When developing a module for an OS or SDK, one may use declarations from other modules that were recently introduced in the in-development OS. Those declarations will be annotated as available at the deployment target of the client module and yet the symbols for that declaration are not available in all development builds of that OS. If the module strongly links those symbols, it will crash on older development builds of the OS. The `-enable-experimental-ad-hoc-availability` flag is designed to give developers the option of weakly linking all symbols in other modules that were introduced at the deployment target.
This change introduces the basic change in linking behavior but does not address typechecking. Use of the declarations that are made unavailable in this mode will need to be diagnosed and developers will need a way to detect the unavailability at runtime before use.
Resolves rdar://96011550
So far, static arrays had to be put into a writable section, because the isa pointer and the (immortal) ref count field were initialized dynamically at the first use of such an array.
But with a new runtime library, which exports the symbols for the (immortal) ref count field and the isa pointer, it's possible to put the whole array into a read-only section. I.e. make it a constant global.
rdar://94185998
This reverts the revert commit df353ff3c0.
Also, I added a frontend option to disable this optimization: `-disable-readonly-static-objects`
llvm/llvm-project removed the default for the `Default` argument in
522712e2d241ea33575a9c7a60ad582634f04f0d. Specify it directly in the
call to `hasFlag`.
Erroneous declaration attributes were sometimes being printed in the private swiftinterfaces of modules because the changes from https://github.com/apple/swift/pull/42276 were effectively corrupting the attribute list for any decl with sythesized conformances (e.g. `Equatable`, `Hashable`). It is necessary to clone the attributes before adding them to the synthesized conformance extension decls.
Resolves rdar://94009296
Using the same feature set logic as experimental features, provide
feature names for "future" features, which are changes that will
become available with Swift 6. Use the feature check when determining
whether to implementation the feature instead of a language version
check, and map existing flags for these features (when available) over
to the feature set.
As an internal implementation detail, this makes it easier to reason
about when specific features are enabled (or not). If we decide to go
with piecemeal adoption support for features, it can provide an
alternative path to enabling features that feeds this mechanism.
Synthesized file units were designed for autodiff to emit synthesized declarations, and also to sidestep the design implications of doing so late in the compiler pipeline.
A call to materialize synthesized file units was added to the GetImplicitSendable request. This introduced a source of iterator invalidation into forEachFileToTypeCheck in whole-module builds. Any call to insert a new file into the module has the potential to cause the underlying SmallVector to reallocate.
This patch provides a narrow workaround that stops using iterators altogether in forEachFileToTypeCheck. However, this bug reveals a severe architectural flaw in the concept of a synthesized file unit. Iterating over the files in a module is an extremely common operation, and there now are myriad ways we could wind up calling a function that mutates the module's list of files in the process. This also means the number and kind of files being visited by compiler analyses is dependent upon whether a request that inserts these files has or has not been called.
This suggests the call to ModuleDecl::addFile in FileUnit::getOrCreateSynthesizedFile is deleterious and should be removed. Doing so will come as part of a larger refactoring.
rdar://94043340
Experimental features can only be enabled in non-production (+Asserts)
builds. They can be detected with `hasFeature` in the same manner as
"future" features.
The `-enable-experimental-feature X` flag will also look for future
features by that name, so that when an experimental feature becomes an
accepted future feature, it will still be enabled in the same manner.
Switch variadic generics over to this approach, eliminating the
specific LangOption for it.
