SCons - a software construction tool
Release Notes
This is SCons, a tool for building software (and other files). SCons is
implemented in Python, and its "configuration files" are actually Python
scripts, allowing you to use the full power of a real scripting language
to solve build problems. You do not, however, need to know Python to
use SCons effectively.
Please go to http://scons.org/pages/download.html to get the latest
production
release of SCons.
So that everyone using SCons can help each other learn how to use it more
effectively, please go to http://scons.org/lists.html#users to sign up for
the scons-users mailing list.
RELEASE 3.0.1 - Mon, 12 Nov 2017 15:31:33 -0700
Please consult the RELEASE.txt file for a summary of changes since the
last
release and consult the CHANGES.txt file for complete a list of changes
since last release. This announcement highlights only the important
changes.
Please note the following important changes since release 2.5.1:
This is the initial release supporting both python 3.5+ and 2.7.x
and pypy
There are some important changes:
- Any print statements must now use python 3 syntax of "print()"
- All node content should be in bytes. This is the default in python
2.7.x,
in Python 3 all strings are by default unicode. byte and/or
bytearray
should be used if you construct content for return by a custom
node type's
get_content() method.
- There are some (as yet unresolved issue) using Literal()'s in some
context with
Python 3
- pypy should be supported, please report any issues to the user's
mailing list.
- Currently if you switch back and forth between python 2.7.x and
3.5+ you will
need to remove your sconsign file. This should be resolves
shortly, but
regardless switching between python 2.7.x and 3.5+ will not use
compatible
sconsigns and as such incremental builds should be expected to
rebuild
anything changed since the previous scons run with the same
version of python.
- It is likely that migrating from 2.5.1 -> 3.0.0 alpha will cause
rebuilds due
to the significant number of changes in the codebase.
- Removed deprecated tools CVS, Perforce, BitKeeper, RCS, SCCS,
Subversion.
- Removed deprecated module SCons.Sig
- See CHANGES.txt for more details on other changes
- 3.0.0 should be slightly faster than 2.5.1. Changes yielded a 15%
speed up for
null incremental builds.
- Updated D language scanner support to latest: 2.071.1.
- python -m SCons should now run SCons if it's installed PYTHONPATH
Please note the following important changes since release 2.4.1:
We're enhancing implicit language scanning functionality to improve
correctness. SCons now honors scanner keys for implicit dependencies
and correctly changes scanner type (if necessary) when traversing
implicit dependency trees.
This enhancement resolves missing dependencies
with built-in scanners including SWIG (#2264) and QT:
* http://scons.tigris.org/issues/show_bug.cgi?id=2264
- This enhancement broadens the horizon for handling heterogeneous
data flow environments (E.G. software builds):
-
http://article.gmane.org/gmane.comp.programming.tools.scons.user/26596
- SCons may find new (and correct) dependencies in cross-langauge
contexts.
- Update may cause rebuilds, especially in heterogeneous data
environments.
- Update may find previously missed dependencies errors (E.G.
cycles).
- Discovered in some QT test cases.
- SCons handles the SCANNERS variable differently.
- Previously, the Install builder would scan implicit
dependencies for
a scanner found in SCANNERS (but not for built-in scanners),
but now
the Install builder will not scan recursively regardless in
order
to optimize Install behaviour and bring orthogonality to
previous behaviour.
- SCons handles cache directories a bit differently/
- Cache files are now stored in 256 subdirectories in the cache
directory by
default (this stresses NFS less). Existing cache directories will
remain as
current, but SCons will prompt you to run scons-configure-cache
which will
allow you to migrate to the new layout, or confirm you want to use
the
existing layout.
- New external tool scons-configurecache which allows some
configuration of
how files in the cache are controlled.
Please note the following important changes since release 2.4.0:
- Fix to swig tool - pick-up 'swig', 'swig3.0' and 'swig2.0' (in order).
- Fix to swig tool - respect env['SWIG'] provided by user.
- Fix for Bug # 2791 - Setup.py fails unnecessarily under Jython.
- Fixed license of SVG titlepage files in the context of Debian
packaging, such that they allow for commercial use too (#2985).
- InstallVersionedLib now available in the DefaultEnvironment context.
- Improves orthogonality of use cases between different Install
functions.
- Added new configure check, CheckProg, to check for
existence of a program.
- Fix for issue #2840 - Fix for two environments specifying same target
with different
actions not throwing hard error. Instead SCons was incorrectly
issuing a warning
and continuing.
- Add support `Microsoft Visual C++ Compiler for Python 2.7'
Compiler can be obtained at:
https://www.microsoft.com/en-us/download/details.aspx?id=44266
- Fixed tigris issue #3011: Glob() excludes didn't work when used with
VariantDir(duplicate=0)
- Fix bug 2831 and allow Help() text to be appended to AddOption() help.
- Reimplemented versioning for shared libraries, with the following
effects
- Fixed tigris issues #3001, #3006.
- Fixed several other issues not reported to tigris, including:
issues with versioned libraries in subdirectories with tricky names,
issues with versioned libraries and variant directories,
issue with soname not being injected to library when using D linkers,
- Switched to direct symlinks instead of daisy-chained ones -- soname
and
development symlinks point directly to the versioned shared library
now),
for rationale see:
https://www.debian.org/doc/debian-policy/ch-sharedlibs.html
https://fedoraproject.org/wiki/Packaging:Guidelines#Devel_Packages
https://bitbucket.org/scons/scons/pull-requests/247/new-versioned-libraries-gnulink-cyglink/diff#comment-10063929
- New construction variables to allow override default behavior: SONAME,
SHLIBVERSIONFLAGS, _SHLIBVERSIONFLAGS, SHLIBNOVERSIONSYMLINKS,
LDMODULEVERSION, LDMODULEVERSIONFLAGS, _LDMODULEVERSIONFLAGS,
LDMODULENOVERSIONSYMLINKS.
