https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70730
Bug ID: 70730
Summary: Inconsistent column number in "error: attempt to take
address of bit-field structure member"
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: ch3root at openwall dot com
Target Milestone: ---
When compiling this program:
/----------------------------------------------------------------------\
#include <stddef.h>
int main()
{
struct s { int x:2; };
typedef struct s s;
offsetof(struct { int x:2; }, x);
offsetof(struct s, x);
offsetof(s, x);
}
\----------------------------------------------------------------------/
I get the following error messages:
/----------------------------------------------------------------------\
In file included from example.c:1:0:
example.c: In function ‘main’:
example.c:8:19: error: attempt to take address of bit-field structure member
‘x’
offsetof(struct { int x:2; }, x);
^
example.c:9:19: error: attempt to take address of bit-field structure member
‘x’
offsetof(struct s, x);
^
example.c:10:3: error: attempt to take address of bit-field structure member
‘x’
offsetof(s, x);
^~~~~~~~
\----------------------------------------------------------------------/
In the first two cases it points inside the first argument while in the third
case it points to the 'offset' itself. This is inconsistent.
Perhaps it's better to point to the second argument instead? This is what clang
outputs:
/----------------------------------------------------------------------\
example.c:8:33: error: cannot compute offset of bit-field 'x'
offsetof(struct { int x:2; }, x);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
.../lib/clang/3.9.0/include/stddef.h:120:46: note: expanded from macro
'offsetof'
#define offsetof(t, d) __builtin_offsetof(t, d)
~~~~~~~~~~~~~~~~~~~~~~^~
example.c:8:25: note: bit-field is declared here
offsetof(struct { int x:2; }, x);
^
example.c:9:22: error: cannot compute offset of bit-field 'x'
offsetof(struct s, x);
~~~~~~~~~~~~~~~~~~~^~
.../lib/clang/3.9.0/include/stddef.h:120:46: note: expanded from macro
'offsetof'
#define offsetof(t, d) __builtin_offsetof(t, d)
~~~~~~~~~~~~~~~~~~~~~~^~
example.c:5:18: note: bit-field is declared here
struct s { int x:2; };
^
example.c:10:15: error: cannot compute offset of bit-field 'x'
offsetof(s, x);
~~~~~~~~~~~~^~
.../lib/clang/3.9.0/include/stddef.h:120:46: note: expanded from macro
'offsetof'
#define offsetof(t, d) __builtin_offsetof(t, d)
~~~~~~~~~~~~~~~~~~~~~~^~
example.c:5:18: note: bit-field is declared here
struct s { int x:2; };
^
3 errors generated.
\----------------------------------------------------------------------/
