test/CodeGenCXX/visibility.cpp

// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -fvisibility hidden -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-HIDDEN

#define HIDDEN __attribute__((visibility("hidden")))
#define PROTECTED __attribute__((visibility("protected")))
#define DEFAULT __attribute__((visibility("default")))

namespace test30 {
  // When H is hidden, it should make X hidden, even if the template argument
  // is not.
  struct H {
  };
  template<H *T>
  struct X {
  };
  H DEFAULT a;
  X<&a> b;
  // CHECK: _ZN6test301bE = global
  // CHECK-HIDDEN: _ZN6test301bE = hidden global
}

namespace test25 {
  template<typename T>
  struct X {
    template<typename U>
    struct definition {
    };
  };

  class DEFAULT A { };

  X<int>::definition<A> a;
  // CHECK: @_ZN6test251aE = global
  // CHECK-HIDDEN: @_ZN6test251aE = hidden global
}

namespace test28 {
  class DEFAULT foo {
  };
  foo myvec;
  // CHECK: @_ZN6test285myvecE = global
  // CHECK-HIDDEN: @_ZN6test285myvecE = hidden global
}

namespace test29 {
#pragma GCC visibility push(hidden)
  struct RECT {
    int top;
  };
  __attribute__ ((visibility ("default"))) extern RECT data_rect;
  RECT data_rect = { -1};
#pragma GCC visibility pop
  // CHECK: @_ZN6test299data_rectE = global
  // CHECK-HIDDEN: @_ZN6test299data_rectE = global
}

namespace test40 {
  template<typename T>
  struct foo {
    DEFAULT static int bar;
  };
  template<typename T>
  int foo<T>::bar;
  template struct foo<int>;
  // CHECK: _ZN6test403fooIiE3barE = weak_odr global
  // CHECK-HIDDEN: _ZN6test403fooIiE3barE = weak_odr global
}

namespace test41 {
  // Unlike gcc we propagate the information that foo not only is hidden, but
  // has been explicitly marked as so. This lets us produce a hidden undefined
  // reference to bar.
  struct __attribute__((visibility("hidden"))) foo {};
  extern foo bar;
  foo *zed() {
    return &bar;
  }
  // CHECK: @_ZN6test413barE = external hidden global
  // CHECK-HIDDEN: @_ZN6test413barE = external hidden global
}

// CHECK: @_ZN5Test425VariableInHiddenNamespaceE = hidden global i32 10
// CHECK: @_ZN5Test71aE = hidden global
// CHECK: @_ZN5Test71bE = global
// CHECK: @test9_var = global
// CHECK-HIDDEN: @test9_var = global
// CHECK: @_ZN6Test121A6hiddenE = external hidden global
// CHECK: @_ZN6Test121A7visibleE = external global
// CHECK-HIDDEN: @_ZN6Test121A6hiddenE = external hidden global
// CHECK-HIDDEN: @_ZN6Test121A7visibleE = external global
// CHECK: @_ZN6Test131B1aE = hidden global
// CHECK: @_ZN6Test131C1aE = global
// CHECK-HIDDEN: @_ZN6Test131B1aE = hidden global
// CHECK-HIDDEN: @_ZN6Test131C1aE = global
// CHECK: @_ZN6Test143varE = external global
// CHECK-HIDDEN: @_ZN6Test143varE = external global
// CHECK: @_ZN6Test154TempINS_1AEE5Inner6bufferE = external global [0 x i8]
// CHECK-HIDDEN: @_ZN6Test154TempINS_1AEE5Inner6bufferE = external global [0 x i8]

namespace test27 {
  template<typename T>
  class C {
    class __attribute__((visibility("default"))) D {
      void f();
    };
  };

  template<>
  class C<int>::D {
    virtual void g();
  };

  void C<int>::D::g() {
  }
  // CHECK: _ZTVN6test271CIiE1DE = unnamed_addr constant
  // CHECK-HIDDEN: _ZTVN6test271CIiE1DE = unnamed_addr constant
}

// CHECK: @_ZZN6Test193fooIiEEvvE1a = linkonce_odr global
// CHECK: @_ZGVZN6Test193fooIiEEvvE1a = linkonce_odr global i64
// CHECK-HIDDEN: @_ZZN6Test193fooIiEEvvE1a = linkonce_odr hidden global
// CHECK-HIDDEN: @_ZGVZN6Test193fooIiEEvvE1a = linkonce_odr hidden global i64
// CHECK-HIDDEN: @_ZTVN6Test161AIcEE = external unnamed_addr constant
// CHECK-HIDDEN: @_ZTTN6Test161AIcEE = external unnamed_addr constant
// CHECK: @_ZTVN5Test63fooE = linkonce_odr hidden unnamed_addr constant

namespace Test1 {
  // CHECK: define hidden void @_ZN5Test11fEv
  void HIDDEN f() { }

