2 files changed, 25 insertions, 9 deletions
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 077658c624d..2847dc10143 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -916,7 +916,13 @@ void Sema::MergeVarDecl(VarDecl *New, Decl *OldD) {
   MergeAttributes(New, Old, Context);
 
   // Merge the types
-  QualType MergedT = Context.mergeTypes(New->getType(), Old->getType());
+  QualType MergedT;
+  if (getLangOptions().CPlusPlus) {
+    if (Context.hasSameType(New->getType(), Old->getType()))
+      MergedT = New->getType();
+  } else {
+    MergedT = Context.mergeTypes(New->getType(), Old->getType());
+  }
   if (MergedT.isNull()) {
     Diag(New->getLocation(), diag::err_redefinition_different_type) 
       << New->getDeclName();
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 4145be6ab76..77902d55130 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -3727,14 +3727,24 @@ QualType Sema::CheckSubtractionOperands(Expr *&lex, Expr *&rex,
                                      rex->getType()))
         return QualType();
 
-      // Pointee types must be compatible.
-      if (!Context.typesAreCompatible(
-              Context.getCanonicalType(lpointee).getUnqualifiedType(),
-              Context.getCanonicalType(rpointee).getUnqualifiedType())) {
-        Diag(Loc, diag::err_typecheck_sub_ptr_compatible)
-          << lex->getType() << rex->getType()
-          << lex->getSourceRange() << rex->getSourceRange();
-        return QualType();
+      if (getLangOptions().CPlusPlus) {
+        // Pointee types must be the same: C++ [expr.add]
+        if (!Context.hasSameUnqualifiedType(lpointee, rpointee)) {
+          Diag(Loc, diag::err_typecheck_sub_ptr_compatible)
+            << lex->getType() << rex->getType()
+            << lex->getSourceRange() << rex->getSourceRange();
+          return QualType();
+        }
+      } else {
+        // Pointee types must be compatible C99 6.5.6p3
+        if (!Context.typesAreCompatible(
+                Context.getCanonicalType(lpointee).getUnqualifiedType(),
+                Context.getCanonicalType(rpointee).getUnqualifiedType())) {
+          Diag(Loc, diag::err_typecheck_sub_ptr_compatible)
+            << lex->getType() << rex->getType()
+            << lex->getSourceRange() << rex->getSourceRange();
+          return QualType();
+        }
       }
 
       if (ComplainAboutVoid)