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

[Nick Roberts <nickrob@snap.net.nz>]

 > > 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