}

namespace Test2 {
  struct HIDDEN A {
    void f();
  };

  // A::f is a member function of a hidden class.
  // CHECK: define hidden void @_ZN5Test21A1fEv
  void A::f() { }
}

namespace Test3 {
  struct HIDDEN A {
    struct B {
      void f();
    };
  };

  // B is a nested class where its parent class is hidden.
  // CHECK: define hidden void @_ZN5Test31A1B1fEv
  void A::B::f() { }
}

namespace Test4 HIDDEN {
  int VariableInHiddenNamespace = 10;

  // Test4::g is in a hidden namespace.
  // CHECK: define hidden void @_ZN5Test41gEv
  void g() { }

  struct DEFAULT A {
    void f();
  };

  // A has default visibility.
  // CHECK: define void @_ZN5Test41A1fEv
  void A::f() { }
}

namespace Test5 {

  namespace NS HIDDEN {
    // f is in NS which is hidden.
    // CHECK: define hidden void @_ZN5Test52NS1fEv()
    void f() { }
  }

  namespace NS {
    // g is in NS, but this NS decl is not hidden.
    // CHECK: define void @_ZN5Test52NS1gEv
    void g() { }
  }
}

// <rdar://problem/8091955>
namespace Test6 {
  struct HIDDEN foo {
    foo() { }
    void bonk();
    virtual void bar() = 0;

    virtual void zonk() {}
  };

  struct barc : public foo {
    barc();
    virtual void bar();
  };

  barc::barc() {}
}

namespace Test7 {
  class HIDDEN A {};
  A a; // top of file

  template <A&> struct Aref {
    static void foo() {}
  };

  class B : public A {};
  B b; // top of file

  // CHECK: define linkonce_odr hidden void @_ZN5Test74ArefILZNS_1aEEE3fooEv()
  void test() {
    Aref<a>::foo();
  }
}

namespace Test8 {
  void foo();
  void bar() {}
  // CHECK-HIDDEN: define hidden void @_ZN5Test83barEv()
  // CHECK-HIDDEN: declare void @_ZN5Test83fooEv()

  void test() {
    foo();
    bar();
  }
}

// PR8457
namespace Test9 {
  extern "C" {
    struct A { int field; };
    void DEFAULT test9_fun(struct A *a) { }
    struct A DEFAULT test9_var; // above
  }
  // CHECK: define void @test9_fun(
  // CHECK-HIDDEN: define void @test9_fun(

  void test() {
    A a = test9_var;
    test9_fun(&a);
  }
}

// PR8478
namespace Test10 {
  struct A;

  class DEFAULT B {
    void foo(A*);
  };

  // CHECK: define void @_ZN6Test101B3fooEPNS_1AE(
  // CHECK-HIDDEN: define void @_ZN6Test101B3fooEPNS_1AE(
  void B::foo(A*) {}
}

// PR8492
namespace Test11 {
  struct A {
    void foo() {}
    void DEFAULT bar() {}
  };

  void test() {
    A a;
    a.foo();
    a.bar();
  }

  // CHECK: define linkonce_odr void @_ZN6Test111A3fooEv(
  // CHECK: define linkonce_odr void @_ZN6Test111A3barEv(
  // CHECK-HIDDEN: define linkonce_odr hidden void @_ZN6Test111A3fooEv(
  // CHECK-HIDDEN: define linkonce_odr void @_ZN6Test111A3barEv(
}

// Tested at top of file.
namespace Test12 {
  struct A {
    // This is hidden in all cases: the explicit attribute takes
    // priority over -fvisibility on the parent.
    static int hidden HIDDEN;

    // This is default in all cases because it's only a declaration.
    static int visible;
  };

  void test() {
    A::hidden = 0;
    A::visible = 0;
  }
}

// Tested at top of file.
namespace Test13 {
  struct HIDDEN A {};

  // Should be hidden in all cases.
  struct B {
    static A a;
  };
  A B::a;

  // Should be default in all cases.
  struct DEFAULT C {
    static A a;
  };
  A C::a;
};

