A new SCons release, 4.5.2, is now available on the SCons download page: https://scons.org/pages/download.html Here is a summary of the changes since 4.5.1: FIXES ----- - Fix a problem (#4321) in 4.5.0/4.5.1 where ParseConfig could cause an exception in MergeFlags when the result would be to add preprocessor defines to existing CPPDEFINES. The following code illustrates the circumstances that could trigger this: env=Environment(CPPDEFINES=['a']) env.Append(CPPDEFINES=['b']) env.MergeFlags({'CPPDEFINES': 'c'}) PACKAGING --------- - Remove the redundant `wheel` dependency from `pyproject.toml`, as it is added automatically by the setuptools PEP517 backend. Thanks to the following contributors listed below for their contributions to this release. ========================================================================================== .. code-block:: text git shortlog --no-merges -ns 4.5.1..HEAD 3 Mats Wichmann 2 William Deegan 1 Michał Górny