gnulib: make use of regex module

basically followed the output of gnulib-tool;

$ gnulib-tool --source-base=gnulib --no-vc-files --import regex
Module list with included dependencies (indented):
...
You may need to add #include directives for the following .h files.
  #include <regex.h>

You may need to use the following Makefile variables when linking.
Use them in <program>_LDADD when linking a program, or
in <library>_a_LDFLAGS or <library>_la_LDFLAGS when linking a library.
  $(LIBTHREAD)
  $(LIB_HARD_LOCALE)
  $(LIB_MBRTOWC)
  $(LIB_SETLOCALE_NULL)
  $(LTLIBINTL) when linking with libtool, $(LIBINTL) otherwise

Don't forget to
  - add "gnulib/Makefile" to AC_CONFIG_FILES in ./configure.ac,
  - mention "gnulib" in SUBDIRS in Makefile.am,
  - mention "-I m4" in ACLOCAL_AMFLAGS in Makefile.am,
  - mention "m4/gnulib-cache.m4" in EXTRA_DIST in Makefile.am,
  - replace AC_PROG_CC_C99 with AC_PROG_CC in ./configure.ac,
  - invoke gl_EARLY in ./configure.ac, right after AC_PROG_CC_C99,
  - invoke gl_INIT in ./configure.ac.
$

.gitignore

@@ -98,3 +98,13 @@ Units/**/Makefile.in
 Tmain/dist.m4
 Units/dist.m4
 VALGRIND.tmp.core.*
+gnulib/inttypes.h
+gnulib/langinfo.h
+gnulib/libgnu.a
+gnulib/limits.h
+gnulib/locale.h
+gnulib/stdlib.h
+gnulib/unistd.h
+gnulib/wchar.h
+gnulib/wctype.h
+gnulib/sys/types.h

Makefile.am

@@ -1,3 +1,7 @@
+ACLOCAL_AMFLAGS = -I m4
+#AM_CPPFLAGS = -I$(top_builddir)/gnulib -I$(top_srcdir)/gnulib
+DEFAULT_INCLUDES = -I$(top_srcdir)/gnulib
+SUBDIRS = gnulib
 
 include $(top_srcdir)/source.mak
 
@@ -12,8 +16,6 @@ EXTRA_DIST   = README.md autogen.sh \
 	       makefiles/list-optlib2c-input.mak misc/optlib2c \
 	       .ctags.d/exclusion.ctags .dir-locals.el .editorconfig .gdbinit .gitignore \
 	       .indent.pro .uncrustify.cfg \
-	       gnu_regex/README.txt gnu_regex/regcomp.c gnu_regex/regexec.c \
-	       gnu_regex/regex_internal.c gnu_regex/regex_internal.h \
 	       misc/ctags-optlib-mode.el \
 	       misc/mk-interactive-request.sh misc/roundtrip misc/tinst \
 	       $(PACKCC_FILES) \
@@ -30,7 +32,7 @@ EXTRA_DIST   = README.md autogen.sh \
 	       man/Makefile man/README man/tags.5.rst \
 	       makefiles/list-txt2cstr-input.mak misc/txt2cstr \
 	       $(PEG_INPUT) $(OPTLIB2C_INPUT) $(TXT2CSTR_INPUT) \
-	       docs Tmain Units
+	       docs Tmain Units m4/gnulib-cache.m4
 
