http://d.puremagic.com/issues/show_bug.cgi?id=5171

           Summary: @disable doesn't work on opEquals functions
           Product: D
           Version: D2
          Platform: Other
               URL: http://www.digitalmars.com/d/2.0/attribute.html#disabl
                    e
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: Jesse.K.Phillips+D@gmail.com
                CC: Jesse.K.Phillips+D@gmail.com


--- Comment #0 from Jesse Phillips <Jesse.K.Phillips+D@gmail.com> 2010-11-05 10:15:28 PDT ---
When overriding a function of a base class @disable does not cause compile time errors when called.

class A {
    @disable override equals_t opEquals(Object other) {
        return false;
    }
}

void main() {
    auto a = new A();
    auto b = new A();

    if(a == b)
        assert(0);
}

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Steven Schveighoffer <schveiguy@yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |schveiguy@yahoo.com
         Resolution|                            |INVALID


--- Comment #1 from Steven Schveighoffer <schveiguy@yahoo.com> 2010-11-05 11:00:33 PDT ---
This isn't actually possible.  What I would suggest is the compiler failing to compile your class instead, because you can't disable a base function.

If for example, you have a function like this:

bool foo(Object o1, Object o2) {...}

Then would it be safe to assume that you could pass both a and b to foo?  If so, then isn't it possible for foo to call o1 == o2?  And how could the compiler possibly statically disable this?

I'm going to mark it as invalid, and if you think you'd rather have the behavior where @disable doesn't compile on overridden functions, then you can reopen with that description.

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bearophile_hugs@eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs@eml.cc


--- Comment #2 from bearophile_hugs@eml.cc 2010-11-05 11:15:45 PDT ---
(In reply to comment #1)
> This isn't actually possible.  What I would suggest is the compiler failing to compile your class instead, because you can't disable a base function.

I agree. Where possible a good compiler has to statically disallow impossible code :-)

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--- Comment #3 from bearophile_hugs@eml.cc 2010-11-05 11:17:54 PDT ---
Added a note to bug 3934

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Jesse Phillips <Jesse.K.Phillips+D@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |
            Summary|@disable doesn't work on    |Prevent compiling of class
                   |opEquals functions          |when @disable is used on an
                   |                            |overriding function
           Severity|normal                      |enhancement


--- Comment #4 from Jesse Phillips <Jesse.K.Phillips+D@gmail.com> 2010-11-09 11:10:36 PST ---
class A {
   void hello() {
   }
}
class B : A {
   @disable override void hello() {
   }
}

void main() {
   auto a = new A();
   A b = new B();

   b.hello();
}

The compiler should not compile the class saying something to the effect of:
Can not disable method hello in base class A from B.
Or another suggestion "Cannot @disable overriding function hello in B"

Note that I think the code below should still compile:

class A {
   @disable void hello() {
   }
}
class B : A {
   override void hello() {
   }
}

void main() {
   auto a = new A();
   B b = new B();

   b.hello();
}

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