On Tuesday, 26 November 2024 at 04:15:35 UTC, Steven
Schveighoffer wrote:
On Monday, 25 November 2024 at 14:24:44 UTC, Bastiaan Veelo
wrote:
// Fishy:
inout(E) gun(inout(E) e)
{
//writeln(e.to!string); // only parameters or stack-based
variables can be `inout`
writeln((cast(Unqual!E)e).to!string); // OK
return e;
}
Longstanding issue. When inout was first proposed, the point
was to prevent people from using in nonsensical ways. But this
really prevents reasonable template usage without all kinds of
static checks.
I went over this in my 2016 talk:
https://dconf.org/2016/talks/schveighoffer.html
1. inout should just be allowed to be returned when parameters
are not inout. The equivalent would just be const.
2. inout member fields should be fine.
In this case the specific limitation getting in the way is that
you cannot pass an `inout` value as an argument to a [template
value parameter][1].
[1]: https://dlang.org/spec/template.html#template_value_parameter
