maint: cleanup up various uses of __attribute__

* src/cfg.mk (sc_prohibit-gl-attributes): Disallow the __attribute()
form without trailing underscores as that is not elided where required.
Also ensure we use gnulib macros rather than defining our own.
* src/system.h: Remove gnulib provided macros.
* src/chown-core.c: Likewise.
* src/chroot.c: Likewise.
* src/copy.c: Likewise.
* src/csplit.c: Likewise.
* src/dd.c: Likewise.
* src/expr.c: Likewise.
* src/extent-scan.c: Likewise.
* src/factor.c: Likewise.
* src/ls.c: Likewise.
* src/od.c: Likewise.
* src/paste.c: Likewise.
* src/ptx.c: Likewise.
* src/sort.c: Likewise.
* src/stat.c: Likewise.
* src/stty.c: Likewise.
* src/system.h: Likewise.
* src/tac.c: Likewise.
* src/test.c: Likewise.
* src/tsort.c: Likewise.

13 files changed, 40 insertions, 34 deletions

diff --git a/cfg.mk b/cfg.mk
index c9952d2c0..6fa7b1f72 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -201,6 +201,16 @@ sc_prohibit-j-printf-format:
 	  && { echo '$(ME): Use PRI*MAX instead of %j' 1>&2; exit 1; }  \
 	  || :
 
+# Ensure the alternative __attribute (keyword) form isn't used as
+# that form is not elided where required.  Also ensure that we don't
+# directly use attributes already defined by gnulib.
+# TODO: move the check for _GL... attributes to gnulib.
+sc_prohibit-gl-attributes:
+	@cd $(srcdir) && GIT_PAGER= git grep -En			\
+	    "__attribute |__(unused|pure|const)__" src gl/lib/*.[ch]	\
+	  && { echo '$(ME): Use _GL... attribute macros' 1>&2; exit 1; }  \
+	  || :
+
 # Look for lines longer than 80 characters, except omit:
 # - program-generated long lines in diff headers,
 # - tests involving long checksum lines, and
diff --git a/src/chown-core.c b/src/chown-core.c
index 3a3044e04..a5a2b4761 100644
--- a/src/chown-core.c
+++ b/src/chown-core.c
@@ -68,7 +68,7 @@ chopt_init (struct Chown_option *chopt)
 }
 
 extern void
-chopt_free (struct Chown_option *chopt ATTRIBUTE_UNUSED)
+chopt_free (struct Chown_option *chopt _GL_UNUSED)
 {
   /* Deliberately do not free chopt->user_name or ->group_name.
      They're not always allocated.  */
diff --git a/src/chroot.c b/src/chroot.c
index 1c1a97695..b77a8bf66 100644
--- a/src/chroot.c
+++ b/src/chroot.c
@@ -57,7 +57,7 @@ static struct option const long_opts[] =
    always-successful replacement to avoid checking for setgroups
    availability everywhere, just to support broken platforms. */
 static int
-setgroups (size_t size ATTRIBUTE_UNUSED, gid_t const *list ATTRIBUTE_UNUSED)
+setgroups (size_t size _GL_UNUSED, gid_t const *list _GL_UNUSED)
 {
   return 0;
 }
diff --git a/src/copy.c b/src/copy.c
index 3f2cc2b0c..244313ee7 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -471,7 +471,7 @@ errno_unsupported (int err)
 
 #if USE_XATTR
 static void
-copy_attr_error (struct error_context *ctx ATTRIBUTE_UNUSED,
+copy_attr_error (struct error_context *ctx _GL_UNUSED,
                  char const *fmt, ...)
 {
   if (!errno_unsupported (errno))
@@ -487,7 +487,7 @@ copy_attr_error (struct error_context *ctx ATTRIBUTE_UNUSED,
 }
 
 static void
-copy_attr_allerror (struct error_context *ctx ATTRIBUTE_UNUSED,
+copy_attr_allerror (struct error_context *ctx _GL_UNUSED,
                  char const *fmt, ...)
 {
   int err = errno;
@@ -500,14 +500,14 @@ copy_attr_allerror (struct error_context *ctx ATTRIBUTE_UNUSED,
 }
 
 static char const *
-copy_attr_quote (struct error_context *ctx ATTRIBUTE_UNUSED, char const *str)
+copy_attr_quote (struct error_context *ctx _GL_UNUSED, char const *str)
 {
   return quote (str);
 }
 
 static void
-copy_attr_free (struct error_context *ctx ATTRIBUTE_UNUSED,
-                char const *str ATTRIBUTE_UNUSED)
+copy_attr_free (struct error_context *ctx _GL_UNUSED,
+                char const *str _GL_UNUSED)
 {
 }
 
