PyObject_IsSubclass() can fail and raise a new exception!

Type "o" format of Py_BuildValue() is invalid: it must be "O".

It was easy to miss the call to type->tp_init because it was done in a long
conditional expression. Split the long expression in multiple lines to make the
debug step by step easier.

and ignores exceptions raised during the call

Pass the MemoryError exception to the caller, instead of using empty keys.

As PyDict_GetItem(), PyDict_GetItemString() suppresses all errors that may
occur for historical reasons.

notify exceptions raised by the _PyUnicodeWriter API

bytes is NULL on _PyBytes_Resize() failure

Useed context managers for file I/O.
Removed out-of-dated code and misleading comments.

Useed context managers for file I/O.
Removed out-of-dated code and misleading comments.

Patch by Vajrasky Kok.

Zachary Ware.)

Zachary Ware.)

_Py_DisplaySourceLine()

For example, _PyGC_DumpShutdownStats() calls PyErr_WarnExplicitFormat() while
the import machinery does not work anymore, _Py_DisplaySourceLine() fails when
trying to import the io module.

earlier

Report _Py_FindSourceFile() error, so the error is cleared;
and clear io.open(filename) exception on failure.

Don't pass a NULL traceback to PyException_SetTraceback(): pass Py_None.
Passing NULL would raise a new exception.

  object's custom `__hash__()` method.

failure

exception was not raised.

Before the process was killed by SIGALRM in another random test (1 second later)

on memory allocation failure

and _PyUnicode_HAS_WSTR_MEMORY() macros

These macros are called in unicode_dealloc(), whereas the unicode object can be
"inconsistent" if the creation of the object failed.

For example, when unicode_subtype_new() fails on a memory allocation,
_PyUnicode_CheckConsistency() fails with an assertion error because data is
NULL.

if the function called failed whereas no exception was raised, to detect bugs
earlier.

Check if XML_ParserCreate_MM() failed (ex: MemoryError) before using
self->itself.