Scons

From Ruben Di Battista:
- Expose `extra_libs` kwarg in Configure checks `CheckLibWithHeader`
and 'CheckLib' and forward it downstream to `CheckLib`

From Joseph Brill:
- Added error handling when creating MSVC detection debug log file specified by
SCONS_MSCOMMON_DEBUG.
- MSVS: Added default HOST_ARCH values to sconstruct/sconscript environment for
select msvs test scripts to allow tests to run on platforms not recognized by
the msvs/msvc tool implementations. Fixes 4608.
- MSVS: Fix early exit after the first msvc version loop execution in select msvs
test scripts. Select msvs test scripts were being invoked for msvc version 8.0
only. Fixes 4609.
- MSVS: Additional minor select msvs test script fixes as a result of the msvs
tests being invoked for all msvc versions: fix vs version number for vc version
14.3, fix expected platform toolset version, add and use a default known
project GUID for some select tests, add AdditionalOptions Condition to expected
vcx project file.
- MSVS: Additional minor changes to the msvs tool as a result of the msvs tests
being invoked for all msvc versions: use environment MSVS_PROJECT_GUID when
generating project files information, fix the visual studio string for VS2015,
add .vcxproj as an expected suffix for assigning the name to the file basename.
- MSVS: Add additional msvs tests for multi-project and solution builds.
- MSVS: Check for variant directory build of MSVSSolution and adjust the source
node similar to the handling for MSVSProject. The solution was generated in
the build directory instead of the source directory. The placeholder solution
file is not generated in the build directory and the solution file is generated
in the source directory similar to the handling for project files.
Fixes 4612.
- MSVS: Add project dsp nodes to the dsw source node list in the msvs tool. This
appears to always cause the project files to be generated before the solution
files which is necessary to retrieve the project GUIDs for use in the solution
file. This does change the behavior of clean for a project generated with
auto_build_solution disabled and explicit solution generation: when the
solution files are cleaned, the project files are also cleaned. The tests for
vs 6.0-7.1 were changed accordingly.
- MSVS: Add an optional keyword argument, auto_filter_projects, to MSVSSolution.
Accepted values for auto_filter_projects are:
- None [default]: raise an exception when solution file names or nodes are
detected in the projects argument list.
- True or evaluates True: automatically remove solution file names and nodes
from the project argument list.
- False or evaluates False: leave solution file names and nodes in the project
argument list. An exception is not raised.
Solution file names and/or nodes in the project argument list cause erroneous
Project records to be produced in the generated solution file. As a
convenience, an end-user may elect to ignore solution file names and nodes in
the projects argument list rather than manually removing solution file names
and nodes from the MSVSProject return values. Resolves 4613.
- MSVS: Remove the platform specification (i.e., platform = 'win32') from select
test script environments. The platform specification appears superfluous.
- SCons C preprocessor changes:
- Preserve literals that contain valid integer substring specifications.
Previously, the integer suffix could be stripped from a symbol that contained
an integer and suffix substring.
- Update the optional integer suffixes to include the z|Z and wb|WB suffixes.
- Update the optional integer suffixes to include support for alternate
orderings of unsigned with long or long long as defined in the c/cpp
grammar.
- Update the optional integer suffixes for case insensitive specifications as
defined in the c/cpp grammar.
- Add support for binary integer constants.
- Add support for octal integer constants. Previously, octal integers were
evaluated as decimal integers. A literal zero (0) is treated as an octal
number.
- Change the attempted conversion of a define expansion from using int() to
a constant expression evaluation.

From Thaddeus Crews:
- Removed Python 3.6 support.
- Ruff/Mypy: Excluded items now synced.
- Ruff: Linter includes new rules - `FA`, `UP006`, `UP007`, and `UP037` - to
detect and upgrade legacy type-hint syntax.
- Removed "SCons.Util.sctyping.py", as the functionality can now be substituted
via top-level `from __future__ import annotations`.
- Implemented type hints for Nodes.

From William Deegan:
- Update ninja tool to use ninja.BIN_DIR to find pypi packaged ninja binary.
python ninja package version 1.11.1.2 changed the location and previous
logic no longer worked.
- Added TestSCons.NINJA_BINARY to TestSCons to centralize logic to find ninja binary
- Refactored SCons.Tool.ninja -> SCons.Tool.ninja_tool, and added alias so
env.Tool('ninja') will still work. This avoids conflicting with the pypi module ninja.
- Renamed env.Help() & Help()'s argument `keep_local` to `local_only`, previously the documentation
specified `local_only`, but the code and tests were using `keep_local`. The functionality
more closely matches local only. NOTE: It doesn't seem like any code in the wild was using
local_only as we'd not received any reports of such until PR 4606 from hedger.
- Fix Issue 2281, AddPreAction() & AddPostAction() were being ignored if no action
was specified when the Alias was initially created.

