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.

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Mercurial supports a functional language for selecting a set of

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files.

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Like other file patterns, this pattern type is indicated by a prefix,

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'set:'. The language supports a number of predicates which are joined

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by infix operators. Parenthesis can be used for grouping.

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Identifiers such as filenames or patterns must be quoted with single

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or double quotes if they contain characters outside of

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``[.*{}[]?/\_a-zA-Z0-9\x80-\xff]`` or if they match one of the

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predefined predicates. This generally applies to file patterns other

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than globs and arguments for predicates.

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Special characters can be used in quoted identifiers by escaping them,

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e.g., ``\n`` is interpreted as a newline. To prevent them from being

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interpreted, strings can be prefixed with ``r``, e.g. ``r'...'``.

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There is a single prefix operator:

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``not x``

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  Files not in x. Short form is ``! x``.

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These are the supported infix operators:

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``x and y``

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  The intersection of files in x and y. Short form is ``x & y``.

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``x or y``

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  The union of files in x and y. There are two alternative short

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  forms: ``x | y`` and ``x + y``.

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``x - y``

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  Files in x but not in y.

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The following predicates are supported:

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.. predicatesmarker

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Some sample queries:

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- Show status of files that appear to be binary in the working directory::

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    hg status -A "set:binary()"

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- Forget files that are in .hgignore but are already tracked::

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    hg forget "set:hgignore() and not ignored()"

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- Find text files that contain a string::

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    hg locate "set:grep(magic) and not binary()"

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- Find C files in a non-standard encoding::

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    hg locate "set:**.c and not encoding('UTF-8')"

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- Revert copies of large binary files::

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    hg revert "set:copied() and binary() and size('>1M')"

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- Remove files listed in foo.lst that contain the letter a or b::

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    hg remove "set: 'listfile:foo.lst' and (**a* or **b*)"

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See also :hg:`help patterns`.