Use v.data() instead of &v[0] when SmallVector v might be empty.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72210 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 08019aa..a5b0911 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -686,7 +686,7 @@
   }
 
   if (!Invalid &&
-      AttachBaseSpecifiers(Instantiation, &InstantiatedBases[0],
+      AttachBaseSpecifiers(Instantiation, InstantiatedBases.data(),
                            InstantiatedBases.size()))
     Invalid = true;
 
@@ -770,7 +770,7 @@
 
   // Finish checking fields.
   ActOnFields(0, Instantiation->getLocation(), DeclPtrTy::make(Instantiation),
-              &Fields[0], Fields.size(), SourceLocation(), SourceLocation(),
+              Fields.data(), Fields.size(), SourceLocation(), SourceLocation(),
               0);
 
   // Add any implicitly-declared members that we might need.