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digitalmars.D.bugs - [Issue 8366] New: Overriding const member function in conjunction with mutable overload causes a strange error

reply d-bugmail puremagic.com writes:
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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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8366


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

           What    |Removed                     |Added
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                 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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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 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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prev sibling parent d-bugmail puremagic.com writes:
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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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