Introduce a last resort check reporting references to
implementation-only dependencies that would appear in the generated
swiftmodule. This check is applied at serialization, long after
exportability checking applied at typechecking. It should act as a back
stop to references missed by typechecking or @_implementationOnly decls
that should have been skipped.
This check is gated behind CheckImplementationOnlyStrict and should be
used with embedded only.
rdar://160697599
Printing shouldn't rely on parameter declaration bit because it only
works in cases when there is an explicit `nonisolated(nonsending)`
modifier on the type.
Always print `nonisolated(nonsending)` before `sending`, `@escaping`
and other declaration attributes/modifiers to avoid parsing issues.
Resolves: rdar://164267736
Implement the @export(implementation) and @export(interface) attributes
to replace @_alwaysEmitIntoClient and @_neverEmitIntoClient. Provide a
warning + Fix-It to start staging out the very-new
@_neverEmitIntoClient. We'll hold off on pushing folks toward
@_alwaysEmitIntoClient for a little longer.
This adds initial support for differentiation of functions that may produce `Error` result.
Essentially we wrap the pullback into `Optional` and emit a diamond-shape control flow pattern depending on whether the pullback value is available or not. VJP emission was modified to accommodate for this. In addition to this, some additional tricks are required as `try_apply` result is not available in the instruction parent block, it is available in normal successor basic block.
As a result we can now:
- differentiate an active `try_apply` result (that would be produced from `do ... try .. catch` constructions)
- `try_apply` when error result is unreachable (usually `try!` and similar source code constructs)
- Support (some) throwing functions with builtin differentiation operators. stdlib change will follow. Though we cannot support typed throws here (yet)
- Correctly propagate error types during currying around differentiable functions as well as type-checking for `@derivative(of:)` attribute, so we can register custom derivatives for functions producing error result
- Added custom derivative for `Optional.??` operator (note that support here is not yet complete as we cannot differentiate through autoclosures, so `x ?? y` works only if `y` is not active, e.g. a constant value).
Some fixes here and there
If we have a custom attribute on a type that does a qualified lookup
into the same type, we need to be able to expand member attribute
macros for that type. As such, the check to see if we already have
a nominal for the attribute would hit a cycle. Limit this check such
that it only applies to local vars, which is the only case where it
actually matters.
rdar://163961797
Allow external declaration of global variables via `@_extern(c)`. Such
variables need to have types represented in C (of course), have only
storage (no accessors), and cannot have initializers. At the SIL
level, we use the SIL asmname attribute to get the appropriate C name.
While here, slightly shore up the `@_extern(c)` checking, which should
fix issue #70776 / rdar://153515764.
Before this patch we referred to builtin names in SILGenBuiltin using raw c
strings. This can lead to potential spelling mistakes yielding bugs. Rather than
doing this, I stole a technique that we use in other parts of the compiler:
constexpr StringLiteral generation using CPP macros. Specifically, I defined in
Builtins.h a new namespace called BuiltinNames and inside of BuiltinNames I used
CPP macros to define a StringLiteral for each Builtin. Thus one can get the
appropriate name for a Builtin by writing:
```
BuiltinNames::Sizeof
```
instead of writing "Sizeof". I also cleaned up the code a little by adding for
functions that take identifiers an additional overload that takes a StringRef
and converts the StringRef to an identifier internally. This just eliminates
unnecessary code from call sites by moving them into the callee.
Don't consider implicitly exposed memory layouts when checking for
usable from inline correctness. That check applies only to memory
layouts marked as exposed explicitly. Consider the implict state only at
the general availability checking.
In non-library-evolution mode, gated behind the CheckImplementationOnly
feature flag, consider structs to be a fragile use site by default,
unless marked `@_implementationOnly`. This prevents them to refer to
restricted imports like implementation-only.
This is necessary because we need to model its stack-allocation
behavior, although I'm not yet doing that in this patch because
StackNesting first needs to be taught to not try to move the
deallocation.
I'm not convinced that `async let` *should* be doing a stack allocation,
but it undoubtedly *is* doing a stack allocation, and until we have an
alternative to that, we will need to model it properly.