 CLEANFILES =
 MOSTLYCLEANFILES =
@@ -66,23 +68,16 @@ readtags_CPPFLAGS = -I. -I$(srcdir) -I$(srcdir)/main -I$(srcdir)/libreadtags
 readtags_CFLAGS = $(COVERAGE_CFLAGS) $(WARNING_CFLAGS)
 dist_readtags_SOURCES = $(READTAGS_SRCS) $(READTAGS_HEADS)
 readtags_CPPFLAGS += -DREADTAGS_DSL -I$(srcdir)/dsl
+readtags_LDADD = gnulib/libgnu.a
 dist_readtags_SOURCES += $(READTAGS_DSL_SRCS) $(READTAGS_DSL_HEADS)
-if !HAVE_REGCOMP
-readtags_CPPFLAGS += $(REGCOMP_CPPFLAGS)
-dist_readtags_SOURCES += $(REGEX_SRCS) $(REGEX_HEADS)
-endif
+
 endif
 
 if !HAVE_FNMATCH
 LIB_SRCS += $(FNMATCH_SRCS)
 LIB_HEADS += $(FNMATCH_HEADS)
 endif
 
-if !HAVE_REGCOMP
-LIB_SRCS += $(REGEX_SRCS)
-LIB_HEADS += $(REGEX_HEADS)
-endif
-
 if HAVE_LIBXML
 PARSER_SRCS += $(XML_SRCS)
 PARSER_HEADS += $(XML_HEADS)
@@ -108,7 +103,6 @@ if HAVE_STRNLEN
 libctags_a_CPPFLAGS += -DUSE_SYSTEM_STRNLEN
 endif
 libctags_a_CPPFLAGS+= $(FNMATCH_CPPFLAGS)
-libctags_a_CPPFLAGS+= $(REGCOMP_CPPFLAGS)
 libctags_a_CPPFLAGS+= -DHAVE_REPOINFO_H
 
 libctags_a_CFLAGS   =
@@ -177,6 +171,7 @@ dist_libctags_a_SOURCES = $(ALL_LIB_HEADS) $(ALL_LIB_SRCS)
 ctags_CPPFLAGS = $(libctags_a_CPPFLAGS)
 ctags_CFLAGS = $(libctags_a_CFLAGS)
 ctags_LDADD  = libctags.a
+ctags_LDADD += gnulib/libgnu.a
 ctags_LDADD += $(LIBXML_LIBS)
 ctags_LDADD += $(JANSSON_LIBS)
 ctags_LDADD += $(LIBYAML_LIBS)
@@ -199,6 +194,7 @@ endif
 mini_geany_CPPFLAGS = $(libctags_a_CPPFLAGS)
 mini_geany_CFLAGS = $(libctags_a_CFLAGS)
 mini_geany_LDADD  = libctags.a
+mini_geany_LDADD += gnulib/libgnu.a
 mini_geany_LDADD += $(LIBXML_LIBS)
 mini_geany_LDADD += $(JANSSON_LIBS)
 mini_geany_LDADD += $(LIBYAML_LIBS)
@@ -211,6 +207,7 @@ optscript_CPPFLAGS = $(libctags_a_CPPFLAGS)
 optscript_CFLAGS = $(libctags_a_CFLAGS)
 optscript_LDADD  = libctags.a
 # TODO: remove these dependencies from optscript command.
+optscript_LDADD += gnulib/libgnu.a
 optscript_LDADD += $(LIBXML_LIBS)
 optscript_LDADD += $(JANSSON_LIBS)
 optscript_LDADD += $(LIBYAML_LIBS)

configure.ac

@@ -6,7 +6,7 @@
 
 #	Process this file with autoconf to produce a configure script.
 
-AC_PREREQ([2.59])
+AC_PREREQ([2.64])
 AC_INIT([universal-ctags],[5.9.0])
 
 if ! test -e "${srcdir}/config.h.in"; then
@@ -98,9 +98,6 @@ AH_TEMPLATE([ICONV_USE_LIB_PREFIX],
 AH_TEMPLATE([TMPDIR],
 	[If you wish to change the directory in which temporary files are stored,
 	define this label to the directory desired.])
-AH_TEMPLATE([CHECK_REGCOMP],
-	[Define this label if you wish to check the regcomp() function at run time
-	for correct behavior. This function is currently broken on Cygwin.])
 AH_TEMPLATE([NON_CONST_PUTENV_PROTOTYPE],
 	[Define this is you have a prototype for putenv() in <stdlib.h>, but
 	doesn't declare its argument as "const char *".])
@@ -249,6 +246,10 @@ AM_CONDITIONAL(ENABLE_DEBUGGING, [test "x$enable_debugging" = "xyes"])
 
