Re: Null pointer check elimination

[Laurent GUERBY <laurent at guerby dot net>]

Note that this correspond to the "not null" feature added to Ada 2006
in various places, including pointer type definitions:

   type Ptr is not null access Integer;

You can also have a regular pointer type and subtype it
with not null, but I guess the Ada front-end introduces
a generated subtype:

   type P is access Integer;
   function F return not null P;

The trunk Ada front-end supports this when the -gnat05
flag is used.

Laurent

On Sat, 2005-11-12 at 09:05 -0800, Per Bothner wrote:
> A "function-never-returns-null" attribute doesn't seem like
> the right mechanism.  Instead, there should be a "never-null"
> attribute on pointer types.  A "function-never-returns-null" is
> just a function whose return-type has the "never-null" attribute.
> 
> A type attribute is much more useful.  For example it allows:
> String x = shared ? "x" : new String("x");
> // The type of x [in a single-assignment-world] is non-null.
> 
> [If we already have such a mechanism, I apologize.]