- Changed logic used to configure the versioning machinery from
platform-centric to linker-oriented.
- The SHLIBVERSION/LDMODULEVERSION variables are no longer validated by
SCons (more freedom to users).
- InstallVersionedLib() doesn't use SHLIBVERSION anymore.
- Enchanced docs for the library versioning stuff.
- New tests for versioned libraries.
- Library versioning is currently implemented for the following linker
tools: 'cyglink', 'gnulink', 'sunlink'.
Please note the following important changes since release 2.3.6:
- Switch several core classes to use "slots" to reduce memory
usage. (PR #2180, #2178, #2198)
Please note the following important changes since release 2.3.5:
- Support for Visual Studio 2015
Please note the following important changes since release 2.3.4:
- Documentation fixes for libraries.xml and
builders-writing.xml (#2989 and #2990)
- Extended docs for InstallVersionedLib/SharedLibrary,
and added SKIP_WIN_PACKAGES argument to build script
bootstrap.py (PR #230, #3002).
- Fixed symlink support (PR #227, #2395).
- Updated debug-count test case (PR #229).
- Fixed incomplete LIBS flattening and substitution in
Program scanner(PR #205, #2954).
- Added new method rentry_exists_on_disk to Node.FS (PR #193).
- Fixed several D tests under the different OS.
- Add support for f08 file extensions for Fortran 2008 code.
- Show --config choices if no argument is specified (PR #202).
- Fixed build crash when XML toolchain isn't installed, and
activated compression for ZIP archives.
- Fix for VersionedSharedLibrary under 'sunos' platform.
- Fixed dll link with precompiled headers on MSVC 2012
- Added an 'exclude' parameter to Glob()
- Support for multiple cmdargs (one per variant) in VS project files.
- Various improvements for TempFileMunge class.
- Added an implementation for Visual Studio users files (PR #209).
- Added support for the 'PlatformToolset' tag in VS project files
(#2978).
- Added support for '-isystem' to ParseFlags.
Please note the following important changes since release 2.3.3:
-- Fix for EnsureSConsVersion regression in 2.3.3.
-- Fix for interactive mode with Configure contexts
Please note the following important changes since release 2.3.2:
-- On Windows, .def files did not work as sources to shared
libraries or executables, due to a regression which is
corrected in 2.3.3.
Please note the following important changes since release 2.3.0:
-- BitKeeper, CVS, Perforce, RCS, SCCS are deprecated from the
default toolset and will be removed from the default toolset
in future SCons versions to speed up SCons initialization.
The tools themselves continue to be supported.
-- Support for Visual Studio 12.0Exp and 2013
-- Revamp of D language support, focusing on D v2.
D v1 is now deprecated.
-- Fixed NoClean() for multi-target builders.
-- RPM and m4 are no longer in the default toolset on Windows.
Should improve startup speed.
-- TeX fixes: -synctex=1 and cleaning auxiliary files.
-- Fixes to the Docbook tool.
Please note the following important changes since release 2.3.0:
-- Fix failure to relink when LINKCOM or libs change, introduced in
2.3.0.
-- Fix MSVC defaulting TARGET_ARCH to HOST_ARCH and other MSVC
issues.
-- Reduced memory consumption in large builds, which should speed
them up as well.
-- Add new cyglink linker for use with cygwin.
-- Fix leaking file handles to subprocesses
-- Support read-only cache (--cache-readonly)
-- Add Pseudo command to mark targets that shouldn't exist after
building
Please note the following important changes since release 2.2.0:
-- SUPPORT FOR PYTHON VERSIONS BEFORE 2.7 IS NOW DEPRECATED
***IMPORTANT***: This release is the last version of SCons to support
Python versions older than 2.7. This release will warn if you are
running on Python 2.6 or older; future releases will probably not
work at all, as we are moving toward supporting Python 3.
Use --warn=no-python-version to suppress the warning if needed.
-- A lot of python pre-2.4 compatibility code was removed
in this release. 2.4 is the official floor for SCons,
but this release will likely enforce it more rigidly.
-- Spawning subprocesses on Windows should now be more reliable with -jN
-- MSVC10 and MSVC11 support improved, and fixed MSVS11 solution
generation.
-- Various TeX/LaTeX builder improvements
-- Support for versioned shared libs on Linux and Mac, via
SHLIBVERSION and InstallVersionedLib.
-- WiX builder updates
Please note the following important changes since release 2.1.0:
-- New gettext toolset for internationalization
-- Support for Visual Studio 11
-- Support for Intel C/C++ compiler v12 on Linux and Mac
-- LaTeX support for multibib, biblatex and biber
Please note the following important changes since release 2.0.0:
-- Support for Windows manifest generation
-- SCons now searches sitewide dirs for site_scons
-- Support for Latex bibunits package has been added along with
support for tex files generated by other builders
Please note the following important changes since release 1.3.0:
-- SUPPORT FOR PYTHON VERSIONS PRIOR TO 2.4 HAS BEEN REMOVED
Although SCons is still tested with Python 2.3, use of Python
versions prior to 2.4 is deprecated.
-- DEPRECATED FEATURES WILL GENERATE MANDATORY WARNINGS IN 2.0.0
In keeping with our deprecation cycle, the following deprecated
features will still be supported in 2.0.0 but will generate
mandatory, non-disableable warnings:
-- The overrides= keyword argument to the Builder() call.
-- The scanner= keyword argument to the Builder() call.
-- The BuildDir() function and env.BuildDir() method.
-- The env.Copy() method.
-- The SourceSignatures() function and
env.SourceSignatures() method.
