Question

From the C++11 standard point of view, is there a technical difference of object status/properties between:

namespace
{
   int foo;
   const int bar = 42;
}

and

namespace
{
   static int foo;
   static const bar = 42;
}

?

---

From questions and answers around here I was believing that objects in anonymous namespace were implicitly static, but someone tell me it’s the linkage only that’s internal, the compiler will not take the object as if it was marked static with implications like how it will implement object construction. So I need some details about what it really means, if there is a difference between with and without static in anonymous namespace.

Answer 1

C++11, 3.5/4:

An unnamed namespace or a namespace declared directly or indirectly
within an unnamed namespace has internal linkage. All other namespaces
have external linkage. A name having namespace scope that has not been
given internal linkage above has the same linkage as the enclosing
namespace if it is the name of — a variable …

So in C++11 both of your foo objects have internal linkage. In C++03, the first one has external linkage.

Regardless of linkage, it has static storage duration.

I don’t think there’s any such thing in the standard as “take the object as if it was marked static”, so I can’t answer to that. If you find some text in the standard that refers to whether the object is “marked static” and doesn’t refer specifically to either linkage or storage duration, then cite it and I can give you an opinion 🙂