Implement -Wmissing-prototypes. Fixes PR3911.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68110 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 15a20bd..f0d32c7 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -341,6 +341,26 @@
   return false;
 }
 
+bool FunctionDecl::isGlobal() const {
+  if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(this))
+    return Method->isStatic();
+
+  if (getStorageClass() == Static)
+    return false;
+
+  for (const DeclContext *DC = getDeclContext(); 
+       DC->isNamespace();
+       DC = DC->getParent()) {
+    if (const NamespaceDecl *Namespace = cast<NamespaceDecl>(DC)) {
+      if (!Namespace->getDeclName())
+        return false;
+      break;
+    }
+  }
+
+  return true;
+}
+
 /// \brief Returns a value indicating whether this function
 /// corresponds to a builtin function.
 ///