In D, lexically, which are the chars that can follow $, exactly ?

[Marc Schütz via Digitalmars-d-learn]

On Sunday, 13 March 2016 at 14:07:31 UTC, Basile B. wrote:
> '$' is only valid in an indexExpression 
> (https://dlang.org/spec/grammar.html#IndexExpression),
> so it can only be followed by
>
> - ' '
> - ']'
> -  operators , usually '-' but also '/', '+', '>>' etc
>
> Is that right ?
>
> I'd like to relax the lexical rule for C.E static macros which 
> currently is
>
> - "^\$\w*[a-zA-Z]$", so for example "$a1A" is valid and "$a1" 
> is not.
>
> But it looks like for example "$)" or "$}" wouldn't be 
> ambiguous since it's not possible in D.

I don't know what C.E is, but `$` is an expansion of 
`PrimaryExpression`, which means it can (syntactically) appear 
anywhere a `PrimaryExpression` is allowed. For example, this 
compiles:

     void main() {
         int[] a;
         a[0 .. ($)] = 0;
     }