When not capturing the return value of a string mixin expression, I get "found `End of File` when expecting `;`"

[Stefan Koch]

On Friday, 12 September 2025 at 08:36:42 UTC, realhet wrote:
> Hi,
>
> ```d
> import std;
>
> void main() {
>     int val = 4;
>     enum prog = q{
>         (){ val += 1; return val; }()
>     };
>     //mixin(prog); //
>     auto dummy = mixin(prog); //Must capture the return value, 
> otherwise it hallucinates EOF.
>     writeln(val);
> }
> ```
>
> When uncommenting    mixin(prog);
> It gives
> ```
> Error: found `End of File` when expecting `;` following 
> expression
> expression: `()
> {
>     val += 1;
>     return val;
> }
> ()`
> ```

Hi realhet,

I can explain what happens here.

When you write `auto x = mixin(bla);`
The mixin it parsed as an expression.
b/c there can only be an expression after the =.
However when you don't do that the mixin is parsed as a 
statement, after which a ; is expected and mandatory.
putting a ; into the string generated by prog should fix that.