swift

648bb8fe - [concurrency] Perform some fixes so that transfernonsendable_closureliterals_isolationinference.swift now passes.

[concurrency] Perform some fixes so that transfernonsendable_closureliterals_isolationinference.swift now passes. The reason why this failed is that concurrently to @xedin landing 79af04ccc41faa717cfa3666e492f396993fcad1, I enabled NonisolatedNonsendingByDefault on a bunch of other tests. That change broke the test and so we needed to fix it. This commit fixes a few issues that were exposed: 1. We do not propagate nonisolated(nonsending) into a closure if its inferred context isolation is global actor isolated or if the closure captures an isolated parameter. We previously just always inferred nonisolated(nonsending). Unfortunately since we do not yet have capture information in CSApply, this required us to put the isolation change into TypeCheckConcurrency.cpp and basically have function conversions of the form: ``` (function_conversion_expr type="nonisolated(nonsending) () async -> Void" (closure_expr type="() async -> ()" isolated_to_caller_isolation)) ``` Notice how we have a function conversion to nonisolated(nonsending) from a closure expr that has an isolation that is isolated_to_caller. 2. With this in hand, we found that this pattern caused us to first thunk a nonisolated(nonsending) function to an @concurrent function and then thunk that back to nonisolated(nonsending), causing the final function to always be concurrent. I put into SILGen a peephole that recognizes this pattern and emits the correct code. 3. With that in hand, we found that we were emitting nonisolated(nonsending) parameters for inheritActorContext functions. This was then fixed by @xedin in With all this in hand, closure literal isolation and all of the other RBI tests with nonisolated(nonsending) enabled pass. rdar://154969621