regex: simplify Gnulib port

This simplifies the code, by removing stuff intended for porting
to Gnulib but no longer needed there.
* posix/regcomp.c [!_LIBC]: No need to put #ifdef _LIBC around
uses of libc_hidden_def, weak_alias.
* posix/regcomp.c, posix/regexec.c: Use __restrict rather than
_Restrict_ except for public-facing headers.
* posix/regex_internal.h (attribute_hidden) [!_LIBC]:
Remove; already defined elsewhere.
* posix/regex.c, posix/regex_internal.h:
Use __GNUC_PREREQ instead of rolling our own.
* posix/regex_internal.h (__GNUC_PREREQ): Remove duplicate defn.

ChangeLog

@@ -1,3 +1,18 @@
+2018-12-27  Paul Eggert  <eggert@cs.ucla.edu>
+
+	regex: simplify Gnulib port
+	This simplifies the code, by removing stuff intended for porting
+	to Gnulib but no longer needed there.
+	* posix/regcomp.c [!_LIBC]: No need to put #ifdef _LIBC around
+	uses of libc_hidden_def, weak_alias.
+	* posix/regcomp.c, posix/regexec.c: Use __restrict rather than
+	_Restrict_ except for public-facing headers.
+	* posix/regex_internal.h (attribute_hidden) [!_LIBC]:
+	Remove; already defined elsewhere.
+	* posix/regex.c, posix/regex_internal.h:
+	Use __GNUC_PREREQ instead of rolling our own.
+	* posix/regex_internal.h (__GNUC_PREREQ): Remove duplicate defn.
+
 2018-12-27  Wilco Dijkstra  <wdijkstr@arm.com>
 
 	* benchtests/bench-strlen.c (generic_strlen): New function.

posix/regcomp.c

@@ -233,9 +233,7 @@ re_compile_pattern (const char *pattern, size_t length,
     return NULL;
   return gettext (__re_error_msgid + __re_error_msgid_idx[(int) ret]);
 }
-#ifdef _LIBC
 weak_alias (__re_compile_pattern, re_compile_pattern)
-#endif
 
 /* Set by 're_set_syntax' to the current regexp syntax to recognize.  Can
    also be assigned to arbitrarily: each pattern buffer stores its own
@@ -260,9 +258,7 @@ re_set_syntax (reg_syntax_t syntax)
   re_syntax_options = syntax;
   return ret;
 }
-#ifdef _LIBC
 weak_alias (__re_set_syntax, re_set_syntax)
-#endif
 
 int
 re_compile_fastmap (struct re_pattern_buffer *bufp)
@@ -281,9 +277,7 @@ re_compile_fastmap (struct re_pattern_buffer *bufp)
   bufp->fastmap_accurate = 1;
   return 0;
 }
-#ifdef _LIBC
 weak_alias (__re_compile_fastmap, re_compile_fastmap)
-#endif
 
 static inline void
 __attribute__ ((always_inline))
@@ -464,7 +458,7 @@ re_compile_fastmap_iter (regex_t *bufp, const re_dfastate_t *init_state,
    the return codes and their meanings.)  */
 
 int
-regcomp (regex_t *_Restrict_ preg, const char *_Restrict_ pattern, int cflags)
+regcomp (regex_t *__restrict preg, const char *__restrict pattern, int cflags)
 {
   reg_errcode_t ret;
   reg_syntax_t syntax = ((cflags & REG_EXTENDED) ? RE_SYNTAX_POSIX_EXTENDED
@@ -515,16 +509,14 @@ regcomp (regex_t *_Restrict_ preg, const char *_Restrict_ pattern, int cflags)
 
   return (int) ret;
 }
-#ifdef _LIBC
 libc_hidden_def (__regcomp)
 weak_alias (__regcomp, regcomp)
-#endif
 
 /* Returns a message corresponding to an error code, ERRCODE, returned
    from either regcomp or regexec.   We don't use PREG here.  */
 
 size_t
-regerror (int errcode, const regex_t *_Restrict_ preg, char *_Restrict_ errbuf,
+regerror (int errcode, const regex_t *__restrict preg, char *__restrict errbuf,
 	  size_t errbuf_size)
 {
   const char *msg;
@@ -555,9 +547,7 @@ regerror (int errcode, const regex_t *_Restrict_ preg, char *_Restrict_ errbuf,
 
   return msg_size;
 }
-#ifdef _LIBC
 weak_alias (__regerror, regerror)
-#endif
 
 
 #ifdef RE_ENABLE_I18N
@@ -657,10 +647,8 @@ regfree (regex_t *preg)
   re_free (preg->translate);
   preg->translate = NULL;
 }
-#ifdef _LIBC
 libc_hidden_def (__regfree)
 weak_alias (__regfree, regfree)
-#endif
 
 /* Entry points compatible with 4.2 BSD regex library.  We don't define
    them unless specifically requested.  */

posix/regex.c

@@ -20,10 +20,10 @@
 #ifndef _LIBC
 # include <libc-config.h>
 
-# if (__GNUC__ == 4 && 6 <= __GNUC_MINOR__) || 4 < __GNUC__
+# if __GNUC_PREREQ (4, 6)
 #  pragma GCC diagnostic ignored "-Wsuggest-attribute=pure"
 # endif
-# if (__GNUC__ == 4 && 3 <= __GNUC_MINOR__) || 4 < __GNUC__
+# if __GNUC_PREREQ (4, 3)
 #  pragma GCC diagnostic ignored "-Wold-style-definition"
 #  pragma GCC diagnostic ignored "-Wtype-limits"
 # endif

posix/regex_internal.h

@@ -144,10 +144,9 @@
 # define __mbrtowc mbrtowc
 # define __wcrtomb wcrtomb
 # define __regfree regfree
-# define attribute_hidden
 #endif /* not _LIBC */
 
-#if __GNUC__ < 3 + (__GNUC_MINOR__ < 1)
+#if !__GNUC_PREREQ (3, 1)
 # define __attribute__(arg)
 #endif
 
@@ -868,15 +867,6 @@ re_string_elem_size_at (const re_string_t *pstr, Idx idx)
 }
 #endif /* RE_ENABLE_I18N */
 
-#ifndef __GNUC_PREREQ
-# if defined __GNUC__ && defined __GNUC_MINOR__
-#  define __GNUC_PREREQ(maj, min) \
-         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
-# else
-#  define __GNUC_PREREQ(maj, min) 0
-# endif
-#endif
-
 #if __GNUC_PREREQ (3,4)
 # undef __attribute_warn_unused_result__
 # define __attribute_warn_unused_result__ \

posix/regexec.c

@@ -189,7 +189,7 @@ static reg_errcode_t extend_buffers (re_match_context_t *mctx, int min_len);
    We return 0 if we find a match and REG_NOMATCH if not.  */
 
 int
-regexec (const regex_t *_Restrict_ preg, const char *_Restrict_ string,
+regexec (const regex_t *__restrict preg, const char *__restrict string,
 	 size_t nmatch, regmatch_t pmatch[], int eflags)
 {
   reg_errcode_t err;
@@ -232,8 +232,8 @@ __typeof__ (__regexec) __compat_regexec;
 
 int
 attribute_compat_text_section
-__compat_regexec (const regex_t *_Restrict_ preg,
+__compat_regexec (const regex_t *__restrict preg,
-		  const char *_Restrict_ string, size_t nmatch,
+		  const char *__restrict string, size_t nmatch,
 		  regmatch_t pmatch[], int eflags)
 {
   return regexec (preg, string, nmatch, pmatch,