undefined_identifier_await

Undefined name 'await' in function body not marked with 'async'.

The analyzer produces this diagnostic when the name await is used in a method or function body without being declared, and the body isn't marked with the async keyword. The name await only introduces an await expression in an asynchronous function.

The following code produces this diagnostic because the name await is used in the body of f even though the body of f isn't marked with the async keyword:

void f(p) { await p; }

Add the keyword async to the function body:

void f(p) async { await p; }