// Tested at top of file.
namespace Test14 {
  // Neither the visibility of the type nor -fvisibility=hidden should
  // apply to declarations.
  extern struct A *var;

  struct A *test() { return var; }
}

// rdar://problem/8613093
namespace Test15 {
  struct A {};
  template <class T> struct Temp {
    struct Inner {
      static char buffer[0];
    };
  };

  char *test() {
    return Temp<A>::Inner::buffer;
  }
}

namespace Test16 {
  struct Base1 { virtual void foo(); };
  struct Base2 : virtual Base1 { virtual void foo(); };
  template <class T> struct A : virtual Base1, Base2 {
    virtual void foo();
  };
  extern template struct A<char>;

  void test() {
    A<char> a;
    a.foo();
  }
}

namespace Test17 {
  struct HIDDEN A {
    static void foo();
    static void DEFAULT bar();
    static void HIDDEN baz();

    struct DEFAULT B {
      static void foo();
      static void DEFAULT bar();
      static void HIDDEN baz();
    };
  };

  void test() {
    A::foo();
    A::bar();
    A::baz();
    A::B::foo();
    A::B::bar();
    A::B::baz();
  }
  // CHECK: declare hidden void @_ZN6Test171A3fooEv()
  // CHECK: declare void @_ZN6Test171A3barEv()
  // CHECK: declare hidden void @_ZN6Test171A3bazEv()
  // CHECK: declare void @_ZN6Test171A1B3fooEv()
  // CHECK: declare void @_ZN6Test171A1B3barEv()
  // CHECK: declare hidden void @_ZN6Test171A1B3bazEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test171A3fooEv()
  // CHECK-HIDDEN: declare void @_ZN6Test171A3barEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test171A3bazEv()
  // CHECK-HIDDEN: declare void @_ZN6Test171A1B3fooEv()
  // CHECK-HIDDEN: declare void @_ZN6Test171A1B3barEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test171A1B3bazEv()
}

namespace Test18 {
  template <class T> struct HIDDEN A {
    static void foo();
    static void DEFAULT bar();
    static void HIDDEN baz();

    struct DEFAULT B {
      static void foo();
      static void DEFAULT bar();
      static void HIDDEN baz();
    };
  };
  struct HIDDEN H;

  void test() {
    A<int>::foo();
    A<int>::bar();
    A<int>::baz();
    A<int>::B::foo();
    A<int>::B::bar();
    A<int>::B::baz();
    A<H>::foo();
    A<H>::bar();
    A<H>::baz();
    A<H>::B::foo();
    A<H>::B::bar();
    A<H>::B::baz();
  }
  // CHECK: declare hidden void @_ZN6Test181AIiE3fooEv()
  // CHECK: declare void @_ZN6Test181AIiE3barEv()
  // CHECK: declare hidden void @_ZN6Test181AIiE3bazEv()
  // CHECK: declare void @_ZN6Test181AIiE1B3fooEv()
  // CHECK: declare void @_ZN6Test181AIiE1B3barEv()
  // CHECK: declare hidden void @_ZN6Test181AIiE1B3bazEv()
  // CHECK: declare hidden void @_ZN6Test181AINS_1HEE3fooEv()
  // CHECK: declare hidden void @_ZN6Test181AINS_1HEE3barEv()
  // CHECK: declare hidden void @_ZN6Test181AINS_1HEE3bazEv()
  // CHECK: declare hidden void @_ZN6Test181AINS_1HEE1B3fooEv()
  // CHECK: declare hidden void @_ZN6Test181AINS_1HEE1B3barEv()
  // CHECK: declare hidden void @_ZN6Test181AINS_1HEE1B3bazEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AIiE3fooEv()
  // CHECK-HIDDEN: declare void @_ZN6Test181AIiE3barEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AIiE3bazEv()
  // CHECK-HIDDEN: declare void @_ZN6Test181AIiE1B3fooEv()
  // CHECK-HIDDEN: declare void @_ZN6Test181AIiE1B3barEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AIiE1B3bazEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AINS_1HEE3fooEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AINS_1HEE3barEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AINS_1HEE3bazEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AINS_1HEE1B3fooEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AINS_1HEE1B3barEv()
  // CHECK-HIDDEN: declare hidden void @_ZN6Test181AINS_1HEE1B3bazEv()
}

namespace Test19 {
  struct A { A(); ~A(); };

