[C++11] Use 'nullptr'.

llvm-svn: 208280
diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index 94a6c3d..fae6a35 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -473,7 +473,7 @@
     yaml::MappingNode *M = dyn_cast<yaml::MappingNode>(N);
     if (!M) {
       error(N, "expected mapping node for file or directory entry");
-      return NULL;
+      return nullptr;
     }
 
     KeyStatusPair Fields[] = {
@@ -501,32 +501,32 @@
       // parsing value.
       SmallString<256> Buffer;
       if (!parseScalarString(I->getKey(), Key, Buffer))
-        return NULL;
+        return nullptr;
 
       if (!checkDuplicateOrUnknownKey(I->getKey(), Key, Keys))
-        return NULL;
+        return nullptr;
 
       StringRef Value;
       if (Key == "name") {
         if (!parseScalarString(I->getValue(), Value, Buffer))
-          return NULL;
+          return nullptr;
         Name = Value;
       } else if (Key == "type") {
         if (!parseScalarString(I->getValue(), Value, Buffer))
-          return NULL;
+          return nullptr;
         if (Value == "file")
           Kind = EK_File;
         else if (Value == "directory")
           Kind = EK_Directory;
         else {
           error(I->getValue(), "unknown value for 'type'");
-          return NULL;
+          return nullptr;
         }
       } else if (Key == "contents") {
         if (HasContents) {
           error(I->getKey(),
                 "entry already has 'contents' or 'external-contents'");
-          return NULL;
+          return nullptr;
         }
         HasContents = true;
         yaml::SequenceNode *Contents =
@@ -534,7 +534,7 @@
         if (!Contents) {
           // FIXME: this is only for directories, what about files?
           error(I->getValue(), "expected array");
-          return NULL;
+          return nullptr;
         }
 
         for (yaml::SequenceNode::iterator I = Contents->begin(),
@@ -543,22 +543,22 @@
           if (Entry *E = parseEntry(&*I))
             EntryArrayContents.push_back(E);
           else
-            return NULL;
+            return nullptr;
         }
       } else if (Key == "external-contents") {
         if (HasContents) {
           error(I->getKey(),
                 "entry already has 'contents' or 'external-contents'");
-          return NULL;
+          return nullptr;
         }
         HasContents = true;
         if (!parseScalarString(I->getValue(), Value, Buffer))
-          return NULL;
+          return nullptr;
         ExternalContentsPath = Value;
       } else if (Key == "use-external-name") {
         bool Val;
         if (!parseScalarBool(I->getValue(), Val))
-          return NULL;
+          return nullptr;
         UseExternalName = Val ? FileEntry::NK_External : FileEntry::NK_Virtual;
       } else {
         llvm_unreachable("key missing from Keys");
@@ -566,20 +566,20 @@
     }
 
     if (Stream.failed())
-      return NULL;
+      return nullptr;
 
     // check for missing keys
     if (!HasContents) {
       error(N, "missing key 'contents' or 'external-contents'");
-      return NULL;
+      return nullptr;
     }
     if (!checkMissingKeys(N, Keys))
-      return NULL;
+      return nullptr;
 
     // check invalid configuration
     if (Kind == EK_Directory && UseExternalName != FileEntry::NK_NotSet) {
       error(N, "'use-external-name' is not supported for directories");
-      return NULL;
+      return nullptr;
     }
 
     // Remove trailing slash(es), being careful not to remove the root path
@@ -591,7 +591,7 @@
     // Get the last component
     StringRef LastComponent = sys::path::filename(Trimmed);
 
-    Entry *Result = 0;
+    Entry *Result = nullptr;
     switch (Kind) {
     case EK_File:
       Result = new FileEntry(LastComponent, std::move(ExternalContentsPath),
@@ -722,14 +722,14 @@
   yaml::Node *Root = DI->getRoot();
   if (DI == Stream.end() || !Root) {
     SM.PrintMessage(SMLoc(), SourceMgr::DK_Error, "expected root node");
-    return NULL;
+    return nullptr;
   }
 
   VFSFromYAMLParser P(Stream);
 
   std::unique_ptr<VFSFromYAML> FS(new VFSFromYAML(ExternalFS));
   if (!P.parse(Root, FS.get()))
-    return NULL;
+    return nullptr;
 
   return FS.release();
 }