Partial template specialization failure

Question

The code below fails to compile with the compiler version Sun C++ 5.9 SunOS_i386 Patch 124864-10 2009/02/03
bash-3.00$ CC -library=stlport4 /tmp/junk.cc -o /tmp/junk
"/tmp/junk.cc", line 17: Error: Multiple declaration for is_equal_size<std::string, void>::value().
"/tmp/junk.cc", line 21: Where: While specializing "is_equal_size<std::string, void>".
"/tmp/junk.cc", line 21: Where: Specialized in non-template code.
<same errors for all instantiated permutations>
#include "iostream"
#include "string"
template <typename T, typename U> struct is_equal_size {
bool value() { return sizeof(T) == sizeof(U); }
template <> struct is_equal_size<void, void> {
bool value() { return true; }
template <typename U> struct is_equal_size<void, U> {
bool value() { return false; }
template <typename T> struct is_equal_size<T, void> {
bool value() { return false; }
int main() {
struct is_equal_size<std::string, void> sv;
struct is_equal_size<void, void> vv;
struct is_equal_size<void, std::string> vs;
struct is_equal_size<std::string, std::string> ss;
std::cout << sv.value() << std::endl;
std::cout << vv.value() << std::endl;
std::cout << vs.value() << std::endl;
std::cout << ss.value() << std::endl;
return 0;
}

Answer 1

Yes, this appears to be a bug in the C++ compiler. Please file a bug report at
[http://bugs.sun.com]
For the test case, neither iostream nor std::string class is needed to demonstrate the bug. Please use a dummy struct instead of std::string, and remove the iostream I/O. Then you don't need to include any headers.
BTW, when posting code here in the Forum, please put the source code inside code tags. Although this particular example was readable, in general the Forum software will otherwise interpret special characters as formatting directives.