swift-mirror/userdocs/diagnostics/nonisolated-nonsending-by-default.md

NonisolatedNonsendingByDefault

Proposed in SE-0461, this feature changes the behavior of nonisolated async functions to run on the actor to which the caller is isolated (if any) by default, and provides an explicit way to express the execution semantics for these functions.

This feature was proposed in SE-0461

• The @concurrent attribute specifies that a function must always switch off of an actor to run. This is the default behavior without NonisolatedNonsendingByDefault.
• The nonisolated(nonsending) modifier specifies that a function must always run on the caller's actor. This is the default behavior with NonisolatedNonsendingByDefault.