With this option turned on, if properly set up, SCons generates a
`build.ninja` file and quits. To actually build the engine, the user can
then call `ninja` with whatever options they might prefer (not
everything is yet transferred properly to this new generated file).
Ideally, the scons file should never be called again, as ninja
automatically detects any SCons build script change and invokes
the required commands to regenerate itself.
This approach speeds up incremental builds considerably, as it limits
SCons to code generation and uses ninja's extremely fast timestamp-based
file change detector.
Previously, all of the code generation routines would just needlessly
write the same files over and over, even when not needed.
This became a problem with the advent of the experimental ninja backend
for SCons, which can be trivially enabled with a few lines of code and
relies on timestamp changes, making it thus impractical.
Follow-up to #75932.
Since these icons are only used by the export plugin, it makes sense to
move them and generate the headers there.
The whole `detect.is_active()` logic seems to be a leftover from before
times, as far back as 1.0-stable it already wasn't used for anything.
So I'm removing it and moving the export icon generation to
`platform_methods`, where it makes more sense.
A new `env.Run` method is added which allows to control the verbosity
of builders output automatically depending on whether the "verbose"
option is set. It also allows to optionally run any SCons commands in a
subprocess using the existing `run_in_subprocess` method, unifying
the interface. `Action` objects wrap all builder functions to include a
short build message associated with any action.
Notably, this removes quite verbose output generated by `make_doc_header`
and `make_editor_icons_action` builders.
Configured for a max line length of 120 characters.
psf/black is very opinionated and purposely doesn't leave much room for
configuration. The output is mostly OK so that should be fine for us,
but some things worth noting:
- Manually wrapped strings will be reflowed, so by using a line length
of 120 for the sake of preserving readability for our long command
calls, it also means that some manually wrapped strings are back on
the same line and should be manually merged again.
- Code generators using string concatenation extensively look awful,
since black puts each operand on a single line. We need to refactor
these generators to use more pythonic string formatting, for which
many options are available (`%`, `format` or f-strings).
- CI checks and a pre-commit hook will be added to ensure that future
buildsystem changes are well-formatted.
- Refactored all builder (make_*) functions into separate Python modules along to the build tree
- Introduced utility function to wrap all invocations on Windows, but does not change it elsewhere
- Introduced stub to use the builders module as a stand alone script and invoke a selected function
There is a problem with file handles related to writing generated content (*.gen.h and *.gen.cpp)
on Windows, which randomly causes a SHARING VIOLATION error to the compiler resulting in flaky
builds. Running all such content generators in a new subprocess instead of directly inside the
build script works around the issue.
Yes, I tried the multiprocessing module. It did not work due to conflict with SCons on cPickle.
Suggested workaround did not fully work either.
Using the run_in_subprocess wrapper on osx and x11 platforms as well for consistency. In case of
running a cross-compilation on Windows they would still be used, but likely it will not happen
in practice. What counts is that the build itself is running on which platform, not the target
platform.
Some generated files are written directly in an SConstruct or SCsub file, before the parallel build starts. They don't need to be written in a subprocess, apparently, so I left them as is.
