view tests/test-convert-hg-source.t @ 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.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert=
  > [convert]
  > hg.saverev=False
  > EOF
  $ hg init orig
  $ cd orig
  $ echo foo > foo
  $ echo bar > bar
  $ hg ci -qAm 'add foo bar' -d '0 0'
  $ echo >> foo
  $ hg ci -m 'change foo' -d '1 0'
  $ hg up -qC 0
  $ hg copy --after --force foo bar
  $ hg copy foo baz
  $ hg ci -m 'make bar and baz copies of foo' -d '2 0'
  created new head
  $ hg bookmark premerge1
  $ hg merge -r 1
  merging baz and foo to baz
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m 'merge local copy' -d '3 0'
  $ hg up -C 1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg bookmark premerge2
  $ hg merge 2
  merging foo and baz to baz
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m 'merge remote copy' -d '4 0'
  created new head
#if execbit
  $ chmod +x baz
#else
  $ echo some other change to make sure we get a rev 5 > baz
#endif
  $ hg ci -m 'mark baz executable' -d '5 0'
  $ cd ..
  $ hg convert --datesort orig new 2>&1 | grep -v 'subversion python bindings could not be loaded'
  initializing destination new repository
  scanning source...
  sorting...
  converting...
  5 add foo bar
  4 change foo
  3 make bar and baz copies of foo
  2 merge local copy
  1 merge remote copy
  0 mark baz executable
  updating bookmarks
  $ cd new
  $ hg out ../orig
  comparing with ../orig
  searching for changes
  no changes found
  [1]
#if execbit
  $ hg bookmarks
     premerge1                 3:973ef48a98a4
     premerge2                 5:13d9b87cf8f8
#else
Different hash because no x bit
  $ hg bookmarks
     premerge1                 3:973ef48a98a4
     premerge2                 5:df0779bcf33c
#endif
  $ cd ..

check shamap LF and CRLF handling

  $ cat > rewrite.py <<EOF
  > import sys
  > # Interlace LF and CRLF
  > lines = [(l.rstrip() + ((i % 2) and '\n' or '\r\n'))
  >          for i, l in enumerate(file(sys.argv[1]))]
  > file(sys.argv[1], 'wb').write(''.join(lines))
  > EOF
  $ python rewrite.py new/.hg/shamap
  $ cd orig
  $ hg up -qC 1
  $ echo foo >> foo
  $ hg ci -qm 'change foo again'
  $ hg up -qC 2
  $ echo foo >> foo
  $ hg ci -qm 'change foo again again'
  $ cd ..
  $ hg convert --datesort orig new 2>&1 | grep -v 'subversion python bindings could not be loaded'
  scanning source...
  sorting...
  converting...
  1 change foo again again
  0 change foo again
  updating bookmarks

init broken repository

  $ hg init broken
  $ cd broken
  $ echo a >> a
  $ echo b >> b
  $ hg ci -qAm init
  $ echo a >> a
  $ echo b >> b
  $ hg copy b c
  $ hg ci -qAm changeall
  $ hg up -qC 0
  $ echo bc >> b
  $ hg ci -m changebagain
  created new head
  $ HGMERGE=internal:local hg -q merge
  $ hg ci -m merge
  $ hg mv b d
  $ hg ci -m moveb

break it

  $ rm .hg/store/data/b.*
  $ cd ..
  $ hg --config convert.hg.ignoreerrors=True convert broken fixed
  initializing destination fixed repository
  scanning source...
  sorting...
  converting...
  4 init
  ignoring: data/b.i@1e88685f5dde: no match found
  3 changeall
  2 changebagain
  1 merge
  0 moveb
  $ hg -R fixed verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 5 changesets, 5 total revisions

manifest -r 0

  $ hg -R fixed manifest -r 0
  a

manifest -r tip

  $ hg -R fixed manifest -r tip
  a
  c
  d