git-gui: Format tracking branch merges as though they were pulls

If we are merging a tracking branch we know exactly what remote URL
that branch is fetched from, and what its name is on that remote
repository.  In this case we can setup a merge message that looks
just like a standard `git-pull $remote $branch` operation by filling
out FETCH_HEAD before we start git-merge, and then run git-merge just
like git-pull does.

I think the result of this behavior is that merges look a lot nicer
when the came off of local tracking branches, because they no longer
say "commit 'origin/...'" to describe the commit being merged but
instead now mention the specific repository we fetched those commits
from.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/lib/merge.tcl b/lib/merge.tcl
index 62434ff310f80c180a31ae3ba985c7db2c3182ba..c8b486710aa66afce100219a1167618a0103cd87 100644 (file)
--- a/lib/merge.tcl
+++ b/lib/merge.tcl
@@ -81,17 +81,41 @@ method _visualize {} {
 }
 
 method _start {} {
-       global HEAD current_branch
+       global HEAD current_branch remote_url
 
        set name [_rev $this]
        if {$name eq {}} {
                return
        }
 
-       set cmd [list git merge $name]
-       set msg "Merging $current_branch and $name"
+       set spec [$w_rev get_tracking_branch]
+       set cmit [$w_rev get_commit]
+       set cmd [list git]
+       lappend cmd merge
+       lappend cmd --strategy=recursive
+
+       set fh [open [gitdir FETCH_HEAD] w]
+       fconfigure $fh -translation lf
+       if {$spec eq {}} {
+               set remote .
+               set branch $name
+               set stitle $branch
+       } else {
+               set remote $remote_url([lindex $spec 1])
+               set branch [lindex $spec 2]
+               set stitle "$branch of $remote"
+       }
+       regsub ^refs/heads/ $branch {} branch
+       puts $fh "$cmit\t\tbranch '$branch' of $remote"
+       close $fh
+
+       lappend cmd [git fmt-merge-msg <[gitdir FETCH_HEAD]]
+       lappend cmd HEAD
+       lappend cmd $cmit
+
+       set msg "Merging $current_branch and $stitle"
        ui_status "$msg..."
-       set cons [console::new "Merge" $cmd]
+       set cons [console::new "Merge" "merge $stitle"]
        console::exec $cons $cmd [cb _finish $cons]
 
        wm protocol $w WM_DELETE_WINDOW {}