[v3] Deprecate regexp.h

From 3ac1a7f71f2f296df0b99a5305415c9e6844aa56 Mon Sep 17 00:00:00 2001
From: Zack Weinberg <zackw@panix.com>
Date: Wed, 15 Jul 2015 09:36:20 -0400
Subject: [PATCH 1/2] Deprecate regexp.h (bug 18681)

	* regexp.h: Add unconditional #warning stating that this header
	will be removed soon.  Revise banner comment to match.
	(compile): Consistently use ERROR instead of RETURN to report
	errors (partial fix for bz#18681).
	* regexp.c: Don't include regexp.h.  Remove some unnecessary
        declarations.
---
 NEWS          |  8 ++++++++
 misc/regexp.c |  8 ++++----
 misc/regexp.h | 31 +++++++++++++++++--------------
 3 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/NEWS b/NEWS
index 65b2172..a0bd93b 100644
--- a/NEWS
+++ b/NEWS
@@ -78,6 +78,14 @@  Version 2.22
 
 * Port to Native Client running on ARMv7-A (--host=arm-nacl).
   Contributed by Roland McGrath (Google).
+
+* The header <regexp.h> is deprecated, and will be removed in a future
+  release.  Use of this header will trigger a deprecation warning.
+  Application developers should update their code to use <regex.h> instead.
+
+  This header was formerly part of SUSv2, but was deprecated in 1997 and
+  removed from the standard in 2001.  Also, the glibc implementation
+  leaks memory.  See BZ#18681 for more details.
 
 Version 2.21
 
diff --git a/misc/regexp.c b/misc/regexp.c
index 3b83203..ee7d572 100644
--- a/misc/regexp.c
+++ b/misc/regexp.c
@@ -17,8 +17,10 @@ 
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#define __DO_NOT_DEFINE_COMPILE
-#include <regexp.h>
+/* We don't include regexp.h here because of the macros it requires, and
+   because it now contains an unconditional #warning.  */
+
+#include <regex.h>
 
 /* Define the variables used for the interface.  */
 char *loc1;
@@ -32,7 +34,6 @@  char *locs;
    found in the buffer starting at EXPBUF.  `loc1' will return the
    first character matched and `loc2' points to the next unmatched
    character.  */
-extern int __step (const char *string, const char *expbuf);
 int
 __step (const char *string, const char *expbuf)
 {
@@ -55,7 +56,6 @@  weak_alias (__step, step)
 /* Match the beginning of STRING with the compiled regular expression
    in EXPBUF.  If the match is successful `loc2' will contain the
    position of the first unmatched character.  */
-extern int __advance (const char *string, const char *expbuf);
 int
 __advance (const char *string, const char *expbuf)
 {
diff --git a/misc/regexp.h b/misc/regexp.h
index 3fc0bc5..3460989 100644
--- a/misc/regexp.h
+++ b/misc/regexp.h
@@ -19,14 +19,17 @@ 
 #ifndef _REGEXP_H
 #define _REGEXP_H	1
 
-/* The contents of this header file was first standardized in X/Open
-   System Interface and Headers Issue 2, originally coming from SysV.
-   In issue 4, version 2, it is marked as TO BE WITDRAWN, and it has
-   been withdrawn in SUSv3.
+/* The contents of this header file were standardized in the
+   Single Unix Specification, Version 2 (1997) but marked as
+   LEGACY; new applications were already being encouraged to
+   use <regex.h> instead.  POSIX.1-2001 removed this header.
 
-   This code shouldn't be used in any newly written code.  It is
-   included only for compatibility reasons.  Use the POSIX definition
-   in <regex.h> for portable applications and a reasonable interface.  */
+   This header is provided only for backward compatibility.
+   It will be removed in the next release of the GNU C Library.
+   New code should use <regex.h> instead.  */
+
+#warning "<regexp.h> will be removed in the next release of the GNU C Library."
+#warning "Please update your code to use <regex.h> instead (no trailing 'p')."
 
 #include <features.h>
 #include <alloca.h>
@@ -182,19 +185,19 @@  compile (char *__restrict instring, char *__restrict expbuf,
       case REG_ERPAREN:
       default:
 	/* There is no matching error code.  */
-	RETURN (36);
+	ERROR (36);
       case REG_ESUBREG:
-	RETURN (25);
+	ERROR (25);
       case REG_EBRACK:
-	RETURN (49);
+	ERROR (49);
       case REG_EPAREN:
-	RETURN (42);
+	ERROR (42);
       case REG_EBRACE:
-	RETURN (44);
+	ERROR (44);
       case REG_BADBR:
-	RETURN (46);
+	ERROR (46);
       case REG_ERANGE:
-	RETURN (11);
+	ERROR (11);
       case REG_ESPACE:
       case REG_ESIZE:
 	ERROR (50);
-- 
2.4.6