From 8ab100c1c7e8e72743505e5c691c842933db4447 Mon Sep 17 00:00:00 2001
From: Martin Whitaker <icarus@martin-whitaker.me.uk>
Date: Fri, 21 Apr 2017 21:37:17 +0100
Subject: [PATCH] Fix for GitHub issue #152 - segfault on gate connection
 syntax error.

If there is a syntax error in the source code, pform_makegate may be
passed a null list of port connections. The error is already reported,
so we just need to ignore it.

(cherry picked from commit 8a5cbd441583f6b24918d9b0f846a74d4f2c9cf1)
---
 pform.cc | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/pform.cc b/pform.cc
index 1fd04e6c5..14eb57a48 100644
--- a/pform.cc
+++ b/pform.cc
@@ -2138,9 +2138,11 @@ static void pform_makegate(PGBuiltin::Type type,
 	    return;
       }
 
-      for (list<PExpr*>::iterator cur = info.parms->begin()
-		 ; cur != info.parms->end() ; ++cur) {
-	    pform_declare_implicit_nets(*cur);
+      if (info.parms) {
+	    for (list<PExpr*>::iterator cur = info.parms->begin()
+		       ; cur != info.parms->end() ; ++cur) {
+		  pform_declare_implicit_nets(*cur);
+	    }
       }
 
       perm_string dev_name = lex_strings.make(info.name);