From 51fd21736b10e2fa04382c5aa71f2044d31e362f Mon Sep 17 00:00:00 2001
From: Robert Maynard <rmaynard@nvidia.com>
Date: Tue, 14 Sep 2021 11:08:42 -0400
Subject: FindFLTK: Safe to include multiple times

FindFLTK could store multiple entries in `FLTK_INCLUDE_DIR`,
and when re-executed would stored into `FLTK_DIR` which had
uses which presumed single entries.

Fixes #13198
---
 Modules/FindFLTK.cmake | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/Modules/FindFLTK.cmake b/Modules/FindFLTK.cmake
index bab7256..d54d2f6 100644
--- a/Modules/FindFLTK.cmake
+++ b/Modules/FindFLTK.cmake
@@ -152,13 +152,17 @@ if(NOT FLTK_DIR)
 endif()
 
 # Check if FLTK was built using CMake
-if(EXISTS ${FLTK_DIR}/FLTKConfig.cmake)
-  set(FLTK_BUILT_WITH_CMAKE 1)
-endif()
+foreach(fltk_include IN LISTS FLTK_DIR)
+  if(EXISTS "${fltk_include}/FLTKConfig.cmake")
+    set(FLTK_BUILT_WITH_CMAKE 1)
+    set(FLTK_CMAKE_PATH "${fltk_include}/FLTKConfig.cmake")
+    break()
+  endif()
+endforeach()
 
 if(FLTK_BUILT_WITH_CMAKE)
   set(FLTK_FOUND 1)
-  include(${FLTK_DIR}/FLTKConfig.cmake)
+  include("${FLTK_CMAKE_PATH}")
 
   # Fluid
   if(FLUID_COMMAND)
-- 
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