test_unraisable() of test_exceptions expects that PyErr_WriteUnraisable(method)
fails on repr(method).
Before the previous change (7b8df4a5d81d), slot_tp_finalize() called
PyErr_WriteUnraisable() with a PyMethodObject. In this case, repr(method) calls
repr(self) which is BrokenRepr.__repr__() and the calls raises a new exception.
After the previous change, slot_tp_finalize() uses an unbound method: repr() is
called on a regular __del__() method which doesn't call repr(self). repr()
doesn't fail anymore.
PyErr_WriteUnraisable() doesn't call __repr__() anymore, so remove BrokenRepr
unit test.
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.
