C# Language Specification

Evaluation of a task-returning async function

Invocation of a task-returning async function causes an instance of the returned task type to be generated. This is called the return task of the async function. The task is initially in an incomplete state.

The async function body is then evaluated until it is either suspended (by reaching an await expression) or terminates, at which point control is returned to the caller, along with the return task.

When the body of the async function terminates, the return task is moved out of the incomplete state:

• 
  If the function body terminates as the result of reaching a return statement or the end of the body, any result value is recorded in the return task, which is put into a succeeded state.
  
• 
  If the function body terminates as the result of an uncaught exception (§8.9.5) the exception is recorded in the return task which is put into a faulted state.
  

2.