@@ -539,11 +539,11 @@ copy_attr (char const *src_path, int src_fd,
 #else /* USE_XATTR */
 
 static bool
-copy_attr (char const *src_path ATTRIBUTE_UNUSED,
-           int src_fd ATTRIBUTE_UNUSED,
-           char const *dst_path ATTRIBUTE_UNUSED,
-           int dst_fd ATTRIBUTE_UNUSED,
-           struct cp_options const *x ATTRIBUTE_UNUSED)
+copy_attr (char const *src_path _GL_UNUSED,
+           int src_fd _GL_UNUSED,
+           char const *dst_path _GL_UNUSED,
+           int dst_fd _GL_UNUSED,
+           struct cp_options const *x _GL_UNUSED)
 {
   return true;
 }
diff --git a/src/extent-scan.c b/src/extent-scan.c
index 5d25b9aab..6d3032a72 100644
--- a/src/extent-scan.c
+++ b/src/extent-scan.c
@@ -218,7 +218,7 @@ extent_scan_read (struct extent_scan *scan)
 }
 #else
 extern bool
-extent_scan_read (struct extent_scan *scan ATTRIBUTE_UNUSED)
+extent_scan_read (struct extent_scan *scan _GL_UNUSED)
 {
   scan->initial_scan_failed = true;
   errno = ENOTSUP;
diff --git a/src/factor.c b/src/factor.c
index 8f1542a2f..257a7ed90 100644
--- a/src/factor.c
+++ b/src/factor.c
@@ -791,7 +791,7 @@ factor_using_division (uintmax_t *t1p, uintmax_t t1, uintmax_t t0,
     {
       for (;;)
         {
-          uintmax_t q1, q0, hi, lo ATTRIBUTE_UNUSED;
+          uintmax_t q1, q0, hi, lo _GL_UNUSED;
 
           q0 = t0 * primes_dtab[i].binv;
           umul_ppmm (hi, lo, q0, p);
@@ -933,7 +933,7 @@ static const unsigned char  binvert_table[128] =
     _q0 = (u0) * _di;                                                   \
     if ((u1) >= (d))                                                    \
       {                                                                 \
-        uintmax_t _p1, _p0 ATTRIBUTE_UNUSED;                            \
+        uintmax_t _p1, _p0 _GL_UNUSED;                            \
         umul_ppmm (_p1, _p0, _q0, d);                                   \
         (q1) = ((u1) - _p1) * _di;                                      \
         (q0) = _q0;                                                     \
@@ -948,7 +948,7 @@ static const unsigned char  binvert_table[128] =
 /* x B (mod n). */
 #define redcify(r_prim, r, n)                                           \
   do {                                                                  \
-    uintmax_t _redcify_q ATTRIBUTE_UNUSED;                              \
+    uintmax_t _redcify_q _GL_UNUSED;                              \
     udiv_qrnnd (_redcify_q, r_prim, r, 0, n);                           \
   } while (0)
 
@@ -981,7 +981,7 @@ static const unsigned char  binvert_table[128] =
 static inline uintmax_t
 mulredc (uintmax_t a, uintmax_t b, uintmax_t m, uintmax_t mi)
 {
-  uintmax_t rh, rl, q, th, tl ATTRIBUTE_UNUSED, xh;
+  uintmax_t rh, rl, q, th, tl _GL_UNUSED, xh;
 
   umul_ppmm (rh, rl, a, b);
   q = rl * mi;
@@ -1001,7 +1001,7 @@ mulredc2 (uintmax_t *r1p,
           uintmax_t a1, uintmax_t a0, uintmax_t b1, uintmax_t b0,
           uintmax_t m1, uintmax_t m0, uintmax_t mi)
 {
-  uintmax_t r1, r0, q, p1, p0 ATTRIBUTE_UNUSED, t1, t0, s1, s0;
+  uintmax_t r1, r0, q, p1, p0 _GL_UNUSED, t1, t0, s1, s0;
   mi = -mi;
   assert ( (a1 >> (W_TYPE_SIZE - 1)) == 0);
   assert ( (b1 >> (W_TYPE_SIZE - 1)) == 0);
@@ -1271,7 +1271,7 @@ prime_p (uintmax_t n)
           a_prim = s0 % n;
         else
           {
-            uintmax_t dummy ATTRIBUTE_UNUSED;
+            uintmax_t dummy _GL_UNUSED;
             udiv_qrnnd (dummy, a_prim, s1, s0, n);
           }
       }
@@ -1803,7 +1803,7 @@ isqrt2 (uintmax_t nh, uintmax_t nl)
   /* Do we need more than one iteration? */
   for (;;)
     {
-      uintmax_t r ATTRIBUTE_UNUSED;
+      uintmax_t r _GL_UNUSED;
       uintmax_t q, y;
       udiv_qrnnd (q, r, nh, nl, x);
       y = (x + q) / 2;
diff --git a/src/ls.c b/src/ls.c
index f1ed43bd2..d9876f842 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -2734,7 +2734,7 @@ has_capability (char const *name)
 }
 #else
 static bool
-has_capability (char const *name ATTRIBUTE_UNUSED)
+has_capability (char const *name _GL_UNUSED)
 {
   errno = ENOTSUP;
   return false;
diff --git a/src/od.c b/src/od.c
index ffccd7410..e7d881b28 100644
--- a/src/od.c
+++ b/src/od.c
@@ -416,7 +416,7 @@ N (size_t fields, size_t blank, void const *block,                      \
   PRINT_FIELDS (N, T, fmt_string, xprintf (fmt_string, adjusted_width, x))
 
