From 6b80071a4d05c9535d3bb26cddaed0895a414f59 Mon Sep 17 00:00:00 2001
From: Tamar Christina <tamar.christina@arm.com>
Date: Fri, 4 Aug 2023 13:48:56 +0100
Subject: [PATCH] gensupport: Don't segfault on empty attrs list

Currently we segfault when len == 0 for an attribute list.

essentially [cons: =0, 1, 2, 3; attrs: ] segfaults but should be equivalent to
[cons: =0, 1, 2, 3] and [cons: =0, 1, 2, 3; attrs:].  This fixes it by just
returning early and leaving it to the validators whether this should error out
or not.

gcc/ChangeLog:

	* gensupport.cc (conlist): Support length 0 attribute.
---
 gcc/gensupport.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/gensupport.cc b/gcc/gensupport.cc
index 959d1d9c83cf..b2feb03363ac 100644
--- a/gcc/gensupport.cc
+++ b/gcc/gensupport.cc
@@ -620,7 +620,7 @@ public:
   conlist (const char *ns, unsigned int len, bool numeric)
   {
     /* Trim leading whitespaces.  */
-    while (ISBLANK (*ns))
+    while (len > 0 && ISBLANK (*ns))
       {
 	ns++;
 	len--;
@@ -632,7 +632,7 @@ public:
 	break;
 
     /* Parse off any modifiers.  */
-    while (!ISALNUM (*ns))
+    while (len > 0 && !ISALNUM (*ns))
       {
 	con += *(ns++);
 	len--;
-- 
2.47.2