-- The TargetSignatures() function and
env.TargetSignatures() method.
-- The Sig module (now an unnused stub).
-- The --debug=dtree, --debug=stree and --debug=tree options.
-- The --debug=nomemoizer option.
-- The Options object and the related BoolOption(),
EnumOption(), ListOption(), PackageOption() and
PathOption() functions.
The mandatory warnings will be issued in order to make sure
users of 1.3.0 notice *prior* to the release of SCons 2.0.0, that
these features will be removed. In SCons 2.0.0 these features
will no longer work at all, and will instead generate specific
fatal errors when anyone tries to use them.
Please note the following important changes since release 1.2.0:
-- MICROSOFT VISUAL STUDIO VERSION/ARCH DETECTION HAS CHANGED
The way SCons detects Visual Studio on Windows has changed in
1.3. By default, it should now use the latest installed
Visual Studio version on your machine, and compile for 32 or
64 bits according to whether your OS is 32 or 64 bits (32/64
bit Python makes no difference).
Two new variables control Visual Studio: MSVC_VERSION and
TARGET_ARCH. These variables ONLY take effect when passed to
the Environment() constructor; setting them later has no
effect. To use a non-default Visual Studio version, set
MSVC_VERSION to e.g. "8.0" or "7.1". Setting it to "xxx" (or
any nonexistent value) will make it print out the valid
versions on your system. To use a non-default architecture,
set TARGET_ARCH to "x86" or "x86_64" (various synonyms are
accepted).
Note that if you use MSVS_VERSION to build Visual Studio
projects from your SConstructs, MSVS_VERSION must be set to
the same version as MSVC_VERSION.
Support for HOST_OS,HOST_ARCH,TARGET_OS, TARGET_ARCH has been
added to allow specifying different target arch than the host
system. This is only supported for Visual Studio/Visual C++
at this time.
-- Support for Latex glossaries and acronyms has been added
-- VISUAL C/C++ PRECOMPILED HEADERS WILL BE REBUILT
Precompiled header files built with Visual C/C++ will be
rebuilt after upgrading from 1.2.0 to a later release.
This rebuild is normal and will occur because the command line
defined by the $PCHCOM construction variable has had the $CCFLAGS
variable added, and has been rearranged to put the "/Fo" output
flag towards the beginning of the line, consistent with the
related command lines for $CCCOM, $CXXCOM, etc.
-- CHANGES TO SOME LINKER COMMAND LINES WILL CAUSE RELINKING
Changes to the command line definitions for the Microsoft link.exe
linker, the OS/2 ilink linker and the Phar Lap linkloc linker
will cause targets built with those tools be to be rebuilt after
upgrading from 1.2.0 to a later release.
This relink is normal and will occur because the command lines for
these tools have been redefined to remove unnecessary nested $(
and $) character strings.
-- MSVS_USE_MFC_DIRS and MSVS_IGNORE_IDE_PATHS are obsoleted and
have no effect.
Please note the following important changes since release 1.1.0:
-- THE $CHANGED_SOURCES, $CHANGED_TARGETS, $UNCHANGED_SOURCES
AND $UNCHANGED_TARGETS VARIABLES WILL BECOME RESERVED
A future release (probably 1.3.0) will make the construction
variable names $CHANGED_SOURCES, $CHANGED_TARGETS,
$UNCHANGED_SOURCES and $UNCHANGED_TARGETS into reserved
construction variable names controlled by SCons itself (like
the current $SOURCE, $TARGETS, etc.).
Setting these variable names in the current release will generate
a warning but still set the variables. When they become reserved
variable names, they will generate a different warning message
and attempts to set these variables will be ignored.
SCons configurations that happen to use these variable names
should be changed to use different variable names, in order
to ensure that the configuration continues to work with future
versions of SCons.
-- THE Options OBJECT AND RELATED FUNCTIONS NOW GENERATE WARNINGS
Use of the Options object, and related functions BoolOption(),
EnumOption(), ListOption(), PackageOption() and PathOption()
were announced as deprecated in release 0.98.1. Since then,
however, no warning messages were ever implemented for the
use of these deprecated functions.
By default, release 1.2.0 prints warning messages when these
deprecated features are used. Warnings about all deprecated
features may be suppressed by using the --warn=no-deprecated
command-line option:
$ scons --warn=no-deprecated
Or by using the appropriate SetOption() call in any SConscript
file:
SetOption('warn', 'no-deprecated')
You may optionally disable just warnings about the deprecation
of the Options object and its related functions as follows:
SetOption('warn', 'no-deprecated-options')
The current plan is for these warnings to become mandatory
(non-suppressible) in release 1.3.0, and for the use of Options
and its related functions to generate errors in release 2.0.
Please note the following important changes since release 0.98.4:
-- scons.bat NOW RETURNS THE REAL SCONS EXIT STATUS
The scons.bat script shipped with SCons used to exit with
a status of 1 when it detected any failed (non-zero) exit
status from the underlying Python execution of SCons itself.
The scons.bat script now exits with the actual status
returned by SCons.
-- SCONS NOW WARNS WHEN TRYING TO LINK C++ AND FORTRAN OBJECT FILES
Some C++ toolchains do not understand Fortran runtimes and create
unpredictable executables when linking C++ and Fortran object
files together. SCons now issues a warning if you try to link
C++ and Fortran object files into the same executable:
scons: warning: Using $CXX to link Fortran and C++ code
together.
This may generate a buggy executable if the
'/usr/bin/gcc'
compiler does not know how to deal with Fortran
runtimes.
