1 files changed, 24 insertions, 1 deletions
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index aef66619f6b..a58752cb42a 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -70,12 +70,13 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc) {
   }
 
   // See if this is a deleted function.
-  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
+  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isDeleted()) {
       Diag(Loc, diag::err_deleted_function_use);
       Diag(D->getLocation(), diag::note_unavailable_here) << true;
       return true;
     }
+  }
 
   // See if the decl is unavailable
   if (D->getAttr<UnavailableAttr>()) {
@@ -83,6 +84,28 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc) {
     Diag(D->getLocation(), diag::note_unavailable_here) << 0;
   }
 
+  if (D->getDeclContext()->isFunctionOrMethod() && 
+      !D->getDeclContext()->Encloses(CurContext)) {
+    // We've found the name of a function or variable that was
+    // declared with external linkage within another function (and,
+    // therefore, a scope where we wouldn't normally see the
+    // declaration). Once we've made sure that no previous declaration
+    // was properly made visible, produce a warning.
+    bool HasGlobalScopedDeclaration = false;
+    for (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D); FD;
+         FD = FD->getPreviousDeclaration()) {
+      if (FD->getDeclContext()->isFileContext()) {
+        HasGlobalScopedDeclaration = true;
+        break;
+      }
+    }
+    // FIXME: do the same thing for variable declarations
+    
+    if (!HasGlobalScopedDeclaration) {
+      Diag(Loc, diag::warn_use_out_of_scope_declaration) << D;
+      Diag(D->getLocation(), diag::note_previous_declaration);
+    }
+  }
 
   return false;
 }