Nuitka Release 0.5.9

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler. Please see the page "What is Nuitka?" for an overview.

This release is mostly a maintenance release, bringing out minor compatibility improvements, and some standalone improvements. Also new options to control the recursion into modules are added.

Bug Fixes

  • Compatibility: Checks for iterators were using PyIter_Check which is buggy when running outside of Python core, because it's comparing pointers we don't see. Replaced with HAS_ITERNEXT helper which compares against the pointer as extracting for a real non-iterator object.

    class Iterable:
        def __init__(self):
            self.consumed = 2
        def __iter__(self):
            return Iterable()
    iter(Iterable()) # This is suppose to raise, but didn't with Nuitka
  • Python3: Errors when creating class dictionaries raised by the __prepare__ dictionary (e.g. enum classes with wrong identifiers) were not immediately raised, but only by the type call. This was not observable, but might have caused issues potentially.

  • Standalone MacOS: Shared libraries and extension modules didn't have their DLL load paths updated, but only the main binary. This is not sufficient for more complex programs.

  • Standalone Linux: Shared libraries copied into the .dist folder were read-only and executing chrpath could potentially then fail. This has not been observed, but is a conclusion of MacOS fix.

  • Standalone: When freezing standard library, the path of Nuitka and the current directory remained in the search path, which could lead to looking at the wrong files.


  • The getattr built-in is now optimized for compile time constants if possible, even in the presence of a default argument. This is more a cleanup than actually useful yet.
  • The calling of PyCFunction from normal Python extension modules got accelerated, especially for the no or single argument cases where Nuitka now avoids building the tuple.

New Features

  • Added the option --recurse-pattern to include modules per filename, which for Python3 is the only way to not have them in a package automatically.

  • Added the option --generate-c++-only to only generate the C++ source code without starting the compiler.

    Mostly used for debugging and testing coverage. In the later case we do not want the C++ compiler to create any binary, but only to measure what would have been used.


  • Renamed the debug option --c++-only to --recompile-c++-only to make its purpose more clear and there now is --generate-c++-only too.


  • Added support for taking coverage of Nuitka in a test run on a given input file.
  • Added support for taking coverage for all Nuitka test runners, migrating them all to common code for searching.
  • Added uniform way of reporting skipped tests, not generally used yet.


This release marks progress towards having coverage testing. Recent releases had made it clear that not all code of Nuitka is actually used at least once in our release tests. We aim at identifying these.

Another direction was to catch cases, where Nuitka leaks exceptions or is subject to leaked exceptions, which revealed previously unnoticed errors.

Important changes have been delayed, e.g. the closure variables will not yet use C++ objects to share storage, but proper PyCellObject for improved compatibility, and to approach a more "C-ish" status. These is unfinished code that does this. And the forward propagation of values is not enabled yet again either.

So this is an interim step to get the bug fixes and improvements accumulated out. Expect more actual changes in the next releases.


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