view tests/test-newbranch.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.

  $ branchcache=.hg/cache/branch2

  $ listbranchcaches() {
  >    for f in .hg/cache/branch2*;
  >       do echo === $f ===;
  >       cat $f;
  >     done;
  > }
  $ purgebranchcaches() {
  >     rm .hg/cache/branch2*
  > }

  $ hg init t
  $ cd t

  $ hg branches
  $ echo foo > a
  $ hg add a
  $ hg ci -m "initial"
  $ hg branch foo
  marked working directory as branch foo
  (branches are permanent and global, did you want a bookmark?)
  $ hg branch
  foo
  $ hg ci -m "add branch name"
  $ hg branch bar
  marked working directory as branch bar
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -m "change branch name"

Branch shadowing:

  $ hg branch default
  abort: a branch of the same name already exists
  (use 'hg update' to switch to it)
  [255]

  $ hg branch -f default
  marked working directory as branch default
  (branches are permanent and global, did you want a bookmark?)

  $ hg ci -m "clear branch name"
  created new head

There should be only one default branch head

  $ hg heads .
  changeset:   3:1c28f494dae6
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     clear branch name
  

  $ hg co foo
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch
  foo
  $ echo bleah > a
  $ hg ci -m "modify a branch"

  $ hg merge default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg branch
  foo
  $ hg ci -m "merge"

  $ hg log
  changeset:   5:530046499edf
  branch:      foo
  tag:         tip
  parent:      4:adf1a74a7f7b
  parent:      3:1c28f494dae6
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     merge
  
  changeset:   4:adf1a74a7f7b
  branch:      foo
  parent:      1:6c0e42da283a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a branch
  
  changeset:   3:1c28f494dae6
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     clear branch name
  
  changeset:   2:c21617b13b22
  branch:      bar
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change branch name
  
  changeset:   1:6c0e42da283a
  branch:      foo
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add branch name
  
  changeset:   0:db01e8ea3388
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  
  $ hg branches
  foo                            5:530046499edf
  default                        3:1c28f494dae6 (inactive)
  bar                            2:c21617b13b22 (inactive)

  $ hg branches -q
  foo
  default
  bar

Test for invalid branch cache:

  $ hg rollback
  repository tip rolled back to revision 4 (undo commit)
  working directory now based on revisions 4 and 3

  $ cp ${branchcache}-served .hg/bc-invalid

  $ hg log -r foo
  changeset:   4:adf1a74a7f7b
  branch:      foo
  tag:         tip
  parent:      1:6c0e42da283a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify a branch
  
  $ cp .hg/bc-invalid $branchcache

  $ hg --debug log -r foo
  changeset:   4:adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6
  branch:      foo
  tag:         tip
  phase:       draft
  parent:      1:6c0e42da283a56b5edc5b4fadb491365ec7f5fa8
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    1:8c342a37dfba0b3d3ce073562a00d8a813c54ffe
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       a
  extra:       branch=foo
  description:
  modify a branch
  
  
  $ purgebranchcaches
  $ echo corrupted > $branchcache

  $ hg log -qr foo
  4:adf1a74a7f7b

  $ listbranchcaches
  === .hg/cache/branch2 ===
  corrupted
  === .hg/cache/branch2-served ===
  adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 4
  c21617b13b220988e7a2e26290fbe4325ffa7139 o bar
  1c28f494dae69a2f8fc815059d257eccf3fcfe75 o default
  adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 o foo

Push should update the branch cache:

  $ hg init ../target

Pushing just rev 0:

  $ hg push -qr 0 ../target

  $ (cd ../target/; listbranchcaches)
  === .hg/cache/branch2-base ===
  db01e8ea3388fd3c7c94e1436ea2bd6a53d581c5 0
  db01e8ea3388fd3c7c94e1436ea2bd6a53d581c5 o default

Pushing everything:

  $ hg push -qf ../target

  $ (cd ../target/; listbranchcaches)
  === .hg/cache/branch2-base ===
  adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 4
  c21617b13b220988e7a2e26290fbe4325ffa7139 o bar
  1c28f494dae69a2f8fc815059d257eccf3fcfe75 o default
  adf1a74a7f7b4cd193d12992f5d0d6a004ed21d6 o foo

Update with no arguments: tipmost revision of the current branch:

  $ hg up -q -C 0
  $ hg up -q
  $ hg id
  1c28f494dae6

  $ hg up -q 1
  $ hg up -q
  $ hg id
  adf1a74a7f7b (foo) tip

  $ hg branch foobar
  marked working directory as branch foobar
  (branches are permanent and global, did you want a bookmark?)

  $ hg up
  abort: branch foobar not found
  [255]

Fastforward merge:

  $ hg branch ff
  marked working directory as branch ff
  (branches are permanent and global, did you want a bookmark?)

  $ echo ff > ff
  $ hg ci -Am'fast forward'
  adding ff

  $ hg up foo
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ hg merge ff
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg branch
  foo
  $ hg commit -m'Merge ff into foo'
  $ hg parents
  changeset:   6:185ffbfefa30
  branch:      foo
  tag:         tip
  parent:      4:adf1a74a7f7b
  parent:      5:1a3c27dc5e11
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Merge ff into foo
  
  $ hg manifest
  a
  ff


Test merging, add 3 default heads and one test head:

  $ cd ..
  $ hg init merges
  $ cd merges
  $ echo a > a
  $ hg ci -Ama
  adding a

  $ echo b > b
  $ hg ci -Amb
  adding b

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo c > c
  $ hg ci -Amc
  adding c
  created new head

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo d > d
  $ hg ci -Amd
  adding d
  created new head

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branch test
  marked working directory as branch test
  (branches are permanent and global, did you want a bookmark?)
  $ echo e >> e
  $ hg ci -Ame
  adding e

  $ hg log
  changeset:   4:3a1e01ed1df4
  branch:      test
  tag:         tip
  parent:      0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     e
  
  changeset:   3:980f7dc84c29
  parent:      0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     d
  
  changeset:   2:d36c0562f908
  parent:      0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  
  changeset:   1:d2ae7f538514
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b
  
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
Implicit merge with test branch as parent:

  $ hg merge
  abort: branch 'test' has one head - please merge with an explicit rev
  (run 'hg heads' to see all heads)
  [255]
  $ hg up -C default
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

Implicit merge with default branch as parent:

  $ hg merge
  abort: branch 'default' has 3 heads - please merge with an explicit rev
  (run 'hg heads .' to see heads)
  [255]

3 branch heads, explicit merge required:

  $ hg merge 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m merge

2 branch heads, implicit merge works:

  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cd ..