Namespaced std symbol interfiers with a global symbol

Question

With this global namespace find() template function:

#include <iostream>
#include <vector>

template <typename Iterator, typename T>
Iterator find(Iterator first, Iterator last, T value) {
  while(first!=last && *first!=value)
      ++first;
  return first;
}

int main(int argc, const char * argv[]) {
  std::vector<int> v = {1,3,5,7};
  std::vector<int>::iterator pos = find(begin(v), end(v), 3);
  if (pos != end(v))
    std::cout << "Found\n";
  return 0;
}

Why, the compiler (clang) fails indicating that there are two candidate template functions: my find() and the standard std::find()?

Yeah, the same reason `begin(v)` works instead of `std::begin(v)`. Check the dup. — DeiDei, Aug 01 '19 at 16:33

score 2 · Accepted Answer · answered Aug 01 '19 at 16:31

2

This is due to Argument-Dependent Lookup (ADL).

To avoid going through ADL, write:

std::vector<int>::iterator pos = ::find(begin(v), end(v), 3);

instead.

answered Aug 01 '19 at 16:31

Acorn

24,970
5
40
69

Namespaced std symbol interfiers with a global symbol

1 Answers1