From 322bbed7c777296fede2473afed9a08716de0f1d Mon Sep 17 00:00:00 2001
From: Cary R <cygcary@yahoo.com>
Date: Fri, 21 Nov 2008 15:37:14 -0800
Subject: [PATCH] V0.8: Don't crash on invalid input.

This patch mirrors what was done in development to prevent a crash
when given invalid input.
---
 elaborate.cc     | 4 ++--
 net_nex_input.cc | 9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/elaborate.cc b/elaborate.cc
index 1092ac906..9d59763af 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -1977,8 +1977,8 @@ NetProc* PEventStatement::elaborate_st(Design*des, NetScope*scope,
 	    if (synthesis) rem_out = true;
 	    NexusSet*nset = enet->nex_input(rem_out);
 	    if (nset == 0) {
-		  cerr << get_line() << ": internal error: No NexusSet"
-		       << " from statement." << endl;
+		  cerr << get_line() << ": error: Unable to elaborate:"
+		       << endl;
 		  enet->dump(cerr, 6);
 		  des->errors += 1;
 		  return enet;
diff --git a/net_nex_input.cc b/net_nex_input.cc
index 1f0d48e9c..0847f505a 100644
--- a/net_nex_input.cc
+++ b/net_nex_input.cc
@@ -65,9 +65,14 @@ NexusSet* NetEBitSel::nex_input(bool rem_out)
 
 NexusSet* NetEConcat::nex_input(bool rem_out)
 {
+      if (parms_[0] == NULL) return NULL;
       NexusSet*result = parms_[0]->nex_input(rem_out);
       for (unsigned idx = 1 ;  idx < parms_.count() ;  idx += 1) {
 	    NexusSet*tmp = parms_[idx]->nex_input(rem_out);
+	    if (tmp == NULL) {
+		  delete result;
+		  return NULL;
+	    }
 	    result->add(*tmp);
 	    delete tmp;
       }
@@ -116,6 +121,10 @@ NexusSet* NetESelect::nex_input(bool rem_out)
 {
       NexusSet*result = base_? base_->nex_input(rem_out) : new NexusSet();
       NexusSet*tmp = expr_->nex_input(rem_out);
+      if (tmp == NULL) {
+	    delete result;
+	    return NULL;
+      }
       result->add(*tmp);
       delete tmp;
       return result;