From 7ac83ac64de432469fe93d2ca707acd8deb18af2 Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <seth@kipro-pcb.com>
Date: Mon, 27 Jan 2020 06:29:54 -0800
Subject: [PATCH] Check recursion before appending

We need to ensure that the appended sheet does not already exist in the
parent hierarchy.  We do this for new sheets but need to check for
existing ones as well.

Fixes #3806 | https://gitlab.com/kicad/code/kicad/issues/3806
---
 eeschema/sheet.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/eeschema/sheet.cpp b/eeschema/sheet.cpp
index 6d571bbcb8..9d1004bf1e 100644
--- a/eeschema/sheet.cpp
+++ b/eeschema/sheet.cpp
@@ -723,7 +723,8 @@ bool SCH_EDIT_FRAME::EditSheet( SCH_SHEET* aSheet, SCH_SHEET_PATH* aHierarchy,
             aHierarchy->LastScreen()->Remove( aSheet );
         }
 
-        if( !LoadSheetFromFile( aSheet, aHierarchy, newFilename ) )
+        if( !LoadSheetFromFile( aSheet, aHierarchy, newFilename )
+                || checkSheetForRecursion( aSheet, aHierarchy ) )
         {
             if( restoreSheet )
                 aHierarchy->LastScreen()->Append( aSheet );