view tests/test-convert-bzr-directories.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.

  $ . "$TESTDIR/bzr-definitions"

empty directory

  $ mkdir test-empty
  $ cd test-empty
  $ bzr init -q source
  $ cd source
  $ echo content > a
  $ bzr add -q a
  $ bzr commit -q -m 'Initial add'
  $ mkdir empty
  $ bzr add -q empty
  $ bzr commit -q -m 'Empty directory added'
  $ echo content > empty/something
  $ bzr add -q empty/something
  $ bzr commit -q -m 'Added file into directory'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  2 Initial add
  1 Empty directory added
  0 Added file into directory
  $ manifest source-hg 1
  % manifest of 1
  644   a
  $ manifest source-hg tip
  % manifest of tip
  644   a
  644   empty/something
  $ cd ..

directory renames

  $ mkdir test-dir-rename
  $ cd test-dir-rename
  $ bzr init -q source
  $ cd source
  $ mkdir tpyo
  $ echo content > tpyo/something
  $ bzr add -q tpyo
  $ bzr commit -q -m 'Added directory'
  $ bzr mv tpyo typo
  tpyo => typo
  $ bzr commit -q -m 'Oops, typo'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  1 Added directory
  0 Oops, typo
  $ manifest source-hg 0
  % manifest of 0
  644   tpyo/something
  $ manifest source-hg tip
  % manifest of tip
  644   typo/something
  $ cd ..

nested directory renames

  $ mkdir test-nested-dir-rename
  $ cd test-nested-dir-rename
  $ bzr init -q source
  $ cd source
  $ mkdir -p firstlevel/secondlevel/thirdlevel
  $ echo content > firstlevel/secondlevel/file
  $ echo this_needs_to_be_there_too > firstlevel/secondlevel/thirdlevel/stuff
  $ bzr add -q firstlevel
  $ bzr commit -q -m 'Added nested directories'
  $ bzr mv firstlevel/secondlevel secondlevel
  firstlevel/secondlevel => secondlevel
  $ bzr commit -q -m 'Moved secondlevel one level up'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  1 Added nested directories
  0 Moved secondlevel one level up
  $ manifest source-hg tip
  % manifest of tip
  644   secondlevel/file
  644   secondlevel/thirdlevel/stuff
  $ cd ..

directory remove

  $ mkdir test-dir-remove
  $ cd test-dir-remove
  $ bzr init -q source
  $ cd source
  $ mkdir src
  $ echo content > src/sourcecode
  $ bzr add -q src
  $ bzr commit -q -m 'Added directory'
  $ bzr rm -q src
  $ bzr commit -q -m 'Removed directory'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  1 Added directory
  0 Removed directory
  $ manifest source-hg 0
  % manifest of 0
  644   src/sourcecode
  $ manifest source-hg tip
  % manifest of tip
  $ cd ..

directory replace

  $ mkdir test-dir-replace
  $ cd test-dir-replace
  $ bzr init -q source
  $ cd source
  $ mkdir first second
  $ echo content > first/file
  $ echo morecontent > first/dummy
  $ echo othercontent > second/something
  $ bzr add -q first second
  $ bzr commit -q -m 'Initial layout'
  $ bzr mv first/file second/file
  first/file => second/file
  $ bzr mv first third
  first => third
  $ bzr commit -q -m 'Some conflicting moves'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  1 Initial layout
  0 Some conflicting moves
  $ manifest source-hg tip
  % manifest of tip
  644   second/file
  644   second/something
  644   third/dummy
  $ cd ..

divergent nested renames (issue3089)

  $ mkdir test-divergent-renames
  $ cd test-divergent-renames
  $ bzr init -q source
  $ cd source
  $ mkdir -p a/c
  $ echo a > a/fa
  $ echo c > a/c/fc
  $ bzr add -q a
  $ bzr commit -q -m 'Initial layout'
  $ bzr mv a b
  a => b
  $ mkdir a
  $ bzr add a
  add(ed|ing) a (re)
  $ bzr mv b/c a/c
  b/c => a/c
  $ bzr status
  added:
    a/
  renamed:
    a/? => b/? (re)
    a/c/? => a/c/? (re)
  $ bzr commit -q -m 'Divergent renames'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  1 Initial layout
  0 Divergent renames
  $ hg -R source-hg st -C --change 1
  A b/fa
    a/fa
  R a/fa
  $ hg -R source-hg manifest -r 1
  a/c/fc
  b/fa
  $ cd ..