IC
// SPEC: When ResourceType is a non-nullable value type, the expansion is:
// SPEC:
// SPEC: {
// SPEC: ResourceType resource = expr;
// SPEC: try { statement; }
// SPEC: finally { ((IDisposable)resource).Dispose(); }
// SPEC: }
// SPEC:
((IDisposable)resource).Dispose();
это каст?