diff --git a/include/libc-diag.h b/include/libc-diag.h
new file mode 100644
index 0000000000..a6a413c567
--- /dev/null
+++ b/include/libc-diag.h
@@ -0,0 +1,57 @@
+/* Macros for controlling diagnostic output from the compiler.  */
+#ifndef _LIBC_DIAG_H
+#define _LIBC_DIAG_H 1
+
+/* Ignore the value of an expression when a cast to void does not
+   suffice (in particular, for a call to a function declared with
+   attribute warn_unused_result).  */
+#define ignore_value(x) \
+  ({ __typeof__ (x) __ignored_value = (x); (void) __ignored_value; })
+
+/* The macros to control diagnostics are structured like this, rather
+   than a single macro that both pushes and pops diagnostic state and
+   takes the affected code as an argument, because the GCC pragmas
+   work by disabling the diagnostic for a range of source locations
+   and do not work when all the pragmas and the affected code are in a
+   single macro expansion.  */
+
+/* Push diagnostic state.  */
+#define DIAG_PUSH_NEEDS_COMMENT _Pragma ("GCC diagnostic push")
+
+/* Pop diagnostic state.  */
+#define DIAG_POP_NEEDS_COMMENT _Pragma ("GCC diagnostic pop")
+
+#define _DIAG_STR1(s) #s
+#define _DIAG_STR(s) _DIAG_STR1(s)
+
+/* Ignore the diagnostic OPTION.  VERSION is the most recent GCC
+   version for which the diagnostic has been confirmed to appear in
+   the absence of the pragma (in the form MAJOR.MINOR for GCC 4.x,
+   just MAJOR for GCC 5 and later).  Uses of this pragma should be
+   reviewed when the GCC version given is no longer supported for
+   building glibc; the version number should always be on the same
+   source line as the macro name, so such uses can be found with grep.
+   Uses should come with a comment giving more details of the
+   diagnostic, and an architecture on which it is seen if possibly
+   optimization-related and not in architecture-specific code.  This
+   macro should only be used if the diagnostic seems hard to fix (for
+   example, optimization-related false positives).  */
+#define DIAG_IGNORE_NEEDS_COMMENT(version, option)     \
+  _Pragma (_DIAG_STR (GCC diagnostic ignored option))
+
+/* Similar to DIAG_IGNORE_NEEDS_COMMENT the following macro ignores the
+   diagnostic OPTION but only if optimizations for size are enabled.
+   This is required because different warnings may be generated for
+   different optimization levels.  For example a key piece of code may
+   only generate a warning when compiled at -Os, but at -O2 you could
+   still want the warning to be enabled to catch errors.  In this case
+   you would use DIAG_IGNORE_Os_NEEDS_COMMENT to disable the warning
+   only for -Os.  */
+#ifdef __OPTIMIZE_SIZE__
+# define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option) \
+  _Pragma (_DIAG_STR (GCC diagnostic ignored option))
+#else
+# define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option)
+#endif
+
+#endif /* libc-diag.h */
diff --git a/include/libc-internal.h b/include/libc-internal.h
index e4395dd5c5..a38a35d87c 100644
--- a/include/libc-internal.h
+++ b/include/libc-internal.h
@@ -74,56 +74,6 @@ extern __typeof (__profile_frequency) __profile_frequency attribute_hidden;
 #define PTR_ALIGN_UP(base, size) \
   ((__typeof__ (base)) ALIGN_UP ((uintptr_t) (base), (size)))
 
-/* Ignore the value of an expression when a cast to void does not
-   suffice (in particular, for a call to a function declared with
-   attribute warn_unused_result).  */
-#define ignore_value(x) \
-  ({ __typeof__ (x) __ignored_value = (x); (void) __ignored_value; })
-
-/* The macros to control diagnostics are structured like this, rather
-   than a single macro that both pushes and pops diagnostic state and
-   takes the affected code as an argument, because the GCC pragmas
-   work by disabling the diagnostic for a range of source locations
-   and do not work when all the pragmas and the affected code are in a
-   single macro expansion.  */
-
-/* Push diagnostic state.  */
-#define DIAG_PUSH_NEEDS_COMMENT _Pragma ("GCC diagnostic push")
-
-/* Pop diagnostic state.  */
-#define DIAG_POP_NEEDS_COMMENT _Pragma ("GCC diagnostic pop")
-
-#define _DIAG_STR1(s) #s
-#define _DIAG_STR(s) _DIAG_STR1(s)
-
-/* Ignore the diagnostic OPTION.  VERSION is the most recent GCC
-   version for which the diagnostic has been confirmed to appear in
-   the absence of the pragma (in the form MAJOR.MINOR for GCC 4.x,
-   just MAJOR for GCC 5 and later).  Uses of this pragma should be
-   reviewed when the GCC version given is no longer supported for
-   building glibc; the version number should always be on the same
-   source line as the macro name, so such uses can be found with grep.
-   Uses should come with a comment giving more details of the
-   diagnostic, and an architecture on which it is seen if possibly
-   optimization-related and not in architecture-specific code.  This
-   macro should only be used if the diagnostic seems hard to fix (for
-   example, optimization-related false positives).  */
-#define DIAG_IGNORE_NEEDS_COMMENT(version, option)	\
-  _Pragma (_DIAG_STR (GCC diagnostic ignored option))
-
-/* Similar to DIAG_IGNORE_NEEDS_COMMENT the following macro ignores the
-   diagnostic OPTION but only if optimizations for size are enabled.
-   This is required because different warnings may be generated for
-   different optimization levels.  For example a key piece of code may
-   only generate a warning when compiled at -Os, but at -O2 you could
-   still want the warning to be enabled to catch errors.  In this case
-   you would use DIAG_IGNORE_Os_NEEDS_COMMENT to disable the warning
-   only for -Os.  */
-#ifdef __OPTIMIZE_SIZE__
-# define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option)	\
-  _Pragma (_DIAG_STR (GCC diagnostic ignored option))
-#else
-# define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option)
-#endif
+#include <libc-diag.h>
 
