Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -6912,12 +6912,14 @@
     // Initialize the elements.
     LValue ArrayElt = Subobject;
     ArrayElt.addArray(Info, E, CAT);
-    for (unsigned I = 0; I != N; ++I)
+    for (unsigned I = 0; I != N; ++I) {
+      BlockScopeRAII Scope(Info);
       if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I),
                                  CAT->getElementType()) ||
           !HandleLValueArrayAdjustment(Info, E, ArrayElt,
                                        CAT->getElementType(), 1))
         return false;
+    }
 
     return true;
   }
Index: test/SemaCXX/constant-expression-cxx1y.cpp
===================================================================
--- test/SemaCXX/constant-expression-cxx1y.cpp
+++ test/SemaCXX/constant-expression-cxx1y.cpp
@@ -1021,3 +1021,10 @@
 }
 static_assert(evalNested(), "");
 } // namespace PR19741
+
+namespace PR34858 {
+struct S {
+  constexpr S(const int & = 0) {}
+};
+constexpr S s[2];
+}