The implementation of weakref.proxy's methods call back into the Python
API using a borrowed references of the weakly referenced object
(acquired via PyWeakref_GET_OBJECT). This API call may delete the last
reference to the object (either directly or via GC), leaving a dangling
pointer, which can be subsequently dereferenced.
To fix this, claim a temporary ownership of the referenced object when
calling the appropriate method. Some functions because at the moment they
do not need to access the borrowed referent, but to protect against
future changes to these functions, ownership need to be fixed in
all potentially affected methods.
Some objects like Py_None are not initialized with conventional means
that prepare the circular linked list pointers, leaving them unlinked
from the rest of the objects. For those objects, NULL pointers does
not mean that they are freed, so we need to skip the check in those
cases.
bpo-36389, bpo-38376: The _PyObject_CheckConsistency() function is
now also available in release mode. For example, it can be used to
debug a crash in the visit_decref() function of the GC.
Modify the following functions to also work in release mode:
* _PyDict_CheckConsistency()
* _PyObject_CheckConsistency()
* _PyType_CheckConsistency()
* _PyUnicode_CheckConsistency()
Other changes:
* _PyMem_IsPtrFreed(ptr) now also returns 1 if ptr is NULL
(equals to 0).
* _PyBytesWriter_CheckConsistency() now returns 1 and is only used
with assert().
* Reorder _PyObject_Dump() to write safe fields first, and only
attempt to render repr() at the end.
bpo-37802, bpo-38321: Fix the following warnings:
longobject.c(420): warning C4244: 'function': conversion from
'unsigned __int64' to 'sdigit', possible loss of data
longobject.c(428): warning C4267: 'function': conversion from
'size_t' to 'sdigit', possible loss of data
Document that lnotab can contain invalid bytecode offsets (because of
terrible reasons that are difficult to fix). Make dis.findlinestarts()
ignore invalid offsets in lnotab. All other uses of lnotab in CPython
(various reimplementations of addr2line or line2addr in Python, C and gdb)
already ignore this, because they take an address to look for, instead.
Add tests for the result of dis.findlinestarts() on wacky constructs in
test_peepholer.py, because it's the easiest place to add them.
Even when the helper is not started yet.
This behavior follows conventional generator one.
There is no reason for `async_generator_athrow` to handle `gen.throw()` differently.
https://bugs.python.org/issue38013
In ArgumentClinic, value "NULL" should now be used only for unrepresentable default values
(like in the optional third parameter of getattr). "None" should be used if None is accepted
as argument and passing None has the same effect as not passing the argument at all.
* Fix a crash in comparing with float (and maybe other crashes).
* They are now never equal to strings and non-integer numbers.
* Comparison with a large number no longer raises OverflowError.
* Arbitrary exceptions no longer silenced in constructors and comparisons.
* TypeError raised in the constructor contains now the name of the type.
* Accept only ChannelID and int-like objects in channel functions.
* Accept only InterpreterId, int-like objects and str in the InterpreterId constructor.
* Accept int-like objects, not just int in interpreter related functions.
All call sites pass NULL for `recode_encoding`, so this path is
completely untested. That's been true since before Python 3.0.
It adds significant complexity to this logic, so it's best to
take it out.
All call sites now have a literal NULL, and that's been true since
commit 768921cf3 eliminated a conditional (`foo ? bar : NULL`) at
the call site in Python/ast.c where we're parsing a bytes literal.
But even before then, that condition `foo` had been a constant
since unadorned string literals started meaning Unicode, in commit
572dbf8f1 aka v3.0a1~1035 .
The `unicode` parameter is already unused, so mark it as unused too.
The code that acted on it was also taken out before Python 3.0, in
commit 8d30cc014 aka v3.0a1~1031 .
The function (PyBytes_DecodeEscape) is exposed in the API, but it's
never been documented.
bpo-37151: remove special case for PyCFunction from PyObject_Call
Alse, make the undocumented function PyCFunction_Call an alias
of PyObject_Call and deprecate it.
The instance destructor for a type is responsible for preparing
an instance for deallocation by decrementing the reference counts
of its referents.
If an instance belongs to a heap type, the type object of an instance
has its reference count decremented while for static types, which
are permanently allocated, the type object is unaffected by the
instance destructor.
Previously, the default instance destructor searched the class
hierarchy for an inherited instance destructor and, if present,
would invoke it.
Then, if the instance type is a heap type, it would decrement the
reference count of that heap type. However, this could result in the
premature destruction of a type because the inherited instance
destructor should have already decremented the reference count
of the type object.
This change avoids the premature destruction of the type object
by suppressing the decrement of its reference count when an
inherited, non-default instance destructor has been invoked.
Finally, an assertion on the Py_SIZE of a type was deleted. Heap
types have a non zero size, making this into an incorrect assertion.
https://github.com/python/cpython/pull/15323
This is the sort of `goto` that requires the reader to stare hard at
the code to unpick what it's doing.
On doing so, the answer is... not very much!
* It jumps from the bottom of the loop to almost the top; the effect
is to bypass the loop condition `s < end` and also the
`if`-condition `*s != '\\'`, acting as if both are true.
* We've just decremented `s`, after incrementing it in the `switch`
condition. So it has the same value as when `s == end` failed.
Before that was another increment... and before that we had
`s < end`. So `s < end` true, then increment, then `s == end`
false... that means `s < end` is still true.
* Also this means `s` points to the same character as it did for the
`switch` condition. And there was a `case '\\'`, which we didn't
hit -- so `*s != '\\'` is also true.
* That means this has no effect on the behavior! The most it might do
is an optimization -- we get to skip those two checks, because (as
just proven above) we know they're true.
* But gosh, this is the *invalid escape sequence* path. This does not
seem like the kind of code path that calls for extreme optimization
tricks.
So, take the `goto` and the label out.
Perhaps the compiler will notice the exact same facts we showed above,
and generate identical code. Or perhaps it won't! That'll be OK.
But then, crucially, if some future edit to this loop causes the
reasoning above to *stop* holding true... the compiler will adjust
this jump accordingly. One of us fallible humans might not.
* Use the 'p' format unit instead of manually called PyObject_IsTrue().
* Pass boolean value instead 0/1 integers to functions that needs boolean.
* Convert some arguments to boolean only once.
Dong-hee Na
Zachary Ware
Pablo Galindo
Serhiy Storchaka
Victor Stinner
Hai Shi
Victor Stinner
Yury Selivanov
T. Wouters
Eddie Elizondo
HongWeipeng
Andrew Svetlov
Greg Price
Raymond Hettinger
Sergey Fedoseev
Daniel Andrade
Valentin Haenel
Jeroen Demeyer
Eddie Elizondo
Jordon Xu
dalgarno
HongWeipeng
Joannah Nanjekye
animalize
Zackery Spytz
Min ho Kim
Rémi Lapeyre