fix version recorded in releases (google#1047)

* cmake: fix handling the case where `git describe` fails

* cmake: fix version recorded in releases

If downloaded as a tarball release, there will be no info from git
to determine the release, so it ends up v0.0.0. If that's the case,
we'll now use the release specified in the project() command,
which needs to be updated for each new release.

* cmake: add `--tags` to `git describe`

That way, lightweight tags will also be taken into account, which should
never hurt, but it'll help in cases where, for some mysterious reason or
other, annotated tags don't make it into a clone.

* update releasing.md

Author: germasch

CMakeLists.txt

@@ -13,7 +13,7 @@ foreach(p
   endif()
 endforeach()
 
-project (benchmark CXX)
+project (benchmark VERSION 1.5.3 LANGUAGES CXX)
 
 option(BENCHMARK_ENABLE_TESTING "Enable testing of the benchmark library." ON)
 option(BENCHMARK_ENABLE_EXCEPTIONS "Enable the use of exceptions in the benchmark library." ON)
@@ -94,8 +94,14 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 include(GetGitVersion)
 get_git_version(GIT_VERSION)
 
+# If no git version can be determined, use the version
+# from the project() command
+if ("${GIT_VERSION}" STREQUAL "0.0.0")
+  set(VERSION "${benchmark_VERSION}")
+else()
+  set(VERSION "${GIT_VERSION}")
+endif()
 # Tell the user what versions we are using
-string(REGEX MATCH "[0-9]+\\.[0-9]+\\.[0-9]+" VERSION ${GIT_VERSION})
 message(STATUS "Version: ${VERSION}")
 
 # The version of the libraries

cmake/GetGitVersion.cmake

@@ -20,16 +20,20 @@ set(__get_git_version INCLUDED)
 
 function(get_git_version var)
   if(GIT_EXECUTABLE)
-      execute_process(COMMAND ${GIT_EXECUTABLE} describe --match "v[0-9]*.[0-9]*.[0-9]*" --abbrev=8
+      execute_process(COMMAND ${GIT_EXECUTABLE} describe --tags --match "v[0-9]*.[0-9]*.[0-9]*" --abbrev=8
           WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
           RESULT_VARIABLE status
-          OUTPUT_VARIABLE GIT_VERSION
+          OUTPUT_VARIABLE GIT_DESCRIBE_VERSION
           ERROR_QUIET)
-      if(${status})
-          set(GIT_VERSION "v0.0.0")
+      if(status)
+          set(GIT_DESCRIBE_VERSION "v0.0.0")
+      endif()
+      
+      string(STRIP ${GIT_DESCRIBE_VERSION} GIT_DESCRIBE_VERSION)
+      if(GIT_DESCRIBE_VERSION MATCHES v[^-]*-) 
+         string(REGEX REPLACE "v([^-]*)-([0-9]+)-.*" "\\1.\\2"  GIT_VERSION ${GIT_DESCRIBE_VERSION})
       else()
-          string(STRIP ${GIT_VERSION} GIT_VERSION)
-          string(REGEX REPLACE "-[0-9]+-g" "-" GIT_VERSION ${GIT_VERSION})
+         string(REGEX REPLACE "v(.*)" "\\1" GIT_VERSION ${GIT_DESCRIBE_VERSION})
       endif()
 
       # Work out if the repository is dirty
@@ -43,12 +47,12 @@ function(get_git_version var)
           ERROR_QUIET)
       string(COMPARE NOTEQUAL "${GIT_DIFF_INDEX}" "" GIT_DIRTY)
       if (${GIT_DIRTY})
-          set(GIT_VERSION "${GIT_VERSION}-dirty")
+          set(GIT_DESCRIBE_VERSION "${GIT_DESCRIBE_VERSION}-dirty")
       endif()
+      message(STATUS "git version: ${GIT_DESCRIBE_VERSION} normalized to ${GIT_VERSION}")
   else()
-      set(GIT_VERSION "v0.0.0")
+      set(GIT_VERSION "0.0.0")
   endif()
 
-  message(STATUS "git Version: ${GIT_VERSION}")
   set(${var} ${GIT_VERSION} PARENT_SCOPE)
 endfunction()

docs/releasing.md

@@ -8,6 +8,12 @@
     * `git log $(git describe --abbrev=0 --tags)..HEAD` gives you the list of
       commits between the last annotated tag and HEAD
     * Pick the most interesting.
+* Create one last commit that updates the version saved in `CMakeLists.txt` to the release version you're creating. (This version will be used if benchmark is installed from the archive you'll be creating in the next step.)
+
+```
+project (benchmark VERSION 1.5.3 LANGUAGES CXX)
+```
+
 * Create a release through github's interface
     * Note this will create a lightweight tag.
     * Update this to an annotated tag: