Why does this mixin fail to compile?

[Dennis]

On Monday, 1 July 2024 at 09:25:39 UTC, ryuukk_ wrote:
> This simple mixin fails to compile, anyone know why?
>
> ```D
> mixin implement;
>
> mixin template implement() {
>     mixin("struct _gen(T) {");
>     mixin("}");
> }

A string mixin must form a complete declaration / statement / 
expression / type, so you can't end on an open brace.