AMDG Niels Dekker - address until 2010-10-10 wrote:
Jean-Francois Bastien wrote:
[pedanticism] Don't both your examples rely on pre-standard C++ friend declarations and definitions injecting the function name in the innermost enclosing namespace? I might be reading this worng, but 7.3.1.2 [namespace.memdef] paragraph 3 states: "The name of the friend is not found by unqualified lookup (3.4.1) or by qualified lookup (3.4.3) until a matching declaration is provided in that namespace scope". So you'd still need to declare in the namespace. From what I understand the examples shouldn't work.
Correct me if I'm wrong :)
Well... I do appreciate your pedanticism, but I think you're wrong. All the compilers I tried accept the function calls to the inline friend function, operator-(safe_int,safe_int), including MSVC 2008 SP1, Comeau (www.comeaucomputing.com/tryitout), and g++ 4.1.2, run at http://codepad.org/dB9IbQJ7
You might want to have a look at [temp.inject] ("Friend names declared within a class template"). Quoting the latest C++0x Working Draft, www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2857.pdf, 14.7.5/2 (slightly reformatted):
"As with non-template classes, the names of namespace-scope friend functions of a class template specialization are not visible during an ordinary lookup unless explicitly declared at namespace scope (11.4). Such names may be found under the rules for associated classes (3.4.2). [ Example: <snip> ]
Exactly. In the current standard, they can be found by argument-dependent lookup: When considering an associated namespace, the lookup is the same as the lookup performed when the associated namespace is used as a qualifier (3.4.3.2) except that: — Any using-directives in the associated namespace are ignored. — Any namespace-scope friend functions declared in associated classes are visible within their respective namespaces even if they are not visible during an ordinary lookup (11.4). In Christ, Steven Watanabe