const violation?

2012-01-13 Thread H. S. Teoh 
Why does the following code compile?

import std.stdio;
int f(ref int x) {
return x++;
}
class A {
int x=123;
int g() const {
return f(x);
}
}
void main() {
auto a = new A;
writeln(a.g());
writeln(a.g());
}

Shouldn't the const member g() be prohibited from passing a ref to a
member variable to f()?

But this code not only compiles, it outputs:

123
124

So I've managed to call a const member of A to alter the value of A.x?
Am I misunderstanding the meaning of const when applied to a member
function, or is this a compiler bug?

P.S. I'm using gdc-4.6; does dmd also have this behaviour?


T

-- 
Lawyer: (n.) An innocence-vending machine, the effectiveness of which
depends on how much money is inserted.

Re: const violation?

2012-01-13 Thread Steven Schveighoffer 
On Fri, 13 Jan 2012 15:27:56 -0500, H. S. Teoh   
wrote:



Why does the following code compile?

import std.stdio;
int f(ref int x) {
return x++;
}
class A {
int x=123;
int g() const {
return f(x);
}
}
void main() {
auto a = new A;
writeln(a.g());
writeln(a.g());
}

Shouldn't the const member g() be prohibited from passing a ref to a
member variable to f()?


Yes, it's a bug (I think already reported, let me check... Yep:  
http://d.puremagic.com/issues/show_bug.cgi?id=5493)



But this code not only compiles, it outputs:

123
124

So I've managed to call a const member of A to alter the value of A.x?
Am I misunderstanding the meaning of const when applied to a member
function, or is this a compiler bug?

P.S. I'm using gdc-4.6; does dmd also have this behaviour?


Yes, the pull request hasn't been merged yet.

BTW, I tested with 2.057, which I downloaded from github.  Holy CRAP,  
downloaded in less than 1 second!!!


Awesome :)

Can we archive all the old DMD downloads there?

-Steve