https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94989
Bug ID: 94989
Summary: missing -Wclass-memaccess on calls to functions with
attribute access
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
Passing the address of a nontrivial object to a function that takes a void*,
especially one declared with attribute access indicating it writes into the
object, should be diagnosed by -Wclass-memaccess for the same reason the same
misuses are when they involve built-ins like memset and memcpy. The test case
below shows that only the latter is the case.
$ cat t.C && gcc -O2 -S -Wall t.C
class C {
int &r;
C ();
C (const C&);
virtual ~C ();
};
__attribute__ ((access (write_only, 1, 2))) void
f (void*, int);
void g (C &c)
{
__builtin_memset (&c, 0, sizeof c); // -Wclass-memaccess (good)
}
void h (C &c)
{
f (&c, sizeof c); // missing warning
}
t.C: In function ‘void g(C&)’:
t.C:13:36: warning: ‘void* __builtin_memset(void*, int, long unsigned int)’
clearing an object of type ‘class C’ with no trivial copy-assignment
[-Wclass-memaccess]
13 | __builtin_memset (&c, 0, sizeof c); // -Wclass-memaccess (good)
| ^
t.C:1:7: note: ‘class C’ declared here
1 | class C {
| ^
