https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70522
Bug ID: 70522
Summary: Hidden friend functions block qualified name lookup
into nested unnamed namespace
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: Casey at Carter dot net
Target Milestone: ---
This program should compile without error:
namespace N {
struct S {
friend void f(S&) {}
};
namespace {
int f;
}
}
int main() {
N::f = 42;
}
yet GCC 6 diagnoses:
prog.cc: In function 'int main()':
prog.cc:11:5: error: 'f' is not a member of 'N'
N::f = 42;
^
prog.cc:11:5: note: suggested alternative:
prog.cc:6:13: note: 'N::{anonymous}::f'
int f;
^
The program compiles correctly if either the friend declaration of f is
commented out, or the unnamed namespace is made an inline namespace.
Language lawyer justification:
The friend declaration of f is not visible to name lookup of N::f per
[namespace.memdef]/3, so the set of declarations S'(N,f) described in
[namespace.qual]/2 is empty. Name lookup should continue into namespaces
"nominated by using directives" in N; unnamed namespaces are such namespaces
per [namespace.unnamed]/1.
