Compiles but does not link

[Paul D Anderson via Digitalmars-d-learn]

On Thursday, 25 June 2015 at 00:24:23 UTC, Paul D Anderson wrote:
> The code snippet below compiles but the linker fails with Error 
> 42: Symbol undefined.
>
> What am I doing wrong?
>
> void main()
> {
> 	int foo(int a);
> 	alias FP = int delegate(int);
> 	FP fp = &foo;
> }
>
> Paul

Uh, never mind. I got so focused on the delegate I forgot to give 
the function a body.