https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84108
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-01-29
Known to work| |5.1.0, 6.3.0, 7.2.0
Summary|incorrect -Wattributes |[8 Regression] incorrect
|warning for packed/aligned |-Wattributes warning for
|conflict |packed/aligned conflict on
| |struct members
Ever confirmed|0 |1
Known to fail| |8.0
--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed. Looks like I missed that the two attributes are treated differently
when used with struct members than with standalone objects. Here's a test case
showing the differences and the expected/bogus warnings:
$ cat pr84108.c && gcc -O2 -S -Wall pr84108.c
#define A(e) _Static_assert (e, #e)
int i2 __attribute__((packed, aligned (2))); // -Wattributes
int j2 __attribute__((aligned (2), packed)); // -Wattributes
int i1 __attribute__((aligned (2))); // okay (reduces alignment)
A (_Alignof (i2) == 2);
A (_Alignof (j2) == 2);
A (_Alignof (i1) == 2);
struct {
int i2 __attribute__((packed, aligned (2))); // bogus -Wattributes in GCC 8
int j2 __attribute__((aligned (2), packed)); // bogus -Wattributes in GCC 8
int i1 __attribute__((aligned (2))); // ignored, no warning
} s;
A (_Alignof (s.i2) == 2);
A (_Alignof (s.j2) == 2);
A (_Alignof (s.i1) == 4);
pr84108.c:3:1: warning: ‘packed’ attribute ignored [-Wattributes]
int i2 __attribute__((packed, aligned (2))); // -Wattributes
^~~
pr84108.c:4:1: warning: ‘packed’ attribute ignored [-Wattributes]
int j2 __attribute__((aligned (2), packed)); // -Wattributes
^~~
pr84108.c:12:3: warning: ignoring attribute ‘aligned’ because it conflicts with
attribute ‘packed’ [-Wattributes]
int i2 __attribute__((packed, aligned (2))); // bogus -Wattributes in GCC
8
^~~
pr84108.c:13:3: warning: ignoring attribute ‘packed’ because it conflicts with
attribute ‘aligned’ [-Wattributes]
int j2 __attribute__((aligned (2), packed)); // bogus -Wattributes in GCC
8
^~~
