https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90264
Roman Zhuykov <zhroma at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Last reconfirmed| |2019-04-29
Resolution|INVALID |---
Summary|[9/10 Regression] |[9/10 Regression]
|-Wnull-dereference false |-Wnull-dereference QoI
|positive after r270574 |issue
Ever confirmed|0 |1
--- Comment #4 from Roman Zhuykov <zhroma at gcc dot gnu.org> ---
Let me perhaps explain better. Function asprintf should set *s to point
allocated memory and return non-negative amount of printed chars. When
allocation fails it will return -1. So, there are really no issue in the
original code, but compiler isn’t clever enough to know how asprintf works.
Gcc 8 doesn’t warn, thats why I’ve created this bugreport as false-positive.
So, here trunk gives a warning: https://godbolt.org/z/-o6UMv
If we decide that warning is correct, we must also warn same code, when -1
bailout removed: https://godbolt.org/z/ayb9pS
Than we have a false negative and it is *not* a “9 Regression”, but we have to
fix it.
I also want to note, that when -2 bail out is removed from both examples, 8.3
and trunk give a warning. There is a separate issue with gcc 8.3 here, it
warns two times.
<source>: In function 'cn_sequence':
<source>:11:8: warning: potential null pointer dereference [-Wnull-dereference]
*out = '\0';
~~~~~^~~~~~
<source>:11:8: warning: potential null pointer dereference [-Wnull-dereference]
Compiler returned: 0
But I haven’t checked recent 8-branch, maybe that was fixed and backported
after 8.3.