From Alex James:
- On Darwin, PermissionErrors are now handled while trying to access
/etc/paths.d. This may occur if SCons is invoked in a sandboxed
environment (such as Nix).

From Prabhu S. Khalsa:
- Fix typo in man page

From Dillan Mills:
- Fix support for short options (`-x`).

From Keith F Prussing:
- Added support for tracking beamer themes in the LaTeX scanner.

From Alex Thiessen:
- Many grammatical and spelling fixes in the documentation.

From Mats Wichmann:
- PackageVariable now does what the documentation always said it does
if the variable is used on the command line with one of the enabling
string as the value: the variable's default value is produced (previously
it always produced True in this case).
- Minor updates to test framework. The functional change is that
test.must_exist() and test.must_exist_one_of() now take an optional
'message' keyword argument which is passed on to fail_test() if
the test fails. The rest is cleanup and type annotations. Be more
careful that the returns from stderr() and stdout(), which *can*
return None, are not used without checking.
- The optparse add_option method supports an additional calling style
that is not directly described in SCons docs, but is included
by reference ("see the optparse documentation for details"):
a single arg consisting of a premade option object. Because optparse
detects that case based on seeing zero kwargs and we always
added at least one (default=) that would fail for AddOption. Fix
for consistency, but don't advertise it further - not added to
manpage synopsis/description.
- Temporary files created by TempFileMunge() are now cleaned up on
scons exit, instead of at the time they're used. Fixes 4595.
- Override environments, created when giving construction environment
keyword arguments to Builder calls (or manually, through the undocumented
Override method), were modified not to "leak" on item deletion. The item
will now not be deleted from the base environment. Override Environments
now also pretend to have a _dict attribute so that regular environment
methods don't have a problem if passed an OE instance.
- Fix a problem with compilation_db component initialization - the
entries for assembler files were not being set up correctly.
- Add clang and clang++ to the default tool search orders for POSIX
and Windows platforms. These will be searched for after gcc and g++,
respectively. Does not affect explicitly requested tool lists.
Note: on Windows, SCons currently only has builtin support for
clang, not for clang-cl, the version of the frontend that uses
cl.exe-compatible command line switches.
- Some manpage cleanup for the gettext and pdf/ps builders.
- Some clarifications in the User Guide "Environments" chapter.
- Fix nasm test for missing include file, cleanup.
- Change long-standing irritant in Environment tests - instead of using
a while loop to pull test info from a list of tests and then delete
the test, structure the test data as a list of tuples and iterate it.
- Skip running a few validation tests if the user is root and the test is
not designed to work for the root user.
- Clarify documentation of Repository() in manpage and user guide.
- Add a tag to each CacheDir to let systems ignore backing it up
(per https://bford.info/cachedir/). Update the way a CacheDir
is created, since it now has to create two files.
- The Dictionary method now has an as_dict flag. If true, Dictionary
always returns a dict. The default remains to return different
types depending on whether zero, one, or multiple construction
variable names are given.
- Update Clean and NoClean documentation.
- Make sure unknown variables from a Variables file are recognized
as such. Previously only unknowns from the command line were
recognized (issue 4645).
- A Variables object now makes available a "defaulted" attribute,
a list of variable names that were set in the environment with
their values taken from the default in the variable description
(if a variable was set to the same value as the default in one
of the input sources, it is not included in this list).
- If a build Variable is created with no aliases, the name of the
Variable is no longer listed in its aliases. Internally, the name
and aliases are considered together anyway so this should not have
any effect except for being visible to custom help text formatters.
- A build Variable is now a dataclass, with initialization moving to
the automatically provided method; the Variables class no longer
writes directly to a Variable (makes static checkers happier).
- Improved Variables documentation.
- The (optional) C Conditional Scanner now does limited macro
replacement on the contents of CPPDEFINES, to improve finding deps
that are conditionally included. Previously replacement was only
done on macro definitions found in the file being scanned.
Only object-like macros are replaced (not function-like), and
only on a whole-word basis; recursion is limited to five levels
and does not error out if that limit is reached (issue 4523).
- Minor modernization: make use of stat object's st_mode, st_mtime
and other attributes rather than indexing into stat return.
- The update-release-info test is adapted to accept changed help output
introduced in Python 3.12.8/3.13.1.
- Update the User Guide Command() example which now shows a target name
being created from '${SOURCE.base}.out' to use a valid special
attribute and to explain what's being done in the example.
- Test framework reformatted using settings from pyproject.toml.
Includes code embedded in docstrings.
- Handle case of "memoizer" as one member of a comma-separated
--debug string - this was previously missed.
- test YACC/live.py fixed - finally started failing on an "old-style"
(K&R flavor) function declaration, updated.
- Test framework - add recognizing list-of-path-components for
the destination of fixtures too (matches docstrings now).

