Modify an assert to capture the restriction on friend declarations more

accurately.  Prevents the assert from triggering incorrectly when friending 
functions first declared in extern "C" contexts.  Fixes bug 4757.

llvm-svn: 80016

2 files changed, 10 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index ee6238c56c4..61f0ce808a7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2390,7 +2390,8 @@ Sema::ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
   FunctionDecl *NewFD;
   if (isFriend) {
     // DC is the namespace in which the function is being declared.
-    assert(DC->isFileContext() || D.getCXXScopeSpec().isSet());
+    assert((DC->isFileContext() || PrevDecl) && "previously-undeclared "
+           "friend function being created in a non-namespace context");
 
     // C++ [class.friend]p5
     //   A function can be defined in a friend declaration of a
diff --git a/clang/test/CXX/class/class.friend/p1.cpp b/clang/test/CXX/class/class.friend/p1.cpp
index 80afe3e7a50..1b2c4dfcd4d 100644
--- a/clang/test/CXX/class/class.friend/p1.cpp
+++ b/clang/test/CXX/class/class.friend/p1.cpp
@@ -18,6 +18,11 @@ struct Derived : public Base {
 
 int myglobal;
 
+void global_function();
+extern "C" {
+  void global_c_function();
+}
+
 class A {
   class AInner {
   };
@@ -29,6 +34,9 @@ class A {
   friend int myoperation(float); // okay
   friend int myglobal;   // expected-error {{ friends can only be classes or functions }}
 
+  friend void global_function();
+  friend void global_c_function();
+
   void a_member();
   friend void A::a_member(); // expected-error {{ friends cannot be members of the declaring class }}
   friend void a_member(); // okay (because we ignore class scopes when looking up friends)