https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84108
Bug ID: 84108
Summary: incorrect -Wattributes warning for packed/aligned
conflict
Product: gcc
Version: 8.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: arnd at linaro dot org
Target Milestone: ---
Marking a struct member as both 'packed' and 'aligned()' triggers a warning in
gcc-8:
struct s {
char x;
int y __attribute__((packed, aligned(2)));
int z __attribute__((aligned(2), packed));
} s;
x86_64-linux-gcc-8.0.1 -c -Wall test.c -O2 -c
test5.c:3:2: warning: ignoring attribute 'aligned' because it conflicts with
attribute 'packed' [-Wattributes]
int y __attribute__((packed, aligned(2)));
^~~
test5.c:4:2: warning: ignoring attribute 'packed' because it conflicts with
attribute 'aligned' [-Wattributes]
int z __attribute__((aligned(2), packed));
^~~
The warning appears to be a mistake, since neither attribute is in fact ignored
here, and both 'y' and 'z' are aligned to two bytes, which matches the gcc
documentation and the behavior of older versions.
