https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50584
nsz at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |nsz at gcc dot gnu.org
--- Comment #12 from nsz at gcc dot gnu.org ---
(1) consider a simplified example from bug 17308
__attribute__((nonnull(1)))
void foo(char *bar) { if (!bar) __builtin_abort(); }
with gcc -O2 -fno-asynchronous-unwind-tables -fomit-frame-pointer -std=c99
-Wall
i get warnings:
a.c: In function 'foo':
a.c:2:27: warning: nonnull argument 'bar' compared to NULL [-Wnonnull]
void foo(char *bar) { if (!bar) __builtin_abort(); }
^
and asm code:
foo:
rep ret
(2) however code with similar semantics:
void foo(char bar[static 1]) { if (!bar) __builtin_abort(); }
gives no warnings and the generated asm is
foo:
testq %rdi, %rdi
je .L7
rep ret
.L7:
pushq %rax
call abort
the code in (2) should at least imply nonnull argument, since this is
the idiomatic nonnull annotation in c since c99.
(unfortunately it does not work for void* arguments, otherwise i think
it is useful for static analysis, but it won't be used in practice
unless compilers make use of it.)
