+##
+## This target generates an include file that contains the git version
+## string of the current branch, it must be continuously updated when
+## we build in the git repo and shipped in dist tarballs to reflect the
+## status of the tree when it was generated. If the tree is clean and
+## the current commit is tag a starting with "v", consider this a
+## release version and set an empty git version.
+##
+## Here is what the inline script does:
+##
+## First, delete any stale "version.i.tmp" file.
+##
+## If "bootstrap" and ".git" exists in the top source directory and the git
+## executable is available, get the current git version string in the form:
+##
+## "latest_tag"(-"number_of_commits_on_top")(-g"latest_commit_hash")(-dirty)
+##
+## And store it in "version.i.tmp", if the current commit is tagged, the tag
+## starts with "v" and the tree is clean, consider this a release version and
+## overwrite the git version with an empty string in "version.i.tmp".
+##
+## If we don't have a "version.i.tmp" nor a "version.i", generate an empty
+## string as a failover. If a "version.i" is present, for example when building
+## from a distribution tarball, get the git_version using grep.
+##
+## Fetch the EXTRA_VERSION_NAME define from "version/extra_version_name" and output it
+## to "version.i.tmp".
+##
+## Fetch the EXTRA_VERSION_DESCRIPTION define from "version/extra_version_description",
+## sanitize and format it with a sed script to replace all non-alpha-numeric values
+## with "-" and join all lines by replacing "\n" with litteral string c-style "\n\t" and
+## output it to "version.i.tmp".
+##
+## Repeat the same logic for the "version/extra_patches" directory.
+## Data fetched from "version/extra_patches" must be sanitized and
+## formatted.
+## The data is fetched using "ls" with an ignore pattern for the README file.
+## The sanitize step uses sed with a script to replace all
+## non-alpha-numeric values, except " " (space), to "-".
+## The formatting step uses sed with a script to join all lines
+## by replacing "\n" with litteral string c-style "\n\t".
+##
+## If we don't have a "version.i" or we have both files (version.i, version.i.tmp)
+## and they are different, copy "version.i.tmp" over "version.i".
+## This way the dependent targets are only rebuilt when the git version
+## string or either one of extra version string change.
+##
+version_verbose = $(version_verbose_@AM_V@)
+version_verbose_ = $(version_verbose_@AM_DEFAULT_V@)
+version_verbose_0 = @echo " GEN " $@;