public static bool ContainsAwait(BoundNode node)
{
var detector = new AwaitDetector();
detector.Visit(node);
return(detector._sawAwait);
}
/// <summary>
/// Rewrite an async method into a state machine type.
/// </summary>
internal static BoundStatement Rewrite(
BoundStatement body,
MethodSymbol method,
int methodOrdinal,
VariableSlotAllocator slotAllocatorOpt,
TypeCompilationState compilationState,
DiagnosticBag diagnostics,
out AsyncStateMachine stateMachineType)
{
if (!method.IsAsync)
{
stateMachineType = null;
return(body);
}
CSharpCompilation compilation = method.DeclaringCompilation;
bool isAsyncEnumerableOrEnumerator = method.IsIAsyncEnumerableReturningAsync(compilation) ||
method.IsIAsyncEnumeratorReturningAsync(compilation);
if (isAsyncEnumerableOrEnumerator && !method.IsIterator)
{
bool containsAwait = AwaitDetector.ContainsAwait(body);
diagnostics.Add(containsAwait ? ErrorCode.ERR_PossibleAsyncIteratorWithoutYield : ErrorCode.ERR_PossibleAsyncIteratorWithoutYieldOrAwait,
method.Locations[0], method.ReturnType);
stateMachineType = null;
return(body);
}
// The CLR doesn't support adding fields to structs, so in order to enable EnC in an async method we need to generate a class.
// For async-iterators, we also need to generate a class.
var typeKind = (compilationState.Compilation.Options.EnableEditAndContinue || method.IsIterator) ? TypeKind.Class : TypeKind.Struct;
var bodyWithAwaitLifted = AwaitExpressionSpiller.Rewrite(body, method, compilationState, diagnostics);
stateMachineType = new AsyncStateMachine(slotAllocatorOpt, compilationState, method, methodOrdinal, typeKind);
compilationState.ModuleBuilderOpt.CompilationState.SetStateMachineType(method, stateMachineType);
AsyncRewriter rewriter = isAsyncEnumerableOrEnumerator
? new AsyncIteratorRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics)
: new AsyncRewriter(bodyWithAwaitLifted, method, methodOrdinal, stateMachineType, slotAllocatorOpt, compilationState, diagnostics);
if (!rewriter.VerifyPresenceOfRequiredAPIs())
{
return(body);
}
try
{
return(rewriter.Rewrite());
}
catch (SyntheticBoundNodeFactory.MissingPredefinedMember ex)
{
diagnostics.Add(ex.Diagnostic);
return(new BoundBadStatement(body.Syntax, ImmutableArray.Create <BoundNode>(body), hasErrors: true));
}
}