From e7852f8f9c2b3dec52f098f726b971e2008dfa79 Mon Sep 17 00:00:00 2001
From: Martin Whitaker <icarus@martin-whitaker.me.uk>
Date: Sat, 17 Sep 2016 19:20:48 +0100
Subject: [PATCH] Fix for GitHub issue #127 - coerce output ports to inout when
 necessary.

(cherry picked from commit 080dd0323dae72f5448e6f4053ce315ddb844d13)
---
 elaborate.cc | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/elaborate.cc b/elaborate.cc
index 0faa7ed2a..f4f99f85f 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -1425,6 +1425,16 @@ void PGModule::elaborate_mod_(Design*des, Module*rmod, NetScope*scope) const
 		       << prts[0]->name() << " is coerced to inout." << endl;
 	    }
 
+	    if (!prts.empty() && (prts[0]->port_type() == NetNet::POUTPUT)
+                && (prts[0]->type() != NetNet::REG)
+                && prts[0]->pin(0).nexus()->has_floating_input()
+                && pins[idx]->is_collapsible_net(des, scope)) {
+                  prts[0]->port_type(NetNet::PINOUT);
+
+		  cerr << pins[idx]->get_fileline() << ": warning: output port "
+		       << prts[0]->name() << " is coerced to inout." << endl;
+	    }
+
 	      // Elaborate the expression that connects to the
 	      // module[s] port. sig is the thing outside the module
 	      // that connects to the port.