[fpc-devel] FreeInstance

[Sven Barth]

Ryan Joseph <ryan at thealchemistguild.com> schrieb am Mi., 1. Aug. 2018,
17:28:

>
>
> > On Aug 1, 2018, at 9:17 AM, Sven Barth via fpc-devel <
> fpc-devel at lists.freepascal.org> wrote:
> >
> > Search the compiler's source for the string 'FREEINSTANCE'; you'll find
> two locations, one in ngenutil and one in psub. The latter is the one you
> want.
> >
>
> Yeah, this is the first place I looked but current_structdef is always nil
> so it never progresses past that point.
>
> Is this test program not enough to get FreeInstance called?
>
> program test;
> var
>         obj1: TObject;
> begin
>         obj1 := TObject.Create;
>         obj1.Free;
> end.
>
>
> ===========
>
>     function generate_bodyexit_block:tnode;
>       var
>         srsym : tsym;
>         para : tcallparanode;
>         newstatement : tstatementnode;
>         oldlocalswitches: tlocalswitches;
>       begin
>         result:=internalstatements(newstatement);
>
>         if assigned(current_structdef) then
>           begin
>             { Don't test self and the vmt here. The reason is that  }
>             { a constructor already checks whether these are valid  }
>             { before. Further, in case of TThread the thread may    }
>             { free the class instance right after AfterConstruction }
>             { has been called, so it may no longer be valid (JM)    }
>             oldlocalswitches:=current_settings.localswitches;
>
> current_settings.localswitches:=oldlocalswitches-[cs_check_object,cs_check_range];
>
>             { a destructor needs a help procedure }
>             if (current_procinfo.procdef.proctypeoption=potype_destructor)
> then
>               begin
>                 if is_class(current_structdef) then
>                   begin
>
> srsym:=search_struct_member(current_structdef,'FREEINSTANCE');
>

If you'd look at the code you quoted you'd see that this is only inserted
*inside* a destructor (the check for potype_destructor; current_procinfo is
the currently compiled routine). So, no, your code is not enough. You need
to declare a class with a destructor, then the code would be entered.

Regards,
Sven

>
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