURCE 2
+// Now we can define the macros to poison uses of non-reserved names:
+#include "names.cc"
-- 
2.46.2