From 8e85c3a96e1af4a4de2dda680c6ec3f28250f8d4 Mon Sep 17 00:00:00 2001
From: Tim Edwards <tim@opencircuitdesign.com>
Date: Fri, 1 Nov 2019 12:01:07 -0400
Subject: [PATCH] Corrected a long-standing error in the "widespacing" rule
 implementation that was intended to avoid computing maxwidth more than
 necessary, but ended up causing the widespacing rule to not be checked in
 certain situations.

---
 drc/DRCbasic.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drc/DRCbasic.c b/drc/DRCbasic.c
index a3d2cbbf..78afd398 100644
--- a/drc/DRCbasic.c
+++ b/drc/DRCbasic.c
@@ -484,6 +484,7 @@ drcTile (tile, arg)
 	int edgeX = LEFT(tile);
 
 	firsttile = TRUE;
+	mrd = NULL;
         for (tpleft = BL(tile); BOTTOM(tpleft) < top; tpleft = RT(tpleft))
         {
 	    /* Get the tile types to the left and right of the edge */
@@ -554,8 +555,6 @@ drcTile (tile, arg)
 			mrd = drcCanonicalMaxwidth(tpleft, GEO_WEST, arg, cptr);
 		    else if (firsttile)
 			mrd = drcCanonicalMaxwidth(tile, GEO_EAST, arg, cptr);
-		    else
-			mrd = NULL;
 		    if (!trigpending || (DRCCurStyle->DRCFlags
 				& DRC_FLAGS_WIDEWIDTH_NONINCLUSIVE))
 			cptr->drcc_dist--;
@@ -610,7 +609,6 @@ drcTile (tile, arg)
 			drcCheckMaxwidth(tile, arg, cptr);
 		    continue;
 		}
-		else if (!triggered) mrd = NULL;
 
 		if (cptr->drcc_flags & DRC_RECTSIZE)
 		{
@@ -870,6 +868,7 @@ checkbottom:
 
 	/* Go right across bottom of tile */
 	firsttile = TRUE;
+	mrd = NULL;
         for (tpbot = LB(tile); LEFT(tpbot) < right; tpbot = TR(tpbot))
         {
 	    /* Get the tile types to the top and bottom of the edge */
@@ -936,8 +935,6 @@ checkbottom:
 			mrd = drcCanonicalMaxwidth(tpbot, GEO_SOUTH, arg, cptr);
 		    else if (firsttile)
 			mrd = drcCanonicalMaxwidth(tile, GEO_NORTH, arg, cptr);
-		    else
-			mrd = NULL;
 		    if (!trigpending || (DRCCurStyle->DRCFlags
 				& DRC_FLAGS_WIDEWIDTH_NONINCLUSIVE))
 			cptr->drcc_dist--;
@@ -992,7 +989,6 @@ checkbottom:
 		    if (trigpending) cptr = cptr->drcc_next;
 		    continue;
 		}
-		else if (!triggered) mrd = NULL;
 
 		result = 0;
 		arg->dCD_radial = 0;