From 3fad1fa81bda4cf847d6729f6646fa4efbd595af Mon Sep 17 00:00:00 2001
From: Ellon Paiva Mendes <ellon.paiva@easymile.com>
Date: Thu, 3 Oct 2019 17:45:58 +0200
Subject: [PATCH] Install GTSAMConfigVersion.cmake

---
 cmake/GtsamMakeConfigFile.cmake | 28 ++++++++++++++++++++++++++--
 gtsam_extra.cmake.in            |  5 ++---
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/cmake/GtsamMakeConfigFile.cmake b/cmake/GtsamMakeConfigFile.cmake
index 74081b58a..2fff888ef 100644
--- a/cmake/GtsamMakeConfigFile.cmake
+++ b/cmake/GtsamMakeConfigFile.cmake
@@ -20,13 +20,37 @@ function(GtsamMakeConfigFile PACKAGE_NAME)
 		set(EXTRA_FILE "_does_not_exist_")
 	endif()
 
+	# GTSAM defines its version variable as GTSAM_VERSION_STRING while other
+	# projects may define it as <ProjectName>_VERSION. Since this file is
+	# installed on the system as part of GTSAMCMakeTools and may be useful in
+	# external projects, we need to handle both cases of version variable naming
+	# here.
+	if(NOT DEFINED ${PACKAGE_NAME}_VERSION AND DEFINED ${PACKAGE_NAME}_VERSION_STRING)
+		set(${PACKAGE_NAME}_VERSION ${${PACKAGE_NAME}_VERSION_STRING})
+	endif()
+
+	# Version file
+	include(CMakePackageConfigHelpers)
+	write_basic_package_version_file(
+	  "${PROJECT_BINARY_DIR}/${PACKAGE_NAME}ConfigVersion.cmake"
+	  VERSION ${${PACKAGE_NAME}_VERSION}
+	  COMPATIBILITY SameMajorVersion
+	)
+
+	# Config file
 	file(RELATIVE_PATH CONF_REL_INCLUDE_DIR "${CMAKE_INSTALL_PREFIX}/${DEF_INSTALL_CMAKE_DIR}" "${CMAKE_INSTALL_PREFIX}/include")
 	file(RELATIVE_PATH CONF_REL_LIB_DIR "${CMAKE_INSTALL_PREFIX}/${DEF_INSTALL_CMAKE_DIR}" "${CMAKE_INSTALL_PREFIX}/lib")
 	configure_file(${GTSAM_CONFIG_TEMPLATE_PATH}/Config.cmake.in "${PROJECT_BINARY_DIR}/${PACKAGE_NAME}Config.cmake" @ONLY)
 	message(STATUS "Wrote ${PROJECT_BINARY_DIR}/${PACKAGE_NAME}Config.cmake")
 
-	# Install config and exports files (for find scripts)
-	install(FILES "${PROJECT_BINARY_DIR}/${PACKAGE_NAME}Config.cmake" DESTINATION "${CMAKE_INSTALL_PREFIX}/${DEF_INSTALL_CMAKE_DIR}")
+	# Install config, version and exports files (for find scripts)
+	install(
+		FILES
+			"${PROJECT_BINARY_DIR}/${PACKAGE_NAME}Config.cmake"
+			"${PROJECT_BINARY_DIR}/${PACKAGE_NAME}ConfigVersion.cmake"
+		DESTINATION
+			"${CMAKE_INSTALL_PREFIX}/${DEF_INSTALL_CMAKE_DIR}"
+	)
 	install(EXPORT ${PACKAGE_NAME}-exports DESTINATION ${DEF_INSTALL_CMAKE_DIR})
 
 endfunction()
diff --git a/gtsam_extra.cmake.in b/gtsam_extra.cmake.in
index b7990b3cc..8a9a13648 100644
--- a/gtsam_extra.cmake.in
+++ b/gtsam_extra.cmake.in
@@ -1,8 +1,7 @@
 # Extra CMake definitions for GTSAM
 
-set (GTSAM_VERSION_MAJOR @GTSAM_VERSION_MAJOR@)
-set (GTSAM_VERSION_MINOR @GTSAM_VERSION_MINOR@)
-set (GTSAM_VERSION_PATCH @GTSAM_VERSION_PATCH@)
+# All version variables are handled by GTSAMConfigVersion.cmake, except these
+# two below. We continue to set them here in case someone uses them
 set (GTSAM_VERSION_NUMERIC @GTSAM_VERSION_NUMERIC@)
 set (GTSAM_VERSION_STRING "@GTSAM_VERSION_STRING@")