http://d.puremagic.com/issues/show_bug.cgi?id=4832

           Summary: Functions external to class break immutability
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: andrej.mitrovich@gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2010-09-06 13:37:14 PDT ---
Code:

import std.stdio : writeln;

void foo(ref int x)
{
    x = 10;
}

class Bar
{
    immutable int x;

    this()
    {
        x = 5;
    }

    void printMe()
    {
        writeln(this.x);
    }

    void change()
    {
        //~ this.x = 20;    // illegal, errors out
    }
}

void main()
{
    Bar bar = new Bar;
    bar.printMe();  // prints 5

    //~ bar.x = 10;  // illegal, errors out

    foo(bar.x);     // no error!
    bar.printMe();  // prints 10
}

The commented out code would error out at compile time, which is expected. But the function bar() is breaking immutability of x.

A relevant bug is bug 4416 , and my comment: http://d.puremagic.com/issues/show_bug.cgi?id=4416#c1

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--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2010-09-06 13:37:55 PDT ---
Sorry, I meant the function foo, not bar.

(In reply to comment #0)
> Code:
> 
> import std.stdio : writeln;
> 
> void foo(ref int x)
> {
>     x = 10;
> }
> 
> class Bar
> {
>     immutable int x;
> 
>     this()
>     {
>         x = 5;
>     }
> 
>     void printMe()
>     {
>         writeln(this.x);
>     }
> 
>     void change()
>     {
>         //~ this.x = 20;    // illegal, errors out
>     }
> }
> 
> void main()
> {
>     Bar bar = new Bar;
>     bar.printMe();  // prints 5
> 
>     //~ bar.x = 10;  // illegal, errors out
> 
>     foo(bar.x);     // no error!
>     bar.printMe();  // prints 10
> }
> 
> The commented out code would error out at compile time, which is expected. But the function bar() is breaking immutability of x.
> 
> A relevant bug is bug 4416 , and my comment: http://d.puremagic.com/issues/show_bug.cgi?id=4416#c1

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yebblies <yebblies@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |yebblies@gmail.com
         Resolution|                            |DUPLICATE


--- Comment #2 from yebblies <yebblies@gmail.com> 2011-01-26 18:27:09 PST ---
*** This issue has been marked as a duplicate of issue 5493 ***

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