3 files changed, 7 insertions, 19 deletions
diff --git a/clang/include/clang/Frontend/ASTUnit.h b/clang/include/clang/Frontend/ASTUnit.h
index 17090893286..634224d08bb 100644
--- a/clang/include/clang/Frontend/ASTUnit.h
+++ b/clang/include/clang/Frontend/ASTUnit.h
@@ -305,7 +305,7 @@ private:
   /// \brief The language options used when we load an AST file.
   LangOptions ASTFileLangOpts;
 
-  static void ConfigureDiags(IntrusiveRefCntPtr<DiagnosticsEngine> &Diags,
+  static void ConfigureDiags(IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
                              ASTUnit &AST, bool CaptureDiagnostics);
 
   void TranslateStoredDiagnostics(FileManager &FileMgr,
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 8a77d87f64e..8742a54c01c 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -642,20 +642,11 @@ ASTUnit::getBufferForFile(StringRef Filename, std::string *ErrorStr) {
 }
 
 /// \brief Configure the diagnostics object for use with ASTUnit.
-void ASTUnit::ConfigureDiags(IntrusiveRefCntPtr<DiagnosticsEngine> &Diags,
+void ASTUnit::ConfigureDiags(IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
                              ASTUnit &AST, bool CaptureDiagnostics) {
-  if (!Diags.get()) {
-    // No diagnostics engine was provided, so create our own diagnostics object
-    // with the default options.
-    DiagnosticConsumer *Client = nullptr;
-    if (CaptureDiagnostics)
-      Client = new StoredDiagnosticConsumer(AST.StoredDiagnostics);
-    Diags = CompilerInstance::createDiagnostics(new DiagnosticOptions(),
-                                                Client,
-                                                /*ShouldOwnClient=*/true);
-  } else if (CaptureDiagnostics) {
+  assert(Diags.get() && "no DiagnosticsEngine was provided");
+  if (CaptureDiagnostics)
     Diags->setClient(new StoredDiagnosticConsumer(AST.StoredDiagnostics));
-  }
 }
 
 std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
@@ -1928,11 +1919,7 @@ ASTUnit *ASTUnit::LoadFromCommandLine(
     bool AllowPCHWithCompilerErrors, bool SkipFunctionBodies,
     bool UserFilesAreVolatile, bool ForSerialization,
     std::unique_ptr<ASTUnit> *ErrAST) {
-  if (!Diags.get()) {
-    // No diagnostics engine was provided, so create our own diagnostics object
-    // with the default options.
-    Diags = CompilerInstance::createDiagnostics(new DiagnosticOptions());
-  }
+  assert(Diags.get() && "no DiagnosticsEngine was provided");
 
   SmallVector<StoredDiagnostic, 4> StoredDiagnostics;
   
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index eab289206e1..552f5a70a5b 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -2807,7 +2807,8 @@ enum CXErrorCode clang_createTranslationUnit2(CXIndex CIdx,
   CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);
   FileSystemOptions FileSystemOpts;
 
-  IntrusiveRefCntPtr<DiagnosticsEngine> Diags;
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+      CompilerInstance::createDiagnostics(new DiagnosticOptions());
   std::unique_ptr<ASTUnit> AU = ASTUnit::LoadFromASTFile(
       ast_filename, Diags, FileSystemOpts, CXXIdx->getOnlyLocalDecls(), None,
       /*CaptureDiagnostics=*/true,