view tests/test-rebase-parameters.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]
  > rebase=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: '{desc}' {branches}\n"
  > EOF


  $ hg init a
  $ cd a
  $ hg unbundle "$TESTDIR/bundles/rebase.hg"
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 7 files (+2 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ echo I > I
  $ hg ci -AmI
  adding I

  $ hg tglog
  @  8: 'I'
  |
  o  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


These fail:

  $ hg clone -q -u . a a1
  $ cd a1

  $ hg rebase -s 8 -d 7
  nothing to rebase
  [1]

  $ hg rebase --continue --abort
  abort: cannot use both abort and continue
  [255]

  $ hg rebase --continue --collapse
  abort: cannot use collapse with continue or abort
  [255]

  $ hg rebase --continue --dest 4
  abort: abort and continue do not allow specifying revisions
  [255]

  $ hg rebase --base 5 --source 4
  abort: cannot specify both a source and a base
  [255]

  $ hg rebase --rev 5 --source 4
  abort: cannot specify both a revision and a source
  [255]
  $ hg rebase --base 5 --rev 4
  abort: cannot specify both a revision and a base
  [255]

  $ hg rebase --rev '1 & !1'
  abort: empty "rev" revision set - nothing to rebase
  [255]

  $ hg rebase --source '1 & !1'
  abort: empty "source" revision set - nothing to rebase
  [255]

  $ hg rebase --base '1 & !1'
  abort: empty "base" revision set - can't compute rebase set
  [255]

  $ hg rebase
  nothing to rebase - working directory parent is also destination
  [1]

  $ hg rebase -b.
  nothing to rebase - e7ec4e813ba6 is both "base" and destination
  [1]

  $ hg up -q 7

  $ hg rebase --traceback
  nothing to rebase - working directory parent is already an ancestor of destination e7ec4e813ba6
  [1]

  $ hg rebase -b.
  nothing to rebase - "base" 02de42196ebe is already an ancestor of destination e7ec4e813ba6
  [1]

  $ hg rebase --dest '1 & !1'
  abort: empty revision set
  [255]

These work:

Rebase with no arguments (from 3 onto 8):

  $ hg up -q -C 3

  $ hg rebase
  saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  o  5: 'I'
  |
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'
  
Try to rollback after a rebase (fail):

  $ hg rollback
  no rollback information available
  [1]

  $ cd ..

Rebase with base == '.' => same as no arguments (from 3 onto 8):

  $ hg clone -q -u 3 a a2
  $ cd a2

  $ hg rebase --base .
  saved backup bundle to $TESTTMP/a2/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  o  5: 'I'
  |
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'
  
  $ cd ..


Rebase with dest == branch(.) => same as no arguments (from 3 onto 8):

  $ hg clone -q -u 3 a a3
  $ cd a3

  $ hg rebase --dest 'branch(.)'
  saved backup bundle to $TESTTMP/a3/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  o  5: 'I'
  |
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'
  
  $ cd ..


Specify only source (from 2 onto 8):

  $ hg clone -q -u . a a4
  $ cd a4

  $ hg rebase --source 'desc("C")'
  saved backup bundle to $TESTTMP/a4/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  o  8: 'D'
  |
  o  7: 'C'
  |
  @  6: 'I'
  |
  o  5: 'H'
  |
  | o  4: 'G'
  |/|
  o |  3: 'F'
  | |
  | o  2: 'E'
  |/
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


Specify only dest (from 3 onto 6):

  $ hg clone -q -u 3 a a5
  $ cd a5

  $ hg rebase --dest 6
  saved backup bundle to $TESTTMP/a5/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  | o  5: 'I'
  | |
  | o  4: 'H'
  | |
  o |  3: 'G'
  |\|
  | o  2: 'F'
  | |
  o |  1: 'E'
  |/
  o  0: 'A'
  
  $ cd ..


Specify only base (from 1 onto 8):

  $ hg clone -q -u . a a6
  $ cd a6

  $ hg rebase --base 'desc("D")'
  saved backup bundle to $TESTTMP/a6/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  o  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  @  5: 'I'
  |
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'
  
  $ cd ..


Specify source and dest (from 2 onto 7):

  $ hg clone -q -u . a a7
  $ cd a7

  $ hg rebase --source 2 --dest 7
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  o  8: 'D'
  |
  o  7: 'C'
  |
  | @  6: 'I'
  |/
  o  5: 'H'
  |
  | o  4: 'G'
  |/|
  o |  3: 'F'
  | |
  | o  2: 'E'
  |/
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


Specify base and dest (from 1 onto 7):

  $ hg clone -q -u . a a8
  $ cd a8

  $ hg rebase --base 3 --dest 7
  saved backup bundle to $TESTTMP/a8/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  o  8: 'D'
  |
  o  7: 'C'
  |
  o  6: 'B'
  |
  | @  5: 'I'
  |/
  o  4: 'H'
  |
  | o  3: 'G'
  |/|
  o |  2: 'F'
  | |
  | o  1: 'E'
  |/
  o  0: 'A'
  
  $ cd ..


Specify only revs (from 2 onto 8)

  $ hg clone -q -u . a a9
  $ cd a9

  $ hg rebase --rev 'desc("C")::'
  saved backup bundle to $TESTTMP/a9/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  o  8: 'D'
  |
  o  7: 'C'
  |
  @  6: 'I'
  |
  o  5: 'H'
  |
  | o  4: 'G'
  |/|
  o |  3: 'F'
  | |
  | o  2: 'E'
  |/
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..

Test --tool parameter:

  $ hg init b
  $ cd b

  $ echo c1 > c1
  $ hg ci -Am c1
  adding c1

  $ echo c2 > c2
  $ hg ci -Am c2
  adding c2

  $ hg up -q 0
  $ echo c2b > c2
  $ hg ci -Am c2b
  adding c2
  created new head

  $ cd ..

  $ hg clone -q -u . b b1
  $ cd b1

  $ hg rebase -s 2 -d 1 --tool internal:local
  saved backup bundle to $TESTTMP/b1/.hg/strip-backup/*-backup.hg (glob)

  $ hg cat c2
  c2

  $ cd ..


  $ hg clone -q -u . b b2
  $ cd b2

  $ hg rebase -s 2 -d 1 --tool internal:other
  saved backup bundle to $TESTTMP/b2/.hg/strip-backup/*-backup.hg (glob)

  $ hg cat c2
  c2b

  $ cd ..


  $ hg clone -q -u . b b3
  $ cd b3

  $ hg rebase -s 2 -d 1 --tool internal:fail
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ hg summary
  parent: 1:56daeba07f4b 
   c2
  parent: 2:e4e3f3546619 tip
   c2b
  branch: default
  commit: 1 modified, 1 unresolved (merge)
  update: (current)
  rebase: 0 rebased, 1 remaining (rebase --continue)

  $ hg resolve -l
  U c2

  $ hg resolve -m c2
  $ hg rebase -c --tool internal:fail
  tool option will be ignored
  saved backup bundle to $TESTTMP/b3/.hg/strip-backup/*-backup.hg (glob)

  $ cd ..