build (--enable-gcc-warnings): enable gcc's -Werror also in lib/

* configure.ac (GNULIB_WARN_CFLAGS): Define.
* lib/Makefile.am (AM_CFLAGS): Use $(GNULIB_WARN_CFLAGS)
rather than $(WARN_CFLAGS) and add $(WERROR_CFLAGS).
* gl/lib/regcomp.c.diff: New file.
* gl/lib/regex_internal.c.diff: New file.
* gl/lib/regexec.c.diff: New file.

configure.ac

@@ -114,6 +114,16 @@ if test "$gl_gcc_warnings" = yes; then
   AC_DEFINE([_FORTIFY_SOURCE], [2],
     [enable compile-time and run-time bounds-checking, and some warnings])
   AC_DEFINE([GNULIB_PORTCHECK], [1], [enable some gnulib portability checks])
+
+  # We use a slightly smaller set of warning options for lib/.
+  # Remove the following and save the result in GNULIB_WARN_CFLAGS.
+  nw=
+  nw="$nw -Wuninitialized"
+  nw="$nw -Wunused-macros"
+  nw="$nw -Wmissing-prototypes"
+  nw="$nw -Wold-style-definition"
+  gl_MANYWARN_COMPLEMENT([GNULIB_WARN_CFLAGS], [$WARN_CFLAGS], [$nw])
+  AC_SUBST([GNULIB_WARN_CFLAGS])
 fi
 
 AC_FUNC_FORK

gl/lib/regcomp.c.diff

@@ -0,0 +1,23 @@
+diff --git a/lib/regcomp.c b/lib/regcomp.c
+index 6472ff6..fadf36d 100644
+--- a/lib/regcomp.c
++++ b/lib/regcomp.c
+@@ -18,6 +18,8 @@
+    with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
++#include "intprops.h"
++#include "verify.h"
+ static reg_errcode_t re_compile_internal (regex_t *preg, const char * pattern,
+ 					  size_t length, reg_syntax_t syntax);
+ static void re_compile_fastmap_iter (regex_t *bufp,
+@@ -2571,7 +2573,8 @@ parse_dup_op (bin_tree_t *elem, re_string_t *regexp, re_dfa_t *dfa,
+   /* This loop is actually executed only when end != REG_MISSING,
+      to rewrite <re>{0,n} as (<re>(<re>...<re>?)?)?...  We have
+      already created the start+1-th copy.  */
+-  if ((Idx) -1 < 0 || end != REG_MISSING)
++  verify (! TYPE_SIGNED (Idx));
++  if (end != REG_MISSING)
+     for (i = start + 2; i <= end; ++i)
+       {
+ 	elem = duplicate_tree (elem, dfa);

gl/lib/regex_internal.c.diff

@@ -0,0 +1,25 @@
+diff --git a/lib/regex_internal.c b/lib/regex_internal.c
+index 904b88e..61c8d9d 100644
+--- a/lib/regex_internal.c
++++ b/lib/regex_internal.c
+@@ -18,6 +18,8 @@
+    with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
++#include "verify.h"
++#include "intprops.h"
+ static void re_string_construct_common (const char *str, Idx len,
+ 					re_string_t *pstr,
+ 					RE_TRANSLATE_TYPE trans, bool icase,
+@@ -1390,7 +1392,10 @@ static void
+ internal_function
+ re_node_set_remove_at (re_node_set *set, Idx idx)
+ {
+-  if (idx < 0 || idx >= set->nelem)
++  verify (! TYPE_SIGNED (Idx));
++  /* if (idx < 0)
++     return; */
++  if (idx >= set->nelem)
+     return;
+   --set->nelem;
+   for (; idx < set->nelem; idx++)

gl/lib/regexec.c.diff

@@ -0,0 +1,45 @@
+diff --git a/lib/regexec.c b/lib/regexec.c
+index 21a8166..3b0d85c 100644
+--- a/lib/regexec.c
++++ b/lib/regexec.c
+@@ -18,6 +18,8 @@
+    with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
++#include "verify.h"
++#include "intprops.h"
+ static reg_errcode_t match_ctx_init (re_match_context_t *cache, int eflags,
+ 				     Idx n) internal_function;
+ static void match_ctx_clean (re_match_context_t *mctx) internal_function;
+@@ -378,8 +380,11 @@ re_search_2_stub (struct re_pattern_buffer *bufp,
+   Idx len = length1 + length2;
+   char *s = NULL;
+
+-  if (BE (length1 < 0 || length2 < 0 || stop < 0 || len < length1, 0))
+-    return -2;
++  verify (! TYPE_SIGNED (Idx));
++  if (BE (len < length1, 0))
++     return -2; */
++  /* if (BE (length1 < 0 || length2 < 0 || stop < 0, 0))
++     return -2; */
+
+   /* Concatenate the strings.  */
+   if (length2 > 0)
+@@ -431,11 +436,14 @@ re_search_stub (struct re_pattern_buffer *bufp,
+   Idx last_start = start + range;
+
+   /* Check for out-of-range.  */
+-  if (BE (start < 0 || start > length, 0))
+-    return -1;
++  verify (! TYPE_SIGNED (Idx));
++  /* if (BE (start < 0, 0))
++     return -1; */
++  if (BE (start > length, 0))
++     return -1;
+   if (BE (length < last_start || (0 <= range && last_start < start), 0))
+     last_start = length;
+-  else if (BE (last_start < 0 || (range < 0 && start <= last_start), 0))
++  else if (BE (/* last_start < 0 || */ (range < 0 && start <= last_start), 0))
+     last_start = 0;
+
+   __libc_lock_lock (dfa->lock);

lib/Makefile.am

@@ -17,7 +17,7 @@
 
 include gnulib.mk
 
-AM_CFLAGS += $(WARN_CFLAGS) # $(WERROR_CFLAGS)
+AM_CFLAGS += $(GNULIB_WARN_CFLAGS) $(WERROR_CFLAGS)
 
 libcoreutils_a_SOURCES += \
   buffer-lcm.c buffer-lcm.h \