Concatenation of ubyte[] to char[] works, but assignation doesn't

[Jonathan M Davis via Digitalmars-d-learn]

On Sunday, October 04, 2015 16:13:47 skilion via Digitalmars-d-learn wrote:
> Is this allowed by the language or it is a compiler bug ?
>
> void main() {
>     char[] a = "abc".dup;
>     ubyte[] b = [1, 2, 3];
>     a = b;   // cannot implicitly convert expression (b) of type
> ubyte[] to char[]
>     a ~= b;  // works
> }

When appending, b to a, the elements in b are being copied onto the end of
a, and presumably it works in this case, because a ubyte is implicitly
convertible to char. But all it's doing is converting the individual
elements. It's not converting the array.

On other hand, assigning b to a would require converting the array, and
array types don't implicitly convert to one another, even if their elements
do.

Honestly, I think that the fact that the character types implicitly convert
to and from the integral types of the corresponding size is problematic at
best and error-prone at worst, since it almost never makes sense to do
something like append a ubyte to string. However, if it didn't work, then
you'd have to do a lot more casting when you do math on characters, which
would cause its own set of potential bugs. So, we're kind of screwed either
way.

- Jonathan M Davis