The warning may be suppressed with either the --warning=no-link
or --warning=no-fortran-cxx-mix command line options, or by
adding either of the following lines to a SConscript file:
SetOption('warn', 'no-link')
SetOption('warn', 'no-fortran-cxx-mix')
Please note the following important changes since release 0.98:
-- SCONS NO LONGER SETS THE GNU TOOLCHAIN -fPIC FLAG IN $SHCXXFLAGS
The GNU toolchain support in previous versions of SCons would
add the -fPIC flag to the $SHCXXFLAGS construction variable.
The -fPIC flag has now been removed from the default
$SHCXXFLAGS setting. Instead, the $SHCXXCOM construction variable
(the default SCons command line for compiling shared objects
from C++ source files) has been changed to add the $SHCCFLAGS
variable, which contains the -fPIC flag.
This change was made in order to make the behavior of the default
C++ compilation line including $SHCCFLAGS consistent with the
default C compilation line including $CCFLAGS.
This change should have no impact on configurations that use
the default $SHCXXCOM command line. It may have an impact on
configurations that were using the default $SHCXXFLAGS value
*without* the $SHCCFLAGS variable to get the -fPIC flag into a
custom command line. You can fix these by adding the $SHCCFLAGS
to the custom command line.
Adding $SHCCFLAGS is backwards compatible with older SCons
releases, although it might cause the -fPIC flag to be repeated
on the command line if you execute it on an older version of
SCons that sets -fPIC in both the $SHCCLAFGS and $SHCXXFLAGS
variables. Duplicating the -fPIC flag on the g++ command line
will not cause any compilation problems, but the change to the
command line may cause SCons to rebuild object files.
-- FORTRAN NOW COMPILES .f FILES WITH gfortran BY DEFAULT
The Fortran Tool modules have had a major overhaul with the intent
of making them work as-is for most configurations. In general,
most configurations that use default settings should not see
any noticeable difference.
One configuration that has changed is if you have both a gfortran
and g77 compiler installed. In this case, previous versions of
SCons would, by default, use g77 by default to compile files with
a .f suffix, while SCons 0.98.1 will use the gfortran compiler
by default. The old behavior may be preserved by explicitly
initializing construction environments with the 'g77' Tool module:
env = Environment(tools = ['g77', 'default'])
The above code is backwards compatible to older versions of SCons.
If you notice any other changes in the behavior of default
Fortran support, please let us know so we can document them in
these release notes for other users.
Please note the following important changes since release 0.97.0d20071212:
-- SUPPORT FOR PYTHON VERSIONS BEFORE 2.2 IS NOW DEPRECATED
SCons now prints the following warning when it is run by any
Python 1.5, 2.0 or 2.1 release or sub-release:
scons: warning: Support for pre-2.2 Python (VERSION) is
deprecated.
If this will cause hardship, contact scons-...@scons.org
You may disable all warnings about deprecated features by adding
the option "--warn=no-deprecated" to the command line or to the
$SCONSFLAGS environment variable:
$ scons --warn=no-deprecated
Using '--warn=no-deprecated' is compatible with earlier versions
of SCons.
You may also, as of this version of SCons, disable all warnings
about deprecated features by adding the following to any
SConscript file:
SetOption('warn', 'no-deprecated')
You may disable only the specific warning about running under
a deprecated Python version by adding the following to any
SConscript file:
SetOption('warn', 'no-python-version')
The warning may also be suppressed on the command line:
$ scons --warn=no-python-version
Or by specifying the --warn=no-python-version option in the
$SCONSFLAGS environment variable.
Using SetOption('warn', ...), and the 'no-python-version'
command-line option for suppressing this specific warning,
are *not* backwards-compatible to earlier versions of SCons.
-- THE env.Copy() METHOD IS NOW OFFICIALLY DEPRECATED
The env.Copy() method is now officially deprecated and will
be removed in a future release. Using the env.Copy() method
now generates the following message:
scons: warning: The env.Copy() method is deprecated; use the
env.Clone() method instead.
You may disable all warnings about deprecated features by adding
the option "--warn=no-deprecated" to the command line or to the
$SCONSFLAGS environment variable:
$ scons --warn=no-deprecated
Using '--warn=no-deprecated' is compatible with earlier versions
of SCons.
You may also, as of this version of SCons, disable all warnings
about deprecated features by adding the following to any
SConscript file:
SetOption('warn', 'no-deprecated')
You may disable only the specific warning about the deprecated
env.Copy() method by adding the following to any SConscript
file:
SetOption('warn', 'no-deprecated-copy')
The warning may also be suppressed on the command line:
$ scons --warn=no-deprecated-copy
Or by specifying the --warn=no-deprecated-copy option in the
$SCONSFLAGS environment variable.
Using SetOption('warn', ...), and the 'no-deprecated-copy'
command-line option for suppressing this specific warning,
are *not* backwards-compatible to earlier versions of SCons.
-- THE --debug=dtree, --debug=stree AND --debug=tree OPTIONS ARE
DEPRECATED
The --debug=dtree, --debug=stree and --debug=tree methods
are now officially deprecated and will be removed in a
future release. Using these options now generate a warning
message recommending use of the --tree=derived, --tree=all,status
and --tree=all options, respectively.
You may disable these warnings, and all warnings about
deprecated features, by adding the option "--warn=no-deprecated"
to the command line or to the $SCONSFLAGS environment
variable:
$ scons --warn=no-deprecated
Using '--warn=no-deprecated' is compatible with earlier versions
of SCons.
-- THE TargetSignatures() AND SourceSignatures() FUNCTIONS ARE
DEPRECATED
The TargetSignatures() and SourceSignatures() functions,
and their corresponding env.TargetSignatures() and
env.SourceSignatures() methods, are now officially deprecated
and will be be removed in a future release. Using ahy of
these functions or methods now generates a message
similar to the following:
scons: warning: The env.TargetSignatures() method is deprecated;
convert your build to use the env.Decider() method
instead.
