The C linkage declaration extern "C" can not be combined with a namespace. In practical terms only one function with that name can be
declared as extern "C" because the namespace is functionally ignored.
Noncompliant code example
namespace ns1 {
extern "C" void doSomething(); // Noncompliant
// ...
}
extern "C" {
namespace ns2 { // Noncompliant
// ...
}
// ...
}
ns1::doSomething();
doSomething(); // Works too, same as above
Compliant solution
extern "C" void doSomething();
namespace ns1 {
// ...
}
extern "C" {
// ...
}
namespace ns2 { // Noncompliant
// ...
}
doSomething();
Exceptions
extern "C" can prefix typedef.
namespace ns1 {
extern "C" typedef void c_function(); // Compliant, type named 'c_function' exists only in 'ns1' and not in the global namespace
// ...
}
