From a27beba41c86c9993d30200a74d8eb37a4ca5b58 Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Thu, 15 Sep 2016 17:45:14 +0200
Subject: [PATCH] Check if the targets already exist

`CGALConfig.cmake` is guarded, but it might be that the targets are
already defined by a sub-directory.
---
 Installation/lib/cmake/CGAL/CGALConfig.cmake | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Installation/lib/cmake/CGAL/CGALConfig.cmake b/Installation/lib/cmake/CGAL/CGALConfig.cmake
index e1b462471e0..fb49e4a6fd2 100644
--- a/Installation/lib/cmake/CGAL/CGALConfig.cmake
+++ b/Installation/lib/cmake/CGAL/CGALConfig.cmake
@@ -73,9 +73,11 @@ endforeach()
 # Define the CGAL targets and theirs CGAL:: aliases
 #
 foreach(cgal_lib CGAL CGAL_Core CGAL_ImageIO CGAL_Qt5)
-  if(${cgal_lib}_FOUND)
+  if(${cgal_lib}_FOUND AND NOT TARGET ${cgal_lib})
     add_library(${cgal_lib} INTERFACE)
-    add_library(CGAL::${cgal_lib} ALIAS ${cgal_lib})
+    if(NOT TARGET CGAL::${cgal_lib})
+      add_library(CGAL::${cgal_lib} ALIAS ${cgal_lib})
+    endif()
   endif()
 endforeach()