 #endif /* _LIBC_INTERNAL  */
diff --git a/malloc/tst-malloc.c b/malloc/tst-malloc.c
index 740ac6ce31..dbc8d4ab56 100644
--- a/malloc/tst-malloc.c
+++ b/malloc/tst-malloc.c
@@ -19,7 +19,7 @@
 #include <errno.h>
 #include <malloc.h>
 #include <stdio.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int errors = 0;
 
diff --git a/malloc/tst-mcheck.c b/malloc/tst-mcheck.c
index 2e3cba96b8..5a66bab331 100644
--- a/malloc/tst-mcheck.c
+++ b/malloc/tst-mcheck.c
@@ -19,7 +19,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int errors = 0;
 
diff --git a/malloc/tst-realloc.c b/malloc/tst-realloc.c
index 7f1f228c06..31a58bd026 100644
--- a/malloc/tst-realloc.c
+++ b/malloc/tst-realloc.c
@@ -19,7 +19,7 @@
 #include <malloc.h>
 #include <stdio.h>
 #include <string.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int errors = 0;
 
diff --git a/misc/tst-error1.c b/misc/tst-error1.c
index a97a22ce9d..9c4a62fbd0 100644
--- a/misc/tst-error1.c
+++ b/misc/tst-error1.c
@@ -3,7 +3,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <wchar.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int
 do_test (int argc, char *argv[])
diff --git a/nptl/tst-mutex1.c b/nptl/tst-mutex1.c
index 8a4f2e6e4e..b2a4b5492a 100644
--- a/nptl/tst-mutex1.c
+++ b/nptl/tst-mutex1.c
@@ -20,7 +20,7 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stdbool.h>
-
+#include <libc-diag.h>
 
 #ifndef ATTR
 # define ATTR NULL
@@ -45,11 +45,16 @@ do_test (void)
       return 1;
     }
 
+  /* This deliberately tests supplying a null pointer to a function whose
+     argument is marked __attribute__ ((nonnull)). */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT (5, "-Wnonnull");
   if (!ATTR_NULL && pthread_mutexattr_destroy (ATTR) != 0)
     {
       puts ("mutexattr_destroy failed");
       return 1;
     }
+  DIAG_POP_NEEDS_COMMENT;
 
   if (pthread_mutex_lock (&m) != 0)
     {
diff --git a/posix/tst-dir.c b/posix/tst-dir.c
index 1a9c7dfe97..fee79b32a0 100644
--- a/posix/tst-dir.c
+++ b/posix/tst-dir.c
@@ -26,7 +26,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/stat.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 /* We expect four arguments:
    - source directory name
diff --git a/stdio-common/bug21.c b/stdio-common/bug21.c
index ca27272ba1..7a8c6a3542 100644
--- a/stdio-common/bug21.c
+++ b/stdio-common/bug21.c
@@ -1,5 +1,5 @@
 #include <stdio.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int
 do_test (void)
diff --git a/stdio-common/scanf14.c b/stdio-common/scanf14.c
index cffccb0b19..2bcd9c9893 100644
--- a/stdio-common/scanf14.c
+++ b/stdio-common/scanf14.c
@@ -2,7 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <wchar.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 #define FAIL() \
   do {							\
diff --git a/stdio-common/scanf4.c b/stdio-common/scanf4.c
index 9bb14bb16b..7a2abec89b 100644
--- a/stdio-common/scanf4.c
+++ b/stdio-common/scanf4.c
@@ -1,6 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 int
 main(int arc, char *argv[])
diff --git a/stdio-common/scanf7.c b/stdio-common/scanf7.c
index 53ddf4cb09..f568738d7e 100644
--- a/stdio-common/scanf7.c
+++ b/stdio-common/scanf7.c
@@ -1,6 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 int
 main (int argc, char *argv[])
diff --git a/stdio-common/test-vfprintf.c b/stdio-common/test-vfprintf.c
index f1805d5d00..f8bb9cee58 100644
--- a/stdio-common/test-vfprintf.c
+++ b/stdio-common/test-vfprintf.c
@@ -25,7 +25,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/stat.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 
 const char *locs[] =
diff --git a/stdio-common/tst-printf.c b/stdio-common/tst-printf.c
index 719b3eb08c..b6d62a5a2f 100644
--- a/stdio-common/tst-printf.c
+++ b/stdio-common/tst-printf.c
@@ -26,7 +26,7 @@
 #endif
 
