contrib/editmerge

setup: make the error "Unable to find a working hg binary" more informative

The error message now shows the attempted hg commands and their stderr, to
make it easier to investigate why things are not working.

Here's an example output

/!\
/!\ Unable to find a working hg binary
/!\ Version cannot be extracted from the repository
/!\ Re-run the setup once a first version is built
/!\ Attempts:
/!\   attempt #0:
/!\     cmd:         ['hg-missing', 'log', '-r.', '-Ttest']
/!\     exception:   [Errno 2] No such file or directory: 'hg-missing': 'hg-missing'
/!\   attempt #1:
/!\     cmd:         ['/usr/bin/python3', 'hg', 'log', '-r.', '-Ttest']
/!\     return code: 255
/!\     std output:
/!\     std error:
*** failed to import extension "topic": No module named 'topic'
*** failed to import extension "evolve": No module named 'evolve'
abort: accessing `dirstate-v2` repository without associated fast implementation.
(check `hg help config.format.use-dirstate-v2` for details)
/!\
/!\ Could not determine the Mercurial version
/!\ You need to build a local version first
/!\ Run `make local` and try again
/!\

#!/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