2 files changed, 30 insertions, 8 deletions
diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
index c45b52a65a4..c05b160b8e3 100644
--- a/clang/lib/AST/APValue.cpp
+++ b/clang/lib/AST/APValue.cpp
@@ -416,18 +416,26 @@ void APValue::printPretty(raw_ostream &Out, ASTContext &Ctx, QualType Ty) const{
         << GetApproxValue(getComplexFloatImag()) << "i";
     return;
   case APValue::LValue: {
-    LValueBase Base = getLValueBase();
-    if (!Base) {
-      Out << "0";
-      return;
-    }
-
     bool IsReference = Ty->isReferenceType();
     QualType InnerTy
       = IsReference ? Ty.getNonReferenceType() : Ty->getPointeeType();
     if (InnerTy.isNull())
       InnerTy = Ty;
 
+    LValueBase Base = getLValueBase();
+    if (!Base) {
+      if (isNullPointer()) {
+        Out << (Ctx.getLangOpts().CPlusPlus11 ? "nullptr" : "0");
+      } else if (IsReference) {
+        Out << "*(" << InnerTy.stream(Ctx.getPrintingPolicy()) << "*)"
+            << getLValueOffset().getQuantity();
+      } else {
+        Out << "(" << Ty.stream(Ctx.getPrintingPolicy()) << ")"
+            << getLValueOffset().getQuantity();
+      }
+      return;
+    }
+
     if (!hasLValuePath()) {
       // No lvalue path: just print the offset.
       CharUnits O = getLValueOffset();
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index f99d7841f39..c0d0e453fc8 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -6191,12 +6191,12 @@ bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
                 BuiltinOp == Builtin::BI__builtin_wmemmove;
 
     // The result of mem* is the first argument.
-    if (!Visit(E->getArg(0)) || Result.Designator.Invalid)
+    if (!Visit(E->getArg(0)))
       return false;
     LValue Dest = Result;
 
     LValue Src;
-    if (!EvaluatePointer(E->getArg(1), Src, Info) || Src.Designator.Invalid)
+    if (!EvaluatePointer(E->getArg(1), Src, Info))
       return false;
 
     APSInt N;
@@ -6209,6 +6209,20 @@ bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
     if (!N)
       return true;
 
+    // Otherwise, if either of the operands is null, we can't proceed. Don't
+    // try to determine the type of the copied objects, because there aren't
+    // any.
+    if (!Src.Base || !Dest.Base) {
+      APValue Val;
+      (!Src.Base ? Src : Dest).moveInto(Val);
+      Info.FFDiag(E, diag::note_constexpr_memcpy_null)
+          << Move << WChar << !!Src.Base
+          << Val.getAsString(Info.Ctx, E->getArg(0)->getType());
+      return false;
+    }
+    if (Src.Designator.Invalid || Dest.Designator.Invalid)
+      return false;
+
     // We require that Src and Dest are both pointers to arrays of
     // trivially-copyable type. (For the wide version, the designator will be
     // invalid if the designated object is not a wchar_t.)