Null pointer check elimination

Sat Nov 12 17:24:00 GMT 2005

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年11月12日 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.]