08 January 2019

Nuitka Release 0.6.1

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler, “download now”.

This release comes after a relatively long time, and contains important new optimization work, and even more bug fixes.

Bug Fixes

  • Fix, the options --[no]follow-import-to=package_name was supposed to not follow into the given package, but the check was executed too broadly, so that e.g. package_name2 was also affected. Fixed in already.

  • Fix, wasn’t detecting multiple recursions into the same package in module mode, when attempting to compile a whole sub-package. Fixed in already.

  • Fix, constant values are used as C boolean values still for some of the cases. Fixed in already.

  • Fix, referencing a function cannot raise an exception, but that was not annotated. Fixed in already.

  • macOS: Use standard include of C bool type instead of rolling our own, which was not compatible with newest Clang. Fixed in already.

  • Python3: Fix, the bytes built-in type actually does have a __float__ slot. Fixed in already.

  • Python3.7: Types that are also sequences still need to call the method __class_getitem__ for consideration. Fixed in already.

  • Python3.7: Error exits from program exit could get lost on Windows due to __spec__ handling not preserving errors. Fixed in already.

  • Windows: Negative exit codes from Nuitka, e.g. due to a triggered assertion in debug mode were not working. Fixed in already.

  • Fix, conditional and expressions were mis-optimized when not used to not execute the right hand side still. Fixed in already.

  • Python3.6: Fix, generators, coroutines, and asyncgen were not properly supporting annotations for local variables. Fixed in already.

  • Python3.7: Fix, class declarations had memory leaks that were untestable before 3.7.1 fixed reference count issues in CPython. Fixed in already.

  • Python3.7: Fix, asyncgen expressions can be created in normal functions without an immediate awaiting of the iterator. This new feature was not correctly supported.

  • Fix, star imports on the module level should disable built-in name optimization except for the most critical ones, otherwise e.g. names like all or pow can become wrong. Previous workarounds for pow were not good enough.

  • Fix, the scons for Python3 failed to properly report build errors due to a regression of the Scons version used for it. This would mask build errors on Windows.

  • Python3.4: Fix, packages didn’t indicate that they are packages in their __spec__ value, causing issues with importlib_resources module.

  • Python3.4: The __spec__ values of compiled modules didn’t have compatible origin and has_location values preventing importlib_resources module from working to load data files.

  • Fix, packages created from .pth files were also considered when checking for sub-packages of a module.

  • Standalone: Handle cases of conflicting DLLs better. On Windows pick the newest file version if different, and otherwise just report and pick randomly because we cannot really decide which ought to be loaded.

  • Standalone: Warn about collisions of DLLs on non-Windows only as this can happen with wheels apparently.

  • Standalone: For Windows Python extension modules .pyd files, remove the SxS configuration for cases where it causes problems, not needed.

  • Fix: The exec statement on file handles was not using the proper filename when compiling, therefore breaking e.g. inspect.getsource on functions defined there.

  • Standalone: Added support for OpenGL platform plugins to be included automatically.

  • Standalone: Added missing implicit dependency for zmq module.

  • Python3.7: Fix, using the -X utf8 flag on the calling interpreter, aka --python-flag=utf8_mode was not preserved in the compiled binary in all cases.


  • Enabled C target type void which will catch creating unused stuff more immediately and give better code for expression only statements.

  • Enabled in-place optimization for module variables, avoiding write back to the module dict for unchanged values, accelerating these operations.

  • Compile time memory savings for the yield node of Python2, no need to track if it is in an exception handler, not relevant there.

  • Using the single child node for the yield nodes gives memory savings at compile time for these, while also making them operate faster.

  • More kinds of in-place operations are now optimized, e.g. int += int and the bytes ones were specialized to perform real in-place extension where possible.

  • Loop variables no longer loose type information, but instead collect the set of possible type shapes allowing optimization for them.


  • Corrected download link for Arch AUR link of develop package.

  • Added repository for Ubuntu Cosmic (18.10) for download.

  • Added repository for Fedora 29 for download.

  • Describe the exact format used for clang-format in the Developer Manual.

  • Added description how to use CondaCC on Windows to the User Manual.


  • The operations used for async for, async with, and await were all doing a look-up of an awaitable, and then executing the yield from that awaitable as one thing. Now this is split into two parts, with a new ExpressionYieldFromAwaitable as a dedicated node.

  • The yield node types, now 3 share a base class and common computation for now, enhancing the one for awaitiable, which was not fully annotating everything that can happen.

  • In code generation avoid statement blocks that are not needed, because there are no local C variables declared, and properly indent them.


  • Fixups for the manual Valgrind runner and the UI changes.

  • Test runner detects lock issue of clcache on Windows and considers it a permission problem that causes a retry.


This addresses even more corner cases not working correctly, the out of the box experience should be even better now.

The push towards C level performance for integer operation was held up by the realization that loop SSA was not yet there really, and that it had to be implemented, which of course now makes a huge difference for the cases where e.g. bool are being used. There is no C type for int used yet, which limits the impact of optimization to only taking shortcuts for the supported types. These are useful and faster of course, but only building blocks for what is to come.

Most of the effort went into specialized helpers that e.g. add a float and and int value in a dedicated fashion, as well as comparison operations, so we can fully operate some minimal examples with specialized code. This is too limited still, and must be applied to ever more operations.

What’s more is that the benchmarking situation has not improved. Work will be needed in this domain to make improvements more demonstrable. It may well end up being the focus for the next release to improve Nuitka speedcenter to give more fine grained insights across minor changes of Nuitka and graphs with more history.