25 January 2021

Nuitka Release 0.6.11

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

This release is a massive improvement in many ways with lots of bug fixes and new features.

Bug Fixes

  • Fix, the .pyi file parser didn’t handle relative imports. Fixed in already.

  • Windows: Fix, multiprocessing plugin was not working reliable following of imports from the additional entry point. Fixed in already.

  • Pipenv: Workaround parsing issue with our setup.py to allow installation from GitHub. Fixed in already.

  • Merging of branches in optimization could give nondeterministic results leading to more iterations than necessary. Fixed in already.

  • Windows: Avoid profile powershell when attempting to resolve symlinks. Fixed in already.

  • Windows: Fix, always check for stdin, stdout, and stderr presence. This was so far restricted to gui mode applications, but it seems to be necessary in other situations too. Fixed in already.

  • Python2: Fix, --trace-execution was not working for standalone mode but can be useful for debugging. Fixed in already.

  • Windows: Onefile could run into path length limits. Fixed in already.

  • Windows: The winlib gcc download link became broken and was updated. Fixed in already.

  • Plugins: The “__main__” module was not triggering all plugin hooks, but it needs to for completeness.

  • Standalone: Fix, symlinked Python installations on Windows were not working, with dependency walker being unable to look into these. Fixed in already.

  • Standalone: Fix support for numpy on Windows and macOS, the plugin failed to copy important DLLs. Fixed in already.

  • Python3: For versions before 3.7, the symlink resolution also needs to be done, but wasn’t handling the bytes output yet. Fixed in already.

  • Fix, folder based inclusion would both pick up namespace folders and modules of the same name, crashing the compilation due to conflicts. Fixed in already.

  • Fix, the --lto wasn’t used for clang on non-Windows yet.

  • Fix, the order of locals dict releases wasn’t enforced, which could lead to differences that break caching of C files potentially. Fixed in already.

  • Fix, hash nodes didn’t consider if their argument was raising, even if the type of the argument was str and therefore the operation should not. Fixed in already.

  • Fix, need to copy type shape and escape description for the replacement inverted comparisons when used with not, otherwise the compilation can crash as these are expected to be present at all times. Fixed in already.

  • Fix, some complex constant values could be confused, e.g. -0j and 0j. These corner cases were not properly considered in the constant loading code, only for float so far.

  • Standalone: Fix, bytecode only standard library modules were not working. This is at least used with Fedora 33.

  • Linux: Fix, extension modules compiled with --lto were not working.

  • Windows: Retry if updating resources fails due to Virus checkers keeping files locked.

  • Plugins: Pre- and postload code of modules should not be allowed to cause ImportError, as these will be invisible to the other parts of optimization, instead make them unraisable error traces.

  • Standalone: Adding missing import for SciPy 1.6 support.

  • Windows: Fix, only export required symbols when using MinGW64 in module mode.

New Features

  • Python3.9: Added official support for this version.

  • Onefile: Added command line options to include data files. These are --include-package-data which will copy all non-DLLs and non-Python files of package names matching the pattern given. And --include-data-file takes source and relative target file paths and copies them. For onefile this is the only way to include files, for standalone mode they are mostly a convenience function.

  • Onefile: Added mode where the file is unpacked to a temporary folder before running instead of doing it to appdata.

  • Onefile: Added linux specific options --linux-onefile-icon to allow provision of an icon to use in onefile mode on Linux, so far this was only available as the hard coded path to a Python icon, which also didn’t exist on all platforms.

  • UI: Major logging cleanup. Everything is now using our tracing classes and even error exits go through there and are therefore colored if possible.

  • Plugins: Make it easier to integrate commercial plugins, now only an environment variable needs to point to them.

  • UI: Enhanced option parsing gives notes. This complains about options that conflict or that are implied in others. Trying to catch more usage errors sooner.

  • Plugins: Ignore exceptions in buggy plugin code, only warn about them unless in debug mode, where they still crash Nuitka.

  • Scons: More complete scons report files, includes list values as well and more modes used.

  • Windows: The clcache is now included and no longer used from the system.

  • Output for clcache and ccache results got improved.

  • Enhanced support for clang, on Windows if present near a gcc.exe like it is the case for some winlibs downloads, it will be used. To use it provide --mingw64 --clang both. Without the first one, it will mean clangcl.exe which uses the MSVC compiler as a host.


  • Some modules had very slow load times, e.g. if they used many list objects due to linear searches for memory deduplication of objects. We now have dictionaries of practically all constant objects loaded, making these more instant.

  • Use less memory at compile time due using __slots__ for all node types, finally figured out, how to achieve this with multiple inheritance.

  • Use hedley for compiler macros like unlikely as they know best how to do these.

