At the request of Michael Spencer, make the VCS version detection logic

in CMake a bit more handy. Previously we would get such charming
versions as the following for revision NNNN and commit-ish XXXXX:
  3.1svnsvn-rNNNN
  3.1svngit-svn-rNNNN
  3.1svngit-svn-XXXXX

The mechanism selecting betwene the latter two was particularly odd, and
didn't work with all of the ways git-svn repos are set up apparently. It
also misses an important point -- both the revision *and* the git commit
might be relevant when working on a local branch some distance from
mainline. The new logic does several things:

1) It strips the redundant initial 'svn'.
2) It always looks for a git-svn revision number base, and when found
   includes it in the version.
3) If the git commit-ish for the current HEAD is not exactly that
   revision number, it is also included.

The resulting strings should roughly be:
  3.1svn-rNNNN
  3.1git-svn-rNNNN
  3.1git-svn-rNNNN-XXXXX

Suggestions on formatting etc always welcome. =] I've only looked at the
LLVM version string here, not Clang's (yet).

Note that the commit-ish reported is *not* terribly accurate. It updates
when 'cmake' is run, not when the binary is built. Still, it may be
better than nothing, especially if people have fairly long-lived git
repos and branches. This is not a new limitation, just didn't want
anyone to be surprised.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146323 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 8 deletions

diff --git a/cmake/modules/VersionFromVCS.cmake b/cmake/modules/VersionFromVCS.cmake
index 81739be927..62bffb02e3 100644
--- a/cmake/modules/VersionFromVCS.cmake
+++ b/cmake/modules/VersionFromVCS.cmake
@@ -3,7 +3,7 @@
 # existence of certain subdirectories under CMAKE_CURRENT_SOURCE_DIR.
 
 function(add_version_info_from_vcs VERS)
-  set(result ${${VERS}})
+  string(REPLACE "svn" "" result "${${VERS}}")
   if( EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.svn" )
     set(result "${result}svn")
     # FindSubversion does not work with symlinks. See PR 8437
@@ -21,24 +21,43 @@ function(add_version_info_from_vcs VERS)
     # Try to get a ref-id
     find_program(git_executable NAMES git git.exe git.cmd)
     if( git_executable )
-      execute_process(COMMAND ${git_executable} show-ref HEAD
+      set(is_git_svn_rev_exact false)
+      execute_process(COMMAND ${git_executable} svn log --limit=1 --oneline
                       WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
                       TIMEOUT 5
                       RESULT_VARIABLE git_result
                       OUTPUT_VARIABLE git_output)
       if( git_result EQUAL 0 )
-        string(SUBSTRING ${git_output} 0 7 git_ref_id)
-        set(result "${result}-${git_ref_id}")
-      else()
-        execute_process(COMMAND ${git_executable} svn log --limit=1 --oneline
+        string(REGEX MATCH r[0-9]+ git_svn_rev ${git_output})
+        string(SUBSTRING "${git_svn_rev}" 1 -1 git_svn_rev_number)
+        set(git_svn_rev "-svn-${git_svn_rev}")
+
+        # Determine if the HEAD points directly at a subversion revision.
+        execute_process(COMMAND ${git_executable} svn find-rev HEAD
                         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
                         TIMEOUT 5
                         RESULT_VARIABLE git_result
                         OUTPUT_VARIABLE git_output)
         if( git_result EQUAL 0 )
-          string(REGEX MATCH r[0-9]+ git_svn_rev ${git_output})
-          set(result "${result}-svn-${git_svn_rev}")
+          string(STRIP "${git_output}" git_head_svn_rev_number)
+          if( git_head_svn_rev_number EQUAL git_svn_rev_number )
+            set(is_git_svn_rev_exact true)
+          endif()
         endif()
+      else()
+        set(git_svn_rev "")
+      endif()
+      execute_process(COMMAND
+                      ${git_executable} show-ref --abbrev --hash --head HEAD
+                      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+                      TIMEOUT 5
+                      RESULT_VARIABLE git_result
+                      OUTPUT_VARIABLE git_output)
+      if( git_result EQUAL 0 AND NOT is_git_svn_rev_exact )
+        string(STRIP "${git_output}" git_ref_id)
+        set(result "${result}${git_svn_rev}-${git_ref_id}")
+      else()
+        set(result "${result}${git_svn_rev}")
       endif()
     endif()
   endif()