Re: [PATCH] -var-update [was Re: Variable objects: references formatting]

Nick Roberts
2006-05-16T23:53:09Z

> > I think this patch works. My reasoning is one of symmetry: whatever is
> > done to val2 should also be done to val1, and that you probably don't want
> > to change the contents of val1 (hence val3). I don't know exactly what
> > coerce_array does, apart from convert the type from TYPE_CODE_REF to
> > TYPE_CODE_INT or TYPE_CODE_FLOAT or whatever, so the comment might not be
> > quite right.
>
> I don't think this is in the right place: you're using an argument of
> symmetry, but in fact, the comments in my_value_equal suggest that
> symmetry is inappropriate.

Also because, its a safe one, particularly if a dummy value variable is used,
because nothing gets changed outhside my_value_equal.

Anyway I now see its the wrong change, it just detects when the reference is
assigned an address, not when the value at that address changes.

> For instance:
>
> /* The contents of VAL1 are supposed to be known. */
> gdb_assert (!value_lazy (val1));
>
> If val1 is the reference at this point, then we haven't checked what we
> think we have.

Trying to interpret the code, given that val1 doesn't hold the value I
wonder why this assertion is true i.e why is value->lazy=0 even though
the value isn't in the contents field.

> Every time my_value_equal is called its first argument comes from a
> varobj's ->value. It seems to me that if we want to properly know
> whether the varobj has changed, we'd better have read its value into
> GDB.

Could it not doing that because GDB's value mechanism isn't working properly
for references?

--
Nick http://www.inet.net.nz/~nickrob