--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2012-04-04  Paul Eggert  <eggert@cs.ucla.edu>
+
+	regex: remove unnecessary type punning
+	Problem reported by Vladimir Serbinenko in
+	<http://lists.gnu.org/archive/html/bug-gnulib/2012-04/msg00006.html>.
+	* lib/regex.h (struct re_pattern_buffer): Change the type of
+	__REPB_PREFIX(buffer) from unsigned char * to struct re_dfa_t *.
+	Fix comment to match code.
+	* lib/regcomp.c (re_compile_fastmap, re_compile_fastmap_iter, regfree)
+	(re_compile_internal, free_workarea_compile, analyze, lower_subexp)
+	(parse, parse_reg_exp, parse_branch, parse_expression, parse_sub_exp):
+	* lib/regexec.c (regexec, re_search_stub, re_search_internal)
+	(set_regs):
+	Omit no-longer-necessary casts.
+
 2012-04-03  Bruno Haible  <bruno@clisp.org>
 
 	Tests for module 'ilogbl'.

--- a/lib/regcomp.c
+++ b/lib/regcomp.c
@@ -272,7 +272,7 @@
 re_compile_fastmap (bufp)
     struct re_pattern_buffer *bufp;
 {
-  re_dfa_t *dfa = (re_dfa_t *) bufp->buffer;
+  re_dfa_t *dfa = bufp->buffer;
   char *fastmap = bufp->fastmap;
 
   memset (fastmap, '\0', sizeof (char) * SBC_MAX);
@@ -306,7 +306,7 @@
 re_compile_fastmap_iter (regex_t *bufp, const re_dfastate_t *init_state,
 			 char *fastmap)
 {
-  re_dfa_t *dfa = (re_dfa_t *) bufp->buffer;
+  re_dfa_t *dfa = bufp->buffer;
   Idx node_cnt;
   bool icase = (dfa->mb_cur_max == 1 && (bufp->syntax & RE_ICASE));
   for (node_cnt = 0; node_cnt < init_state->nodes.nelem; ++node_cnt)
@@ -660,7 +660,7 @@
 regfree (preg)
     regex_t *preg;
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   if (BE (dfa != NULL, 1))
     free_dfa_content (dfa);
   preg->buffer = NULL;
@@ -767,7 +767,7 @@
   preg->regs_allocated = REGS_UNALLOCATED;
 
   /* Initialize the dfa.  */
-  dfa = (re_dfa_t *) preg->buffer;
+  dfa = preg->buffer;
   if (BE (preg->allocated < sizeof (re_dfa_t), 0))
     {
       /* If zero allocated, but buffer is non-null, try to realloc
@@ -778,7 +778,7 @@
       if (dfa == NULL)
 	return REG_ESPACE;
       preg->allocated = sizeof (re_dfa_t);
-      preg->buffer = (unsigned char *) dfa;
+      preg->buffer = dfa;
     }
   preg->used = sizeof (re_dfa_t);
 
@@ -993,7 +993,7 @@
 static void
 free_workarea_compile (regex_t *preg)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   bin_tree_storage_t *storage, *next;
   for (storage = dfa->str_tree_storage; storage; storage = next)
     {
@@ -1177,7 +1177,7 @@
 static reg_errcode_t
 analyze (regex_t *preg)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   reg_errcode_t ret;
 
   /* Allocate arrays.  */
@@ -1358,7 +1358,7 @@
 static bin_tree_t *
 lower_subexp (reg_errcode_t *err, regex_t *preg, bin_tree_t *node)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   bin_tree_t *body = node->left;
   bin_tree_t *op, *cls, *tree1, *tree;
 
@@ -2139,7 +2139,7 @@
 parse (re_string_t *regexp, regex_t *preg, reg_syntax_t syntax,
        reg_errcode_t *err)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   bin_tree_t *tree, *eor, *root;
   re_token_t current_token;
   dfa->syntax = syntax;
@@ -2173,7 +2173,7 @@
 parse_reg_exp (re_string_t *regexp, regex_t *preg, re_token_t *token,
 	       reg_syntax_t syntax, Idx nest, reg_errcode_t *err)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   bin_tree_t *tree, *branch = NULL;
   tree = parse_branch (regexp, preg, token, syntax, nest, err);
   if (BE (*err != REG_NOERROR && tree == NULL, 0))
@@ -2215,7 +2215,7 @@
 	      reg_syntax_t syntax, Idx nest, reg_errcode_t *err)
 {
   bin_tree_t *tree, *expr;
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   tree = parse_expression (regexp, preg, token, syntax, nest, err);
   if (BE (*err != REG_NOERROR && tree == NULL, 0))
     return NULL;
@@ -2259,7 +2259,7 @@
 parse_expression (re_string_t *regexp, regex_t *preg, re_token_t *token,
 		  reg_syntax_t syntax, Idx nest, reg_errcode_t *err)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   bin_tree_t *tree;
   switch (token->type)
     {
@@ -2475,7 +2475,7 @@
 parse_sub_exp (re_string_t *regexp, regex_t *preg, re_token_t *token,
 	       reg_syntax_t syntax, Idx nest, reg_errcode_t *err)
 {
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
   bin_tree_t *tree;
   size_t cur_nsub;
   cur_nsub = preg->re_nsub++;

--- a/lib/regex.h
+++ b/lib/regex.h
@@ -421,10 +421,9 @@
 
 struct re_pattern_buffer
 {
-  /* Space that holds the compiled pattern.  It is declared as
-     'unsigned char *' because its elements are sometimes used as
-     array indexes.  */
-  unsigned char *__REPB_PREFIX(buffer);
+  /* Space that holds the compiled pattern.  The type
+     'struct re_dfa_t' is private and is not declared here.  */
+  struct re_dfa_t *__REPB_PREFIX(buffer);
 
   /* Number of bytes to which 'buffer' points.  */
   __re_long_size_t __REPB_PREFIX(allocated);

--- a/lib/regexec.c
+++ b/lib/regexec.c
@@ -228,7 +228,7 @@
   reg_errcode_t err;
   Idx start, length;
 #ifdef _LIBC
-  re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
+  re_dfa_t *dfa = preg->buffer;
 #endif
 
   if (eflags & ~(REG_NOTBOL | REG_NOTEOL | REG_STARTEND))
@@ -421,7 +421,7 @@
   regoff_t rval;
   int eflags = 0;
 #ifdef _LIBC
-  re_dfa_t *dfa = (re_dfa_t *) bufp->buffer;
+  re_dfa_t *dfa = bufp->buffer;
 #endif
   Idx last_start = start + range;
 
@@ -639,7 +639,7 @@
 		    int eflags)
 {
   reg_errcode_t err;
-  const re_dfa_t *dfa = (const re_dfa_t *) preg->buffer;
+  const re_dfa_t *dfa = preg->buffer;
   Idx left_lim, right_lim;
   int incr;
   bool fl_longest_match;
@@ -1432,7 +1432,7 @@
 set_regs (const regex_t *preg, const re_match_context_t *mctx, size_t nmatch,
 	  regmatch_t *pmatch, bool fl_backtrack)
 {
-  const re_dfa_t *dfa = (const re_dfa_t *) preg->buffer;
+  const re_dfa_t *dfa = preg->buffer;
   Idx idx, cur_node;
   re_node_set eps_via_nodes;
   struct re_fail_stack_t *fs;