Fix the lookup of names used in a friend declaration to not attempt to

re-declare them. This fixes PR6317. Also add the beginnings of an interesting
test case for p1 of [class.friend] which also covers PR6317.

llvm-svn: 97499

clang/lib/Sema/SemaDecl.cpp

@@ -4535,8 +4535,9 @@ Sema::DeclPtrTy Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
   bool isStdBadAlloc = false;
   bool Invalid = false;
 
-  RedeclarationKind Redecl = (TUK != TUK_Reference ? ForRedeclaration
+  RedeclarationKind Redecl = ForRedeclaration;
-                                                   : NotForRedeclaration);
+  if (TUK == TUK_Friend || TUK == TUK_Reference)
+    Redecl = NotForRedeclaration;
 
   LookupResult Previous(*this, Name, NameLoc, LookupTagName, Redecl);
 

clang/test/CXX/class.access/class.friend/p1.cpp

@@ -0,0 +1,62 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// C++'0x [class.friend] p1:
+//   A friend of a class is a function or class that is given permission to use
+//   the private and protected member names from the class. A class specifies
+//   its friends, if any, by way of friend declarations. Such declarations give
+//   special access rights to the friends, but they do not make the nominated
+//   friends members of the befriending class.
+//
+// FIXME: Add tests for access control when implemented. Currently we only test
+// for parsing.
+
+struct S { static void f(); };
+S* g() { return 0; }
+
+struct X {
+  friend struct S;
+  friend S* g();
+};
+
+void test1() {
+  S s;
+  g()->f();
+  S::f();
+  X::g(); // expected-error{{no member named 'g' in 'struct X'}}
+  X::S x_s; // expected-error{{no member named 'S' in 'struct X'}}
+  X x;
+  x.g(); // expected-error{{no member named 'g' in 'struct X'}}
+}
+
+// Test that we recurse through namespaces to find already declared names, but
+// new names are declared within the enclosing namespace.
+namespace N {
+  struct X {
+    friend struct S;
+    friend S* g();
+
+    friend struct S2;
+    friend struct S2* g2();
+  };
+
+  struct S2 { static void f2(); };
+  S2* g2() { return 0; }
+
+  void test() {
+    g()->f();
+    S s;
+    S::f();
+    X::g(); // expected-error{{no member named 'g' in 'struct N::X'}}
+    X::S x_s; // expected-error{{no member named 'S' in 'struct N::X'}}
+    X x;
+    x.g(); // expected-error{{no member named 'g' in 'struct N::X'}}
+
+    g2();
+    S2 s2;
+    ::g2(); // expected-error{{no member named 'g2' in the global namespace}}
+    ::S2 g_s2; // expected-error{{no member named 'S2' in the global namespace}}
+    X::g2(); // expected-error{{no member named 'g2' in 'struct N::X'}}
+    X::S2 x_s2; // expected-error{{no member named 'S2' in 'struct N::X'}}
+    x.g2(); // expected-error{{no member named 'g2' in 'struct N::X'}}
+  }
+}