C++ function pointer weirdness
Yesterday the output of the following program changed
(probably due to the fix for PR19076):
==
template typename T int ref (T){ return 0; }
template typename T int ref (const T) { return 1; }
template typename T int ref (const volatile T) { return 2; }
template typename T int ref (volatile T) { return 4; }
template typename T int ptr (T*){ return 0; }
template typename T int ptr (const T*) { return 8; }
template typename T int ptr (const volatile T*) { return 16; }
template typename T int ptr (volatile T*) { return 32; }
void foo() {}
int main()
{
return ref(foo) + ptr(foo);
}
==
GCC 2.95.3 - 3.4.0 return 0, GCC 3.4.1 - 3.4.4-20050222 return 2,
and now mainline again returns 0.
So the question is: What is the correct return value?
Btw, we really should have this in the testsuite.
In any case, we have a wrong-code regression here, either on the
3.4 branch or on mainline. But before I open a PR I'd like to sort
out which is the correct behavior.
When the result changed in 3.4.1 I bugged Nathan (who caused this
change) about it, and he claimed that '2' is the correct result.
Intel's compiler indeed returns 2.
Regards,
Volker
Re: C++ function pointer weirdness
Volker Reichelt [EMAIL PROTECTED] writes:
| Yesterday the output of the following program changed
| (probably due to the fix for PR19076):
Thanks for raising this issue.
|
| ==
| template typename T int ref (T){ return 0; }
| template typename T int ref (const T) { return 1; }
| template typename T int ref (const volatile T) { return 2; }
| template typename T int ref (volatile T) { return 4; }
|
| template typename T int ptr (T*){ return 0; }
| template typename T int ptr (const T*) { return 8; }
| template typename T int ptr (const volatile T*) { return 16; }
| template typename T int ptr (volatile T*) { return 32; }
|
| void foo() {}
|
| int main()
| {
| return ref(foo) + ptr(foo);
| }
| ==
|
| GCC 2.95.3 - 3.4.0 return 0, GCC 3.4.1 - 3.4.4-20050222 return 2,
| and now mainline again returns 0.
I would say that is the behaviour I would expect. I don't understand
the answer 2. I'll check with the C++ Core Working Group.
| So the question is: What is the correct return value?
|
| Btw, we really should have this in the testsuite.
|
| In any case, we have a wrong-code regression here, either on the
| 3.4 branch or on mainline. But before I open a PR I'd like to sort
| out which is the correct behavior.
|
| When the result changed in 3.4.1 I bugged Nathan (who caused this
| change) about it, and he claimed that '2' is the correct result.
| Intel's compiler indeed returns 2.
Well, I definitely needs an answer better than that is what Intel's
compiler does :-)
-- Gaby
