view contrib/win32/ReadMe.html @ 20742:3681de20b0a7

parsers: fail fast if Python has wrong minor version (issue4110) This change causes an informative ImportError to be raised when importing the parsers extension module if the minor version of the currently-running Python interpreter doesn't match that of the Python used when compiling the extension module. This change also exposes a parsers.versionerrortext constant in the C implementation of the module. Its presence can be used to determine whether this behavior is present in a version of the module. The value of the constant is the leading text of the ImportError raised and is set to "Python minor version mismatch". Here is an example of what the new error looks like: Traceback (most recent call last): File "test.py", line 1, in <module> import mercurial.parsers ImportError: Python minor version mismatch: The Mercurial extension modules were compiled with Python 2.7.6, but Mercurial is currently using Python with sys.hexversion=33883888: Python 2.5.6 (r256:88840, Nov 18 2012, 05:37:10) [GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] at: /opt/local/Library/Frameworks/Python.framework/Versions/2.5/Resources/ Python.app/Contents/MacOS/Python The reason for raising an error in this scenario is that Python's C API is known not to be compatible from minor version to minor version, even if sys.api_version is the same. See for example this Python bug report about incompatibilities between 2.5 and 2.6+: http://bugs.python.org/issue8118 These incompatibilities can cause Mercurial to break in mysterious, unforeseen ways. For example, when Mercurial compiled with Python 2.7 was run with 2.5, the following crash occurred when running "hg status": http://bz.selenic.com/show_bug.cgi?id=4110 After this crash was fixed, running with Python 2.5 no longer crashes, but the following puzzling behavior still occurs: $ hg status ... File ".../mercurial/changelog.py", line 123, in __init__ revlog.revlog.__init__(self, opener, "00changelog.i") File ".../mercurial/revlog.py", line 251, in __init__ d = self._io.parseindex(i, self._inline) File ".../mercurial/revlog.py", line 158, in parseindex index, cache = parsers.parse_index2(data, inline) TypeError: data is not a string which can be reproduced more simply with: import mercurial.parsers as parsers parsers.parse_index2("", True) Both the crash and the TypeError occurred because the Python C API's PyString_Check() returns the wrong value when the C header files from Python 2.7 are run with Python 2.5. This is an example of an incompatibility of the sort mentioned in the Python bug report above. Failing fast with an informative error message results in a better user experience in cases like the above. The information in the ImportError also simplifies troubleshooting for those on Mercurial mailing lists, the bug tracker, etc. This patch only adds the version check to parsers.c, which is sufficient to affect command-line commands like "hg status" and "hg summary". An idea for a future improvement is to move the version-checking C code to a more central location, and have it run when importing all Mercurial extension modules and not just parsers.c.
author Chris Jerdonek <chris.jerdonek@gmail.com>
date Wed, 04 Dec 2013 20:38:27 -0800
parents 9c963a43ecfb
children 8fe5fc8d7b8e
line wrap: on
line source

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>Mercurial for Windows</title>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8" >
    <style type="text/css">
      <!--
      html {
        font-family: sans-serif;
        margin: 1em 2em;
      }

      p {
        margin-top: 0.5em;
        margin-bottom: 0.5em;
      }

      pre {
        margin: 0.25em 0em;
        padding: 0.5em;
        background-color: #EEE;
        border: thin solid #CCC;
      }

      .indented {
        padding-left: 10pt;
      }
      -->
    </style>
  </head>

  <body>
    <h1>Mercurial for Windows</h1>

    <p>Welcome to Mercurial for Windows!</p>

    <p>
      Mercurial is a command-line application. You must run it from
      the Windows command prompt (or if you're hard core, a <a
      href="http://www.mingw.org/">MinGW</a> shell).
    </p>

    <p class="indented">
      <i>Note: the standard <a href="http://www.mingw.org/">MinGW</a>
      msys startup script uses rxvt which has problems setting up
      standard input and output. Running bash directly works
      correctly.</i>
    </p>

    <p>
      For documentation, please visit the <a
      href="http://mercurial.selenic.com/">Mercurial web site</a>.
      You can also download a free book, <a
      href="http://hgbook.red-bean.com/">Mercurial: The Definitive
      Guide</a>.
    </p>

    <p>
      By default, Mercurial installs to <tt>C:\Program
      Files\Mercurial</tt>. The Mercurial command is called
      <tt>hg.exe</tt>.
    </p>

    <h1>Testing Mercurial after you've installed it</h1>

    <p>
      The easiest way to check that Mercurial is installed properly is
      to just type the following at the command prompt:
    </p>

    <pre>
hg
</pre>

    <p>
      This command should print a useful help message. If it does,
      other Mercurial commands should work fine for you.
    </p>

    <h1>Configuration notes</h1>
    <h4>Default editor</h4>
    <p>
      The default editor for commit messages is 'notepad'. You can set
      the <tt>EDITOR</tt> (or <tt>HGEDITOR</tt>) environment variable
      to specify your preference or set it in <tt>mercurial.ini</tt>:
    </p>
    <pre>
[ui]
editor = whatever
</pre>

    <h4>Configuring a Merge program</h4>
    <p>
      It should be emphasized that Mercurial by itself doesn't attempt
      to do a Merge at the file level, neither does it make any
      attempt to Resolve the conflicts.
    </p>

    <p>
      By default, Mercurial will use the merge program defined by the
      <tt>HGMERGE</tt> environment variable, or uses the one defined
      in the <tt>mercurial.ini</tt> file. (see <a
      href="http://mercurial.selenic.com/wiki/MergeProgram">MergeProgram</a>
      on the Mercurial Wiki for more information)
    </p>

    <h1>Reporting problems</h1>

    <p>
      Before you report any problems, please consult the <a
      href="http://mercurial.selenic.com/">Mercurial web site</a>
      and see if your question is already in our list of <a
      href="http://mercurial.selenic.com/wiki/FAQ">Frequently
      Answered Questions</a> (the "FAQ").
    </p>

    <p>
      If you cannot find an answer to your question, please feel free
      to send mail to the Mercurial mailing list, at <a
      href="mailto:mercurial@selenic.com">mercurial@selenic.com</a>.
      <b>Remember</b>, the more useful information you include in your
      report, the easier it will be for us to help you!
    </p>

    <p>
      If you are IRC-savvy, that's usually the fastest way to get
      help. Go to <tt>#mercurial</tt> on <tt>irc.freenode.net</tt>.
    </p>

    <h1>Author and copyright information</h1>

    <p>
      Mercurial was written by <a href="http://www.selenic.com">Matt
      Mackall</a>, and is maintained by Matt and a team of volunteers.
    </p>

    <p>
      The Windows installer was written by <a
      href="http://www.serpentine.com/blog">Bryan O'Sullivan</a>.
    </p>

    <p>
      Mercurial is Copyright 2005-2014 Matt Mackall and others. See
      the <tt>Contributors.txt</tt> file for a list of contributors.
    </p>

    <p>
      Mercurial is free software; you can redistribute it and/or
      modify it under the terms of the <a
      href="http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt">GNU
      General Public License version 2</a> or any later version.
    </p>

    <p>
      Mercurial is distributed in the hope that it will be useful, but
      <b>without any warranty</b>; without even the implied warranty
      of <b>merchantability</b> or <b>fitness for a particular
      purpose</b>. See the GNU General Public License for more
      details.
    </p>
  </body>
</html>