The following code throws a VariantException complaining about different types (char and immutable(char)[]):
unittest {
import std.variant;
Variant v = "";
v ~= 'a';
}
It's correct in some ways, but clearly a more useful behavior would be to concat the string and char and move on.
Comment #1 by shove — 2019-07-08T02:10:01Z
(In reply to Simen Kjaeraas from comment #0)
> The following code throws a VariantException complaining about different
> types (char and immutable(char)[]):
>
> unittest {
> import std.variant;
> Variant v = "";
> v ~= 'a';
> }
>
> It's correct in some ways, but clearly a more useful behavior would be to
> concat the string and char and move on.
This shouldn't be a bug. Variant's design has strict restrictions on type qualifiers, because string = immutable (char) [], so the ~ operator restricts char. v ~= cast (immutable char)'a'; is possible because its qualifier is consistent.
For these limitations, you can see the unittest:
https://github.com/dlang/phobos/blob/master/std/variant.d#L2655
There are many anomaly collection behaviors for qualifier inconsistencies.
I don't know whether it was intentionally designed to do this, or because it was temporarily done for the sake of simplicity. I think, if there are no other factors, it would be better to fix the variant implementation and remove these restrictions.
Comment #2 by robert.schadek — 2024-12-01T16:35:11Z