view tests/test-issue3084.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.

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "largefiles =" >> $HGRCPATH

Create the repository outside $HOME since largefiles write to
$HOME/.cache/largefiles.

  $ hg init test
  $ cd test
  $ echo "root" > root
  $ hg add root
  $ hg commit -m "Root commit"

  $ echo "large" > foo
  $ hg add --large foo
  $ hg commit -m "Add foo as a largefile"

  $ hg update -r 0
  getting changed largefiles
  0 largefiles updated, 1 removed
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo "normal" > foo
  $ hg add foo
  $ hg commit -m "Add foo as normal file"
  created new head

Normal file in the working copy, keeping the normal version:

  $ echo "n" | hg merge --config ui.interactive=Yes
  remote turned local normal file foo into a largefile
  use (l)argefile or keep (n)ormal file? 0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed

  $ hg status
  $ cat foo
  normal

Normal file in the working copy, keeping the largefile version:

  $ hg update -q -C
  $ echo "l" | hg merge --config ui.interactive=Yes
  remote turned local normal file foo into a largefile
  use (l)argefile or keep (n)ormal file? 1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed

  $ hg status
  M foo

  $ hg diff --nodates
  diff -r fa129ab6b5a7 .hglf/foo
  --- /dev/null
  +++ b/.hglf/foo
  @@ -0,0 +1,1 @@
  +7f7097b041ccf68cc5561e9600da4655d21c6d18
  diff -r fa129ab6b5a7 foo
  --- a/foo
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -normal

  $ cat foo
  large

Largefile in the working copy, keeping the normal version:

  $ hg update -q -C -r 1
  $ echo "n" | hg merge --config ui.interactive=Yes
  remote turned local largefile foo into a normal file
  keep (l)argefile or use (n)ormal file? 1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed

  $ hg status
  M foo

  $ hg diff --nodates
  diff -r ff521236428a .hglf/foo
  --- a/.hglf/foo
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -7f7097b041ccf68cc5561e9600da4655d21c6d18
  diff -r ff521236428a foo
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,1 @@
  +normal

  $ cat foo
  normal

Largefile in the working copy, keeping the largefile version:

  $ hg update -q -C -r 1
  $ echo "l" | hg merge --config ui.interactive=Yes
  remote turned local largefile foo into a normal file
  keep (l)argefile or use (n)ormal file? 0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed

  $ hg status

  $ cat foo
  large

Whatever ... commit something so we can invoke merge when updating

  $ hg commit -m '3: Merge'

Updating from largefile to normal - no reason to prompt

  $ hg up -r 2
  getting changed largefiles
  0 largefiles updated, 0 removed
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cat foo
  normal

(the update above used to leave the working dir in a very weird state - clean it
  $ hg up -qr null
  $ hg up -qr 2
)

Updating from normal to largefile - no reason to prompt

  $ hg up -r 3
  getting changed largefiles
  1 largefiles updated, 0 removed
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ cat foo
  large

  $ cd ..


Systematic testing of merges involving largefiles:

Ancestor: normal  Parent: normal=  Parent: large   result: large
Ancestor: normal  Parent: normal2  Parent: large   result: ?
Ancestor: large   Parent: large=   Parent: normal  result: normal
Ancestor: large   Parent: large2   Parent: normal  result: ?

All cases should try merging both ways.
"=" means same file content.

Prepare test repo:

  $ hg init merges
  $ cd merges
  $ touch f1
  $ hg ci -Aqm "0-root"

ancestor is "normal":
  $ echo normal > f
  $ hg ci -Aqm "1-normal-ancestor"
  $ touch f2
  $ hg ci -Aqm "2-normal-unchanged"
  $ hg tag -l "normal="
  $ echo normal2 > f
  $ hg ci -m "3-normal2"
  $ hg tag -l "normal2"
  $ hg up -qr 1
  $ hg rm f
  $ echo large > f
  $ hg add --large f
  $ hg ci -qm "4-normal-to-large"
  $ hg tag -l "large"

