https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99367
Bug ID: 99367
Summary: missing warning on constructing/destroying class
objects in insufficient space
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
Except in the most trivial cases GCC fails to diagnose invalid attempts to
invoke nontrivial constructors or destructors of classes in insufficient space.
They should be easily detectable in the middle end.
$ cat u.C && gcc -O2 -S -Wall u.C
void* operator new (__SIZE_TYPE__, void *p) { return p; }
struct A { A (); ~A (); int i; };
void f0 (void*);
char a[sizeof (A)];
void f1 ()
{
A *q = new (a + 1) A (); // -Wplacement-new (good)
f0 (q);
}
void g ()
{
char *p = a + 1;
A *q = new (p) A (); // missing warning
f0 (q);
}
void f2 ()
{
A *q = (A*)(a + 1);
q->~A (); // missing warning
}
u.C: In function ‘void f1()’:
u.C:11:17: warning: placement new constructing an object of type ‘A’ and size
‘4’ in a region of type ‘char [4]’ and size ‘3’ [-Wplacement-new=]
11 | A *q = new (a + 1) A (); // -Wplacement-new (good)
| ~~^~~
u.C:7:6: note: at offset 1 from ‘a’ declared here
7 | char a[sizeof (A)];
| ^