  // Tested at top of file.
  template <class T> void foo() {
    static A a;
  }

  void test() {
    foo<int>();
  }
}

// Various things with class template specializations.
namespace Test20 {
  template <unsigned> struct HIDDEN A {};

  // An explicit specialization inherits the explicit visibility of
  // the template.
  template <> struct A<0> {
    static void test0();
    static void test1();
  };

  // CHECK: define hidden void @_ZN6Test201AILj0EE5test0Ev()
  void A<0>::test0() {}

  // CHECK: declare hidden void @_ZN6Test201AILj0EE5test1Ev()
  void test1() {
    A<0>::test1();
  }

  // ...unless that's explicitly overridden.
  template <> struct DEFAULT A<1> {
    static void test2();
    static void test3();
  };

  // CHECK: define void @_ZN6Test201AILj1EE5test2Ev()
  void A<1>::test2() {}

  // CHECK: declare void @_ZN6Test201AILj1EE5test3Ev()
  void test3() {
    A<1>::test3();
  }

  // <rdar://problem/8778497>
  // But we should assume that an unknown specialization has the
  // explicit visibility settings of the template.
  template <class T> struct B {
    static void test4() {}
    static void test5();
  };

  // CHECK: define linkonce_odr hidden void @_ZN6Test201BINS_1AILj2EEEE5test4Ev()
  void test4() {
    B<A<2> >::test4();
  }

  // CHECK: declare hidden void @_ZN6Test201BINS_1AILj2EEEE5test5Ev()
  void test5() {
    B<A<2> >::test5();
  }
}

// PR9371
namespace test21 {
  enum En { en };
  template<En> struct A {
    __attribute__((visibility("default"))) void foo() {}
  };

  // CHECK: define weak_odr void @_ZN6test211AILNS_2EnE0EE3fooEv(
  template void A<en>::foo();
}

// rdar://problem/9616154
// Visibility on explicit specializations should take precedence.
namespace test22 {
  class A1 {};
  class A2 {};

  template <class T> struct B {};
  template <> struct DEFAULT B<A1> {
    static void foo();
    static void bar() {}
  };
  template <> struct B<A2> {
    static void foo();
    static void bar() {}
  };

  void test() {
    B<A1>::foo();
    B<A1>::bar();
    B<A2>::foo();
    B<A2>::bar();
  }
  // CHECK: declare void @_ZN6test221BINS_2A1EE3fooEv()
  // CHECK: define linkonce_odr void @_ZN6test221BINS_2A1EE3barEv()
  // CHECK: declare void @_ZN6test221BINS_2A2EE3fooEv()
  // CHECK: define linkonce_odr void @_ZN6test221BINS_2A2EE3barEv()
  // CHECK-HIDDEN: declare void @_ZN6test221BINS_2A1EE3fooEv()
  // CHECK-HIDDEN: define linkonce_odr void @_ZN6test221BINS_2A1EE3barEv()
  // CHECK-HIDDEN: declare void @_ZN6test221BINS_2A2EE3fooEv()
  // CHECK-HIDDEN: define linkonce_odr hidden void @_ZN6test221BINS_2A2EE3barEv()
}

namespace PR10113 {
  namespace foo DEFAULT {
    template<typename T>
      class bar {
      void zed() {}
    };
  }
  template class foo::bar<char>;
  // CHECK: define weak_odr void @_ZN7PR101133foo3barIcE3zedEv
  // CHECK-HIDDEN: define weak_odr void @_ZN7PR101133foo3barIcE3zedEv

  struct zed {
  };
  template class foo::bar<zed>;
  // CHECK: define weak_odr void @_ZN7PR101133foo3barINS_3zedEE3zedEv

  // FIXME: This should be hidden as zed is hidden.
  // CHECK-HIDDEN: define weak_odr void @_ZN7PR101133foo3barINS_3zedEE3zedEv
}

namespace PR11690 {
  template<class T> struct Class {
    void size() const {
    }
  };
  template class DEFAULT Class<char>;
  // CHECK: define weak_odr void @_ZNK7PR116905ClassIcE4sizeEv
  // CHECK-HIDDEN: define weak_odr void @_ZNK7PR116905ClassIcE4sizeEv

  template<class T> void Method() {}
  template  DEFAULT void Method<char>();
  // CHECK: define weak_odr void @_ZN7PR116906MethodIcEEvv
  // CHECK-HIDDEN: define weak_odr void @_ZN7PR116906MethodIcEEvv
}

namespace PR11690_2 {
  namespace foo DEFAULT {
    class bar;
    template<typename T1, typename T2 = bar>
    class zed {
      void bar() {
      }
    };
  }
  struct baz {
  };
  template class foo::zed<baz>;
  // CHECK: define weak_odr void @_ZN9PR11690_23foo3zedINS_3bazENS0_3barEE3barEv

