> Nick Ing-Simmons <[EMAIL PROTECTED]> writes:
>
> > To let Tk list know a major gotcha blocking Tk release is fixed.
> > Thanks to Steve Lide for the guest account on his G5 machine
> > to track this!
> >
> > To let perl-xs list know even I am human and do dumb things ...
> >
> > void
> > WidgetMethod(widget,name,...)
> > SV * widget;
> > SV * name;
> > CODE:
> > {
> > Lang_CmdInfo *info = WindowCommand(widget, NULL, 1);
> > XSRETURN(Call_Tk(info, items, &ST(0)));
> > }
> >
> > Looks neat and tidy - but is fatally flawed.
> > XSRETURN macro is basically
> >
> > THE_PERL_STACK_POINTER += Something.
> >
> > On Steve's G5 - that gets compiled as
> > Get PERL_STACK_POINTER
> > call function which returns value
> > add
> > Set PERL_STACK_POINTER
> >
> > The snag is that when function which returns value is a
> > perl callback it can move the stack.
> > So after above the stack pointer is pointing into an old stack
> > which has now been free'd and re-used => CORE.
> >
> > Changing it to:
> >
> > void
> > WidgetMethod(widget,name,...)
> > SV * widget;
> > SV * name;
> > CODE:
> > {
> > Lang_CmdInfo *info = WindowCommand(widget, NULL, 1);
> > IV count = Call_Tk(info, items, &ST(0));
> > XSRETURN(count);
> > }
> >
> > Fixes the problem.
>
> Is this worth a note in perlapi.pod?
How about also fixing the source of the problem?
--- XSUB.h.orig Wed Dec 10 20:39:37 2003
+++ XSUB.h Wed Dec 10 20:43:26 2003
@@ -193,7 +193,8 @@
#define XSRETURN(off) \
STMT_START { \
- PL_stack_sp = PL_stack_base + ax + ((off) - 1); \
+ IV tMpOfF = off; \
+ PL_stack_sp = PL_stack_base + ax + (tMpOfF - 1);\
return; \
} STMT_END
-- Marcus
