Merge pull request #92 from kwryankrattiger/version_detection

Version detection updates

CMake/version.cmake

@@ -1,16 +1,27 @@
-set(tmp)
-find_package(Git QUIET)
-if(GIT_FOUND)
-  execute_process(COMMAND ${GIT_EXECUTABLE}
-      --git-dir=${CMAKE_SOURCE_DIR}/.git describe --tags
-      OUTPUT_VARIABLE tmp OUTPUT_STRIP_TRAILING_WHITESPACE)
-endif()
-if(NOT tmp)
-  # Set this to the latest released version.
-  # This version is used when using release tarballs
+set(SENSEI_VERSION "<DEFAULT>" CACHE STRING "SENSEI version")
+
+# Default detection of version
+if (SENSEI_VERSION STREQUAL "<DEFAULT>")
+  # The default version is the current major release
+  # This is required for computing version in released
+  # source tarballs.
   set(tmp "v4.0.0")
+
+  # If inside a git repo, attempt to inspect the tag instead
+  # of using the hardcoded value
+  if (EXISTS ${CMAKE_SOURCE_DIR}/.git)
+    find_package(Git QUIET)
+    if(GIT_FOUND)
+      execute_process(COMMAND ${GIT_EXECUTABLE}
+          --git-dir=${CMAKE_SOURCE_DIR}/.git describe --tags
+          OUTPUT_VARIABLE tmp OUTPUT_STRIP_TRAILING_WHITESPACE)
+    endif()
+  endif ()
+
+  # Override the CACHE variable for configure with the computed
+  # version
+  set(SENSEI_VERSION ${tmp})
 endif()
-set(SENSEI_VERSION ${tmp} CACHE STRING "SENSEI version" FORCE)
 
 string(REGEX REPLACE "^v([0-9]+)\\.([0-9]+)\\.([0-9]+)(.*$)"
   "\\1" SENSEI_VERSION_MAJOR ${SENSEI_VERSION})