What guarantees does D 'const' provide, compared to C++?

[Jonathan M Davis]

On Friday, August 17, 2012 03:00:34 Chris Cain wrote:
> On Friday, 17 August 2012 at 00:44:20 UTC, Chris Cain wrote:
> > Also, D's const is _not_ a guarantee that there are no mutable
> > references to something. That'd be immutable.
> 
> And, by the way, I'd call this a bug (not sure if reported yet):
> 
> 
> 
> int yourGlobalCounter;
> 
> struct S
> {
> int*[] items;
> 
> this(int i)
> {
> items = new int*[1];
> items[0] = &yourGlobalCounter;
> yourGlobalCounter = i;
> }
> 
> ref const(int*[]) getItems() const
> {
> ++yourGlobalCounter;
> return items;
> }
> }
> 
> import std.stdio;
> 
> void main() {
> immutable(S) s = immutable(S)(0);
> auto it = s.getItems();
> writeln(*it[0]);
> s.getItems();
> writeln(*it[0]);
> }

How is it a bug? The variable that you're altering is not part of the object. 
That's part of why having pure with const in so valuable. It prevents stuff 
like what you're doing here.

- Jonathan M Davis