You may disable all warnings about deprecated features by adding
the option "--warn=no-deprecated" to the command line or to the
$SCONSFLAGS environment variable:
$ scons --warn=no-deprecated
Using '--warn=no-deprecated' is compatible with earlier versions
of SCons.
You may also, as of this version of SCons, disable all warnings
about deprecated features by adding the following to any
SConscript file:
SetOption('warn', 'no-deprecated')
You may disable only the specific warning about the use of
TargetSignatures() or SourceSignatures() by adding the
following to any SConscript file:
SetOption('warn', 'no-deprecated-target-signatures')
SetOption('warn', 'no-deprecated-source-signatures')
The warnings may also be suppressed on the command line:
$ scons --warn=no-deprecated-target-signatures
--warn=no-deprecated-source-signatures
Or by specifying these options in the $SCONSFLAGS environment
variable.
Using SetOption('warn', ...), or the command-line options
for suppressing these warnings, is *not* backwards-compatible
to earlier versions of SCons.
-- File(), Dir() and Entry() NOW RETURN A LIST WHEN THE INPUT IS A
SEQUENCE
Previously, if these methods were passed a list, the list was
substituted and stringified, then passed as a single string to
create a File/Dir/Entry Node. This rarely if ever worked with
more than one element in the list. They now return a list of
Nodes when passed a list.
One case that works differently now is a passing in a
single-element sequence; that formerly was stringified
(returning its only element) and then a single Node would be
returned. Now a single-element list containing the Node will
be returned, for consistency.
-- THE env.subst() METHOD NOW RETURNS A LIST WHEN THE INPUT IS A
SEQUENCE
The env.subst() method now returns a list with the elements
expanded when given a list as input. Previously, the env.subst()
method would always turn its result into a string.
This behavior was changed because it interfered with being able
to include things like lists within the expansion of variables
like $CPPPATH and then have SCons understand that the elements
of the "internal" lists still needed to be treated separately.
This would cause a $CPPPATH list like ['subdir1', 'subdir']
to show up in a command line as "-Isubdir1 subdir".
-- THE Jar() BUILDER NOW USES THE Java() BUILDER CLASSDIR BY DEFAULT
By default, the Jar() Builder will now use the class directory
specified when the Java() builder is called. So the following
input:
classes = env.Java('classes', 'src')
env.Jar('out.jar', classes)
Will cause "-C classes" to be passed the "jar" command invocation,
and the Java classes in the "out.jar" file will not be prefixed
"classes/".
Explicitly setting the $JARCHDIR variable overrides this default
behavior. The old behavior of not passing any -C option to the
"jar" command can be preserved by explicitly setting $JARCHDIR
to None:
env = Environment(JARCHDIR = None)
The above setting is compatible with older versions of SCons.
Please note the following important changes since release 0.97.0d20070918:
-- SCons REDEFINES PYTHON open() AND file() ON Windows TO NOT PASS
ON OPEN FILE HANDLES TO CREATED PROCESSES
On Windows systems, SCons now redefines the Python open()
and file() functions so that, if the Python Win32 extensions
are available, the file handles for any opened files will *not*
be inherited by subprocesses, such as the spawned compilers and
other tools invoked to build the software.
This prevents certain race conditions where a file handle for
a file opened by Python (either in a Python function action,
or directly in a SConscript file) could be inherited and help
open by a subprocess, interfering with the ability of other
processes to create or modify the file.
In general, this should not cause problems for the vast majority
of configurations. The only time this would be a problem would be
in the unlikely event that a process spawned by SCons specifically
*expected* to use an inherited file handle opened by SCons.
If the Python Win32 extensions are not installed or are an
earlier version that does not have the ability to disable file
handle inheritance, SCons will print a warning message when the
-j option is used. The warning message may be suppressed by
specifying --warn=no-parallel-support.
Please note the following important changes since release 0.97.0d20070809:
-- "content" SIGNATURES ARE NOW THE DEFAULT BEHAVIOR
The default behavior of SCons is now to use the MD5 checksum of
all file contents to decide if any files have changed and should
cause rebuilds of their source files. This means that SCons may
decide not to rebuild "downstream" targets if a a given input
file is rebuilt to the exact same contents as the last time.
The old behavior may preserved by explicity specifying:
TargetSignatures("build")
In any of your SConscript files.
-- TARGETS NOW IMPLICITLY DEPEND ON THE COMMAND THAT BUILDS THEM
For all targets built by calling external commands (such as a
compiler or other utility), SCons now adds an implicit dependency
on the command(s) used to build the target.
This will cause rebuilds of all targets built by external commands
when running SCons in a tree built by previous version of SCons,
in order to update the recorded signatures.
The old behavior of not having targets depend on the external
commands that build them can be preserved by setting a new
$IMPLICIT_COMMAND_DEPENDENCIES construction variable to a
non-True value:
env = Environment(IMPLICIT_COMMAND_DEPENDENCIES = 0)
or by adding Ignore() calls for any targets where the behavior
is desired:
Ignore('/usr/bin/gcc', 'foo.o')
Both of these settings are compatible with older versions
of SCons.
-- CHANGING SourceSignature() MAY CAUSE "UNECESSARY" REBUILDS
If you change the SourceSignature() value from 'timestamp' to
'MD5', SCons will now rebuild targets that were already up-to-date
with respect to their source files.
This will happen because SCons did not record the content
signatures of the input source files when the target was last
built--it only recorded the timestamps--and it must record them
to make sure the signature information is correct. However,
the content of source files may have changed since the last
timestamp build was performed, and SCons would not have any way to
verify that. (It would have had to open up the file and record
a content signature, which is one of the things you're trying to
avoid by specifying use of timestamps....) So in order to make
sure the built targets reflect the contents of the source files,
the targets must be rebuilt.
