Cyclic Dependencies

[Jarrett Billingsley]

On Tue, Dec 9, 2008 at 12:00 PM, Ellery Newcomer
<ellery-newcomer at utulsa.edu> wrote:
> Derek Parnell wrote:
>  > It is not a bug. A string literal such as "true" is a char[] type (UTF8),
>>
>> and the compiler will not implicitly convert UTF8 to UTF16 (wchar[]).
>
> Which would then beg the obvious
>
> wchar[] w = "true";

It's a sort of special case.  String literals are, by default, UTF-8.
But if you use a string literal in a situation where it can only be
UTF-16 or UTF-32, it's automatically converted.

However if a string literal is used in a context where it can be
multiple encodings, an error results:

void foo(char[] s) {}
void foo(wchar[] s) {}

foo("hello") fails because string literals are implicitly convertible
to both char[] and wchar[], so you have to append either a c or a w to
the literal.

As for why 'wchar[] s = true ? "true" : "false"' doesn't work, it's
because the initializer expression is semantically analyzed before
looking at the destination type.  The type of the initializer is
determined to be char[], which is not implicitly convertible to
wchar[].

It can obviously be argued that since the operands of ?: are constant,
the compiler _could_ figure out that they should be of type wchar[],
but that would make the semantic analysis more complicated, and since
appending 'w' to the strings is far easier, it probably won't change
any time soon.