Mercurial has a color extension that I hoped might let us pretty-print bugids in hg log output, but never got around to trying to make it happen.

Well, a while ago, I burnt an afternoon to get it working. This is (really) ugly, but does the trick. Just add the following to your ~/.hgstyle  and update your ~/.hgstyle file:

# This syntax-highlights ON-format commit messages, writing
# the bugids in a lovely shade of blue. To use, add the
# following to your ~/.hgrc
# [ui]
# hgstyle = ~timf/.hgstyle
# [extensions]
# color =
# pager =

# My hacks for 'changeset' are horrendous. startswith can't
# take a regexp, but sub can, so to detect bugids, we replace
# a regexp with a string, then search for that string.
# I'm sorry.

# We see if we can find a bug id in the first word of the
# line. If we do, we color it blue and emit it,
# otherwise we emit nothing.
# Then, for printing the synopsis, we check (again)
# for a bugid and if we find one, remove it from the line and
# emit the rest of the line, otherwise we emit the whole line.

# While this is really really ugly, it protects us from
# a problem when printing the synopsis where if we tried
# doing:
#     sub(word('0', line), line)
# we would blow up if word 0 in a synopsis line is an invalid
# regular expression.
# (which actually happens in changeset 67b47fad41d4 in the
# IPS gate)"

# Developer note: Mercurial templating functions are weird. In
# particular, if-statements take the form
#   if(expression, action, else-action)
# See

changeset = 'changeset:   {label("log.changeset changeset.{phase}", "[{phase}]")} \
        {label("red", "{rev}:{node|short}")} {branches}\n\
        {tags}{parents}user:        {author}\n\
        date:        {date|date}\ndescription:
        \t{splitlines(desc) % "{if(startswith('BUGID',
                                              sub('[0-9]+', 'BUGID', word('0', line))),
                                   label('blue', word('0', line)))
                                              sub('[0-9]+', 'BUGID_FOR_SYNOPSIS', word('0', line))),
                                   sub(word('0', line), '', line),

Which results in hg log output like this:

Syntax-highlighted hg log output

I hope you find this useful! (comments on better implementations are welcome)

Updated 13th March 2016: I needed to make a few changes for Mercurial 3.4.1 which didn’t like the previous version, and have include those chages in the text above