 #include <float.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 /* This whole file is picayune tests of corner cases of printf format strings.
    The compiler warnings are not useful here.  */
diff --git a/stdio-common/tst-printfsz.c b/stdio-common/tst-printfsz.c
index 8a3385f94d..47aa8536b3 100644
--- a/stdio-common/tst-printfsz.c
+++ b/stdio-common/tst-printfsz.c
@@ -2,7 +2,7 @@
 #include <printf.h>
 #include <stdio.h>
 #include <string.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 #define V       12345678.12345678
 
diff --git a/stdio-common/tst-sprintf.c b/stdio-common/tst-sprintf.c
index d5284b9697..cbd35447a9 100644
--- a/stdio-common/tst-sprintf.c
+++ b/stdio-common/tst-sprintf.c
@@ -2,7 +2,7 @@
 #include <stdlib.h>
 #include <locale.h>
 #include <string.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 
 static int
diff --git a/stdio-common/tst-unlockedio.c b/stdio-common/tst-unlockedio.c
index 6eec6fdbac..35652ce772 100644
--- a/stdio-common/tst-unlockedio.c
+++ b/stdio-common/tst-unlockedio.c
@@ -20,7 +20,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 int fd;
 static void do_prepare (void);
diff --git a/stdio-common/tstdiomisc.c b/stdio-common/tstdiomisc.c
index 9c7342d55f..89009e0549 100644
--- a/stdio-common/tstdiomisc.c
+++ b/stdio-common/tstdiomisc.c
@@ -3,7 +3,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <wchar.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int
 t1 (void)
diff --git a/stdlib/bug-getcontext.c b/stdlib/bug-getcontext.c
index c4072129a6..163400acba 100644
--- a/stdlib/bug-getcontext.c
+++ b/stdlib/bug-getcontext.c
@@ -5,7 +5,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <ucontext.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int
 do_test (void)
diff --git a/stdlib/tst-environ.c b/stdlib/tst-environ.c
index 6a29fed62a..b2301641f5 100644
--- a/stdlib/tst-environ.c
+++ b/stdlib/tst-environ.c
@@ -19,7 +19,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-
+#include <libc-diag.h>
 
 #define VAR "FOOBAR"
 
@@ -196,12 +196,17 @@ do_test (void)
       result = 1;
     }
 
+  /* This deliberately tests supplying a null pointer to a function whose
+     argument is marked __attribute__ ((nonnull)). */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT(5, "-Wnonnull");
   errno = 0;
   if (unsetenv (NULL) >= 0 || errno != EINVAL)
     {
       puts ("unsetenv #1 failed");
       result = 1;
     }
+  DIAG_POP_NEEDS_COMMENT;
 
   errno = 0;
   if (unsetenv ("") >= 0 || errno != EINVAL)
diff --git a/string/tester.c b/string/tester.c
index ec350243eb..4b928b4f5e 100644
--- a/string/tester.c
+++ b/string/tester.c
@@ -32,7 +32,7 @@
 #include <string.h>
 #include <strings.h>
 #include <fcntl.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 
 #define	STREQ(a, b)	(strcmp((a), (b)) == 0)
diff --git a/string/tst-endian.c b/string/tst-endian.c
index 7d39131a68..d3c7c2c4c5 100644
--- a/string/tst-endian.c
+++ b/string/tst-endian.c
@@ -3,7 +3,7 @@
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 #if __GNUC_PREREQ (6, 0)
 /* GCC 6.0 warns on big endian systems about:
diff --git a/time/tst-strptime2.c b/time/tst-strptime2.c
index 9273568b6f..8019e7f5d8 100644
--- a/time/tst-strptime2.c
+++ b/time/tst-strptime2.c
@@ -4,7 +4,7 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <time.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 /* Dummy string is used to match strptime's %s specifier.  */
 
diff --git a/wcsmbs/tst-wcstof.c b/wcsmbs/tst-wcstof.c
index 861f65905a..d3d75f8f60 100644
--- a/wcsmbs/tst-wcstof.c
+++ b/wcsmbs/tst-wcstof.c
@@ -3,7 +3,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <wctype.h>
-#include <libc-internal.h>
+#include <libc-diag.h>
 
 static int
 do_test (void)
