http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53788
Bug #: 53788
Summary: C++11 decltype sfinae static member function check
(4.7.1)
Classification: Unclassified
Product: gcc
Version: 4.7.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: [email protected]
ReportedBy: [email protected]
Greetings all. The following code should *not* compile (one of the ways for
detecting the presence or not of a static member function), because of a typo I
did in T/X substitution in the check function template:
Here is the testcase:
/* BEGIN TESTCASE */
#include <cstdio>
#include <type_traits>
template<typename T>
struct has_static {
// NOTICE THE T/X substitution error, T::fun() should have been X::fun()
// thanks to dgregor in http://llvm.org/bugs/show_bug.cgi?id=13223
template<typename X>
static std::true_type check(X*, decltype(T::fun())* = 0);
static std::false_type check(...);
typedef decltype(check((T*)(0))) _tmp;
static const bool value = _tmp::value;
};
struct test {
int fun() { return 0; }
};
int main() {
printf("%d\n", has_static<test>::value);
return(0);
}
/* END TESTCASE */
used: g++ (GCC) 4.7.1 with --std=c++0x
According to dgregor's reply in the aforementioned llvm bugzilla entry, clang
is right to not compile this while g++ tacitly accepts it before its time (from
4.5.1 to 4.7.1 at least). Is this something requiring fixing?
thanks.