  $ hg up -qr null

ancestor is "large":
  $ echo large > f
  $ hg add --large f
  $ hg ci -qm "5-large-ancestor"
  $ touch f2
  $ hg ci -Aqm "6-large-unchanged"
  $ hg tag -l "large="
  $ echo large2 > f
  $ hg ci -m "7-large2"
  $ hg tag -l "large2"
  $ hg up -qr 5
  $ hg rm f
  $ echo normal > f
  $ hg ci -qAm "8-large-to-normal"
  $ hg tag -l "normal"

Ancestor: normal  Parent: normal=  Parent: large   result: large

  $ hg up -Cqr normal=
  $ hg merge -r large
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed
  $ cat f
  large

swap

  $ hg up -Cqr large
  $ hg merge -r normal=
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed
  $ cat f
  large

Ancestor: normal  Parent: normal2  Parent: large   result: ?
(annoying extra prompt ... but it do not do any serious harm)

  $ hg up -Cqr normal2
  $ hg merge -r large
  local changed f which remote deleted
  use (c)hanged version or (d)elete? c
  remote turned local normal file f into a largefile
  use (l)argefile or keep (n)ormal file? l
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed
  $ cat f
  large

  $ hg up -Cqr normal2
  $ ( echo c; echo n ) | hg merge -r large --config ui.interactive=Yes
  local changed f which remote deleted
  use (c)hanged version or (d)elete? remote turned local normal file f into a largefile
  use (l)argefile or keep (n)ormal file? 0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed
  $ cat f
  normal2

  $ hg up -Cqr normal2
  $ echo d | hg merge -r large --config ui.interactive=Yes
  local changed f which remote deleted
  use (c)hanged version or (d)elete? 1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed
  $ cat f
  large

swap

  $ hg up -Cqr large
  $ hg merge -r normal2
  remote changed f which local deleted
  use (c)hanged version or leave (d)eleted? c
  remote turned local largefile f into a normal file
  keep (l)argefile or use (n)ormal file? l
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed
  $ cat f
  large

  $ hg up -Cqr large
  $ ( echo c; echo n ) | hg merge -r normal2 --config ui.interactive=Yes
  remote changed f which local deleted
  use (c)hanged version or leave (d)eleted? remote turned local largefile f into a normal file
  keep (l)argefile or use (n)ormal file? 2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed
  $ cat f
  normal2

  $ hg up -Cqr large
  $ echo d | hg merge -r normal2 --config ui.interactive=Yes
  remote changed f which local deleted
  use (c)hanged version or leave (d)eleted? 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed
  $ cat f
  large

Ancestor: large   Parent: large=   Parent: normal  result: normal

  $ hg up -Cqr large=
  $ hg merge -r normal
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed
  $ cat f
  normal

swap

  $ hg up -Cqr normal
  $ hg merge -r large=
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat f
  normal

Ancestor: large   Parent: large2   Parent: normal  result: ?
(annoying extra prompt ... but it do not do any serious harm)

  $ hg up -Cqr large2
  $ hg merge -r normal
  local changed .hglf/f which remote deleted
  use (c)hanged version or (d)elete? c
  remote turned local largefile f into a normal file
  keep (l)argefile or use (n)ormal file? l
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed
  $ cat f
  large2

  $ hg up -Cqr large2
  $ echo d | hg merge -r normal --config ui.interactive=Yes
  local changed .hglf/f which remote deleted
  use (c)hanged version or (d)elete? 1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  0 largefiles updated, 0 removed
  $ cat f
  normal

swap

  $ hg up -Cqr normal
  $ hg merge -r large2
  remote changed .hglf/f which local deleted
  use (c)hanged version or leave (d)eleted? c
  remote turned local normal file f into a largefile
  use (l)argefile or keep (n)ormal file? l
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  getting changed largefiles
  1 largefiles updated, 0 removed
  $ cat f
  large2

  $ hg up -Cqr normal
  $ echo d | hg merge -r large2 --config ui.interactive=Yes
  remote changed .hglf/f which local deleted
  use (c)hanged version or leave (d)eleted? 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat f
  normal

  $ cd ..