breakpoint for accessing memory location

[Eli Zaretskii]

> Date: Sun, 22 Oct 2006 18:48:34 -0400
> From: Robert Dewar <dewar@adacore.com>
> CC:  rodney.bates@wichita.edu,  gdb@sourceware.org
> 
> I have no idea why you would think this is invalid, i.e. what the
> general semantic rule is that makes this expression invalid.

The general rule is that watching a constant expression is silly,
since its value never changes and thus the watchpoint will never
break.  Thus, it's probably not what the user wanted, and a warning
would be a Good Thing, IMO.