# What's new in PyPy2.7 5.7

Since a while now, PyPy preserves the order of dictionaries and sets. However, the set literal syntax `{x, y, z}` would by mistake build a set with the opposite order: `set([z, y, x])`. This has been fixed. Note that CPython is inconsistent too: in 2.7.12, `{5, 5.0}` would be `set([5.0])`, but in 2.7.trunk it is `set([5])`. PyPy's behavior changed in exactly the same way because of this fix.

Backport rpython changes made directly on the py3k and py3.5 branches.

Any uncaught RPython exception (from a PyPy bug) is turned into an app-level SystemError. This should improve the lot of users hitting an uncaught RPython error.

Try to improve the consistency of RPython annotation unions.

Clean-ups in the jit optimizeopt

Add jit.conditional_call_elidable(), a way to tell the JIT "conditionally call this function" returning a result.

Refactor FunctionDesc.specialize() and related code (RPython annotator).

Assign `tp_doc` to the new TypeObject's type dictionary `__doc__` key so it will be picked up by app-level objects of that type

Module cppyy now uses cling as its backend (Reflex has been removed). The user-facing interface and main developer tools (genreflex, selection files, class loader, etc.) remain the same. A libcppyy_backend.so library is still needed but is now available through PyPI with pip: PyPy-cppyy-backend.

The Cling-backend brings support for modern C++ (11, 14, etc.), dynamic template instantiations, and improved integration with CFFI for better performance. It also provides interactive C++ (and bindings to that).

Improve the performance of `PyDict_Next`. When trying `PyDict_Next` on a typedef dict, the test exposed a problem converting a `GetSetProperty` to a `PyGetSetDescrObject`. The other direction seem to be fully implemented. This branch made a minimal effort to convert the basic fields to avoid segfaults, but trying to use the `PyGetSetDescrObject` will probably fail.

Updated the implementation to match CPython 2.7.13 instead of 2.7.13.

Fix `PyObject_GetBuffer` and `PyMemoryView_GET_BUFFER`, which leaked memory and held references. Add a finalizer to CPyBuffer, add a PyMemoryViewObject with a PyBuffer attached so that the call to `PyMemoryView_GET_BUFFER` does not leak a PyBuffer-sized piece of memory. Properly call `bf_releasebuffer` when not `NULL`.

Support translations of cpyext with the Boehm GC (for special cases like revdb).

Implement StringBuffer.get_raw_address (missing feature for the buffer protocol). More generally it is now possible to obtain the address of any object (if it is readonly) without pinning it.

Refactor cpyext initialisation.

Fix a test failure introduced by strbuf-as-buffer

Do not recreate the object in PyMemoryView_FromBuffer, rather pass it to the returned PyMemoryViewObject, to take ownership of it. Fixes a ref leak.

Give (almost?) all GetSetProperties a valid __objclass__.

Improve mixing app-level classes in c-extensions, especially if the app-level class has a `tp_new` or `tp_dealloc`. The issue is that c-extensions expect all the method slots to be filled with a function pointer, where app-level will search up the mro for an appropriate function at runtime. With this branch we now fill many more slots in the c-extenion type objects. Also fix for c-extension type that calls `tp_hash` during initialization (str, unicode types), and fix instantiating c-extension types from built-in classes by enforcing an order of instaniation.

rffi structures in cpyext can now be created by parsing simple C headers. Additionally, the cts object that holds the parsed information can act like cffi's ffi objects, with the methods cts.cast() and cts.gettype().

Don't freeze hashes in the translated pypy. In practice, that means that we can now translate PyPy with the option --hash=siphash24 and get the same hashes as CPython 3.5, which can be randomized (in a crypographically good way). It is the default in PyPy3. The default of PyPy2 remains unchanged: there are user programs out there that depend on constant hashes (or even sometimes on specific hash results).

Our dicts, which are always ordered, now have an extra "method" for Python 3.x which moves an item to first or last position. In PyPy 3.5 it is the standard `OrderedDict.move_to_end()` method, but the behavior is also available on Python 2.x or for the `dict` type by calling `__pypy__.move_to_end(dict, key, last=True)`.

Improve the optimization of branchy Python code by retaining more information across failing guards.

Internal refactoring of `space.wrap()`, which is now replaced with explicitly-typed methods. Notably, there are now `space.newbytes()` and `space.newtext()`: these two methods are identical on PyPy 2.7 but not on PyPy 3.x. The latter is used to get an app-level unicode string by decoding the RPython string, assumed to be utf-8.

Fix for `ctypes.c_bool`-returning ctypes functions

space.text_w now encodes to utf-8 not preserving surrogates.

Improve handling of the Py3-style buffer slots in cpyext: fix memoryviews keeping objects alive forever (missing decref), and make sure that bf_releasebuffer is called when it should, e.g. from PyBuffer_Release.

Fix bug (bad reported info) when asked to translate SyntaxWarning to SyntaxError.

Improve the optimization of branchy Python code by retaining more information across failing guards. This is done by appending some carefully encoded extra information into the resume code.

Two changes that together bring the performance of shadowstack close to asmgcc---close enough that we can now make shadowstack the default even on Linux. This should remove a whole class of rare bugs introduced by asmgcc.