  • Special case the merging of 2 branches avoiding generic code and being much faster.

  • Hard imports have better code generated, and are being optimized into for the few standard library modules and builtin modules we handle, they also now annotate the type shape to be module.

  • No longer annotate hard module import attribute lookups as control flow escapes. Not present attributes are changed into static raises. Trust for values is configured for a few values, and experimental.

  • Avoid preloaded packages for modules that have no side effects and are in the standard library, typically .pth files will use e.g. os but that’s not needed to be preserved.

  • Use incbin for including binary data through inline assembly of the C compiler. This covers many more platforms than our previous linker option hacks, and the fallback to generated C code. In fact everything but Windows uses this now.


  • Windows: For Scons we now require a Python 3.5 or higher to be installed to use it.

  • Windows: Removed support for gcc older than version 8. This specifically affects CondaCC and older MinGW64 installations. Since Nuitka can now download the MinGW64 10, there is no point in having these and they cause issues.

  • We took over the maintenance of clcache as Nuitka/clcache which is not yet ready for public consumption, but should become the new source of clache in the future.

  • Include an inline copy of clcache in Nuitka and use it on Windows for MSVC and ClangCL.

  • Removed compatibility older aliases of follow option, --recurse-* and require --follow-* options to be used instead.

  • For pylint checking, the tool now supports a --diff mode where only the changed files get checked. This is much faster and allows to do it more often before commit.

  • Check the versions of isort and black when doing the auto-format to avoid using outdated versions.

  • Handling missing pylint more gracefully when checking source code quality.

  • Make sure to use the codespell tool with Python3 and make sure to error exit when spelling problems were found, so we can use this in GitHub actions too.

  • Removed Travis config, we now only use GitHub actions.

  • Removed landscape config, it doesn’t really exist anymore.

  • Bumped all PyPI dependnecies to their latest versions.

  • Recommend ccache on Debian, as we now consider the absence of ccache something to warn about.

  • Plugins: The DLLs asked for by plugins that are not found are no longer warned about.

  • Allow our checker and format tools to run on outside of tree code. We are using that for Nuitka/clcache.

  • Added support for Fedora 33 and openSUSE 15.3, as well as Ubuntu Groovy.

  • Windows: Check if Windows SDK is installed for MSVC and ClangCL.

  • Windows: Enhanced wording in case no compiler was found. No longer tell people how to manually install MinGW64, that is no longer necessary and pywin32 is not needed to detect MSVC, so it’s not installed if not found.

  • Detect “embeddable Python” by missing include files, and reject it with proper error message.

  • Added onefile and standalone as a use case to the manual and put also the DLL and data files problems as typically issues.


  • Avoid decimal and string comparisons for Python versions checks, these were lazy and are going to break once 3.10 surfaces. In testing we now use tuples, in Nuitka core hexacimal values much like CPython itself does.

  • Stop using subnode child getters and setters, and instead only use subnode attributes. This was gradually changed so far, but in this release all remaining uses have migrated. This should also make the optimization stage go faster.

  • Change node constructors to not use a decorator to resolve conflicts with builtin names, rather handle these with manual call changes, the decorator only made it difficult to read and less performant.

  • Move safe string helpers to their own dedicated helper file, allowing for reuse in plugin code that doesn’t want to use all of Nuitka C helpers.

  • Added utils code for inline copy imports, as we use that for quite a few things now.

  • Further restructured the Scons files to use more common code.

  • Plugins: The module name objects now reject many str specific APIs that ought to not be used, and the code got changed to use these instead, leading to cleaner and more correct usages.

  • Using named tuples to specify included data files and entry points.

  • Use pkgutil in plugins to scan for modules rather than listing directories.


  • New option to display executed commands during comparisons.

  • Added test suite for onefile testing.


This release has seen Python3.9 and Onefile both being completed. The later needs compression added on Windows, but that can be added in a coming release, for now it’s fully functional.

The focus clearly has been on massive cleanups, some of which will affect compile time performance. There is relatively little new optimization otherwise.

The adoption of clcache enables a very fast caching, as it’s now loaded directly into the Scons process, avoiding a separate process fork.

Generally a lot of polishing has been applied with many cleanups lowering the technical debt. It will be interesting to see where the hard module imports can lead us in terms of more optimization. Static optimization of the Python version comparisons and checks is needed to lower the amount of imports to be processed.

Important fixes are also included, e.g. the constants loading performance was too slow in some cases. The multiprocessing on Windows and numpy plugins were regressed and finally everything ought to be back to working fine.

Future work will have to aim at enhanced scalability. In some cases, Nuitka still takes too much time to compile if projects like Pandas include virtually everything installed as an option for it to use.