@@ -831,8 +831,10 @@ endif
# disable any optimization that assume default rounding mode.
+math-flags = -frounding-math
-# Build libc/libm using -fno-math-errno, but run testsuite with -fmath-errno.
-+extra-math-flags = $(if $(filter libnldbl nonlib testsuite,$(in-module)),-fmath-errno,-fno-math-errno)
+# Logically only "libnldbl", "nonlib" and "testsuite" should be using
+# -fno-math-errno. However due to GCC bug #88576, only "libm" can use
+# -fno-math-errno.
++extra-math-flags = $(if $(filter libm,$(in-module)),-fno-math-errno,-fmath-errno)
# We might want to compile with some stack-protection flag.
ifneq ($(stack-protector),)
@@ -64,6 +64,12 @@ tests := tester inl-tester noinl-tester testcopy test-ffs \
# This test allocates a lot of memory and can run for a long time.
xtests = tst-strcoll-overflow
+# This test needs libdl.
+ifeq (yes,$(build-shared))
+tests += test-strerror-errno
+LDLIBS-test-strerror-errno = $(libdl)
+endif
+
ifeq ($(run-built-tests),yes)
tests-special += $(objpfx)tst-svc-cmp.out
endif
new file mode 100644
@@ -0,0 +1,58 @@
+/* BZ #24024 strerror and errno test.
+
+ Copyright (C) 2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <support/support.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <string.h>
+
+/* malloc is allowed to change errno to a value different than 0, even when
+ there is no actual error. This happens for example when the memory
+ allocation through sbrk fails. Simulate this by interposing our own
+ malloc implementation which sets errno to ENOMEM and calls the original
+ malloc. */
+void
+*malloc (size_t size)
+{
+ static void *(*real_malloc) (size_t size);
+
+ if (!real_malloc)
+ real_malloc = dlsym(RTLD_NEXT, "malloc");
+
+ errno = ENOMEM;
+
+ return (*real_malloc) (size);
+}
+
+/* strerror must not change the value of errno. Unfortunately due to GCC bug
+ * #88576, this happens when -fmath-errno is used. This simple test checks
+ * that it doesn't happen. */
+static int
+do_test (void)
+{
+ char *msg;
+
+ errno = 0;
+ msg = strerror (-3);
+ (void) msg;
+
+ return errno;
+}
+
+#include <support/test-driver.c>