view tests/test-mq-qnew.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.

  $ catpatch() {
  >     cat $1 | sed -e "s/^\(# Parent \).*/\1/"
  > }
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH
  $ runtest() {
  >     hg init mq
  >     cd mq
  > 
  >     echo a > a
  >     hg ci -Ama
  > 
  >     echo '% qnew should refuse bad patch names'
  >     hg qnew series
  >     hg qnew status
  >     hg qnew guards
  >     hg qnew .
  >     hg qnew ..
  >     hg qnew .hgignore
  >     hg qnew .mqfoo
  >     hg qnew 'foo#bar'
  >     hg qnew 'foo:bar'
  > 
  >     hg qinit -c
  > 
  >     echo '% qnew with name containing slash'
  >     hg qnew foo/
  >     hg qnew foo/bar.patch
  >     hg qnew foo
  >     hg qseries
  >     hg qpop
  >     hg qdelete foo/bar.patch
  > 
  >     echo '% qnew with uncommitted changes'
  >     echo a > somefile
  >     hg add somefile
  >     hg qnew uncommitted.patch
  >     hg st
  >     hg qseries
  > 
  >     echo '% qnew implies add'
  >     hg -R .hg/patches st
  > 
  >     echo '% qnew missing'
  >     hg qnew missing.patch missing
  > 
  >     echo '% qnew -m'
  >     hg qnew -m 'foo bar' mtest.patch
  >     catpatch .hg/patches/mtest.patch
  > 
  >     echo '% qnew twice'
  >     hg qnew first.patch
  >     hg qnew first.patch
  > 
  >     touch ../first.patch
  >     hg qimport ../first.patch
  > 
  >     echo '% qnew -f from a subdirectory'
  >     hg qpop -a
  >     mkdir d
  >     cd d
  >     echo b > b
  >     hg ci -Am t
  >     echo b >> b
  >     hg st
  >     hg qnew -g -f p
  >     catpatch ../.hg/patches/p
  > 
  >     echo '% qnew -u with no username configured'
  >     HGUSER= hg qnew -u blue red
  >     catpatch ../.hg/patches/red
  > 
  >     echo '% qnew -e -u with no username configured'
  >     HGUSER= hg qnew -e -u chartreuse fucsia
  >     catpatch ../.hg/patches/fucsia
  > 
  >     echo '% fail when trying to import a merge'
  >     hg init merge
  >     cd merge
  >     touch a
  >     hg ci -Am null
  >     echo a >> a
  >     hg ci -m a
  >     hg up -r 0
  >     echo b >> a
  >     hg ci -m b
  >     hg merge -f 1
  >     hg resolve --mark a
  >     hg qnew -f merge
  > 
  >     cd ../../..
  >     rm -r mq
  > }

plain headers

  $ echo "[mq]" >> $HGRCPATH
  $ echo "plain=true" >> $HGRCPATH
  $ mkdir sandbox
  $ (cd sandbox ; runtest)
  adding a
  % qnew should refuse bad patch names
  abort: "series" cannot be used as the name of a patch
  abort: "status" cannot be used as the name of a patch
  abort: "guards" cannot be used as the name of a patch
  abort: "." cannot be used as the name of a patch
  abort: ".." cannot be used as the name of a patch
  abort: patch name cannot begin with ".hg"
  abort: patch name cannot begin with ".mq"
  abort: "#" cannot be used in the name of a patch
  abort: ":" cannot be used in the name of a patch
  % qnew with name containing slash
  abort: path ends in directory separator: foo/ (glob)
  abort: "foo" already exists as a directory
  foo/bar.patch
  popping foo/bar.patch
  patch queue now empty
  % qnew with uncommitted changes
  uncommitted.patch
  % qnew implies add
  A .hgignore
  A series
  A uncommitted.patch
  % qnew missing
  abort: missing: * (glob)
  % qnew -m
  foo bar
  
  % qnew twice
  abort: patch "first.patch" already exists
  abort: patch "first.patch" already exists
  % qnew -f from a subdirectory
  popping first.patch
  popping mtest.patch
  popping uncommitted.patch
  patch queue now empty
  adding d/b
  M d/b
  diff --git a/d/b b/d/b
  --- a/d/b
  +++ b/d/b
  @@ -1,1 +1,2 @@
   b
  +b
  % qnew -u with no username configured
  From: blue
  
  % qnew -e -u with no username configured
  From: chartreuse
  
  % fail when trying to import a merge
  adding a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  created new head
  merging a
  warning: conflicts during merge.
  merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  abort: cannot manage merge changesets
  $ rm -r sandbox

hg headers

  $ echo "plain=false" >> $HGRCPATH
  $ mkdir sandbox
  $ (cd sandbox ; runtest)
  adding a
  % qnew should refuse bad patch names
  abort: "series" cannot be used as the name of a patch
  abort: "status" cannot be used as the name of a patch
  abort: "guards" cannot be used as the name of a patch
  abort: "." cannot be used as the name of a patch
  abort: ".." cannot be used as the name of a patch
  abort: patch name cannot begin with ".hg"
  abort: patch name cannot begin with ".mq"
  abort: "#" cannot be used in the name of a patch
  abort: ":" cannot be used in the name of a patch
  % qnew with name containing slash
  abort: path ends in directory separator: foo/ (glob)
  abort: "foo" already exists as a directory
  foo/bar.patch
  popping foo/bar.patch
  patch queue now empty
  % qnew with uncommitted changes
  uncommitted.patch
  % qnew implies add
  A .hgignore
  A series
  A uncommitted.patch
  % qnew missing
  abort: missing: * (glob)
  % qnew -m
  # HG changeset patch
  # Parent 
  foo bar
  
  % qnew twice
  abort: patch "first.patch" already exists
  abort: patch "first.patch" already exists
  % qnew -f from a subdirectory
  popping first.patch
  popping mtest.patch
  popping uncommitted.patch
  patch queue now empty
  adding d/b
  M d/b
  # HG changeset patch
  # Parent 
  diff --git a/d/b b/d/b
  --- a/d/b
  +++ b/d/b
  @@ -1,1 +1,2 @@
   b
  +b
  % qnew -u with no username configured
  # HG changeset patch
  # Parent 
  # User blue
  % qnew -e -u with no username configured
  # HG changeset patch
  # Parent 
  # User chartreuse
  % fail when trying to import a merge
  adding a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  created new head
  merging a
  warning: conflicts during merge.
  merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  abort: cannot manage merge changesets
  $ rm -r sandbox