On 20/08/2011 07:28, Bernard Helyer wrote:
On Sat, 20 Aug 2011 01:42:56 +0100, Stewart Gordon wrote:
So essentially you're looking to catch cases where, if you consider the
function as a flow chart, there is no chain of arrows from the start of
the function to the statement in question. That should be
straightforward. But you're not worrying about catching cases where
some arrow would never be followed. Have I got that right?
Pretty much, minor correction on the last part -- an arrow means that the
compiler considers it a possibility, so it's not considered in so far as
the data structure doesn't make the distinction.
That's more or less what I meant. The compiler can't identify all arrows that will never
be followed - this would mean solving the halting problem. So it takes the view that any
arrow _may_ be followed. But if there's no arrow at all leading to a statement, the
compiler can easily see that it's unreachable and so issue a warning/error.
Stewart.
