Folding a series of commits into one required either an interactive
rebase where each commit after the first was hand-edited to "fixup", or
a "git reset --soft" to the merge base followed by "git commit --amend".
Add "git history squash <revision-range>" to do this directly. It folds
every commit in the range into the oldest one, keeping that commit's
authorship and taking the tree of the newest commit, then replays the
commits above the range on top. The squashed message comes from the
oldest commit by default, or from the body of the last amend! commit
targeting it. An editor opens with the selected message when
--reedit-message is given. A fixup!, squash! or amend! commit is refused
unless the commit it targets is also in the range, so the fold does not
silently absorb a marker meant for a commit outside it. The check runs
the range through todo_list_rearrange_squash(), which leaves such a
marker as a plain pick. Markers whose target is in the range fold in as
usual. As an exception, a range made up entirely of markers for one
target is combined anyway, taking its message from the last amend! if
there is one, so a batch of fixups for the same commit can be collapsed.
The range is read like the arguments to "git rev-list", so several
revisions such as "HEAD~3..HEAD ^topic" may be given, and rev-list
options are accepted too. As "git replay" does, the walk options the fold
relies on are forced after setup_revisions() and a warning is printed if
an option changed them, so the first commit returned is the range's
oldest and its parent is the base regardless of what the user passed
(including after a "--"). A merge inside the range is folded when its
other parent is reachable from the base, otherwise the range has more
than one base and is rejected. By default the command also refuses when a
ref points at a commit that the fold would discard. Use --update-refs=head
to rewrite only the current branch instead.
Inspired-by: Sergey Chernov <serega.morph@gmail.com>
Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
e439185efd