From Adam Scott:
- Changed Ninja's TEMPLATE rule pool to use `install_pool` instead of
`local_pool`, hoping it will fix a race condition that can occurs when
Ninja defers to SCons to build.

From Thaddeus Crews:
- Add explicit return types to sctypes `is_*` functions. For Python <=3.9,
the return type is simply `bool`, same as before. Python 3.10 and later
will benefit from `TypeGuard`/`TypeIs`, to produce intellisense similar
to using `isinstance` directly.

From Anthony Siegrist;
- On win32 platform, handle piped process output more robustly. Output encoding
now uses 'oem' which should be the systems default encoding for the shell where
the process is being spawned.

From Mats Wichmann:
- env.Dump() now considers the "key" positional argument to be a varargs
type (zero, one or many). However called, it returns a serialized
result that looks like a dict. Previously, only a single "key" was
accepted, and unlike the zero-args case, it was serialized to a
string containing just the value (without the key). For example, if
"print(repr(env.Dump('CC'))" previously returned "'gcc'", it will now
return "{'CC': 'gcc'}".
- Add a timeout to test/ninja/default_targets.py - it's gotten stuck on
the GitHub Windows action and taken the run to the full six hour timeout.
Usually runs in a few second, so set the timeout to 3min (120).
- SCons 4.8.0 added an `__all__` specifier at the top of the Variables
module (`Variables/__init__.py`) to control what is made available in
a star import. However, there was existing usage of doing
`from SCons.Variables import *` which expected the variable *types*
to be available. While we never advertised this usage, there's no
real reason it shouldn't keep working - add to `__all__`.
- Switch SCons build to use setuptools' supported version fetcher from
the old homegrown one.
- Improve wording of manpage "Functions and Environment Methods" section.
Make doc function signature style more consistent - tweaks to AddOption,
DefaultEnvironment and Tool,.
- Fix a problem with AppendUnique and PrependUnique where a value could
be erroneously removed due to a substring match.
- Fix handling of ListVariable when supplying a quoted choice containing
a space character (issue 4585).

From Joseph Brill:
- For msvc version specifications without an 'Exp' suffix, an express installation
is used when no other edition is detected for the msvc version. Similarly, an
express installation of the IDE binary is used when no other IDE edition is
detected.
- VS2015 Express (14.0Exp) does not support the sdk version argument. VS2015 Express
does not support the store argument for target architectures other than x86.
Script argument validation now takes into account these restrictions.
- VS2015 BuildTools (14.0) does not support the sdk version argument and does not
support the store argument. Script argument validation now takes into account
these restrictions.
- The Windows SDK for Windows 7 and .NET Framework 4" (SDK 7.1) populates the
registry keys in a manner in which the msvc detection would report that VS2010
(10.0) is installed when only the SDK was installed. The installed files are
intended to be used via the sdk batch file setenv.cmd. The installed msvc
batch files will fail. The msvc detection logic now ignores SDK-only VS2010
installations. Similar protection is implemented for the sdk-only installs that
populate the installation folder and registry keys for VS2008 (9.0), if necessary.
- For VS2005 (8.0) to VS2015 (14.0), vsvarsall.bat is employed to dispatch to a
dependent batch file when configuring the msvc environment. Previously, only the
existence of the compiler executable was verified. In certain installations, the
dependent batch file (e.g., vcvars64.bat) may not exist while the compiler
executable does exist resulting in build failures. The existence of vcvarsall.bat,
the dependent batch file, and the compiler executable are now validated.
- MSVC configuration data specific to versions VS2005 (8.0) to VS2008 (9.0) was added
as the dependent batch files have different names than the batch file names used
for VS2010 (10.0) and later. The VS2008 (9.0) Visual C++ For Python installation
is handled as a special case as the dependent batch files are: (a) not used and (b)
in different locations.
- When VS2008 (9.0) Visual C++ For Python is installed using the ALLUSERS=1 option
(i.e., msiexec /i VCForPython27.msi ALLUSERS=1), the registry keys are written to
HKEY_LOCAL_MACHINE rather than HKEY_CURRENT_USER. An entry was added to query the
Visual C++ For Python keys in HKLM following the HKCU query, if necessary.
- For VS2008, a full development edition (e.g., Professional) is now selected before
a Visual C++ For Python edition. Prior to this change, Visual C++ For Python was
selected before a full development edition when both editions are installed.
- The registry detection of VS2015 (14.0), and earlier, is now cached at runtime and
is only evaluated once for each msvc version.
- The vswhere executable is frozen upon initial detection. Specifying a different
vswhere executable via the construction variable VSWHERE after the initial
detection now results in an exception. Multiple bugs in the implementation of
specifying a vswhere executable via the construction variable VSWHERE have been
fixed. Previously, when a user specified vswhere executable detects new msvc
installations after the initial detection, the internal msvc installation cache
and the default msvc version based on the initial detection are no longer valid.
For example, when no vswhere executable is found for the initial detection
and then later an environment is constructed with a user specified vswhere
executable that detects new msvc installations.
- The vswhere detection of VS2017 (14.1), and later, is now cached at runtime and is
only evaluated once using a single vswhere invocation for all msvc versions.
Previously, the vswhere executable was invoked for each supported msvc version.
- The vswhere executable locations for the WinGet and Scoop package managers were
added to the default vswhere executable search list after the Chocolatey
installation location.
- Fix issue 4543: add support for msvc toolset versions 14.4X installed as the
latest msvc toolset versions for msvc buildtools v143. The v143 msvc buildtools
may contain msvc toolset versions from 14.30 to 14.4X.

