SCons 4.2.0 is Available

A new SCons release, 4.2.0, is now available
on the SCons download page:

  https://scons.org/pages/download.html

Here is a summary of the changes since 4.1.0:

NOTE: The 4.2.0 Release of SCons will deprecate Python 3.5 Support. Python 3.5 support will be dropped in the next major release.

NEW FUNCTIONALITY

- Add support for the (TARGET,SOURCE,TARGETS,SOURCES,CHANGED_TARGETS,CHANGED_SOURCES}.relpath property.
  This will provide a path relative to the top of the build tree (where the SConstruct is located)
  Fixes #396
- Added --experimental flag, to enable various experimental features/tools.  You can specify
  'all', 'none', or any combination of available experimental features.
- Added affect_signature flag to  _concat function.  If set to False, it will prepend and append $( and $).
  That way the various Environment variables can use that rather than "$( _concat(...) $)".

DEPRECATED FUNCTIONALITY

- Deprecate Python 3.5 as a supported version.

CHANGED/ENHANCED EXISTING FUNCTIONALITY

- SCons now supports the command-line parameter `--hash-format` to override the default
  hash format that SCons uses. It can also be set via `SetOption('hash_format')`. Supported
  values are: `md5`, `sha1`, and `sha256`. For all hash formats other than
  the default of `md5`, the SConsign database will include the name of the hash format.
  For example, `--hash-format=sha256` will create a SConsign with name
  `.sconsign_sha256.dblite.`.
- Improve Subst()'s logic to check for proper callable function or class's argument list.
  It will now allow callables with expected args, and any extra args as long as they
  have default arguments. Additionally functions with no defaults for extra arguments
  as long as they are set using functools.partial to create a new callable which set them.
- Internal has_key methods removed from SCons' dictionary-like objects
  SubstitutionEnvironment and OverrideEnvironment - in other words,
  an env - to match Python 3 which no longer has dict.has_key.
- Removed long-deprecated construction variables PDFCOM, WIN32_INSERT_DEF,
  WIN32DEFPREFIX, WIN32DEFSUFFIX, WIN32EXPPREFIX, WIN32EXPSUFFIX.
  All have been replaced by other names since at least 1.0.
- Added CACHEDIR_CLASS construction variable and expanded CacheDir method args
  to support SCons invoking CacheDir derived classes for CacheDir customization.
  Moved copy_from_cache attribute from the Environment class to CacheDir class.
  Code contributed by MongoDB.
- Update BuildTask to pass all targets to the progress object fixing an issue
  where multi-target build nodes only got the first target passed to the progress
  object.
- Change SConscript() missing SConscript behavior - if must_exist=False,
  the warning is suppressed.

FIXES

- The command-line parameter `--md5-chunksize` is now deprecated. Use `--hash-chunksize`
  instead.
- Fix Issue #3906 - `IMPLICIT_COMMAND_DEPENDENCIES` was not properly disabled when
  set to any string value (For example ['none','false','no','off'])
  Also previously 'All' wouldn't have the desired affect.
- DocbookXslt tool: The XSLT stylesheet file is now initialized to an env.File() Node, 
  such that dependencies work correctly in hierarchical builds (eg when using 
  DocbookXslt in SConscript('subdir/SConscript') context.
- The Install builder will now set the writable mode on the file(s) it
  copies. This restores the (previously undocumented) SCons behavior
  that regressed as of 4.0.0.
- Fix issue #3790: Generators in CPPDEFINES now have access to populated source
  and target lists
- Fix a potential race condition in shared cache environments where the permissions are
  not writeable for a moment after the file has been renamed and other builds (users) will copy
  it out of the cacheSmall reorganization of logic to copy files from cachedir. Moved CacheDir 
  writeable permission code for copy to cache behind the atomic rename operation.
- Fixed intermediate and and multi target nodes generated from SConf tests not being marked
  as is_conftest().

Thanks to the following contributors listed below for their contributions to this release.

.. code-block:: text

git shortlog --no-merges -ns 4.1.0..HEAD
   177  William Deegan
   101  Daniel Moody
    95  Mats Wichmann
    25  Adam Gross
     4  greenbender
     4  Daniel
     4  Henrik Maier
     4  Mathew Robinson
     3  Andrew Morrow
     3  Ivan Kravets
     3  Dillan Mills
     1  WholesomeIsland
     1  dependabot[bot]
     1  djh
     1  Joseph Brill