From 08a42cf35b94b147eb4ac3b499bb32a1cf970358 Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Fri, 11 Oct 2019 11:00:29 +0200
Subject: [PATCH] Fix the detection of CGAL_ROOT

On Debian, CMake files are in
`/usr/local/lib/x86_64-linux-gnu/cmake/CGAL/` are our previous heuristic fails.
---
 Installation/CMakeLists.txt                      |  3 +++
 .../CGAL/CGALConfig-installation-dirs.cmake.in   |  1 +
 Installation/lib/cmake/CGAL/CGALConfig.cmake     | 16 +++++++++-------
 3 files changed, 13 insertions(+), 7 deletions(-)
 create mode 100644 Installation/lib/cmake/CGAL/CGALConfig-installation-dirs.cmake.in

diff --git a/Installation/CMakeLists.txt b/Installation/CMakeLists.txt
index 51c8abdaeca..0bf3e4b575d 100644
--- a/Installation/CMakeLists.txt
+++ b/Installation/CMakeLists.txt
@@ -928,7 +928,10 @@ if(NOT CGAL_HEADER_ONLY)
     ${CMAKE_BINARY_DIR}/config/CGALConfig.cmake
     DESTINATION ${CGAL_INSTALL_CMAKE_DIR} )
 else()
+  configure_file(${CMAKE_CURRENT_LIST_DIR}/lib/cmake/CGAL/CGALConfig-installation-dirs.cmake.in
+    ${CMAKE_BINARY_DIR}/config/CGALConfig-installation-dirs.cmake)
   install(FILES
+    ${CMAKE_BINARY_DIR}/config/CGALConfig-installation-dirs.cmake
     ${CMAKE_CURRENT_LIST_DIR}/lib/cmake/CGAL/CGALConfig.cmake
     DESTINATION ${CGAL_INSTALL_CMAKE_DIR} )
 endif()
diff --git a/Installation/lib/cmake/CGAL/CGALConfig-installation-dirs.cmake.in b/Installation/lib/cmake/CGAL/CGALConfig-installation-dirs.cmake.in
new file mode 100644
index 00000000000..81ca96bb586
--- /dev/null
+++ b/Installation/lib/cmake/CGAL/CGALConfig-installation-dirs.cmake.in
@@ -0,0 +1 @@
+set(CGAL_ROOT @CMAKE_INSTALL_PREFIX@)
diff --git a/Installation/lib/cmake/CGAL/CGALConfig.cmake b/Installation/lib/cmake/CGAL/CGALConfig.cmake
index 2d3f7790135..497e706ed83 100644
--- a/Installation/lib/cmake/CGAL/CGALConfig.cmake
+++ b/Installation/lib/cmake/CGAL/CGALConfig.cmake
@@ -43,15 +43,17 @@ if(BRANCH_BUILD)
     endif()
   endforeach()
 else()
-  set(CGAL_ROOT ${CGAL_CONFIG_DIR})
-  get_filename_component(CGAL_ROOT "${CGAL_ROOT}" DIRECTORY)
-  if(NOT EXISTS ${CGAL_ROOT}/include/CGAL/config.h)
+  include(${CGAL_CONFIG_DIR}/CGALConfig-installation-dirs.cmake OPTIONAL RESULT_VARIABLE _has_installation_dirs)
+  if(NOT _has_installation_dirs)
+    set(CGAL_ROOT ${CGAL_CONFIG_DIR})
     get_filename_component(CGAL_ROOT "${CGAL_ROOT}" DIRECTORY)
+    if(NOT EXISTS ${CGAL_ROOT}/include/CGAL/config.h)
+      get_filename_component(CGAL_ROOT "${CGAL_ROOT}" DIRECTORY)
+    endif()
+    if(NOT EXISTS ${CGAL_ROOT}/include/CGAL/config.h)
+      get_filename_component(CGAL_ROOT "${CGAL_ROOT}" DIRECTORY)
+    endif()
   endif()
-  if(NOT EXISTS ${CGAL_ROOT}/include/CGAL/config.h)
-    get_filename_component(CGAL_ROOT "${CGAL_ROOT}" DIRECTORY)
-  endif()
-
   # not BRANCH_BUILD: it can be an installed CGAL, or the tarball layout
   if(EXISTS ${CGAL_CONFIG_DIR}/CGAL_add_test.cmake)
     # installed CGAL