Compile error with libc++'s bind

Clang Frontend
1

Hi Jonathan,

the following program fails to compile with clang trunk and libc++ trunk
(note the implicit conversion from <const char*>
to <std::string> when calling the functor in <doIt>):

#include <functional>

using namespace std::placeholders;

template <typename Functor> static void doIt(Functor f) {
f(""); }

static void method(const std::string&); // A //static void method(const
char*); // B

int main(int, char**) {
doIt(std::bind(&method, _1));
}

You're missing the #include <string>. It appears that <functional> is
pulling in a forward-declaration of it, but that's not enough for clang to
know that an implicit conversion from const char* exists.

Regards,
Richard

2

Richard Smith wrote:

Hi Jonathan,

the following program fails to compile with clang trunk and libc++ trunk
(note the implicit conversion from <const char*>
to <std::string> when calling the functor in <doIt>):

#include <functional>

using namespace std::placeholders;

template <typename Functor> static void doIt(Functor f) {
f(""); }

static void method(const std::string&); // A //static void

method(const

char*); // B

int main(int, char**) {
doIt(std::bind(&method, _1));
}

You're missing the #include <string>. It appears that <functional> is
pulling in a forward-declaration of it, but that's not enough for clang to
know that an implicit conversion from const char* exists.

Hi! Is this program not ill-formed? Clang accepts it without moaning,
silently choosing the second "f":

template<typename T>
struct A;
typedef A<int> aint;

void f(aint);
void f(...) { }

int main() {
  f(0);
}

But the FDIS says that if the completeness of A<int> might affect the
semantics of the program, it is instantiated.

The FDIS says if the implicit instantiation of a class template
specialization is required, but the class template is only declared but not
defined, the program is ill-formed (14.7.1p7).