1 // DR 743: A type without linkage shall not be used as the type of a
2 // variable or function with linkage, unless
3 // o the variable or function has extern "C" linkage (7.5 [dcl.link]), or
4 // o the variable or function is not used (3.2 [basic.def.odr]) or is
5 // defined in the same translation unit.
6
7 // { dg-do compile { target c++11 } }
8
9 template <typename T> struct B {
gB10 void g(T){}
11 void h(T); // { dg-error "never defined" }
iB12 friend void i(B, T){}
13 static T t1; // { dg-error "never defined" }
14 static T t2;
15 };
16
17 template <typename T> T B<T>::t2 = { };
18
19 enum { E1 } e1; // OK, defined
20 extern enum { E2 } e2; // { dg-error "never defined" }
21 extern "C" enum { E3 } e3; // OK, extern "C"
22
f()23 void f() {
24 struct A { int x; }; // no linkage
25 A a = {1};
26 B<A> ba; // declares B<A>::g(A) and B<A>::h(A)
27 ba.t1 = a; // error, B<T>::t never defined
28 ba.t2 = a; // OK
29 ba.g(a); // OK
30 ba.h(a); // error, B<T>::h never defined
31 i(ba, a); // OK
32 e1+e2+e3; // { dg-warning "arithmetic between different enumeration types" "" { target c++20 } }
33 }
34