On Thu, Mar 16, 2017 at 04:59:40PM +0000, Adam D. Ruppe via Digitalmars-d-learn
wrote:
> On Thursday, 16 March 2017 at 16:47:14 UTC, Carl Sturtivant wrote:
> > Silently <expletive-deleted> cast to immutable without copying!??!!
> > This is so wrong.
>
> It is the implicit slicing that I really want removed from the
> language, it serves no real benefit and brings a lot of accidental
> complexity. Casting the static array to immutable is actually OK in
> isolation, because it is a value type and thus a unique copy... but
> once you slice it, that promise is gone.
[...]
I'm not convinced casting static array to immutable is OK. Check this
out:
import std.stdio;
char[32] func() {
char[32] staticArr = "A123456789abcdefB123456789abcdef";
return staticArr; // OK, by-value return
}
string gunk() {
string x = func(); // implicit conversion char[32] -> string
writeln(x.ptr);
writeln(x); // prints "A123456789abcdefB123456789abcdef"
return x;
}
void main() {
auto s = gunk();
writeln(s.ptr); // prints same address as in gunk()
writeln(s); // prints corrupted string
}
Run this code and you'll see that s.ptr has the same address as x.ptr,
and that x.ptr is the address of a local variable. This is blatantly
wrong.
Filed a new issue for this:
https://issues.dlang.org/show_bug.cgi?id=17261
T
--
I am a consultant. My job is to make your job redundant. -- Mr Tom