  // FIXME: This should be hidden as baz is hidden.
  // CHECK-HIDDEN: define weak_odr void @_ZN9PR11690_23foo3zedINS_3bazENS0_3barEE3barEv
}

namespace test23 {
  // Having a template argument that is explicitly visible should not make
  // the template instantiation visible.
  template <typename T>
  struct X {
    static void f() {
    }
  };

  class DEFAULT A;

  void g() {
    X<A> y;
    y.f();
  }
  // CHECK: define linkonce_odr void @_ZN6test231XINS_1AEE1fEv
  // CHECK-HIDDEN: define linkonce_odr hidden void @_ZN6test231XINS_1AEE1fEv
}

namespace PR12001 {
  template <typename P1>
  void Bind(const P1& p1) {
  }

  class DEFAULT Version { };

  void f() {
    Bind(Version());
  }
  // CHECK: define linkonce_odr void @_ZN7PR120014BindINS_7VersionEEEvRKT_
  // CHECK-HIDDEN: define linkonce_odr hidden void @_ZN7PR120014BindINS_7VersionEEEvRKT_
}

namespace test24 {
  class DEFAULT A { };

  struct S {
    template <typename T>
    void mem() {}
  };

  void test() {
    S s;
    s.mem<A>();
  }
  // CHECK: define linkonce_odr void @_ZN6test241S3memINS_1AEEEvv
  // CHECK-HIDDEN: define linkonce_odr hidden void @_ZN6test241S3memINS_1AEEEvv
}

namespace test26 {
  template<typename T>
  class C {
    __attribute__((visibility("default")))  void f();
  };

  template<>
  void C<int>::f() { }

  // CHECK: define void @_ZN6test261CIiE1fEv
  // CHECK-HIDDEN: define void @_ZN6test261CIiE1fEv
}

namespace test31 {
  struct A {
    struct HIDDEN B {
      static void DEFAULT baz();
    };
  };
  void f() {
    A::B::baz();
  }
  // CHECK: declare void @_ZN6test311A1B3bazEv()
  // CHECK-HIDDEN: declare void @_ZN6test311A1B3bazEv()
}

namespace test32 {
  struct HIDDEN A {
    struct DEFAULT B {
      void DEFAULT baz();
    };
  };
  void A::B::baz() {
  }
  // CHECK: define void @_ZN6test321A1B3bazEv
  // CHECK-HIDDEN: define void @_ZN6test321A1B3bazEv
}

namespace test33 {
  template<typename T>
  class foo {
    void bar() {}
  };
  struct HIDDEN zed {
  };
  template class DEFAULT foo<zed>;
  // CHECK: define weak_odr void @_ZN6test333fooINS_3zedEE3barEv
  // CHECK-HIDDEN: define weak_odr void @_ZN6test333fooINS_3zedEE3barEv
}

namespace test34 {
  struct foo {
  };
  template<class T>
  void bar() {}
  template DEFAULT void bar<foo>();
  // CHECK: define weak_odr void @_ZN6test343barINS_3fooEEEvv
  // CHECK-HIDDEN: define weak_odr void @_ZN6test343barINS_3fooEEEvv
}

namespace test35 {
  // This is a really ugly testcase. GCC propagates the DEFAULT in zed's
  // definition. What we do instead is be conservative about merging
  // implicit visibilities.
  // FIXME: Maybe the best thing to do here is error? The test at least
  // makes sure we don't produce a hidden symbol for foo<zed>::bar.
  template<typename T>
  struct DEFAULT foo {
    void bar() {}
  };
  class zed;
  template class foo<zed>;
  class DEFAULT zed {
  };
  // CHECK: define weak_odr void @_ZN6test353fooINS_3zedEE3barEv
  // CHECK-HIDDEN: define weak_odr void @_ZN6test353fooINS_3zedEE3barEv
}

namespace test36 {
  template<typename T1, typename T2>
  class foo {
    void bar() {}
  };
  class DEFAULT S1 {};
  struct HIDDEN S2 {};
  template class foo<S1, S2>;
  // CHECK: define weak_odr hidden void @_ZN6test363fooINS_2S1ENS_2S2EE3barEv
  // CHECK-HIDDEN: define weak_odr hidden void @_ZN6test363fooINS_2S1ENS_2S2EE3barEv
}

