From a865522e67806d1dd84df83c837030cb38d7395a Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Tue, 28 May 2019 17:55:28 +0200
Subject: [PATCH] Use existing TARGET_INCLUDE_DIRECTORY_BUILD_INTERFACE

---
 cmake/modules/LibraryTarget.cmake | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/cmake/modules/LibraryTarget.cmake b/cmake/modules/LibraryTarget.cmake
index 6134179..897486a 100644
--- a/cmake/modules/LibraryTarget.cmake
+++ b/cmake/modules/LibraryTarget.cmake
@@ -85,7 +85,9 @@ if (NOT BUILTIN_TRANSLATIONS)
 endif ()
 
 # determine include path used when building the project itself
-if (IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/include")
+if (TARGET_INCLUDE_DIRECTORY_BUILD_INTERFACE)
+    # use existing TARGET_INCLUDE_DIRECTORY_BUILD_INTERFACE if already defined
+elseif (IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/include")
     # use special include directory if available
     set(TARGET_INCLUDE_DIRECTORY_BUILD_INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}/include")
 else ()