http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53837
Bug #: 53837
Summary: Unpacking variadic template parameters in a method
parameter default value gives parse error
Classification: Unclassified
Product: gcc
Version: 4.7.1
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c++
AssignedTo: [email protected]
ReportedBy: [email protected]
-------- bug.cpp --------
template <typename... Args>
int f() { return 42; }
template <typename... Args>
struct B1 {
B1(int i = f<Args...>()); // ERROR
void m(int i = f<Args...>()); // ERROR
};
struct B2 {
template <typename... Args>
void m(int i = f<Args...>()); // ERROR
};
template <typename... Args>
struct B3 {
B3(int i = call_f()); // OK
void m(int i = call_f()); // OK
static int call_f() { return f<Args...>(); }
};
template <typename... Args>
void g(int i = f<Args...>()); // OK
int main() {}
-------- bug.cpp --------
$ g++ -std=c++0x bug.cpp
bug.cpp:6:22: error: expected ‘)’ before ‘>’ token
bug.cpp:6:19: error: expected ‘;’ at end of member declaration
bug.cpp:6:22: error: expected unqualified-id before ‘>’ token
bug.cpp:7:26: error: expected ‘)’ before ‘>’ token
bug.cpp:7:23: error: expected ‘;’ at end of member declaration
bug.cpp:7:26: error: expected unqualified-id before ‘>’ token
bug.cpp:6:13: error: parse error in template argument list
bug.cpp:7:17: error: parse error in template argument list
bug.cpp:12:26: error: expected ‘)’ before ‘>’ token
bug.cpp:12:26: error: expected initializer before ‘>’ token
$ clang++ -std=c++0x bug.cpp
$
GCC versions 4.4.3, 4.6.2, and 4.7.1 give parse errors on the marked lines.
Clang 3.0 doesn't complain.
Note that g() parses fine.