From Thaddeus Crews:
- GetSConsVersion() to grab the latest SCons version without needing to
access SCons internals.
- Migrate setup.cfg logic to pyproject.toml; remove setup.cfg.
- Update .gitattributes to match .editorconfig; enforce eol settings.
- Replace black/flake8 with ruff for more efficient formatting & linting.
- When debugging (--debug=pdb), the filename SCsub is now recognized when
manipulating breakpoints.

From Raymond Li:
- Fix issue 3935: OSErrors are now no longer hidden during execution of
Actions. All exceptions during the execution of an Action are now
returned by value rather than by raising an exception, for more
consistent behavior.
NOTE: With this change, user created Actions should now catch and handle
expected exceptions (whereas previously many of these were silently
caught and suppressed by the SCons Action execution code).

From Ryan Carsten Schmidt:
- Teach ParseFlags to put a --stdlib=libname argument into CXXFLAGS.
If placed in CCFLAGS (the default location), it could be fed to the
C compiler (gcc, clang) where it is not applicable and causes a
warning message.

From Mats Wichmann:
- Updated Value Node docs and tests.
- Python 3.13 compat: re.sub deprecated count, flags as positional args,
caused update-release-info test to fail.
- Dump() with json format selected now recognizes additional compound types
(UserDict and UserList), which improves the detail of the display.
json output is also sorted, to match the default display.
- Python 3.13 (alpha) changes the behavior of isabs() on Windows. Adjust
SCons usage of in NodeInfo classes to match. Fixes 4502, 4504.
- Drop duplicated __getstate__ and __setstate__ methods in AliasNodeInfo,
FileNodeInfo and ValueNodeInfo classes, as they are identical to the
ones in parent NodeInfoBase and can just be inherited.
- Update manpage for Tools, and for TOOL, which also gets a minor
tweak for how it's handled (should be more accurate in a few situations).
- Test framework now uses a subdirectory named "scons" below the base
temporary directory. This gives something invariant to tell antivirus
to ignore without having to exclude tmpdir itself. Fixes 4509.
- MSVS "live" tests of project files adjusted to look for the generated
executable with an exe sufffix
- Documentation build now properly passes through skipping the PDF
(and EPUB) builds of manpage and user guide; this can also be done
manually if directly calling doc/man/SConstruct and doc/user/SConstruct
by adding SKIP_PDF=1. This should help with distro packaging of SCons,
which now does not need "fop" and other tools to be set up in order to
build pdf versions which are then ignored.
- Add the ability to print a Variables object for debugging purposes
(provides a __str__ method in the class).
- Mark Python 3.6 support as deprecated.
- Clean up Variables: more consistently call them variables (finish the
old change from Options) in docstrings, etc.; some typing and other
tweaks. Update manpage and user guide for Variables usage.
- Regularize internal usage of Python version strings and drop one
old Python 2-only code block in a test.
- scons-time tests now supply a "filter" argument to tarfile.extract
to quiet a warning which was added in Python 3.13 beta 1.
- Improved the conversion of a "foreign" exception from an action
into BuildError by making sure our defaults get applied even in
corner cases. Fixes 4530.
- Restructured API docs build (Sphinx) so main module contents appear
on a given page *before* the submodule docs, not after. Also
tweaked the Util package doc build so it's structured more like the
other packages (a missed part of the transition when it was split).
- Updated manpage description of Command "builder" and function.
- Framework for scons-time tests adjusted so a path with a long username
Windows has squashed doesn't get re-expanded. Fixes a problem seen
on GitHub Windows runner which uses a name "runneradmin".
- SCons.Environment.is_valid_construction_var() now returns a boolean to
match the convention that functions beginning with "is" have yes/no
answers (previously returned either None or an re.match object).
Now matches the annotation and docstring (which were prematurely
updated in 4.6). All SCons usage except unit test was already fully
consistent with a bool.
- When a variable is added to a Variables object, it can now be flagged
as "don't perform substitution" by setting the argument subst.
This allows variables to contain characters which would otherwise
cause expansion. Fixes 4241.
- The test runner now recognizes the unittest module's return code of 5,
which means no tests were run. SCons/Script/MainTests.py currently
has no tests, so this particular error code is expected - should not
cause runtest to give up with an "unknown error code".
- Updated the notes about reproducible builds with SCons and the example.
- The Clone() method now respects the variables argument (fixes 3590)
- is_valid_construction_var() (not part of the public API) moved from
SCons.Environment to SCons.Util to avoid the chance of import loops. Variables
and Environment both use the routine and Environment() uses a Variables()
object so better to move to a safer location.
- Performance tweak: the __setitem__ method of an Environment, used for
setting construction variables, now uses the string method isidentifier
to validate the name (updated from microbenchmark results).
- AddOption and the internal add_local_option which AddOption calls now
recognize a "settable" keyword argument to indicate a project-added
option can also be modified using SetOption. Fixes 3983.
NOTE: If you were using ninja and using SetOption() for ninja options
in your SConscripts prior to loading the ninja tool, you will now
see an error. The fix is to move the SetOption() to after you've loaded
the ninja tool.
- ListVariable now has a separate validator, with the functionality
that was previously part of the converter. The main effect is to
allow a developer to supply a custom validator, which previously
could be inhibited by the converter failing before the validator
is reached.
- Regularized header (copyright, licens) at top of documentation files
using SPDX.
- Updated introductory section of manual page.
- Minor cleanups in tests - drop unused "% locals()" stanzas.

