This is the start of the removal of the C++ implementation of libSyntax
in favor of the new Swift Parser and Swift Syntax libraries. Now that
the Swift Parser has switched the SwiftSyntaxParser library over to
being a thin wrapper around the Swift Parser, there is no longer any
reason we need to retain any libSyntax infrastructure in the swift
compiler.
As a first step, delete the infrastructure that builds
lib_InternalSwiftSyntaxParser and convert any scripts that mention
it to instead mention the static mirror libraries. The --swiftsyntax
build-script flag has been retained and will now just execute the
SwiftSyntax and Swift Parser builds with the just-built tools.
On both macOS and Linux `python` is not symlinked to `python3` by default. To avoid confusion, we should update our documentation that instructs users to run scripts with `python` to use `python3` instead.
Similar to the way the early Swift Driver is built, introduce a
build-script option `--early-swiftsyntax` that uses the host Swift and
CMake to build the parts of the swift-syntax package that are expected
to become be used in the compiler.
Note that this does not obviate the need for the `--swiftsyntax`
option, because that build product uses the just-built Swift compiler
and SwiftPM to build, test, and install everything from the
swift-syntax package.
The `__future__` we relied on is now, where the 3 specific things are
all included [since Python 3.0](https://docs.python.org/3/library/__future__.html):
* absolute_import
* print_function
* unicode_literals
* division
These import statements are no-ops and are no longer necessary.
This patch adds a zlib and static-zlib build product, respectively
producing a dynamic and static zlib library. This is a dependency of
building Foundation.
The library `six` provides compatibility between Python 2, and 3. It's no
longer necessary once we migrate of Python 2 completely.
Also remove any custom logic for Python 2 (the ones referenced by
a commentanyways).
https://bugs.swift.org/browse/SR-16025
Internal configurations targeting Darwin employ ThinLTO to
improve compiler performance, however using it on all executable
causes build time to increase with no matching benefit.
To reduce build times in such configurations, we allow some
ancillary targets to opt out of LLVM IR optimizations when linking
ThinLTO with ld64 (e.g. tools used for bootstrapping or debugging the
Swift compiler) -- this behaviour is opt in through a new flag
`--swift-tools-ld64-lto-codegen-only-for-supporting-targets`.
Addresses rdar://76702687
