For synthesized `<async iterator>.next()` calls expression rewriter
has to check whether witness is throwing and add `try` when necessary,
in order to do that injector needs to look through opened existentials,
erasures, and other implicitly injected AST nodes.
The concurrency runtime now deploys back to macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, which corresponds to the 5.1 release of the stdlib.
Adjust macro usages accordingly.
If `async` effect has been inferred from the body of the closure,
let's find out the first occurrence of `async` node and point it out
to make it clear why closure is `async`.
Resolves: rdar://70610141
AsyncSequence is only polymorphic over 'throws' effects, not 'async',
because it is @rethrows and not @reasync. So the logic here was wrong,
and it would incorrectly conclude that a 'for await' with a concrete
conformance did not require the outer function to be 'async'.
Fixes rdar://problem/75436909.
This allows programs to target older OSes while using Concurrency behind an availability check. When targeting older OSes, the symbols are weak-linked and the compiler will require the use of Concurrency features to be guarded by an availability check.
rdar://75850003
Previously we diagnosed here if a thrown error was
unhandled, but we also have to set the flag, otherwise
we produce a warning saying that a 'do/catch' has
no throwing operations in its body.
Fixes rdar://problem/75274975.
SILGen verification crash when no other async functions are called in a function body not marked as async when a for-await-in syntax is used. This corrects the diagnostics to ensure that the type check effects sees the proper async call that the for-await-in syntax infers.
for-await-in syntax was missing a diagnistic hint for inserting a try when the protocol conformance of the sequence shows a potential of throwing. (also there was a superfluous check for the nominal type in that type check (which was removed).
for-await-in syntax and for-try-await-in syntax did not infer async or throwing to closure constraints, both were added to properly identify the asyncy-ness/throwy-ness of the iteration.
