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.

debuginstall: change showing to checking for consistency and future checking

debuginstall: add Python information to debuginstall output (issue4128) This change adds to the output of "hg debuginstall" information about the Python being used by Mercurial. It adds both the path to the Python executable (i.e. the value of sys.executable) and the version of Python (specifically the major, minor, and micro versions). Below is an example of what the output looks like after this change. The marked lines are the new output lines: $ hg debuginstall checking encoding (UTF-8)... -->showing Python executable (/Users/chris/.virtualenvs/default/bin/python) -->showing Python version (2.7.6) checking Python lib (/Users/chris/.virtualenvs/default/lib/python2.7)... checking installed modules (/Users/chris/mercurial)... checking templates (/Users/chris/mercurial/templates)... checking commit editor... checking username... no problems detected Note that we use the word "showing" without an ellipsis for the new lines because, unlike the other lines (except for "Python lib" which will be adjusted in a subsequent commit), no check follows the display of this information.

revset: add documentation and comment for _generatorset (clean up some old irrelevant comment in the process)

revset: add some documentation for lazyset

revset: added documentation and comment for spanset class

revset: extend sorting tests

merge with crew

revset: changed smartset methods to return ordered addsets Now when adding two structures that are ordered, they are wrapped into an _addset and they get added lazily while keeping the order.

revset: added isascending and isdescending methods to _addset This methods are intended to duck-type baseset, so we will still have _addset as a private class but now we can return it without wrapping it into an orderedlazyset or a lazyset. These were the last methods to add for smartset compatibility.