local const functions - bug ?

[Marc Schütz via Digitalmars-d-learn]

On Sunday, 10 July 2016 at 07:20:29 UTC, Meta wrote:
> On Friday, 8 July 2016 at 09:01:10 UTC, Marc Schütz wrote:
>> `foo()` is effectively a delegate, therefore `const` applies 
>> to the context.
>
> AFAIK const on a function can only ever refer to the `this` 
> pointer, but there is no `this` pointer.

To the `this` pointer, or the context, in case of delegates. 
Here, `foo()` is a nested function that accesses a variable in 
the outer scope. This qualifies it as a delegate [1]:

"When comparing with nested functions, the function form is 
analogous to static or non-nested functions, and the delegate 
form is analogous to non-static nested functions. In other words, 
a delegate literal can access stack variables in its enclosing 
function, a function literal cannot."

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