2 files changed, 28 insertions, 84 deletions

diff --git a/src/conf_post.h b/src/conf_post.h
index 8a6b32998d8..953b783ebea 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -30,13 +30,15 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #endif
 
 /* To help make dependencies clearer elsewhere, this file typically
-   does not #include other files.  The exceptions are first stdbool.h
+   does not #include other files.  The exceptions are stdbool.h
    because it is unlikely to interfere with configuration and bool is
-   such a core part of the C language, and second ms-w32.h (DOS_NT
+   such a core part of the C language, attribute.h because its
+   ATTRIBUTE_* macros are used here, and ms-w32.h (DOS_NT
    only) because it historically was included here and changing that
    would take some work.  */
 
 #include <stdbool.h>
+#include <attribute.h>
 
 #if defined WINDOWSNT && !defined DEFER_MS_W32_H
 # include <ms-w32.h>
@@ -65,31 +67,30 @@ typedef unsigned int bool_bf;
 typedef bool bool_bf;
 #endif
 
-/* Simulate __has_attribute on compilers that lack it.  It is used only
-   on arguments like alloc_size that are handled in this simulation.
-   __has_attribute should be used only in #if expressions, as Oracle
+/* A substitute for __has_attribute on compilers that lack it.
+   It is used only on arguments like cleanup that are handled here.
+   This macro should be used only in #if expressions, as Oracle
    Studio 12.5's __has_attribute does not work in plain code.  */
-#ifndef __has_attribute
-# define __has_attribute(a) __has_attribute_##a
-# define __has_attribute_alloc_size GNUC_PREREQ (4, 3, 0)
-# define __has_attribute_cleanup GNUC_PREREQ (3, 4, 0)
-# define __has_attribute_cold GNUC_PREREQ (4, 3, 0)
-# define __has_attribute_externally_visible GNUC_PREREQ (4, 1, 0)
-# define __has_attribute_no_address_safety_analysis false
-# define __has_attribute_no_sanitize_address GNUC_PREREQ (4, 8, 0)
-# define __has_attribute_no_sanitize_undefined GNUC_PREREQ (4, 9, 0)
-# define __has_attribute_returns_nonnull GNUC_PREREQ (4, 9, 0)
-# define __has_attribute_warn_unused_result GNUC_PREREQ (3, 4, 0)
+#ifdef __has_attribute
+# define HAS_ATTRIBUTE(a) __has_attribute (__##a##__)
+#else
+# define HAS_ATTRIBUTE(a) HAS_ATTR_##a
+# define HAS_ATTR_cleanup GNUC_PREREQ (3, 4, 0)
+# define HAS_ATTR_no_address_safety_analysis false
+# define HAS_ATTR_no_sanitize_address GNUC_PREREQ (4, 8, 0)
+# define HAS_ATTR_no_sanitize_undefined GNUC_PREREQ (4, 9, 0)
 #endif
 
-/* Simulate __has_feature on compilers that lack it.  It is used only
+/* A substitute for __has_feature on compilers that lack it.  It is used only
    to define ADDRESS_SANITIZER below.  */
-#ifndef __has_feature
-# define __has_feature(a) false
+#ifdef __has_feature
+# define HAS_FEATURE(a) __has_feature (a)
+#else
+# define HAS_FEATURE(a) false
 #endif
 
 /* True if addresses are being sanitized.  */
-#if defined __SANITIZE_ADDRESS__ || __has_feature (address_sanitizer)
+#if defined __SANITIZE_ADDRESS__ || HAS_FEATURE (address_sanitizer)
 # define ADDRESS_SANITIZER true
 #else
 # define ADDRESS_SANITIZER false
@@ -226,37 +227,8 @@ extern void _DebPrint (const char *fmt, ...);
 extern char *emacs_getenv_TZ (void);
 extern int emacs_setenv_TZ (char const *);
 
-/* Avoid __attribute__ ((cold)) on MinGW; see thread starting at
-   <https://lists.gnu.org/r/emacs-devel/2019-04/msg01152.html>. */
-#if __has_attribute (cold) && !defined __MINGW32__
-# define ATTRIBUTE_COLD __attribute__ ((cold))
-#else
-# define ATTRIBUTE_COLD
-#endif
-
-#if __GNUC__ >= 3  /* On GCC 3.0 we might get a warning.  */
-#define NO_INLINE __attribute__((noinline))
-#else
-#define NO_INLINE
-#endif
-
-#if __has_attribute (externally_visible)
-#define EXTERNALLY_VISIBLE __attribute__((externally_visible))
-#else
-#define EXTERNALLY_VISIBLE
-#endif
-
-#if GNUC_PREREQ (2, 7, 0)
-# define ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
-#else
-# define ATTRIBUTE_FORMAT(spec) /* empty */
-#endif
-
-#if GNUC_PREREQ (7, 0, 0)
-# define FALLTHROUGH __attribute__ ((__fallthrough__))
-#else
-# define FALLTHROUGH ((void) 0)
-#endif
+#define NO_INLINE ATTRIBUTE_NOINLINE
+#define EXTERNALLY_VISIBLE ATTRIBUTE_EXTERNALLY_VISIBLE
 
