https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98826
Bug ID: 98826
Summary: [gcc vs g++] qualified type of members of anonymous
struct
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: ndesaulniers at google dot com
CC: richard-gccbugzilla at metafoo dot co.uk
Target Milestone: ---
Consider the following code:
struct dummy {
const struct {
int a;
volatile struct { int b; };
};
int c;
};
extern void fn(const int *);
extern void fn2(volatile int *);
void test(struct dummy *a) {
fn(&a->b);
fn2(&a->b);
a->a = a->c;
}
I noticed that g++ does not produce any diagnostics for the above, but gcc will
produce 3 diagnostics:
bar.c: In function ‘test’:
bar.c:13:6: warning: passing argument 1 of ‘fn’ discards ‘volatile’ qualifier
from pointer target type [-Wdiscarded-qualifiers]
13 | fn(&a->b);
| ^~~~~
bar.c:9:16: note: expected ‘const int *’ but argument is of type ‘const
volatile int *’
9 | extern void fn(const int *);
| ^~~~~~~~~~~
bar.c:14:7: warning: passing argument 1 of ‘fn2’ discards ‘const’ qualifier
from pointer target type [-Wdiscarded-qualifiers]
14 | fn2(&a->b);
| ^~~~~
bar.c:10:17: note: expected ‘volatile int *’ but argument is of type ‘const
volatile int *’
10 | extern void fn2(volatile int *);
| ^~~~~~~~~~~~~~
bar.c:15:8: error: assignment of member ‘a’ in read-only object
15 | a->a = a->c;
| ^
So it seems that the members of the anonymous struct are inheriting the
qualifications of the containing anonymous struct? This also seems to apply
recursively for nested anonymous structs.
Is this an intentional difference between C and C++?
