An "API descriptor" file is JSON describing the externally accessible symbols
of a module and metadata associated with those symbols like availability and
SPI status. This output was previously only generated by the
`swift-api-extract` alias of `swift-frontend`, which is desgined to take an
already built module as input. Post-processing a built module to extract this
information is inefficient because the module and the module's dependencies
need to be deserialized in order to visit the entire AST. We can generate this
output more efficiently as a supplementary output of the -emit-module job that
originally produced the module (since the AST is already available in-memory).
The -emit-api-descriptor flag can be used to request this output.
This change lays the groundwork by introducing frontend flags. Follow up
changes are needed to make API descriptor emission during -emit-module
functional.
Part of rdar://110916764.
This change removes the -emit-cxx-header option, and adds a new -emit-clang-header-path option instead. It's aliased to -emit-objc-header-path for now, but in the future, -emit-objc-header-path will alias to it. After this change Swift can start emitting a single header file that can be expose declarations to C, Objective-C, or C++. For now C++ interface is generated (for all public decls) only when -enable-cxx-interop flag is passed, but that behavior will change once attribute is supported.
Previously we may have silently bailed if a private
module interface path was specified, but the
frontend action didn't support it. Instead, make
sure we enforce the same restrictions that we
enforce for public module interfaces.
Commit to a command line option spelling so that build systems can
start testing it. I deliberately picked one of the longer names we
were considering because we can always decide to add a shorter alias,
but can't decide a shorter name was too generic.
Like the other supplementary output flags,
-emit-parseable-module-interface-path will emit a .swiftinterface file
to a particular path, while -emit-parseable-module-interface will put
it next to the main output (the one specified with -o).
rdar://problem/43776945
We already have something called "module interfaces" -- it's the
generated interface view that you can see in Xcode, the interface
that's meant for developers using a library. Of course, that's also a
textual format. To reduce confusion, rename the new module stability
feature to "parseable [module] interfaces".
Textual module interfaces don't actually depend on SILGen, so we
shouldn't need to run SILGen (or serialize an entire binary module) if
we're just trying to emit a textual interface. On the other hand, if
we /are/ going to run SILGen and then SIL diagnostics, we shouldn't
delay those diagnostics by spending time emitting a textual interface,
or for that matter a TBD file.
Using this, update all the ModuleInterface tests that use
`-emit-module -o /dev/null` to use `-typecheck` instead, except for
those using `-merge-modules`.
...but don't hook it up to anything yet.
This is the very very start of the module stability / textual
interfaces feature described at
https://forums.swift.org/t/plan-for-module-stability/14551/
For now I've just made it a frontend option (not a driver option),
which is good enough for testing.
This dates back to the early days when the Driver was still being
brought up, but there's no reason to put them together now.
Reorganization and elimination of redundancy only.
