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digitalmars.D.bugs - [Issue 2511] New: dmd finds a proper overload as a non-covariant

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2511

           Summary: dmd finds a proper overload as a non-covariant
           Product: D
           Version: 2.021
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: 2korden gmail.com


Here is a sample code that triggers an error:

// File I.d
module I;

import Base;

interface I
{
}

interface SubI : I
{
}

// File Base.d
module Base;

import I;

class Base
{
    I create() {
        return null;
    }
}

class Derived : Base
{
    SubI create() {
        return null;
    }
}

Compilation options: "dmd I.d"
Note that "dmd Base.d" compiles okay.


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Dec 13 2008
next sibling parent d-bugmail puremagic.com writes:
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And here is an error message:

Base.d(15): function Base.Derived.create of type SubI() overrides but is not
covariant with Base.Base.create of type I()


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Dec 13 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
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2korden gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |blocker





The error can fixed by removing "import Base;" from the I.d, but unfortunately
I can't do this in my application because interfaces have methods that accept
and return references to Base and Derived:

interface I
{
    void doStuff(Base b);
}

interface SubI : I
{
    void doStuff(Derived b);
}

A possible solution is to merge them into a single file (which is not
acceptable). You should also have a proper file order to compile them at once:

dmd Base I // okay
dmd I Base // fails to compile

Rising its severity until I find a workaround.


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Dec 13 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
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smjg iname.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smjg iname.com
            Summary|dmd finds a proper overload |Covariant return type
                   |as a non-covariant          |doesn't work with circular
                   |                            |import
            Version|2.021                       |1.043





This sounds related to old bug 125.  And it occurs in the D1 line too.

Also rewriting the summary line as the one that was there was confusing.


--
Apr 13 2009
prev sibling next sibling parent d-bugmail puremagic.com writes:
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PDT ---
Created an attachment (id=456)
better detection if a base class is forward referenced

The current implementation (as of DMD 2.032) defers covariance analysis only if
the base class is not yet semantically analysed and it is not an interface. The
patch refines this condition by testing whether the class has any forward
referenced base classes or interfaces.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla digitalmars.com



22:33:25 PDT ---
The patch breaks this code:

class UA {
    A29 f() { return null; }
}

class UB : UA {
    B29 f() { return null; }
}

class A29
{
}

class B29 : A29
{
}

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22:49:56 PDT ---
Partial apply of patch:

http://www.dsource.org/projects/dmd/changeset/638

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PDT ---
Oh, it's only been tested on interfaces. ClassDeclaration::isBaseInfoComplete()
is broken, class Object doesn't need a base class:

int ClassDeclaration::isBaseInfoComplete()
{
    if (!baseClass)
        return ident == Id::Object;
...

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12:55:08 PDT ---
This now fails:

class UA {
    A29 f() { return null; }
}

class UB : UA {
    B29 f() { return null; }
}

class A29
{
}

class B29 : A29
{
}

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Aug 29 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Brad Roberts <braddr puremagic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |braddr puremagic.com



---
NOTE: these tests are part of the dmd svn depot these days.. so if you check it
out from dsource you can run them yourself

cd $(dir}/dmd/src
make
cd ../test
make

It's only known to work on linux, though ought to work on any posix system and
will need work to work on windows.  Any fixes that are required I'd be happy to
fold in.

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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED



14:31:42 PDT ---
http://www.dsource.org/projects/dmd/changeset/650

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