Change the SourceSignature() value from 'MD5' to 'timestamp'
should correctly not rebuild target files, because the timestamp
of the files is always recorded.
In previous versions of SCons, changing the SourceSignature()
value would lead to unpredictable behavior, usually including
rebuilding targets.
-- THE Return() FUNCTION NOW ACTUALLY RETURNS IMMEDIATELY
The Return() function now immediately stops processing the
SConscript file in which it appears and returns the values of the
variables named in its arguments. It used to continue processing
the rest of the SConscript file, and then return the values of the
specified variables at the point the Return() function was called.
The old behavior may be requested by adding a "stop=False"
keyword argument to the Return() call:
Return('value', stop=False)
The "stop=" keyword argument is *not* compatible with SCons
versions 0.97.0d20070809 or earlier.
Please note the following important changes since release 0.97:
-- env.CacheDir() NOW ONLY AFFECTS CONSTRUCTION ENVIRONMENT TARGETS
The env.CacheDir() method now only causes derived files to be
retrieved from the specified cache directory for targets built
with the specified specified construction environment ("env").
Previously, any call to env.CacheDir() or CacheDir() would modify
a global setting and cause all built targets to be retrieved
from the specified cache directory. This behavior was changed so
that env.CacheDir() would be consistent with other construction
environment methods, which only affect targets built with the
specified construction environment.
The old behavior of changing the global behavior may be preserved
by changing any env.CacheDir() calls to:
CacheDir('/path/to/cache/directory')
The above change is backwards-compatible and works in all earlier
versions of SCons that support CacheDir().
-- INTERPRETATION OF SUFFIX-LESS SOURCE ARGUMENTS HAS CHANGED
The interpretation of source arguments (files) without suffixes
has changed in one specific configuration.
Previously, if a Builder had a src_suffix specified (indicating
that source files without suffixes should have that suffix
appended), the suffix would only be applied to suffix-less source
arguments if the Builder did *not* have one or more attached
source Builders (that is, the Builder was not a "multi-stage"
Builder). So in the following configuration:
build_foo = Builder(src_suffix = '.foo')
build_bar = Builder(src_suffix = '.bar',
src_builder = build_bar)
env = Environment(BUILDERS = {
'Foo' : build_foo,
'Boo' : build_bar,
})
env.Foo('tgt1', 'src1')
env.Bar('tgt2', 'src2')
SCons would have expected to find a source file 'src1.foo' for the
env.Foo() call, but a source file 'src2' for the env.Bar() call.
This behavior has now been made consistent, so that the two
above calls would expect source files named 'src1.foo' and
'src2.bar', respectively.
Note that, if genuinely desired, the old behavior of building
from a source file without a suffix at all (when the Builder has
a src_suffix *and* a src_builder) can be specified explicity by
turning the string into a File Node directly:
env.Bar('tgt2', File('src2'))
The above use of File() is backwards-compatible and will work
on earlier versions of SCons.
-- THE DEFAULT EXECUTION PATH FOR Solaris HAS CHANGED
On Solaris systems, SCons now adds the "/opt/SUNWspro/bin"
directory to the default execution $PATH variable before the
"/usr/ccs/bin" directory. This was done to reflect the fact
that /opt/SUNWspro/ is the default for SUN tools, but it may
cause a different compiler to be used if you have compilers
installed in both directories.
-- GENERATED config.h FILES NOW SAY "#define HAVE_{FEATURE} 1"
When generating a "config.h" file, SCons now defines values that
record the existence of a feature with a "1" value:
#define HAVE_FEATURE 1
Instead of printing the line without a "1", as it used to:
#define HAVE_FEATURE
This should not cause any problems in the normal use of "#ifdef
HAVE_{FEATURE}" statements interpreted by a C preprocessor, but
might cause a compatibility issue if a script or other utility
looks for an exact match of the previous text.
Please note the following planned, future changes:
-- THE Options OBJECT AND RELATED FUNCTIONS WILL BE DEPRECATED
The Options object is being replaced by a new Variables
object, which uses a new Variables.AddVariable() method
where the previous interface used Options.AddOptions().
Similarly, the following utility functions are being replaced
by the following similarly-named functions:
BoolOption() BoolVariable()
EnumOption() EnumVariable()
ListOption() ListVariable()
PackageOption() PackageVariable()
PathOption() PathVariable()
And also related, the options= keyword argument when creating
construction environments with the Environment() functions is
being replaced with a variables= keyword argument.
In some future release a deprecation warning will be added to
existing uses of the Options object, its methods, the above
utility functions, and the options= keyword argument of the
Environment() function. At some point after the deprecation
warning is added, the Options object, related functions and
options= keyword argument will be removed entirely.
You can prepare for this by changing all your uses of the Options
object and related functions to the Variables object and the new
function names, and changing any uses of the options= keyword
argument to variables=.
NOTE: CONVERTING TO USING THE NEW Variables OBJECT OR THE
RELATED *Variable() FUNCTIONS, OR USING THE NEW variable=
KEYWORD ARGUMENT, IS NOT BACKWARDS COMPATIBLE TO VERSIONS OF
SCons BEFORE 0.98. YOUR SConscript FILES WILL NOT WORK ON
EARLIER VERSIONS OF SCons AFTER MAKING THIS CHANGE.
If you change SConscript files in software that you make available
for download or otherwise distribute, other users may try to
build your software with an earlier version of SCons that does
not have the Variables object or related *Variable() functions.
