partial initialization of fixed size ("static") arrays

[kdevel]

On Saturday, 14 August 2021 at 13:01:13 UTC, frame wrote:
> I would say case [...] 3 is not [a bug]. It's just the element 
> type conversion and mismatched lengths of the ranges.

~~~
    char [7] d7 = "x"; // okay

    string s = "x";
    char [7] c7 = s; // throws RangeError
~~~

What justifies that the compiler behaves differently on two terms 
('s', '"x"') which are of equal size, type, length and value?