[fpc-devel] Can someone confirm if this is a bug? (ancestor in TWRiter.WriteProperty)

[Martin]

I may have mis-judged t, but the problem is still the same:

when you get to write TPersistenChild  you enter the following code

    tkClass:
      begin
        ObjValue := TObject(GetObjectProp(Instance, PropInfo));
        if HasAncestor then
        begin
          AncestorObj := TObject(GetObjectProp(Ancestor, PropInfo));
          if Assigned(AncestorObj) then
            if Assigned(ObjValue) and
              (TComponent(AncestorObj).Owner = FRootAncestor) and
              (TComponent(ObjValue).Owner = Root) and
              (UpperCase(TComponent(AncestorObj).Name) = 
UpperCase(TComponent(ObjValue).Name)) then
              AncestorObj := ObjValue
//            else
//              AncestorObj := nil;
        end else
          AncestorObj := nil;
--------------

TObject(GetObjectProp(Ancestor, PropInfo));  returns the TpersistentChil
as well as ObjValue being TPersistent


both get casted to TComponent with no check?



Martin wrote:
> I am not very familiar with the code, so before reporting, I'd like to 
> ask:
>
> trunc\rtl\objpas\classes\writer.inc
> procedure TWriter.WriteProperty(Instance: TPersistent; PropInfo: 
> Pointer);
>
> Imagine you a writing an Component, that does have an ancestor.
> The same component should have
>   property Foo: TPersistentChild read FFoo write FFoo;
>
> You should end up in the following code: (line 1091 in recent (a few 
> weeks) trunc )
> // this is the last else, it's not a component, and it is not a 
> collection
>          else
>            begin
>            SavedAncestor := Ancestor;
>            SavedPropPath := FPropPath;
>            try
>              FPropPath := FPropPath + PPropInfo(PropInfo)^.Name + '.';
>              if HasAncestor then
>                Ancestor := TPersistent(GetObjectProp(Ancestor, 
> PropInfo));              WriteProperties(TPersistent(ObjValue));
>            finally
>              Ancestor := SavedAncestor;
>              FPropPath := SavedPropPath;
>            end;
>            end;
> --------------------------------------
>              if HasAncestor then
>                Ancestor := TPersistent(GetObjectProp(Ancestor, 
> PropInfo));
> sets the ancestor to a persitent object
>
> Now if TPersistentChild  itself has
>  property Some: TComponent
>
> then you end up again in TWriter.WriteProperty  writing a tclass property
>
>    tkClass:
>      begin
>        ObjValue := TObject(GetObjectProp(Instance, PropInfo));
>        if HasAncestor then
>        begin
>          AncestorObj := TObject(GetObjectProp(Ancestor, PropInfo));
>          if Assigned(AncestorObj) then
>            if Assigned(ObjValue) and
>              (TComponent(AncestorObj).Owner = FRootAncestor) and
>              (TComponent(ObjValue).Owner = Root) and
>              (UpperCase(TComponent(AncestorObj).Name) = 
> UpperCase(TComponent(ObjValue).Name)) then
>              AncestorObj := ObjValue
> //            else
> //              AncestorObj := nil;
>        end else
>          AncestorObj := nil;
>
>
> and this code assumes that the ancestor is a TComponent, but as seen 
> before, the ancestor is not.
>
>
> Shall I report a bug, or do I miss understand something?
> (is there a workaround?)
>
> Martin
>
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