http://d.puremagic.com/issues/show_bug.cgi?id=8366

           Summary: Overriding const member function in conjunction with
                    mutable overload causes a strange error
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: blocker
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: k.hara.pg@gmail.com


--- Comment #0 from Kenji Hara <k.hara.pg@gmail.com> 2012-07-09 21:26:12 PDT ---
I think this problem blocks 2.060 release.

code:
----
class C {
    // overrides Object.opEquals
    bool opEquals(const Object o) const {}

    // introduce mutable overload
    bool opEquals(const Object o) {}  // line8
}
void main(){}

output:
----
test.d(8): Error: function test.C.opEquals multiple overrides of same function

The second opEquals should *introduce* new member function. But, by the const attribute inference, it is determined as *multiple overrides".

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Benjamin Thaut <code@benjamin-thaut.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |code@benjamin-thaut.de


--- Comment #1 from Benjamin Thaut <code@benjamin-thaut.de> 2012-07-09 22:01:38 PDT ---
I reported the same issue with shared a while back, and it was stated that this is intentional.

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Jonathan M Davis <jmdavisProg@gmx.com> changed:

           What    |Removed                     |Added
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                 CC|                            |jmdavisProg@gmx.com


--- Comment #2 from Jonathan M Davis <jmdavisProg@gmx.com> 2012-07-09 22:14:16 PDT ---
Well, certainly for const, it's a _big_ problem.

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull


--- Comment #3 from Kenji Hara <k.hara.pg@gmail.com> 2012-07-10 09:48:50 PDT ---
https://github.com/D-Programming-Language/dmd/pull/1042 https://github.com/D-Programming-Language/druntime/pull/272 https://github.com/D-Programming-Language/phobos/pull/680

I think we must kill the attribute inference for 'const' attribute. It requires much compiler implementation cost against its little benefit.

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--- Comment #4 from github-bugzilla@puremagic.com 2012-11-21 20:37:45 PST ---
Commits pushed to master at https://github.com/D-Programming-Language/druntime

https://github.com/D-Programming-Language/druntime/commit/d57d808db194c3f1ee6af4d8251478309f0bab49
fix Issue 8366 - Overriding const member function in conjunction with mutable
overload causes a strange error

https://github.com/D-Programming-Language/druntime/commit/771c2a1503c91df79704277444c550ad463c590c Merge pull request #353 from 9rnsr/fix8366

Issue 8366 - Overriding const member function in conjunction with mutable overload causes a strange error

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #5 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-01-13 10:39:23 PST ---
What's the state of this? I'm getting different error messages, such as:

Deprecation: class test.C use of object.Object.opEquals(Object o) hidden by C is deprecated. Use 'alias Object.opEquals opEquals;' to introduce base class overload set.

Is that ok?

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--- Comment #6 from Kenji Hara <k.hara.pg@gmail.com> 2013-01-13 17:45:09 PST ---
(In reply to comment #5)
> What's the state of this? I'm getting different error messages, such as:
> 
> Deprecation: class test.C use of object.Object.opEquals(Object o) hidden by C is deprecated. Use 'alias Object.opEquals opEquals;' to introduce base class overload set.
> 
> Is that ok?

No.

In 2.060 release, all Object class method signatures are reverted, so the original code is not correct in current. More generic case is:

class B
{
    bool foo(in Object o) const { return true; }
}
class C : B
{
    bool foo(in Object o)       { return true; }   // line 10
  override
    bool foo(in Object o) const { return false; }  // line 12
}
void main()
{
          C mc = new C();
    const C cc = new C();
          B mb  = mc;
    const B cb  = cc;
    assert(mc.foo(null) == true);
    assert(cc.foo(null) == false);
    assert(mb.foo(null) == false);
    assert(cb.foo(null) == false);
}

This code should compile but outputs:
---
test.d(10): Deprecation: overriding base class function without using override
attribute is deprecated (test.C.foo overrides test.B.foo)
test.d(12): Error: function test.C.foo multiple overrides of same function

Mutable foo in class C is incorrectly overrides const foo in class B. That is the bug.

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--- Comment #7 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-01-13 17:57:08 PST ---
Ah I'm sorry, I haven't seen your comment here: http://d.puremagic.com/issues/show_bug.cgi?id=8366#c3

I saw github-bugzilla@puremagic.com posting and thought it was done, but there are 3 pulls.

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--- Comment #8 from github-bugzilla@puremagic.com 2013-03-06 15:05:44 PST ---
Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/de9e8b3073aa3abc2bb93d5482a7dcbe66aab92c
fix Issue 8366 - Overriding const member function in conjunction with mutable
overload causes a strange error

We MUST kill attribute inference with const. To implement it correctly without
breaking overriding and overloading features, re-scanning and arrangement of
vtbl entries is needed in the end of Classdeclaration::semantic, it will
decrease compile speed.
I think that is a big drawbacks than the benefit.

https://github.com/D-Programming-Language/dmd/commit/2cab1b0c852e7f86f9553940ab8441c7efee31f4 Merge pull request #1042 from 9rnsr/fix8366

Issue 8366 - Overriding const member function in conjunction with mutable overload causes a strange error

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@digitalmars.com
         Resolution|                            |FIXED


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