Member predicate Impl::InvocationExpr::getSyntacticReceiver

Gets the syntactic receiver of this expression, if any.

Examples:

foo(42, "bar");    // no syntactic receiver
foo.bar(42);       // `foo` is syntactic receiver
Foo::bar(foo, 42); // no syntactic receiver
Option::Some(x);   // no syntactic receiver
x + y;             // no syntactic receiver
-x;                // no syntactic receiver
x[y];              // no syntactic receiver