In the spec's section on function literals [1], the example demonstrating inference of the `function` and `delegate` keywords does not compile, due to multiple parsing errors.

---
int abc(int delegate(int i));
int def(int function(int s));

void test()
{
    int b = 3;

    abc( int(int c) { return 6 + b; } );  // inferred to delegate
    def( uint(uint c) { return c * 2; } ); // inferred to function
  //def( int(int c) { return c * b; } );  // error!
    // Because the FunctionLiteralBody accesses b, then the function literal type
    // is inferred to delegate. But def cannot accept a delegate argument.
}
---

[1]: https://dlang.org/spec/expression.html#function_literals