add git hash as a property

CMakeLists.txt

@@ -60,3 +60,24 @@ install(EXPORT CsgEbConfig
 if (CSG_CGAL_ENABLED)
    target_compile_definitions(csg-eb PUBLIC USE_CGAL)
 endif()
+
+set(CSGEB_GIT_HASH "")
+execute_process(
+   COMMAND git describe --abbrev=12 --dirty --always --tags
+   WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+   OUTPUT_VARIABLE CSGEB_GIT_HASH
+   ERROR_VARIABLE  _tmperr
+   OUTPUT_STRIP_TRAILING_WHITESPACE
+   )
+if(_tmperr)
+   message(WARNING "Failing to retrieve Git commit from repo: ${PROJECT_SOURCE_DIR}")
+endif()
+set_target_properties(csg-eb PROPERTIES CSGEB_GIT_HASH ${CSGEB_GIT_HASH}
+   EXPORT_PROPERTIES CSGEB_GIT_HASH)
+
+# to be used by gnumake
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/CsgEbConfig.mk 
+   "CSGEB_GIT_HASH := ${CSGEB_GIT_HASH}")
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/CsgEbConfig.mk
+    DESTINATION "${CMAKE_INSTALL_PREFIX}"
+)