This restores details lost in revision 097f4fda61a4 (since Python 3.3,
related to the new OSError subclasses). Further additions:
* Markup for attributes and constructor signature
* Explain "winerror" and "filename2"
* Extend test to check for filename2 defaulting to None
* Clarify that the constructor can return a subclass
I have intentionally left out any details of allowing more than five
arguments, or how the "args" attribute is set for four or more arguments.
These details seem to be dependent on the Python version and platform.
now register both filenames in the exception on failure.
This required adding new C API functions allowing OSError exceptions
to reference two filenames instead of one.
ImportError.
The exception is raised by import when a module could not be found.
Technically this is defined as no viable loader could be found for the
specified module. This includes ``from ... import`` statements so that
the module usage is consistent for all situations where import
couldn't find what was requested.
This should allow for the common idiom of::
try:
import something
except ImportError:
pass
to be updated to using ModuleNotFoundError and not accidentally mask
ImportError messages that should propagate (e.g. issues with a
loader).
This work was driven by the fact that the ``from ... import``
statement needed to be able to tell the difference between an
ImportError that simply couldn't find a module (and thus silence the
exception so that ceval can raise it) and an ImportError that
represented an actual problem.
Currently import does not use these attributes as they are planned
for use by importlib (which will be another commit).
Thanks to Filip Gruszczyński for the initial patch and Brian Curtin
for refining it.
Many tests simply didn't care if they unset a pre-existing trace function. This
made test coverage impossible. This patch fixes various tests to put back any
pre-existing trace function. It also introduces test.support.no_tracing as a
decorator which will temporarily unset the trace function for tests which
simply fail otherwise.
Thanks to Kristian Vlaardingerbroek for helping to find the cause of various
trace function unsets.
Serhiy Storchaka
Martin Panter
Yury Selivanov
Victor Stinner
Antoine Pitrou
Benjamin Peterson
Larry Hastings
Brett Cannon
Andrew Svetlov
Philip Jenvey
Nadeem Vawda
Richard Oudkerk
Nick Coghlan
Brett Cannon
Ezio Melotti