Why does assign of string literal to fixed char array fail?

[Jonathan M Davis]

On 2011-05-24 15:26, bearophile wrote:
> rthiebaud:
> > fails on Windows with:
> > 
> > First-chance exception at 0x7c812afb in ConsoleApp1.exe: 0xE0440001:
> > 0xe0440001.
> > 
> > What is wrong?
> 
> To me it gives:
> object.Exception at src\rt\arraycat.d(31): lengths don't match for array copy
> 
> When you assign to a fixed-sized array the source and destination lengths
> must match (this is not true for global variables. In Bugzilla I have
> asked to remove this special case, despite some people say this is not a
> special case).

It may be useful, but it's still a special case. You're asking the compiler to 
copy an array of a particular length to an array of another length. I don't 
see how you could argue that it isn't a special case.

Regardless, even if it would be useful to allow such a copy, what would it do? 
If you have

char[20] a = "abc:

which characters are assigned the 'a', the 'b', and the 'c'? a[0 .. 3]? a[17 
.. 20]? Characters in the middle of the char array? I really think that it 
makes perfect sense for the compiler to complain about this. It doesn't allow 
you to copy arrays of differing lengths anywhere else. Allowing it here would 
not only be a special case, but the syntax doesn't give you any way to say 
where the character literal is being copied to. I think that the compiler is 
definitely doing the correct thing here.

- Jonathan M Davis