 #if GNUC_PREREQ (4, 4, 0) && defined __GLIBC_MINOR__
 # define PRINTF_ARCHETYPE __gnu_printf__
@@ -288,16 +260,8 @@ extern int emacs_setenv_TZ (char const *);
 #define ATTRIBUTE_FORMAT_PRINTF(string_index, first_to_check) \
   ATTRIBUTE_FORMAT ((PRINTF_ARCHETYPE, string_index, first_to_check))
 
-#define ARG_NONNULL _GL_ARG_NONNULL
-#define ATTRIBUTE_CONST _GL_ATTRIBUTE_CONST
-#define ATTRIBUTE_PURE _GL_ATTRIBUTE_PURE
-#define ATTRIBUTE_UNUSED _GL_UNUSED
-
-#if GNUC_PREREQ (3, 3, 0) && !defined __ICC
-# define ATTRIBUTE_MAY_ALIAS __attribute__ ((__may_alias__))
-#else
-# define ATTRIBUTE_MAY_ALIAS
-#endif
+#define ARG_NONNULL ATTRIBUTE_NONNULL
+#define ATTRIBUTE_UNUSED MAYBE_UNUSED
 
 /* Declare NAME to be a pointer to an object of type TYPE, initialized
    to the address ADDR, which may be of a different type.  Accesses
@@ -308,27 +272,13 @@ extern int emacs_setenv_TZ (char const *);
   type ATTRIBUTE_MAY_ALIAS *name = (type *) (addr)
 
 #if 3 <= __GNUC__
-# define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 # define ATTRIBUTE_SECTION(name) __attribute__((section (name)))
 #else
-# define ATTRIBUTE_MALLOC
 #define ATTRIBUTE_SECTION(name)
 #endif
 
-#if __has_attribute (alloc_size)
-# define ATTRIBUTE_ALLOC_SIZE(args) __attribute__ ((__alloc_size__ args))
-#else
-# define ATTRIBUTE_ALLOC_SIZE(args)
-#endif
-
 #define ATTRIBUTE_MALLOC_SIZE(args) ATTRIBUTE_MALLOC ATTRIBUTE_ALLOC_SIZE (args)
 
-#if __has_attribute (returns_nonnull)
-# define ATTRIBUTE_RETURNS_NONNULL __attribute__ ((returns_nonnull))
-#else
-# define ATTRIBUTE_RETURNS_NONNULL
-#endif
-
 /* Work around GCC bug 59600: when a function is inlined, the inlined
    code may have its addresses sanitized even if the function has the
    no_sanitize_address attribute.  This bug is fixed in GCC 4.9.0 and
diff --git a/src/systhread.h b/src/systhread.h
index 005388fd5a4..73c764a9401 100644
--- a/src/systhread.h
+++ b/src/systhread.h
@@ -21,12 +21,6 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 #include <stdbool.h>
 
-#if __has_attribute (warn_unused_result)
-# define ATTRIBUTE_WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))
-#else
-# define ATTRIBUTE_WARN_UNUSED_RESULT
-#endif
-
 #ifdef THREADS_ENABLED
 
 #ifdef HAVE_PTHREAD
@@ -108,13 +102,13 @@ extern void sys_cond_broadcast (sys_cond_t *);
 extern void sys_cond_destroy (sys_cond_t *);
 
 extern sys_thread_t sys_thread_self (void)
-  ATTRIBUTE_WARN_UNUSED_RESULT;
+  NODISCARD;
 extern bool sys_thread_equal (sys_thread_t, sys_thread_t)
-  ATTRIBUTE_WARN_UNUSED_RESULT;
+  NODISCARD;
 
 extern bool sys_thread_create (sys_thread_t *, thread_creation_function *,
                                void *)
-  ATTRIBUTE_WARN_UNUSED_RESULT;
+  NODISCARD;
 
 extern void sys_thread_yield (void);
 extern void sys_thread_set_name (const char *);