Include/pyerrors.h (part 2)

cpython 3.14 @ ab2d84fe1023/Include/pyerrors.h ↗

This annotation covers the exception-testing macros, the OS-error helpers, the warning API, and the chained-exception utilities declared in Include/pyerrors.h. For the core PyErr_SetString / PyErr_Occurred / PyErr_Fetch declarations see the include_pyerrors_h annotation.

Map

Lines	Symbol	Role
1-60	PyExceptionInstance_Check, PyExceptionClass_Check	Type predicates for exception objects
61-110	PyErr_SetFromErrno, PyErr_SetFromErrnoWithFilename	OS errno to Python OSError conversion
111-160	PyErr_WarnEx, PyErr_WarnFormat, PyErr_WarnExplicit	Warning API
161-220	_PyErr_ChainExceptions, PyErr_SetImportErrorWithNameFrom	Chaining and import errors

Reading

PyExceptionInstance_Check

// CPython: Include/pyerrors.h:22 PyExceptionInstance_Check
#define PyExceptionInstance_Check(x) \
    (PyType_IsSubtype(Py_TYPE(x), (PyTypeObject *)PyExc_BaseException))

This macro is the standard way to test whether an arbitrary Python object is an exception instance. It returns true for Exception, BaseException, and all their subclasses.

PyErr_SetFromErrno

PyErr_SetFromErrno(exc) reads errno and calls PyErr_SetObject(exc, OSError(errno, strerror(errno))). PyErr_SetFromErrnoWithFilename additionally sets the filename attribute, which is printed in FileNotFoundError messages.

Warning API

PyErr_WarnEx(category, message, stacklevel) issues a warning by calling the warnings.warn machinery. stacklevel controls how far up the call stack the warning appears to originate. stacklevel=2 (common in C extensions) attributes the warning to the Python caller rather than to the C function.

_PyErr_ChainExceptions

This internal function sets __context__ on the current exception to a prior exception, implementing the "during handling of the above exception" chain without going through Python-level raise.

gopy notes

PyExceptionInstance_Check maps to py.IsInstance(x, py.BaseException) in gopy. The warning API maps to module/warnings/. _PyErr_ChainExceptions is internal to Python/errors.c; the gopy analogue is handled in vm/eval_unwind.go.