 AC_PROG_CC
 AC_PROG_CC_C99
+# For gnulib.
+#  Typically, this is immediately after AC_PROG_CC, ...
+gl_EARLY
+
 AC_PROG_RANLIB
 AC_C_BIGENDIAN
 
@@ -529,6 +530,11 @@ PRETTY_ARG_VAR([EXTRA_CFLAGS], [extra C compiler flags],
 PRETTY_ARG_VAR([WARNING_CFLAGS], [C compiler warning flags],
 	       [-Wall])
 
+# For gnulib.
+#   Place it further down in the file, typically where you normally check for
+#   header files or functions.
+gl_INIT
+
 # Checks for library functions
 # ----------------------------
 AC_CHECK_FUNCS(fnmatch,[have_fnmatch=yes],[
@@ -586,45 +592,6 @@ if test "$have_setenv" != yes ; then
 	fi
 fi
 
-dnl
-dnl
-dnl Check regcomp
-dnl
-dnl If it is found but broken, abort with a message.
-dnl If it is found but cannot be test brokenness, define CHECK_REGCOMP.
-dnl If it is not found, use bundled implementation.
-dnl
-dnl If CHECK_REGCOMP is defined, ctags itself check the brokenness at runtime
-dnl (cross-compiling is assumed here).
-dnl
-dnl
-dnl The final result can be check with ./ctags --list-features.
-dnl
-dnl
-AC_CHECK_FUNCS(regcomp,[
-AC_MSG_CHECKING(if regcomp works)
-AC_RUN_IFELSE([AC_LANG_SOURCE([
-#include <sys/types.h>
-#include <regex.h>
-int main(void) {
-	regex_t patbuf;
-	return (regcomp (&patbuf, "/hello/", 0) != 0);
-}
-])],[regcomp_works=yes],[regcomp_works=no],[AC_DEFINE(CHECK_REGCOMP)])
-AC_MSG_RESULT($regcomp_works)
-if test no = "$regcomp_works"; then
-	AC_MSG_ERROR([regcomp() on this system is broken.])
-fi
-have_regcomp=yes
-],[
-dnl Using bundled regex implementation
-AC_LIBOBJ([regex])
-REGCOMP_CPPFLAGS="-I${srcdir}/gnu_regex -D__USE_GNU"
-AC_DEFINE(HAVE_REGCOMP)
-have_regcomp=no])
-AC_SUBST([REGCOMP_CPPFLAGS])
-AM_CONDITIONAL([HAVE_REGCOMP], [test "xyes" = "x$have_regcomp"])
-
 have_scandir=no
 AC_CHECK_FUNCS(scandir,have_scandir=yes)
 
@@ -821,7 +788,7 @@ fi
 
 AC_CHECK_FUNCS(mblen)
 
-AC_CONFIG_FILES([Makefile
+AC_CONFIG_FILES([Makefile gnulib/Makefile
 		 man/ctags.1.rst
 		 man/ctags-client-tools.7.rst
 		 man/ctags-incompatibilities.7.rst

source.mak

@@ -347,8 +347,9 @@ ALL_SRCS = $(ALL_LIB_SRCS) $(CMDLINE_SRCS)
 ENVIRONMENT_HEADS =
 ENVIRONMENT_SRCS =
 
-REGEX_HEADS = gnu_regex/regex.h
-REGEX_SRCS = gnu_regex/regex.c
+# only for non-Autotool configuration (mk_mingw.mak and mk_mvc.mak)
+REGEX_HEADS = gnulib/regex.h
+REGEX_SRCS = gnulib/regex.c
 REGEX_OBJS = $(REGEX_SRCS:.c=.$(OBJEXT))
 
 FNMATCH_HEADS = fnmatch/fnmatch.h