view contrib/mergetools.hgrc @ 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.

# Some default global settings for common merge tools

[merge-tools]
kdiff3.args=--auto --L1 base --L2 local --L3 other $base $local $other -o $output
kdiff3.regkey=Software\KDiff3
kdiff3.regkeyalt=Software\Wow6432Node\KDiff3
kdiff3.regappend=\kdiff3.exe
kdiff3.fixeol=True
kdiff3.gui=True
kdiff3.diffargs=--L1 '$plabel1' --L2 '$clabel' $parent $child

gvimdiff.args=--nofork -d -g -O $local $other $base
gvimdiff.regkey=Software\Vim\GVim
gvimdiff.regkeyalt=Software\Wow6432Node\Vim\GVim
gvimdiff.regname=path
gvimdiff.priority=-9

vimdiff.args=$local $other $base -c 'redraw | echomsg "hg merge conflict, type \":cq\" to abort vimdiff"'
vimdiff.check=changed
vimdiff.priority=-10

merge.check=conflicts
merge.priority=-100

gpyfm.gui=True

meld.gui=True
meld.args=--label='local' $local --label='merged' $base --label='other' $other -o $output
meld.check=changed
meld.diffargs=-a --label='$plabel1' $parent --label='$clabel' $child

tkdiff.args=$local $other -a $base -o $output
tkdiff.gui=True
tkdiff.priority=-8
tkdiff.diffargs=-L '$plabel1' $parent -L '$clabel' $child

xxdiff.args=--show-merged-pane --exit-with-merge-status --title1 local --title2 base --title3 other --merged-filename $output --merge $local $base $other
xxdiff.gui=True
xxdiff.priority=-8
xxdiff.diffargs=--title1 '$plabel1' $parent --title2 '$clabel' $child

diffmerge.regkey=Software\SourceGear\SourceGear DiffMerge\
diffmerge.regkeyalt=Software\Wow6432Node\SourceGear\SourceGear DiffMerge\
diffmerge.regname=Location
diffmerge.priority=-7
diffmerge.args=-nosplash -merge -title1=local -title2=merged -title3=other $local $base $other -result=$output
diffmerge.check=changed
diffmerge.gui=True
diffmerge.diffargs=--nosplash --title1='$plabel1' --title2='$clabel' $parent $child

p4merge.args=$base $local $other $output
p4merge.regkey=Software\Perforce\Environment
p4merge.regkeyalt=Software\Wow6432Node\Perforce\Environment
p4merge.regname=P4INSTROOT
p4merge.regappend=\p4merge.exe
p4merge.gui=True
p4merge.priority=-8
p4merge.diffargs=$parent $child

tortoisemerge.args=/base:$base /mine:$local /theirs:$other /merged:$output
tortoisemerge.regkey=Software\TortoiseSVN
tortoisemerge.regkeyalt=Software\Wow6432Node\TortoiseSVN
tortoisemerge.check=changed
tortoisemerge.gui=True
tortoisemerge.priority=-8
tortoisemerge.diffargs=/base:$parent /mine:$child /basename:'$plabel1' /minename:'$clabel'

ecmerge.args=$base $local $other --mode=merge3 --title0=base --title1=local --title2=other --to=$output
ecmerge.regkey=Software\Elli\xc3\xa9 Computing\Merge
ecmerge.regkeyalt=Software\Wow6432Node\Elli\xc3\xa9 Computing\Merge
ecmerge.gui=True
ecmerge.diffargs=$parent $child --mode=diff2 --title1='$plabel1' --title2='$clabel'

filemerge.executable=/Developer/Applications/Utilities/FileMerge.app/Contents/MacOS/FileMerge
filemerge.args=-left $other -right $local -ancestor $base -merge $output
filemerge.gui=True

; Windows version of Beyond Compare
beyondcompare3.args=$local $other $base $output /ro /lefttitle=local /centertitle=base /righttitle=other /automerge /reviewconflicts /solo
beyondcompare3.regkey=Software\Scooter Software\Beyond Compare 3
beyondcompare3.regname=ExePath
beyondcompare3.gui=True
beyondcompare3.priority=-2
beyondcompare3.diffargs=/lro /lefttitle='$plabel1' /righttitle='$clabel' /solo /expandall $parent $child

; Linux version of Beyond Compare
bcompare.args=$local $other $base -mergeoutput=$output -ro -lefttitle=parent1 -centertitle=base -righttitle=parent2 -outputtitle=merged -automerge -reviewconflicts -solo
bcompare.premerge=False
bcompare.gui=True
bcompare.priority=-1
bcompare.diffargs=-lro -lefttitle='$plabel1' -righttitle='$clabel' -solo -expandall $parent $child

winmerge.args=/e /x /wl /ub /dl other /dr local $other $local $output
winmerge.regkey=Software\Thingamahoochie\WinMerge
winmerge.regkeyalt=Software\Wow6432Node\Thingamahoochie\WinMerge\
winmerge.regname=Executable
winmerge.check=changed
winmerge.gui=True
winmerge.priority=-10
winmerge.diffargs=/r /e /x /ub /wl /dl '$plabel1' /dr '$clabel' $parent $child

araxis.regkey=SOFTWARE\Classes\TypeLib\{46799e0a-7bd1-4330-911c-9660bb964ea2}\7.0\HELPDIR
araxis.regappend=\ConsoleCompare.exe
araxis.priority=-2
araxis.args=/3 /a2 /wait /merge /title1:"Other" /title2:"Base" /title3:"Local :"$local $other $base $local $output
araxis.premerge=False
araxis.checkconflict=True
araxis.binary=True
araxis.gui=True
araxis.diffargs=/2 /wait /title1:"$plabel1" /title2:"$clabel" $parent $child

diffuse.priority=-3
diffuse.args=$local $base $other
diffuse.gui=True
diffuse.diffargs=$parent $child

UltraCompare.regkey=Software\Microsoft\Windows\CurrentVersion\App Paths\UC.exe
UltraCompare.regkeyalt=Software\Wow6432Node\Microsoft\Windows\CurrentVersion\App Paths\UC.exe
UltraCompare.args = $base $local $other -title1 base -title3 other
UltraCompare.priority = -2
UltraCompare.gui = True
UltraCompare.binary = True
UltraCompare.check = conflicts,changed
UltraCompare.diffargs=$child $parent -title1 $clabel -title2 $plabel1