view contrib/editmerge @ 30580:51e7c83e05ee

rebase: calculate ancestors for --base separately (issue5420)

Previously, the --base option only works with a single "branch" - if there
is one changeset in the "--base" revset whose branching point(s) is/are
different from another changeset in the "--base" revset, "rebase" will error
out with:

  abort: source is ancestor of destination

This happens if the user has multiple draft branches, and uses "hg rebase -b
'draft()' -d master", for example. The error message looks cryptic to users
who don't know the implementation detail.

This patch changes the logic to calculate the common ancestor for every
"base" changeset separately so we won't (incorrectly) select "source" which
is an ancestor of the destination.

This patch should not change the behavior where all changesets specified by
"--base" have the same branching point(s).

A new situation is: some of the specified changesets could be rebased, while
some couldn't (because they are descendants of the destination, or they do
not share a common ancestor with the destination). The current behavior is
to show "nothing to rebase" and exits with 1.

This patch maintains the current behavior (show "nothing to rebase") even if
part of the "--base" revset could be rebased. A clearer error message may be
"cannot find branching point for X", or "X is a descendant of destination".
The error message issue is tracked by issue5422 separately.

A test is added with all kinds of tricky cases I could think of for now.

#!/usr/bin/env bash
# A simple script for opening merge conflicts in the editor.
# Use the following Mercurial settings to enable it.
#
# [ui]
# merge = editmerge
#
# [merge-tools]
# editmerge.args=$output
# editmerge.check=changed
# editmerge.premerge=keep

FILE="$1"

getlines() {
  grep -n "^<<<<<<" "$FILE" | cut -f1 -d:
}

# editor preference loosely based on https://mercurial-scm.org/wiki/editor
# hg showconfig is at the bottom though, since it's slow to run (0.15 seconds)
ED="$HGEDITOR"
if [ "$ED" = "" ] ; then
  ED="$VISUAL"
fi
if [ "$ED" = "" ] ; then
  ED="$EDITOR"
fi
if [ "$ED" = "" ] ; then
  ED="$(hg showconfig ui.editor)"
fi
if [ "$ED" = "" ] ; then
  echo "merge failed - unable to find editor"
  exit 1
fi

if [ "$ED" = "emacs" ] || [ "$ED" = "nano" ] || [ "$ED" = "vim" ] ; then
  FIRSTLINE="$(getlines | head -n 1)"
  PREVIOUSLINE=""

  # open the editor to the first conflict until there are no more
  # or the user stops editing the file
  while [ ! "$FIRSTLINE" = "" ] && [ ! "$FIRSTLINE" = "$PREVIOUSLINE" ] ; do
    $ED "+$FIRSTLINE" "$FILE"
    PREVIOUSLINE="$FIRSTLINE"
    FIRSTLINE="$(getlines | head -n 1)"
  done
else
  $ED "$FILE"
fi

# get the line numbers of the remaining conflicts
CONFLICTS="$(getlines | sed ':a;N;$!ba;s/\n/, /g')"
if [ ! "$CONFLICTS" = "" ] ; then
  echo "merge failed - resolve the conflicts (line $CONFLICTS) then use 'hg resolve --mark'"
  exit 1
fi

exit 0