`??` operator is overloaded on optionality of its result. When the
first argument matches exactly, the ranking is going to be skewed
towards selecting an overload choice that returns a non-optional type.
This is not always correct i.e. when operator is involved in optional
chaining. To avoid producing an incorrect favoring, let's skip the this
disjunction when constraints associated with result type indicate
that it should be optional.
Simply adding it as a binding won't work because if the second argument
is non-optional the overload that returns `T?` would still have a lower
score.
Resolves: rdar://164201746
Make sure we only ever type-check the `do` body of a `do-catch`
statement when lazily type-checking the bound error type, which we can
do for completion.
rdar://164481242
Missed this in my original patch, handle pack parameters the same as
regular generic parameters, ensuring we don't prefer a pack overload
over a generic overload just because there are pointer conversions
involved. Note this doesn't fix the wider issue of rdar://122011759,
I'm planning on looking into that in a follow-up.
Fixes#85376.
This fixes a compiler crash that occurred when diagnosing an ambiguous call
using trailing closure syntax, where one of the candidates was a function or
initializer with no parameters.
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 is a fix for the ported "calls with a single unlabeled argument"
hack. If overload doesn't match context on async effect, let's not favor
it because that is more important than defaulted parameters.
Resolves: rdar://164269641
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.
