utils: retire the fixbounds() function -- it is no longer needed

All tested systems (FreeBSD, NetBSD, OpenBSD, Alpine, and Ubuntu)
support the GNU-style word boundaries (\< and \>), either natively
or through using the regex module from gnulib.

If this change breaks regexes containing \< or \> on your system,
please report a bug: https://savannah.gnu.org/bugs/?group=nano

This addresses https://savannah.gnu.org/bugs/?55207.

configure.ac

@@ -665,55 +665,6 @@ fi
 AC_DEFINE_UNQUOTED(NANO_REG_EXTENDED, $nano_reg_extended,
 				   [Flag(s) to use to get the full range of extended regular expressions])
 
-# Check for word-boundary support (/< and />).
-AC_MSG_CHECKING([for GNU-style word boundary regex support])
-AC_ARG_WITH(wordbounds,
-AS_HELP_STRING([--with-wordbounds], [Use GNU-style word boundary delimiters]),
-		[with_wordbounds=$withval], [with_wordbounds=auto])
-if test "$with_wordbounds" != "no"; then
-	dnl If we're using the bundled gnulib regex module, we know it's supported.
-	if test "$ac_use_included_regex" = "yes"; then
-	    with_wordbounds="yes"
-	fi
-
-	dnl We explicitly don't check if the user forced the option, because
-	dnl this is needed for cross compilers and we can't test the target.
-	if test "$with_wordbounds" != "yes"; then
-	    AC_TRY_RUN([
-#ifdef HAVE_SYS_TYPES_H
-#include <sys/types.h>
-#endif
-#include <regex.h>
-int main(void)
-{
-	regex_t r;
-	size_t nmatch;
-	regmatch_t pmatch;
-
-	if (regcomp(&r, "\\\\>", $nano_reg_extended|REG_NOSUB))
-		return 1;
-	if (regexec(&r, "word boundary", nmatch, &pmatch, 0))
-		return 1;
-	return 0;
-}],
-	    with_wordbounds="yes",
-	    with_wordbounds="no",
-	    with_wordbounds="cross")
-	fi
-fi
-case $with_wordbounds in
-yes)
-	AC_MSG_RESULT(yes)
-	AC_DEFINE(GNU_WORDBOUNDS, 1, [Define this if the system supports GNU-style word boundaries in regexes.])
-	;;
-no)
-	AC_MSG_RESULT(no)
-	;;
-cross)
-	AC_MSG_WARN([*** Can't check for GNU-style word boundary support when cross-compiling])
-	;;
-esac
-
 if test x$color_support = xyes; then
 #    if test x$CURSES_LIB_NAME = xcurses; then
 		AC_MSG_CHECKING([whether _XOPEN_SOURCE_EXTENDED is needed])

src/color.c

@@ -144,7 +144,7 @@ bool found_in_list(regexlisttype *head, const char *shibboleth)
 	regex_t rgx;
 
 	for (item = head; item != NULL; item = item->next) {
-		regcomp(&rgx, fixbounds(item->full_regex), NANO_REG_EXTENDED);
+		regcomp(&rgx, item->full_regex, NANO_REG_EXTENDED);
 
 		if (regexec(&rgx, shibboleth, 0, NULL, 0) == 0) {
 			regfree(&rgx);
@@ -273,12 +273,12 @@ void color_update(void)
 	for (ink = openfile->colorstrings; ink != NULL; ink = ink->next) {
 		if (ink->start == NULL) {
 			ink->start = (regex_t *)nmalloc(sizeof(regex_t));
-			regcomp(ink->start, fixbounds(ink->start_regex), ink->rex_flags);
+			regcomp(ink->start, ink->start_regex, ink->rex_flags);
 		}
 
 		if (ink->end_regex != NULL && ink->end == NULL) {
 			ink->end = (regex_t *)nmalloc(sizeof(regex_t));
-			regcomp(ink->end, fixbounds(ink->end_regex), ink->rex_flags);
+			regcomp(ink->end, ink->end_regex, ink->rex_flags);
 		}
 	}
 }

src/proto.h

@@ -563,7 +563,6 @@ void sunder(char *str);
 #if !defined(ENABLE_TINY) || defined(ENABLE_TABCOMP) || defined(ENABLE_BROWSER)
 void free_chararray(char **array, size_t len);
 #endif
-const char *fixbounds(const char *r);
 #ifdef ENABLE_SPELLER
 bool is_separate_word(size_t position, size_t length, const char *buf);
 #endif

src/rcfile.c

@@ -240,15 +240,14 @@ char *parse_next_regex(char *ptr)
 bool nregcomp(const char *regex, int compile_flags)
 {
 	regex_t preg;
-	const char *r = fixbounds(regex);
-	int rc = regcomp(&preg, r, compile_flags);
+	int rc = regcomp(&preg, regex, compile_flags);
 
 	if (rc != 0) {
 		size_t len = regerror(rc, &preg, NULL, 0);
 		char *str = charalloc(len);
 
 		regerror(rc, &preg, str, len);
-		rcfile_error(N_("Bad regex \"%s\": %s"), r, str);
+		rcfile_error(N_("Bad regex \"%s\": %s"), regex, str);
 		free(str);
 	}
 

src/search.c

@@ -35,7 +35,7 @@ static bool have_compiled_regexp = FALSE;
  * Return TRUE if the expression is valid, and FALSE otherwise. */
 bool regexp_init(const char *regexp)
 {
-	int value = regcomp(&search_regexp, fixbounds(regexp),
+	int value = regcomp(&search_regexp, regexp,
 				NANO_REG_EXTENDED | (ISSET(CASE_SENSITIVE) ? 0 : REG_ICASE));
 
 	/* If regex compilation failed, show the error message. */

src/utils.c

@@ -200,37 +200,6 @@ void free_chararray(char **array, size_t len)
 }
 #endif
 
-/* Fix the regex if we're on platforms which require an adjustment
- * from GNU-style to BSD-style word boundaries. */
-const char *fixbounds(const char *r)
-{
-#ifndef GNU_WORDBOUNDS
-	int i, j = 0;
-	char *r2 = charalloc(strlen(r) * 5);
-	char *r3;
-
-	for (i = 0; i < strlen(r); i++) {
-		if (r[i] != '\0' && r[i] == '\\' && (r[i + 1] == '>' || r[i + 1] == '<')) {
-			strcpy(&r2[j], "[[:");
-			r2[j + 3] = r[i + 1];
-			strcpy(&r2[j + 4], ":]]");
-			i++;
-			j += 6;
-		} else
-			r2[j] = r[i];
-		j++;
-	}
-
-	r2[j] = '\0';
-	r3 = mallocstrcpy(NULL, r2);
-	free(r2);
-
-	return (const char *) r3;
-#endif /* !GNU_WORDBOUNDS */
-
-	return r;
-}
-
 #ifdef ENABLE_SPELLER
 /* Is the word starting at the given position in buf and of the given length
  * a separate word?  That is: is it not part of a longer word?*/