From Ataf Fazledin Ahamed:
- Use of NotImplemented instead of NotImplementedError for special methods
of _ListVariable class

From Joseph Brill:
- Fix issue 2755: the msvs tool no longer writes the OS environment SCONS_HOME
value into the SCons environment when the SCONS_HOME variable already exists
in the SCons environment. Prior to this change, a valid user-defined SCons
environment value for SCONS_HOME would be overwritten with the OS environment
value of SCONS_HOME which could be None (i.e., undefined).
- Update the windows registry keys for detection of Visual Studio 2015 Express
('14.0Exp'): the VS2015 registry key ('WDExpress') appears to be different
than the registry key ('VCExpress') for earlier Visual Studio express
versions. The registry key value is relative to the installation root rather
than the VC folder and requires additional path components during evaluation.
- Fix the vs-6.0-exec.py test script: the msvs generated project is 'foo.dsp'
and the command-line invocation of the Visual Studio development environment
program was attempting to build 'test.dsp'. The command-line invocation was
changed to build 'foo.dsp'.
- Update the msvs project generation test scripts: the msvs project execution
tests could produce a "false positive" test result when the test executable is
correctly built via the SConstruct env.Program() call and the command-line
invocation of the Visual Studio development environment program fails. The
test passes due to the existence of the test executable from the initial
build. The tests were modified to delete the test executable, object file,
and sconsign file prior to the command-line invocation of the VS development
binary.
- Method unlink_files was added to the TestCmd class that unlinks a list of
files from a specified directory. An attempt to unlink a file is made only
when the file exists; otherwise, the file is ignored.
- Fix issue 4320: add an optional argument list string to configure's CheckFunc
method so that the generated function argument list matches the function's
prototype when including a header file.

From Thaddeus Crews:
- Explicitly wrap non-serializable values in json dump
- Implemented SCons.Util.sctyping as a safe means of hinting complex types. Currently
only implemented for `Executor` as a proof-of-concept.

