[Findutils-patches] [PATCH] Switch to using a merge driver for the ChangeLog file.

[James Youngman]

* import-gnulib.sh (check_merge_driver): New function; verifies
that we have a merge driver installed for the ChangeLog file (if
we're on the master or release branch, the check is skipped).
Also check that the .gitattributes file exists.
* README-hacking: Point out that using a merge driver for ChangeLog is
a good idea.
* .gitattributes: new file

Signed-off-by: James Youngman <address@hidden>
---
 .gitattributes   |    1 +
 ChangeLog        |    9 +++++++
 README-hacking   |    9 +++++++
 import-gnulib.sh |   71 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 89 insertions(+), 1 deletions(-)
 create mode 100644 .gitattributes

diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..384e031
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+ChangeLog    merge=cl-merge
diff --git a/ChangeLog b/ChangeLog
index 8a9e28b..ee9f8f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2009-03-08  James Youngman  <address@hidden>
 
+       Switch to using a merge driver for the ChangeLog file.
+       * import-gnulib.sh (check_merge_driver): New function; verifies
+       that we have a merge driver installed for the ChangeLog file (if
+       we're on the master or release branch, the check is skipped).
+       Also check that the .gitattributes file exists.
+       * README-hacking: Point out that using a merge driver for
+       ChangeLog is a good idea.
+       * .gitattributes: New file
+
        Optimise away calls to stat if all we need is the inode number.
        This fixes Savannah bug #24342.
        * find/util.c (get_info): call get_statinfo if need_inum and we
diff --git a/README-hacking b/README-hacking
index 224fb2e..bd967f2 100644
--- a/README-hacking
+++ b/README-hacking
@@ -96,6 +96,15 @@ example values:
   email = address@hidden
 
 
+In order to simplify the handling of merges, we recommend that you
+use a specialised merge driver for the ChangeLog file.  Otherwise,
+you will end up spending time resolving merge conflicts for your
+ChangeLog edits.  You can install the ChangeLog merge driver by
+following the instructions in the README section of the file
+gnulib-git/gnulib/lib/git-merge-changelog.c.
+
+
+
 Making commits locally
 ======================
 
diff --git a/import-gnulib.sh b/import-gnulib.sh
index 3543e37..2d97f9f 100755
--- a/import-gnulib.sh
+++ b/import-gnulib.sh
@@ -234,6 +234,73 @@ EOF
 }
 
 
+check_merge_driver() {
+    local config_file=".git/config"
+    fixmsg="
+
+We recommend that you use a git merge driver for the ChangeLog file.
+This simplifies the task of merging branches.
+Please see the README section in gnulib-git/gnulib/lib/git-merge-changelog.c
+
+If you've read that and don't want to use it, just set the environment variable
+DO_NOT_WANT_CHANGELOG_DRIVER.
+
+Example:
+  git config merge.cl-merge.name 'GNU-style ChangeLog merge driver'
+  git config merge.cl-merge.driver /usr/local/bin/git-merge-changelog
+  echo 'ChangeLog    merge=cl-merge' >> .gitattributes
+"
+    if [[ -z "$DO_NOT_WANT_CHANGELOG_DRIVER" ]] ; then
+       if git branch | egrep -q '\* *(master|rel-)'; then
+       # We are on the master branch or a release branch.
+       # Perhaps the user is simply building from git sources.
+       # Issue our message as a warning rather than an error.
+           fatal=false
+           label="Warning"
+       else
+           fatal=true
+           label="ERROR"
+       fi
+    else
+       fatal=false
+       label="Warning"
+    fi
+    if git config --get  merge.cl-merge.name >/dev/null ; then
+       driver="$(git config --get merge.cl-merge.driver)"
+       if [[ $? -eq 0 ]]; then
+           if ! [[ -x "$driver" ]]; then
+               echo "ERROR: Merge driver $driver is not executable." >&2
+               echo "ERROR: Please fix $config_file or install $driver" >&2
+               # Always fatal - if configured, the merge driver should work.
+               exit 1
+           else
+               if [[ -f .gitattributes ]] ; then
+                   echo "The ChangeLog merge driver configuration seems OK."
+               else
+                   echo "$label"': you have no .gitattributes file' >&2
+                   echo "$fixmsg" >&2
+                   if $fatal; then
+                       exit 1
+                   fi
+               fi
+           fi
+       else
+           echo "$label"': There is no driver specified in [merge "cl-merge"] 
in' "$config_file" >&2
+           echo "$fixmsg" >&2
+           if $fatal; then
+               exit 1
+           fi
+       fi
+    else
+       echo "$label"': There is no name specified in [merge "cl-merge"] in' 
"$config_file" >&2
+       echo "$fixmsg" >&2
+       if $fatal; then
+           exit 1
+       fi
+    fi
+}
+
+
 move_cvsdir() {
     local cvs_git_root=":pserver:address@hidden:/gnulib.git"
 
@@ -281,6 +348,7 @@ EOF
        fi
        move_cvsdir
        do_checkout gnulib-git
+       check_merge_driver
        gnulibdir=gnulib-git/gnulib
     else
        echo "Warning: using gnulib code which already exists in $gnulibdir" >&2
@@ -293,7 +361,8 @@ EOF
        hack_gnulib_tool_output "${gnulibdir}" &&
        refresh_output_files &&
        update_licenses &&
-       update_version_file   ; then
+       update_version_file
+    then
        echo Done.
     else
        echo FAILED >&2
-- 
1.5.6.5