 #define PRINT_FLOATTYPE(N, T, FTOASTR, BUFSIZE)                         \
-  PRINT_FIELDS (N, T, fmt_string ATTRIBUTE_UNUSED,                      \
+  PRINT_FIELDS (N, T, fmt_string _GL_UNUSED,                      \
                 char buf[BUFSIZE];                                      \
                 FTOASTR (buf, sizeof buf, 0, 0, x);                     \
                 xprintf ("%*s", adjusted_width, buf))
@@ -452,7 +452,7 @@ dump_hexl_mode_trailer (size_t n_bytes, const char *block)
 
 static void
 print_named_ascii (size_t fields, size_t blank, void const *block,
-                   const char *unused_fmt_string ATTRIBUTE_UNUSED,
+                   const char *unused_fmt_string _GL_UNUSED,
                    int width, int pad)
 {
   unsigned char const *p = block;
@@ -483,7 +483,7 @@ print_named_ascii (size_t fields, size_t blank, void const *block,
 
 static void
 print_ascii (size_t fields, size_t blank, void const *block,
-             const char *unused_fmt_string ATTRIBUTE_UNUSED, int width,
+             const char *unused_fmt_string _GL_UNUSED, int width,
              int pad)
 {
   unsigned char const *p = block;
@@ -1056,8 +1056,8 @@ skip (uintmax_t n_skip)
 }
 
 static void
-format_address_none (uintmax_t address ATTRIBUTE_UNUSED,
-                     char c ATTRIBUTE_UNUSED)
+format_address_none (uintmax_t address _GL_UNUSED,
+                     char c _GL_UNUSED)
 {
 }
 
diff --git a/src/stat.c b/src/stat.c
index dd210d181..232669811 100644
--- a/src/stat.c
+++ b/src/stat.c
@@ -583,7 +583,7 @@ out_minus_zero (char *pformat, size_t prefix_len)
    acts like printf's %f format.  */
 static void
 out_epoch_sec (char *pformat, size_t prefix_len,
-               struct stat const *statbuf ATTRIBUTE_UNUSED,
+               struct stat const *statbuf _GL_UNUSED,
                struct timespec arg)
 {
   char *dot = memchr (pformat, '.', prefix_len);
diff --git a/src/stty.c b/src/stty.c
index ee891a593..e518839d5 100644
--- a/src/stty.c
+++ b/src/stty.c
@@ -745,7 +745,7 @@ main (int argc, char **argv)
   int argi = 0;
   int opti = 1;
   bool require_set_attr;
-  bool speed_was_set ATTRIBUTE_UNUSED;
+  bool speed_was_set _GL_UNUSED;
   bool verbose_output;
   bool recoverable_output;
   int k;
diff --git a/src/system.h b/src/system.h
index 1677999ef..0605a2f2e 100644
--- a/src/system.h
+++ b/src/system.h
@@ -425,10 +425,6 @@ enum
 # define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
 #endif
 
-#ifndef ATTRIBUTE_UNUSED
-# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
-#endif
-
 /* The warn_unused_result attribute appeared first in gcc-3.4.0 */
 #undef ATTRIBUTE_WARN_UNUSED_RESULT
 #if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
diff --git a/src/tac.c b/src/tac.c
index c6a8cf695..5bf40a7e8 100644
--- a/src/tac.c
+++ b/src/tac.c
@@ -409,7 +409,7 @@ record_or_unlink_tempfile (char const *fn, FILE *fp)
 #else
 
 static void
-record_or_unlink_tempfile (char const *fn, FILE *fp ATTRIBUTE_UNUSED)
+record_or_unlink_tempfile (char const *fn, FILE *fp _GL_UNUSED)
 {
   unlink (fn);
 }
diff --git a/src/tsort.c b/src/tsort.c
index d22f1f051..93ff89499 100644
--- a/src/tsort.c
+++ b/src/tsort.c
@@ -280,7 +280,7 @@ record_relation (struct item *j, struct item *k)
 }
 
 static bool
-count_items (struct item *unused ATTRIBUTE_UNUSED)
+count_items (struct item *unused _GL_UNUSED)
 {
   n_strings++;
   return false;