From William Deegan:
- Fix sphinx config to handle SCons versions with post such as: 4.6.0.post1

From Michał Górny:
- Remove unnecessary dependencies on pypi packages from setup.cfg

From Sten Grüner:
- Fix of the --debug=sconscript option to return exist statements when using return
statement with stop flag enabled

From Prabhu S. Khalsa:
- Fix typo in user documentation (issue 4458)

From Andrew Morrow:
- The NewParallel scheduler is now the default, the `tm_v2` flag is removed,
and the old scheduler is opt-in under `--experimental=legacy_sched`. Additionally,
the new scheduler is now used for -j1 builds as well.
- A python interpreter with support for the `threading` package is now required,
and this is enforced on startup. SCons currently sets its minimum supported
Python to 3.6, and it was not until Python 3.7 where `threading` became
default supported. In practice, we expect most real world Python 3.6 deployments
will have `threading` support enabled, so this will not be an issue.
- CacheDir writes no longer happen within the taskmaster critical section,
and therefore can run in parallel with both other CacheDir writes and the
taskmaster DAG walk.
- The NewParallel scheduler now only adds threads as new work requiring execution
is discovered, up to the limit set by -j. This should reduce resource utilization
when the achievable parallelism in the DAG is less than the -j limit.

From Mats Wichmann:
- Add support for Python 3.13 (as of alpha 2). So far only affects
expected bytecodes in ActionTests.py.
- sconsign cleanup - remove some dead code, minor manpage tweaks.
- Be more cautious about encodings fetching command output on Windows.
Problem occurs in piped-spawn scenario, used by Configure tests.
Fixes 3529.
- Clarify/fix documentation of Scanners in User Guide and Manpage.
Fixes 4468.
- Fix bad typing in Action.py: process() and strfunction().
- Add Pseudo() to global functions, had been omitted. Fixes 4474.
- Improve handling of file data that SCons itself processes - try
harder to decode non-UTF-8 text. SCons.Util.to_Text now exists
to convert a byte stream, such as "raw" file data. Fixes 3569, 4462.
The Pseudo manpage entry was updated to provide more clarity.
- Clarify how SCons finds the project top directory, and what that is used for.
- The internal routine which implements the PyPackageDir function
would fail with an exception if called with a module which is
not found. It will now return None. Updated manpage entry and
docstring..
- Doc update: standardized on the use of a new entity &MSVC; to
describe the Microsoft C++ compiler. Update the version table slightly.
Amplified the usage of MSVC_VERSION.
- Improve SharedLibrary docs a bit.
- More consistent use of &Python; in the manpage. A few links added.
A warning about overwriting env['ENV'] and one about Configure
checks possibly not running in in no-exec mode also added.
- Update warnings module: adds docstrings, drop three unused warnings
(DeprecatedSourceCodeWarning, TaskmasterNeedsExecuteWarning,
DeprecatedMissingSConscriptWarning) add two warnings to manpage
(cache-cleanup-error, future-reserved-variable), improve unittest, tweak
Sphinx build.
- Add locking around creation of CacheDir config file. Fixes 4489.
- Clarify MergeFlags usage of a dict argument.
- SCons documentation build can now be controlled through SKIP_DOC
variable - rather than just true/false can now specify
skip none, skip all, skip pdf docs, skip api docs.

From Max Bachmann:
- Add missing directories to searched paths for mingw installs

From Joseph Brill:
- Fix issue 4312: the cached installed msvc list had an indirect dependency
on the target architecture in the environment dictionary. The first call
to construct the installed msvc list now forces the target architecture to be
undefined, constructs the installed msvc list, and then restores the original
target architecture.
Note: an indirect dependency on the VSWHERE construction variable in the
environment remains.
- Fix issue 4312: explicitly guard against an empty regular expression list
when msvc is not installed.
- When trying to find a valid msvc batch file, check that the compiler executable
(cl.exe) exists for VS6 to VS2015 to avoid executing the msvc batch file. Always
check that the compiler executable is found on the msvc script environment path
after running the msvc batch file. Only use the sdk batch files when all of the
msvc script host/target combinations have been exhausted and a valid script was
not found.
- Add ARM64 host configurations for windows and msvc.
Note: VS2013 and earlier has not been tested on ARM64.
- If necessary, automatically define VSCMD_SKIP_SENDTELEMETRY for VS2019 and later
on ARM64 hosts when using an arm32 build of python to prevent a powershell dll
not found error pop-up window.
- Fix an issue where test SConfTests.py would fail when mscommon debugging
was enabled. The mscommon debug filter class registered with the logging
module was refactored.
- Add arm64 to the MSVS supported architectures list for VS2017 and later to be
consistent with the current documentation of MSVS_ARCH.
- Fix an issue with an unhandled MissingConfiguration exception due to an msvc
registry query that returns a path that does not exist. Multiple invocation
paths were not prepared to handle the MissingConfiguration exception. The
MissingConfiguration exception type was removed.
- The MSCommon module import was changed from a relative import to a top-level
absolute import in the following Microsoft tools: midl, mslib, mslink, mssdk, msvc,
msvs. Moving any of these tools that used relative imports to the scons site tools
folder would fail on import (i.e., the relative import paths become invalid when
moved).
- The detection of the msvc compiler executable (cl.exe) has been modified:
* The host os environment path is no longer evaluated for the existence of the
msvc compiler executable when searching the detection dictionary.
* The existence of the msvc compiler executable is checked in the detection
dictionary and the scons ENV path before the detection dictionary is merged
into the scons ENV.
* Different warnings are produced when the msvc compiler is not detected in the
detection dictionary based on whether or not an msvc compiler was detected in
the scons ENV path (i.e., a msvc compiler executable already exists in the
user's ENV path prior to detection).
* The warning message issued when a msvc compiler executable is not found in the
detection dictionary was modified by adding the word "requested":
Old warning: "Could not find MSVC compiler 'cl'."
New warning: "Could not find requested MSVC compiler 'cl'.".
* An additonal sentence is appended to the warning message issued when an msvc
compiler executable is not found in the msvc detection dictionary and is found
in the user's ENV path prior to detection:
" A 'cl' was found on the scons ENV path which may be erroneous."