namespace test37 {
  struct HIDDEN foo {
  };
  template<class T>
  DEFAULT void bar() {}
  template DEFAULT void bar<foo>();
  // CHECK: define weak_odr void @_ZN6test373barINS_3fooEEEvv
  // CHECK-HIDDEN: define weak_odr void @_ZN6test373barINS_3fooEEEvv
}

namespace test38 {
  template<typename T>
  class DEFAULT foo {
    void bar() {}
  };
  struct HIDDEN zed {
  };
  template class foo<zed>;
  // CHECK: define weak_odr hidden void @_ZN6test383fooINS_3zedEE3barEv
  // CHECK-HIDDEN: define weak_odr hidden void @_ZN6test383fooINS_3zedEE3barEv
}

namespace test39 {
  class DEFAULT default_t;
  class HIDDEN hidden_t;
  template <class T> class A {
    template <class U> class B {
      HIDDEN void hidden() {}
      void noattr() {}
      template <class V> void temp() {}
    };
  };
  template class DEFAULT A<hidden_t>;
  template class DEFAULT A<hidden_t>::B<hidden_t>;
  template void A<hidden_t>::B<hidden_t>::temp<default_t>();
  template void A<hidden_t>::B<hidden_t>::temp<hidden_t>();

  // CHECK: define weak_odr hidden void @_ZN6test391AINS_8hidden_tEE1BIS1_E6hiddenEv
  // CHECK: define weak_odr void @_ZN6test391AINS_8hidden_tEE1BIS1_E6noattrEv
  // CHECK: define weak_odr void @_ZN6test391AINS_8hidden_tEE1BIS1_E4tempINS_9default_tEEEvv

  // GCC produces a default for this one. Why?
  // CHECK: define weak_odr hidden void @_ZN6test391AINS_8hidden_tEE1BIS1_E4tempIS1_EEvv

  // CHECK-HIDDEN: define weak_odr hidden void @_ZN6test391AINS_8hidden_tEE1BIS1_E6hiddenEv
  // CHECK-HIDDEN: define weak_odr void @_ZN6test391AINS_8hidden_tEE1BIS1_E6noattrEv
  // CHECK-HIDDEN: define weak_odr void @_ZN6test391AINS_8hidden_tEE1BIS1_E4tempINS_9default_tEEEvv

  // GCC produces a default for this one. Why?
  // CHECK-HIDDEN: define weak_odr hidden void @_ZN6test391AINS_8hidden_tEE1BIS1_E4tempIS1_EEvv
}

namespace test42 {
  struct HIDDEN foo {
  };
  template <class P>
  struct bar {
  };
  template <>
  struct HIDDEN bar<foo> {
    DEFAULT static void zed();
  };
  void bar<foo>::zed() {
  }
  // CHECK: define hidden void @_ZN6test423barINS_3fooEE3zedEv
  // CHECK-HIDDEN: define hidden void @_ZN6test423barINS_3fooEE3zedEv
}

namespace test43 {
  struct HIDDEN foo {
  };
  template <class P>
  void bar() {
  }
  template <>
  DEFAULT void bar<foo>() {
  }
  // CHECK: define hidden void @_ZN6test433barINS_3fooEEEvv
  // CHECK-HIDDEN: define hidden void @_ZN6test433barINS_3fooEEEvv
}

namespace test44 {
  template <typename T>
  struct foo {
    foo() {}
  };
  namespace {
    struct bar;
  }
  template struct DEFAULT foo<bar>;
  foo<bar> x;
  // CHECK: define internal void @_ZN6test443fooINS_12_GLOBAL__N_13barEEC1Ev
  // CHECK-HIDDEN: define internal void @_ZN6test443fooINS_12_GLOBAL__N_13barEEC1Ev
}

namespace test45 {
  template <typename T>
  struct foo {
    template <typename T2>
    struct bar {
      bar() {};
    };
  };
  namespace {
    struct zed;
  }
  template struct DEFAULT foo<int>::bar<zed>;
  foo<int>::bar<zed> x;
  // CHECK: define internal void @_ZN6test453fooIiE3barINS_12_GLOBAL__N_13zedEEC1Ev
  // CHECK-HIDDEN: define internal void @_ZN6test453fooIiE3barINS_12_GLOBAL__N_13zedEEC1Ev
}