From fe6d82a8f319d88df3cea26b28b50dd10695a224 Mon Sep 17 00:00:00 2001
From: Emden Gansner <erg@research.att.com>
Date: Mon, 16 Apr 2012 14:31:37 -0400
Subject: [PATCH] Fix bug 2217

---
 doc/info/attrs.html   | 4 ++--
 doc/infosrc/attrs     | 4 ++--
 lib/dotgen/sameport.c | 1 +
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/doc/info/attrs.html b/doc/info/attrs.html
index f7cd5778d..3b88e6f07 100644
--- a/doc/info/attrs.html
+++ b/doc/info/attrs.html
@@ -1640,12 +1640,12 @@ This field indicates which graph component uses the attribute.
 
 <DT><A NAME=d:samehead HREF=#a:samehead><STRONG>samehead</STRONG></A>
 <DD>  Edges with the same head and the same <B>samehead</B> value are aimed
-  at the same point on the head.
+  at the same point on the head. This has no effect on loops.
   See <A HREF=#h:undir_note>limitation</A>.
 
 <DT><A NAME=d:sametail HREF=#a:sametail><STRONG>sametail</STRONG></A>
 <DD>  Edges with the same tail and the same <B>sametail</B> value are aimed
-  at the same point on the tail.
+  at the same point on the tail. This has no effect on loops.
   See <A HREF=#h:undir_note>limitation</A>.
 
 <DT><A NAME=d:samplepoints HREF=#a:samplepoints><STRONG>samplepoints</STRONG></A>
diff --git a/doc/infosrc/attrs b/doc/infosrc/attrs
index b87998d5f..6ac5182ff 100644
--- a/doc/infosrc/attrs
+++ b/doc/infosrc/attrs
@@ -1060,11 +1060,11 @@ If 90, set drawing orientation to landscape.
 Causes the final layout to be rotated counter-clockwise by the specified number of degrees.
 :samehead:E:string:"";  dot
 Edges with the same head and the same <B>samehead</B> value are aimed
-at the same point on the head.
+at the same point on the head. This has no effect on loops.
 See <A HREF=#h:undir_note>limitation</A>.
 :sametail:E:string:"";  dot
 Edges with the same tail and the same <B>sametail</B> value are aimed
-at the same point on the tail.
+at the same point on the tail. This has no effect on loops.
 See <A HREF=#h:undir_note>limitation</A>.
 :samplepoints:N:int:8(output)/20(overlap and image maps);
 If the input graph defines the <A HREF=#d:vertices><B>vertices</B></A>
diff --git a/lib/dotgen/sameport.c b/lib/dotgen/sameport.c
index 5adc75273..f3dc765a4 100644
--- a/lib/dotgen/sameport.c
+++ b/lib/dotgen/sameport.c
@@ -53,6 +53,7 @@ void dot_sameports(graph_t * g)
     for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
 	n_same = 0;
 	for (e = agfstedge(g, n); e; e = agnxtedge(g, e, n)) {
+	    if (aghead(e) == agtail(e)) continue;  /* Don't support same* for loops */
 	    if (aghead(e) == n && E_samehead &&
 #ifndef WITH_CGRAPH
 		(id = agxget(e, E_samehead->index))[0])
-- 
2.50.1