C and C++ could have non_nullable pointers, easily [LWN.net]

C and C++ could have non_nullable pointers, easily

Posted Aug 21, 2009 7:48 UTC (Fri) by dgm (subscriber, #49227)
In reply to: C and C++ could have non_nullable pointers, easily by nix
Parent article: Null pointers, one month later

This would be useful if the type system _forced_ you to check before assigning a maybe-null-pointer to a never-null-pointer. And to be really useful, only never-null-pointers should be dereferenced, and the compiler would only allow pointer arithmetic on maybe-null-pointers.

The gotcha is that null pointers are just _one_ type of invalid pointer.

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C and C++ could have non_nullable pointers, easily

Posted Aug 21, 2009 19:10 UTC (Fri) by nix (subscriber, #2304) [Link] (1 responses)

Yes, those changes would make the idea genuinely useful. They'd also break
compatibility with almost all previous code: this from a language so
conservative that by word-of-dmr the precedence of && and || was
intentionally set wrong so as to avoid breaking code running on three
sites :)

C and C++ could have non_nullable pointers, easily

Posted Aug 22, 2009 1:10 UTC (Sat) by njs (subscriber, #40338) [Link]

Yeah, it's more of a thought experiment, though one could enable it only for certain (new) compilation units, or treat them as annotations for a tool like sparse.