We recommend preparing for this in one of two ways:
-- Make your SConscript files backwards-compatible by
modifying your calls with Python try:-except: blocks
as follows:
try:
vars = Variables('custom.py', ARGUMENTS)
vars.AddVariables(
BoolVariable('WARNINGS', 'cmopile with -Wall',
1),
EnumVariable('DEBUG', 'debug version', 'no'
allowed_values=('yes', 'no', 'full'),
map={}, ignorecase=0),
ListVariable('SHAREDLIBS',
'libraries to build shared',
'all',
names = list_of_libs),
PackageVariable('X11',
'use X11 from here',
'/usr/bin/X11'),
PathVariable('QTDIR', 'root of Qt', qtdir),
)
except NameError:
vars = Options('custom.py', ARGUMENTS)
vars.AddOptions(
BoolOption('WARNINGS', 'cmopile with -Wall', 1),
EnumOption('DEBUG', 'debug version', 'no'
allowed_values=('yes', 'no', 'full'),
map={}, ignorecase=0),
ListOption('SHAREDLIBS',
'libraries to build shared',
'all',
names = list_of_libs),
PackageOption('X11',
'use X11 from here',
'/usr/bin/X11'),
PathOption('QTDIR', 'root of Qt', qtdir),
)
Additionally, you can check for availability of the new
variables= keyword argument as follows:
try:
env = Environment(variables=vars)
except TypeError:
env = Environment(options=vars)
(Note that we plan to maintain the existing Options object
name for some time, to ensure backwards compatibility,
so in practice it may be easier to just continue to use
the old name until you're reasonably sure you won't have
people trying to build your software with versions of
SCons earlier than 0.98.1.)
-- Use the EnsureSConsVersion() function to provide a
descriptive error message if your SConscript files
are executed by an earlier version of SCons:
EnsureSConsVersion(0, 98, 1)
-- THE BuildDir() METHOD AND FUNCTION WILL BE DEPRECATED
The env.BuildDir() method and BuildDir() function are being
replaced by the new env.VariantDir() method and VariantDir()
function.
In some future release a deprecation warning will be added
to existing uses of the env.BuildDir() method and BuildDir()
function. At some point after the deprecation warning, the
env.Builder() method and BuildDir() function will either
be removed entirely or have their behavior changed.
You can prepare for this by changing all your uses of the
env.BuildDir() method to env.VariantDir() and uses of the
global BuildDir() function to VariantDir(). If you use a
named keyword argument of "build_dir" when calling
env.BuildDir() or BuildDir():
env.BuildDir(build_dir='opt', src_dir='src')
The keyword must be changed to "variant_dir":
env.VariantDir(variant_dir='opt', src_dir='src')
NOTE: CHANGING USES OF env.BuildDir() AND BuildDir() to
env.VariantDir() AND VariantDir() IS NOT BACKWARDS COMPATIBLE
TO VERSIONS OF SCons BEFORE 0.98. YOUR SConscript FILES
WILL NOT WORK ON EARLIER VERSIONS OF SCons AFTER MAKING
THIS CHANGE.
If you change SConscript files in software that you make
available for download or otherwise distribute, other users
may try to build your software with an earlier version of
SCons that does not have the env.VariantDir() method or
VariantDir() fnction. We recommend preparing for this in
one of two ways:
-- Make your SConscript files backwards-compatible by
including the following code near the beginning of your
top-level SConstruct file:
import SCons.Environment
try:
SCons.Environment.Environment.VariantDir
except AttributeError:
SCons.Environment.Environment.VariantDir = \
SCons.Environment.Environment.BuildDir
-- Use the EnsureSConsVersion() function to provide a
descriptive error message if your SConscript files
are executed by an earlier version of SCons:
EnsureSConsVersion(0, 98)
-- THE SConscript() "build_dir" KEYWORD ARGUMENT WILL BE DEPRECATED
The "build_dir" keyword argument of the SConscript function
and env.SConscript() method are being replaced by a new
"variant_dir" keyword argument.
In some future release a deprecation warning will be added
to existing uses of the SConscript()/env.SConscript()
"build_dir" keyword argument. At some point after the
deprecation warning, support for this keyword argument will
be removed entirely.
You can prepare for this by changing all your uses of the
SConscript()/env.SConscript() 'build_dir" keyword argument:
SConscript('src/SConscript', build_dir='opt')
To use the new "variant_dir" keyword argument:
SConscript('src/SConscript', variant_dir='opt')
NOTE: USING THE NEW "variant_dir" KEYWORD IS NOT BACKWARDS
COMPATIBLE TO VERSIONS OF SCons BEFORE 0.98. YOUR SConscript
FILES WILL NOT WORK ON EARLIER VERSIONS OF SCons AFTER
MAKING THIS CHANGE.
If you change SConscript files in software that you make
available for download or otherwise distribute, other users
may try to build your software with an earlier version of
SCons that does not support the "variant_dir" keyword.
If you can insist that users use a recent version of SCons
that supports "variant_dir", we recommend using the
EnsureSConsVersion() function to provide a descriptive error
message if your SConscript files are executed by an earlier
version of SCons:
EnsureSConsVersion(0, 98)
If you want to make sure that your SConscript files will
still work with earlier versions of SCons, then your best
bet is to continue to use the "build_dir" keyword until the
support is removed (which, in all likelihood, won't happen
for quite some time).
-- SCANNER NAMES HAVE BEEN DEPRECATED AND WILL BE REMOVED
Several internal variable names in SCons.Defaults for various
pre-made default Scanner objects have been deprecated and will
be removed in a future revision. In their place are several new
global variable names that are now part of the publicly-supported
interface:
NEW NAME DEPRECATED NAME
-------- ----------------------------
CScanner SCons.Defaults.CScan
DSCanner SCons.Defaults.DScan
SourceFileScanner SCons.Defaults.ObjSourceScan
ProgramScanner SCons.Defaults.ProgScan
Of these, only ObjSourceScan was probably used at all, to add
new mappings of file suffixes to other scanners for use by the
Object() Builder. This should now be done as follows:
SourceFileScanner.add_scanner('.x', XScanner)
-- THE env.Copy() METHOD WILL CHANGE OR GO AWAY ENTIRELY
The env.Copy() method (to make a copy of a construction
environment) is being replaced by the env.Clone() method.
