digitalmars.D.bugs - [Issue 3674] New: forward reference error with multiple overloads with same name
- d-bugmail puremagic.com (39/39) Jan 05 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3674
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- d-bugmail puremagic.com (10/10) Jan 17 2010 http://d.puremagic.com/issues/show_bug.cgi?id=3674
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http://d.puremagic.com/issues/show_bug.cgi?id=3674
Summary: forward reference error with multiple overloads with
same name
Product: D
Version: 2.037
Platform: Other
OS/Version: Windows
Status: NEW
Keywords: rejects-valid
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: r.sagitario gmx.de
PST ---
The following code fails to compile:
public interface IQGraphicsItem
{
public QGraphicsObject toGraphicsObject();
public QGraphicsObject toGraphicsObject() const;
}
public class QGraphicsLineItem : IQGraphicsItem
{
public final QGraphicsObject toGraphicsObject() { return null; } // Line 10
public final QGraphicsObject toGraphicsObject() const { return null; }
}
public abstract class QGraphicsObject : IQGraphicsItem // line 14
{
public final QGraphicsObject toGraphicsObject() { return null; }
public final QGraphicsObject toGraphicsObject() const { return null; }
}
with error:
test.d(14): Error: class test.QGraphicsObject base class is forward referenced
by QGraphicsObject
Actually the error is caused on by the reference in line 11.
The error does not happen there is only a single method toGraphicsObject().
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d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=3674
Rainer Schuetze <r.sagitario gmx.de> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
PST ---
The error occurs when dmd tries to match the overloaded member function to the
functions in the base class, but hits the slightly different prototype. It then
tries to check the return type for covariance, which fails on the forward
referenced class.
here's a patch (or maybe just a workaround as I'm not perfectly sure what this
does to erronous declarations), but it also fixes the problem, if the return
type is actually a forward referenced covariant class.
Index: func.c
===================================================================
--- func.c (revision 324)
+++ func.c (working copy)
-510,9 +510,20
/* Only need to have a tintro if the vptr
* offsets differ
*/
+ unsigned errors = global.errors;
+ global.gag++; // suppress printing of error messages
int offset;
- if (fdv->type->nextOf()->isBaseOf(type->nextOf(), &offset))
+ int baseOf = fdv->type->nextOf()->isBaseOf(type->nextOf(),
&offset);
+ global.gag--; // suppress printing of error messages
+ if(errors != global.errors)
{
+ // any error in isBaseOf() is a forward reference error, so we
bail out
+ global.errors = errors;
+ cd->sizeok = 2; // can't finish due to forward reference
+ return;
+ }
+ if (baseOf)
+ {
ti = fdv->type;
#if 0
if (offset)
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Jan 05 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3674
Eldar Insafutdinov <e.insafutdinov gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |e.insafutdinov gmail.com
00:14:03 PST ---
As it implies from the testcase this is a blocker for QtD.
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Jan 06 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3674
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugzilla digitalmars.com
23:55:32 PST ---
Changeset 338
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Jan 17 2010
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PST ---
The current revision (342) now shows a different error, even with a slightly
reduced test case:
public class IQGraphicsItem
{
public QGraphicsObject toGraphicsObject();
public QGraphicsObject toGraphicsObject() const;
}
public abstract class QGraphicsObject : IQGraphicsItem
{
public final QGraphicsObject toGraphicsObject() { return null; } // Line
10
public final QGraphicsObject toGraphicsObject() const { return null; } //
Line 11
}
and causes
test.d(11): Error: function test.QGraphicsObject.toGraphicsObject cannot
override final function test.QGraphicsObject.toGraphicsObject
This is what happens:
dmd searches its vtbl for a covariant function that is overridden by
"toGraphicsObject() const". The rules in Type::covariant() state, that it's ok
to match the non-const version of toGraphicsObject(). This triggers two
problems:
- The first match is taken, not the best.
- The class's vtbl is searched, not the vtbl of the base class. As the
non-const version of the function is already matched and placed into the vtbl,
the function type might have changed due to covariance. In this case, it is
final now.
Here's a patch to solve both issues:
Index: func.c
===================================================================
--- func.c (revision 342)
+++ func.c (working copy)
-382,7 +382,7
}
// Find index of existing function in vtbl[] to override
- vi = findVtblIndex(&cd->vtbl, cd->baseClass ? cd->baseClass->vtbl.dim :
0);
+ vi = cd->baseClass ? findVtblIndex(&cd->baseClass->vtbl,
cd->baseClass->vtbl.dim) : -1;
switch (vi)
{
case -1:
-426,7 +426,7
return;
default:
- { FuncDeclaration *fdv = (FuncDeclaration *)cd->vtbl.data[vi];
+ { FuncDeclaration *fdv = (FuncDeclaration
*)cd->baseClass->vtbl.data[vi];
// This function is covariant with fdv
if (fdv->isFinal())
error("cannot override final function %s", fdv->toPrettyChars());
-1689,11 +1689,15
int FuncDeclaration::findVtblIndex(Array *vtbl, int dim)
{
+ FuncDeclaration *mismatch = 0;
+ int bestvi = -1;
for (int vi = 0; vi < dim; vi++)
{
FuncDeclaration *fdv = ((Dsymbol *)vtbl->data[vi])->isFuncDeclaration();
if (fdv && fdv->ident == ident)
{
+ if (type->equals(fdv->type))
+ return vi;
int cov = type->covariant(fdv->type);
//printf("\tbaseclass cov = %d\n", cov);
switch (cov)
-1702,14 +1706,15
break;
case 1:
- return vi;
+ bestvi = vi; // covariant, but not identical
+ break;
case 2:
+ if(!mismatch) // give a second chance to find exact match
+ mismatch = fdv;
//type->print();
//fdv->type->print();
//printf("%s %s\n", type->deco, fdv->type->deco);
- error("of type %s overrides but is not covariant with %s of type
%s",
- type->toChars(), fdv->toPrettyChars(), fdv->type->toChars());
break;
case 3:
-1720,7 +1725,10
}
}
}
- return -1;
+ if(bestvi < 0 && mismatch)
+ error("of type %s overrides but is not covariant with %s of type %s",
+ type->toChars(), mismatch->toPrettyChars(),
mismatch->type->toChars());
+ return bestvi;
}
/****************************************************
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Jan 20 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3674
13:37:38 PST ---
When fixing this also make sure this testcase passes:
public class IQGraphicsItem
{
public QGraphicsObject toGraphicsObject();
public const(QGraphicsObject) toGraphicsObject() const;
}
public abstract class QGraphicsObject : IQGraphicsItem
{
public final QGraphicsObject toGraphicsObject() { return null; }
public final const(QGraphicsObject) toGraphicsObject() const { return null;
}
}
As it currently doesn't, with a different error message.
Thanks.
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Jan 21 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3674 20:21:23 PST --- Changeset 344 for second problem. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jan 21 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3674 PST --- Thanks, it works now. This also fixes issue 3282 which is what happened if you did not use "final" to produce an error at compile time. See comments there for another quirk. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jan 22 2010
http://d.puremagic.com/issues/show_bug.cgi?id=3674
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
22:41:16 PST ---
fixed dmd 1.056 and 2.040
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Jan 30 2010