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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95354] GCC misuse "nonnull-attribute" option and can not
 detect it as UB as well
Date: Wed, 27 May 2020 10:46:24 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95354

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Haoxin Tu from comment #3)
> I see. Are there any cases that can trigger the UB of nonnull-attribute? I
> doubt the usage of =E2=80=9C-fsanitize=3Dnonnull-attribute=E2=80=9D in GC=
C...

Yes, just use the attribute correctly.

Using:

__attribute__((nonnull)) void has_nonnull_argument(int *p) {=20
     ;=20
}

will cause UBsan to diagnose it:

nn.cc:7:25: runtime error: null pointer passed as argument 1, which is decl=
ared
to never be null=