hg

errors: create "similarity hint" for UnknownIdentifier eagerly in constructor

No code wanted to do anything but to produce a hint from it anyway, so
we might as well just store the hint in the exception (which already
extended `Hint`). That way we can easily convert it to a
`ConfigException` when it's parsing of configuration that fails.

I was wondering if the purpose of lazily creating the string was so we
don't create it in cases where it won't get printed anyway. However, I
couldn't find any places where that could happen. If we do find such
places, we could instead revert to making it lazy but add a function
on `UnknownIdentifier` for creating the hint string.

I dropped the comment saying "make sure to check fileset first, as
revset can invoke fileset", which was added in 4e240d6ab898 (dispatch:
offer near-edit-distance suggestions for {file,rev}set functions,
2015-01-26). I couldn't figure out what it meant. The author of that
patch also did not remember the reason for it. Perhaps changes that
have happened since then made it so it no longer matters.

Differential Revision: https://phab.mercurial-scm.org/D9346

#!/usr/bin/env python3
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import

import os
import sys

libdir = '@LIBDIR@'

if libdir != '@' 'LIBDIR' '@':
    if not os.path.isabs(libdir):
        libdir = os.path.join(
            os.path.dirname(os.path.realpath(__file__)), libdir
        )
        libdir = os.path.abspath(libdir)
    sys.path.insert(0, libdir)

from hgdemandimport import tracing

with tracing.log('hg script'):
    # enable importing on demand to reduce startup time
    try:
        if sys.version_info[0] < 3 or sys.version_info >= (3, 6):
            import hgdemandimport

            hgdemandimport.enable()
    except ImportError:
        sys.stderr.write(
            "abort: couldn't find mercurial libraries in [%s]\n"
            % ' '.join(sys.path)
        )
        sys.stderr.write("(check your install and PYTHONPATH)\n")
        sys.exit(-1)

    from mercurial import dispatch

    dispatch.run()