From Vitaly Cheptsov:
- Fix race condition in `Mkdir` which can happen when two `SConscript`
are processed simultaneously by two separate build commands.

From William Deegan:
- The --debug flag now has a 'json' option which will write information
generated by --debug={count, memory, time, action-timestamps} and about
the build.
- Obsoleted YACCVCGFILESUFFIX, being replaced by YACC_GRAPH_FILE_SUFFIX.
If YACC_GRAPH_FILE_SUFFIX is not set, it will respect YACCVCGFILESUFFIX.

From Sten Grüner
- The newly added --debug=sconscript option (new) will output notices when
entering an exiting each SConscript as they are processed.

From Philipp Maierhöfer:
- Fix gfortran tool initialization. Defaults to using binary named gfortran
as would be expected, and properly set's SHFORTRAN flags to include -fPIC
where previously it was only doing so for the other fortran versions (F77,..)

From Jonathon Reinhart:
- Fix another instance of `int main()` in CheckLib() causing failures
when using -Wstrict-prototypes.

From Mats Wichmann
- C scanner's dictifyCPPDEFINES routine did not understand the possible
combinations of CPPDEFINES - not aware of a "name=value" string either
embedded in a sequence, or by itself. The conditional C scanner thus
did not always properly apply the defines. The regular C scanner does
not use these, so was not affected. [fixes 4193]
- Minor cleanup for ValidateOptions - docs and docstring tweaked,
add missed versionadded indicator.
- Added some typing annotations generated by a tool, to eliminate manual
work in future on things which are safe for the tool to produce.
Then manually fixed up some things related to bool that the tool did
not handly ideally. For example, simple functions which just did
"return 1" were interpreted by the tool as returning int, when bool
was really the intent. Functions/methods named like "is_*", "has_*",
"exists" are now pretty consistently marked as "-> bool".
- Simplify some code due to pylint observation: "C2801: Unnecessarily
calls dunder method __call__. Invoke instance directly."
- Python 3.9 dropped the alias base64.decodestring, deprecated since 3.1.
Only used in msvs.py. Use base64.decodebytes instead.
- When debugging (--debug=pdb), the filenames SConstruct and SConscript
are now recognized when manipulating breakpoints. Previously,
only a full pathname to an sconscript file worked, as pdb requires
a .py extension to open a file that is not an absolute path.
- SCons test runner now uses pathlib to normalize and compare paths
to test files.
- D compilers : added support for generation of .di interface files.
New variables DI_FILE_DIR, DI_FILE_DIR_PREFIX, DI_FILE_DIR_SUFFIX,
DI_FILE_SUFFIX.
- Fixed: when using the mingw tool, if an msys2 Python is used (os.sep
is '/' rather than the Windows default '\'), certain Configure checks
could fail due to the construction of the path to run the compiled check.
- Added effort to find mingw if it comes from Chocolatey install of msys2.
- Minor doc fixes: signature of Alias() now matches implementation
to avoid problem if kwargs used; case of Alias with no targets is
mentioned in text (was already shown in example); now mention that
Action([item]) does not return a ListAction - previously implied
that if arg was a list, a ListAction was *always* returned; mention
default Decider and sort the names of available decider functions,
and add a version marking. Minor fiddling with Alias.py docstrings.
- Python 3.12 support: new bytecodes for ActionTests.py, adapt to
changes to pathlib module in runtest.py (PosixPath no longer
converts slashes if given a Windows-style path). Also switch to
using `subTest` in `ActionTests`, so that we can see all 21 fails
due to bytecode changes (previously testcases aborted on the first
assert fail so we only saw seven), and use unittest asserts to
simplify complex printing stanzas.
- Added copyright headers to files in test/ that didn't have them.
- Drop three unused methods from the Environment Base class:
get_src_sig_type and get_tgt_sig_type, as well as "private"
_changed_source. These were orphaned when the long-deprecated
Source Signatures and Target Signatures were removed, these were
missed at that time.
- Remove dead code: some mocked classes in unit tests had methods
which have been removed from the Node class they're mocking,
there's no need to shadow those any more as there are no callers.
The methods are depends_on (base functionality removed in 2005)
and is_pseudeo_derived (base functionality removed in 2006). There
