Merge pull request #6751 from tjhei/git-worktree-support

CMake: support worktrees for git information

Author: gassmoeller

cmake/macro_aspect_query_git_information.cmake

@@ -53,20 +53,38 @@ macro(ASPECT_QUERY_GIT_INFORMATION)
 
   find_package(Git)
 
+
+  set(_head_location "")
+
   #
   # Only run the following if we have git and the source directory seems to
   # be under version control.
   #
-  if(GIT_FOUND AND EXISTS ${CMAKE_SOURCE_DIR}/.git/HEAD)
-    #
+  if(GIT_FOUND AND EXISTS ${CMAKE_SOURCE_DIR}/.git)
+
+    if (EXISTS ${CMAKE_SOURCE_DIR}/.git/HEAD)
+      # A normal git repository
+      set(_head_location ${CMAKE_SOURCE_DIR}/.git/HEAD)
+     else()
+     # Likely a git worktree: Read .git file, which has the format "gitdir: <absolute path>"
+     file(STRINGS ${CMAKE_SOURCE_DIR}/.git _gitdir LIMIT_COUNT 1)
+     string(REGEX REPLACE "gitdir: " "" _gitdir ${_gitdir})
+     if(EXISTS ${_gitdir}/HEAD)
+       set(_head_location ${_gitdir}/HEAD)
+     endif()
+    endif()
+  endif()
+
+  if (EXISTS ${_head_location})
+    # We have a git repository, now grab the details
+
     # Bogus configure_file calls to trigger a reconfigure, and thus an
     # update of branch and commit information every time HEAD has changed.
-    #
     configure_file(
-      ${CMAKE_SOURCE_DIR}/.git/HEAD
+      ${_head_location}
       ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/HEAD
       )
-    file(STRINGS ${CMAKE_SOURCE_DIR}/.git/HEAD _head_ref LIMIT_COUNT 1)
+    file(STRINGS ${_head_location} _head_ref LIMIT_COUNT 1)
     string(REPLACE "ref: " "" _head_ref ${_head_ref})
     if(EXISTS ${CMAKE_SOURCE_DIR}/.git/${_head_ref})
       configure_file(
@@ -78,7 +96,6 @@ macro(ASPECT_QUERY_GIT_INFORMATION)
     #
     # Query for revision:
     #
-
     execute_process(
        COMMAND ${GIT_EXECUTABLE} log -n 1 --pretty=format:"%H %h"
        WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}