mercurial/txnutil.py

config: move message about leading spaces in config to config.py

When the config parser raises a ParseError, it uses the line that
failed to parse as the error message. It doesn't currently tell the
user anything about why it failed to parse. b13b99d39a46 (config:
highlight parse error caused by leading spaces (issue3214),
2014-03-16) added a checked based on the error *message* having
leading spaces. That has worked fine because only the config parser
uses the line itself as error message (I think the revset and fileset
parsers use more user-friendly proper messages). It still feels like a
hack. Let's make the config parser give a useful message about leading
whitespace instead. We should ideally follow up with more useful
messages for other parse errors in config files.

Differential Revision: https://phab.mercurial-scm.org/D9241

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# 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 errno

from . import encoding


def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get(b'HG_PENDING')


def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)