Made some corrections to the "extresist" code to avoid issues with

extracting a port-to-port net that does not touch any devices.
The error happens in a fairly rare set of cases.

VERSION

@@ -1 +1 @@
-8.3.294
+8.3.295

extflat/EFbuild.c

@@ -449,12 +449,13 @@ efBuildKill(def, name)
  */
 
 void
-efBuildEquiv(def, nodeName1, nodeName2)
+efBuildEquiv(def, nodeName1, nodeName2, resist)
     Def *def;		/* Def for which we're adding a new node name */
     char *nodeName1;	/* One of node names to be made equivalent */
     char *nodeName2;	/* Other name to be made equivalent.  One of nodeName1
 			 * or nodeName2 must already be known.
 			 */
+    bool resist;	/* True if "extresist on" option was selected */
 {
     EFNodeName *nn1, *nn2;
     HashEntry *he1, *he2;
@@ -520,12 +521,15 @@ efBuildEquiv(def, nodeName1, nodeName2)
 	    freeMagic(argv[7]);
 	    return;
 	}
-	else
+	else if (!resist)
 	{
 	    /* Flag a strong warning */
 	    TxError("Warning:  Ports \"%s\" and \"%s\" are electrically shorted.\n",
 			nodeName1, nodeName2);
 	}
+	else
+	    /* Do not merge the nodes when folding in extresist parasitics */
+	    return;
     }
 
     /* If both names exist and are for different nodes, merge them */

extflat/EFread.c

@@ -313,7 +313,7 @@ readfile:
 
 	    /* equiv node1 node2 */
 	    case EQUIV:
-		efBuildEquiv(def, argv[1], argv[2]);
+		efBuildEquiv(def, argv[1], argv[2], resist);
 		break;
 
 	    /* replaces "fet" (below) */

lef/defWrite.c

@@ -1499,6 +1499,7 @@ defCountVias(rootDef, MagicToLefTable, defViaTable, oscale)
 
 int
 defCheckFunc(tile)
+    Tile *tile;
 {
     return 1;
 }

resis/ResReadSim.c

@@ -172,7 +172,9 @@ ResReadSim(simfile, fetproc, capproc, resproc, attrproc, mergeproc, subproc)
 		if (resproc) result = (*resproc)(line);
 		break;
 	    case '=':
-		if (mergeproc) result = (*mergeproc)(line);
+		/* Do not merge nodes, as this interferes with	*/
+		/* extresist's primary function.		*/
+		/* if (mergeproc) result = (*mergeproc)(line);	*/
 		break;
 	    case 'A':
 		if (attrproc)

resis/ResRex.c

@@ -710,6 +710,9 @@ resPortFunc(scx, lab, tpath, result)
     HashEntry *entry;
     ResSimNode *node;
 
+    // Ignore the top level cell
+    if (scx->scx_use->cu_id == NULL) return 0;
+
     GeoTransRect(&scx->scx_trans, &lab->lab_rect, &r);
 
     // To be expanded.  Currently this handles digital signal inputs
@@ -723,7 +726,8 @@ resPortFunc(scx, lab, tpath, result)
 	// direction is either INPUT or OUTPUT, then use SIGNAL is implied.
 
 	if ((puse == 0) && ((pclass == PORT_CLASS_INPUT)
-		|| (pclass == PORT_CLASS_OUTPUT)))
+		|| (pclass == PORT_CLASS_OUTPUT)
+		|| (pclass == PORT_CLASS_DEFAULT)))
 	    puse = PORT_USE_SIGNAL;
 
 	if (puse == PORT_USE_SIGNAL || puse == PORT_USE_CLOCK) {
@@ -742,7 +746,8 @@ resPortFunc(scx, lab, tpath, result)
 	    if (lab->lab_flags & PORT_DIR_WEST)
 		portloc.p_x = r.r_xbot;
 
-	    if ((pclass == PORT_CLASS_INPUT) || (pclass == PORT_CLASS_OUTPUT)) {
+	    if ((pclass == PORT_CLASS_INPUT) || (pclass == PORT_CLASS_OUTPUT)
+			|| (pclass == PORT_CLASS_DEFAULT)) {
 		int len;
 		char *nodename;