The following very simple program is giving me a warning with g++ 4.4.2 with
-Wall (or -Wstrict-aliasing=1, 2 or 3). I don't think it should be giving the
warning, so I think this is a bug.
Replacing std::complex with a simple user-defined complex-like class makes the
warning go away, so maybe there is a bug in the complex class?
Also, replacing the virtual inheritance with normal inheritance makes the
warning go away.
Likewise removing the A class and moving the virtual inheritance to C : virtual
public B.
Or if I make the argument of foo a reference.
===========================================================
#include <complex>
struct A {
virtual int value() const=0;
};
struct B : virtual public A {
bool isOne() const { return A::value() == 1; }
};
struct C : public B {
int value() const { return 1; }
};
struct D {
void foo(std::complex<float> x) const; // foo is extern
};
void callFoo()
{
C c;
D d;
if (c.isOne()) d.foo(0);
}
===========================================================
The warning produced is:
>g++-4 -c -O2 -Wstrict-aliasing foo.cpp
foo.cpp: In function void callFoo():
foo.cpp:9: warning: dereferencing pointer <anonymous> does break
strict-aliasing rules
foo.cpp:9: note: initialized from here
This appears to me to be different from similar bugs: 41838, 39390 which
reference the same warning, but maybe it is related.
--
Summary: spurious strict-aliasing warning
Product: gcc
Version: 4.4.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: michael at jarvis dot net
GCC build triplet: i686-apple-darwin9
GCC host triplet: i686-apple-darwin9
GCC target triplet: i686-apple-darwin9
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42488