may well be more!
- Added pass_test() call to test/MSVC/MSVC_BATCH-spaces-targetdir.py.
It looked it was missing a more detailed check, but it should be
sufficient just to check the build worked. Renamed the fixture
dir to follow naming convention in test/MSVC overall, and added
a sconstest.skip file, also to follow convention.
- Marked some scanner methods as staticmethod.
- Class ActionBase is now an abstract base class to more accurately
reflect its usage. Derived _ActionAction inherits the ABC, so it
now declares (actually raises NotImplementedError) two methods it
doesn't use so it can be instantiated by unittests and others.
- The yacc tool now understands the bison behavior of --header,
--defines and --graph being called without option-argument as being
synonyms for -d (first two) and -g. -H also recognized as a synonym
for -d. Default value for $YACC_GRAPH_FILE_SUFFIX changed to '.gv'
to match current bison default (since bison 3.8). Set this variable
to '.dot' if using byacc. The graph file name (-g) is now generated
relative to the requested target file name, not to the source file
name, to match actual current behavior (only affects if target
explicitly requested with a different base name
than source). Docs updated. Fixes 4326 and 4327.
- Cleaned up dblite module (checker warnings, etc.).
- Some cleanup in the FortranCommon tool.
- Rewrite the internal _subproc routine - a new scons_subproc_run() now
makes use of Python's subprocess.run in a more natural way, getting
around some of the issues with attempted context manager use, fetching
output, etc. - we let the subprocess module do the hard work,
since it's well debugged and supported. _subproc is no longer
called by internal code, but remains in place in case there are builds
which call to it (even though it was never "published API").
- Changed the message about scons -H to clarify it shows built-in options.
- Improve CacheDir() Documentation.
- Release-building setup tweaked. (most of) the targets listed in
SCons' own "scons --help" now work again.
- Fix platform unit test on Windows for Py 3.12+. Fixes 4376.
- More tweaking of test framework overview (which is duplicated onto
the website, but not in the regular documentation section).
- Extend range of recognized Java versions to 20.
- Builder calls now accept PathLike objects in source lists. Fixes 4398.
- The Help() function now takes an additional keyword argument
keep_local: when starting to build a help message, you can now
retain help from AddOption calls, but omit help for SCons' own
command-line options with "Help(newtext, append=True, local_only=True)".
- A little more code "modernization", done via "pypgrade" tool set
to "3.6 and above" setting.
- Finish the change to make calling SConscript() with a nonexistent
file an error. It has issued a warning since 3.0, with "warn instead
of fail" deprecated since 3.1. Fixes 3958.
- Minor (non-functional) cleanup of some tests, particuarly test/MSVC.
- Added more error handling while reading msvc config cache.
(Enabled/specified by SCONS_CACHE_MSVC_CONFIG).
The existing cache will be discarded if there's a decode error reading it.
It's possible there's a race condition creating this issue in certain CI
builds. Also add a simple filesystem-based locking protocol to try to
avoid the problem occuring.
- Update the first two chapters on building with SCons in the User Guide.
- Update docs on Export/Import - make sure mutable/immutable status has
been mentioned.
- Some cleanup to the Util package, including renaming SCons.Util.types
to SCons.Util.sctypes to avoid any possible confusion with the
Python stdlib types module.
- TeX tests: skip tests that use makeindex or epstopdf not installed, or
if `kpsewhich glossaries.sty` fails.
- Added a .note.GNU-stack section to the test assembler files to
avoid the GNU linker issuing warnings for its absence.
- Eliminate more http: references (mostly in comments/docstrings where
they really weren't harmful). A few links labeled dead with no alt.
- Add JDK 21 LTS support
- Add a LIBLITERALPREFIX variable which can be set to the linker's
prefix for considering a library argument unmodified (e.g. for the
GNU linker, the ':' in '-l:libfoo.a'). Fixes Github issue 3951.
- Update PCH builder docs with some usage notes.

From Michał Górny:
- Remove the redundant `wheel` dependency from `pyproject.toml`,
as it is added automatically by the setuptools PEP517 backend.

From Mats Wichmann
- 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'})