As of SCons 0.98, a deprecation warning has been added to
current uses of the env.Copy() method. At some point in
the future, the env.Copy() method will either be removed
entirely or have its behavior changed.
You can prepare for this by changing all your uses of env.Copy()
to env.Clone(), which has the exact same calling arguments.
NOTE: CHANGING USES OF env.Copy() TO env.Clone() WILL MAKE
YOUR SConscript FILES NOT WORK ON VERSIONS OF SCons BEFORE
0.96.93.
If you change SConscript files in software that you make
available for download or otherwise distribute, other users
may try to build your software with an earlier version of
SCons that does not have the env.Clone() method. We recommend
preparing for this in one of two ways:
-- Make your SConscript files backwards-compatible by
including the following code near the beginning of your
top-level SConstruct file:
import SCons.Environment
try:
SCons.Environment.Environment.Clone
except AttributeError:
SCons.Environment.Environment.Clone = \
SCons.Environment.Environment.Copy
-- Use the EnsureSConsVersion() function to provide a
descriptive error message if your SConscript files
are executed by an earlier version of SCons:
EnsureSConsVersion(0, 96, 93)
-- THE CheckLib Configure TEST WILL CHANGE BEHAVIOR
The CheckLib() Configure test appends the lib(s) to the
Environment's LIBS list in 1.3 and earlier. In 1.3 there is a
new CheckLib argument, append, which defaults to True to
preserve the old behavior. In a future release, append will
be changed to default to False, to conform with autoconf and
user expectations, since it is usually used to build up
library lists in a right-to-left way.
SCons is developed with an extensive regression test suite, and a
rigorous development methodology for continually improving that suite.
Because of this, SCons is of sufficient quality that you can use it
for real work.
The interfaces in release 1.0 will *not* be knowingly changed in
any new, future 1.x release. If an interface change should ever
become necessary due to extraordinary circumstances, the change
and an appropriate transition strategy will be documented in these
RELEASE notes.
As you use SCons, please heed the following:
- Please report any bugs or other problems that you find to our bug
tracker at our SourceForge project page:
http://sourceforge.net/tracker/?func=add&group_id=30337&atid=398971
We have a reliable bug-fixing methodology already in place and
strive to respond to problems relatively quickly.
- Documentation is spottier than we'd like. You may need to dive
into the source code to figure out how to do something. Asking
questions on the scons-users mailing list is also welcome. We
will be addressing the documentation in upcoming releases, but
would be more than glad to have your assistance in correcting this
problem... :-)
- The "SCons Design" documentation on the SCons web site is very
out of date, as we made significant changes to portions of the
interface as we figured out what worked and what didn't during the
extensive beta implementation. The "SCons Design" document should
be used only for historical purposes, or for just an extremely
general understanding of SCons' architectural goals.
- There may be performance issues. Improving SCons performance
is an ongoing priority. If you still find the performance
unacceptable, we would very much like to hear from you and learn
more about your configuration so we can optimize the right things.
- Error messages don't always exist where they'd be helpful.
Please let us know about any errors you ran into that would
have benefitted from a (more) descriptive message.
KNOWN PROBLEMS IN THIS RELEASE:
For a complete list of known problems, consult the SCons Issue Tracker
at tigris.org:
http://scons.tigris.org/project_issues.html
- Support for parallel builds (-j) does not work on WIN32 systems
prior to *official* Python release 2.2 (not 2.2 pre-releases).
Prior to Python 2.2, there is a bug in Python's Win32
implementation such that when a thread spawns an external command,
it blocks all threads from running. This breaks the SCons
multithreading architecture used to support -j builds.
We have included a patch file, os_spawnv_fix.diff, that you can
use if you you want to fix your version of Python to support
parallel builds in SCons.
- Again, the "SCons Design" documentation on the SCons web site is
out of date. Take what you read there with a grain of salt.
- On Win32 systems, you must put a space between the redirection
characters < and >, and the specified files (or construction
variable expansions):
command < $SOURCE > $TARGET
If you don't supply a space (for example, "<$SOURCE"), SCons will
not recognize the redirection.
- MSVC .res files are not rebuilt when icons change.
- The -c option does not clean up .sconsign files or directories
created as part of the build, and also does not clean up
SideEffect files (for example, Visual Studio .pdb files).
- When using multiple Repositories, changing the name of an include
file can cause an old version of the file to be used.
- There is currently no way to force use of a relative path (../*)
for directories outside the top-level SConstruct file.
- The Jar() Builder will, on its second or subsequent invocation,
package up the .sconsign files that SCons uses to track signatures.
You can work around this by using the SConsignFile() function
to collect all of the .sconsign information into a single file
outside of the directory being packaged by Jar().
- SCons does not currently have a way to detect that an intermediate
file has been corrupted from outside and should be rebuilt.
- Unicode characters in path names do not work in all circumstances.
- SCons does not currently automatically check out SConstruct or
SConscript files from SCCS, RCS or BitKeeper.
- No support yet for the following planned command-line options:
-d -e -l --list-actions --list-derived --list-where
-o --override -p -r -R -w --write-filenames
-W --warn-undefined-variables
Thank you for your interest, and please let us know how we can help
improve SCons for your needs.
-- The SCons Development Team
Gary Oberbrunner and Bill Deegan, maintainers
Thanks to all the contributors for all your help!
--
https://mail.python.org/mailman/listinfo/python-announce-list
Support the Python Software Foundation:
http://www.python.org/psf/donations/
