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On 11/17/21 01:06, Alejandro Colomar (man-pages) wrote:
Hi,
Sorry for Clang people,
when I started this thread,
I wasn't subscribed to your list,
and some messages are not on your list.
You can find the complete thread on the GCC list:
<https://gcc.gnu.org/pipermail/gcc/2021-November/237743.html>
I have a few questions for you.
See below, please.
On 11/16/21 13:34, Alejandro Colomar (man-pages) wrote:
$ cat _Nonnull.c
#include <stdlib.h>
int *_Nonnull f(int *_Nullable p)
{
if (!p)
exit(1);
return p;
}
- I get a warning from f().
Ideally,
a programmer should not need to cast
(casts are dangerous),
to convert a nullable pointer to a _Nonnull pointer.
For that,
appropriate checks should be in the preceeding code.
Otherwise, a diagnostic should be issued.
To be on the safe side,
if a compiler has doubts,
it should diagnose.
There's some Clang document that talks about something similar.
I don't know its validity,
or if it was a draft before _Nonnull qualifiers.
<https://clang.llvm.org/docs/analyzer/developer-docs/nullability.html>
That document suggests that I shouldn't get a diagnostic from f().
Why did I get a diagnostic? (I tried clang 11, 13 & 14(experimental))
Is it talking about a different nonnull attribute/qualifier?
Was it about a proposal prior to the current _Nonnull?
Why is it not in use? Was it too difficult to implement?
Do you think Clang could be improved to not warn on f()?
Thanks,
Alex
--
Alejandro Colomar
Linux man-pages comaintainer; http://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
