From: Markus Schöpflin (markus.schoepflin_at_[hidden])
Date: 2005-10-13 10:09:18
Douglas Gregor wrote:
> Oops, sorry! Brad King tracked down a problem with similar symptoms
> to what is happening with Signals, and got it down to this test case:
Thanks for the test case. But see below.
> #include <stdio.h>
>
> struct A
> {
> A() { printf("A(): %p\n", this); }
> A(const A&) { printf("A(const A&): %p\n", this); }
> ~A() { printf("~A(): %p\n", this); }
> };
>
> struct B: public A
> {
> B() { printf("B(): %p\n", this); }
> B(const B& b): A(b) { printf("B(const B&): %p\n", this); }
> ~B() { printf("~B(): %p\n", this); }
> };
>
> struct C
> {
> operator B () { printf("operator B()\n"); return B(); }
> };
>
> void f(A) { printf("f()\n"); }
>
> int main()
> {
> C c;
> f(c);
> return 0;
> }
>
> IIRC, B::~B() doesn't get called properly for the temporary returned
> from operator C::B(), but you'll want to check that before you report
> anything.
> cxx -version V6.5-042 main.cc && ./a.out
operator B()
A(): 11fffbfd0
B(): 11fffbfd0
A(const A&): 11fffbfd8
B(const B&): 11fffbfd8 <- ###
f()
~A(): 11fffbfd8
~B(): 11fffbfd0
~A(): 11fffbfd0
> cxx -version V7.1-006 main.cc && ./a.out
operator B()
A(): 11fffbfe0
B(): 11fffbfe0
A(const A&): 11fffbfe8
f()
~A(): 11fffbfe8
~B(): 11fffbfe0
~A(): 11fffbfe0
As you can see, the old compiler version creates an extraneous call to B's
copy constructor. This is fixed in the latest release.
Therefore I assume that this isn't the root of the problem we see in the
signals tests, as the failures show up for both the latest Tru64/CXX
compiler (which uses Comeau) and for Comeau on windows.
Markus