Apply Axel's suggestion for PR "Fixed cling argumenent --cuda-path"

- see: https://github.com/root-project/root/pull/6707

include/cling/Interpreter/Interpreter.h

@@ -693,7 +693,9 @@ namespace cling {
     clang::Sema& getSema() const;
     clang::DiagnosticsEngine& getDiagnostics() const;
 
-    IncrementalCUDADeviceCompiler* getCUDACompiler() const;
+    IncrementalCUDADeviceCompiler* getCUDACompiler() const {
+      return m_CUDACompiler.get();
+    }
 
     ///\brief Create suitable default compilation options.
     CompilationOptions makeDefaultCompilationOpts() const;

lib/Interpreter/CIFactory.cpp

@@ -873,7 +873,7 @@ static void stringifyPreprocSetting(PreprocessorOptions& PPOpts,
   }
 
   static llvm::IntrusiveRefCntPtr<DiagnosticsEngine>
-  SetupDiagnostics(DiagnosticOptions& DiagOpts, std::string ExeName) {
+  SetupDiagnostics(DiagnosticOptions& DiagOpts, const std::string& ExeName) {
     // The compiler invocation is the owner of the diagnostic options.
     // Everything else points to them.
     llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs> DiagIDs(new DiagnosticIDs());
@@ -1336,9 +1336,11 @@ static void stringifyPreprocSetting(PreprocessorOptions& PPOpts,
     DiagnosticOptions& DiagOpts = InvocationPtr->getDiagnosticOpts();
     // add prefix to diagnostic messages if second compiler instance is existing
     // e.g. in CUDA mode
-    llvm::IntrusiveRefCntPtr<DiagnosticsEngine> Diags = SetupDiagnostics(
-        DiagOpts,
-        COpts.CUDAHost ? (COpts.CUDADevice ? "cling-ptx" : "cling") : "");
+    std::string ExeName = "";
+    if (COpts.CUDAHost)
+      ExeName = COpts.CUDADevice ? "cling-ptx" : "cling";
+    llvm::IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+        SetupDiagnostics(DiagOpts, ExeName);
     if (!Diags) {
       cling::errs() << "Could not setup diagnostic engine.\n";
       return nullptr;

lib/Interpreter/IncrementalCUDADeviceCompiler.cpp

@@ -157,7 +157,7 @@ namespace cling {
         additionalPtxOpt.push_back(s);
     }
 
-    // add manual path to CUDA SDK
+    // use custom CUDA SDK path
     if(!invocationOptions.CompilerOpts.CUDAPath.empty()){
       additionalPtxOpt.push_back("--cuda-path=" + invocationOptions.CompilerOpts.CUDAPath);
     }

lib/Interpreter/Interpreter.cpp

@@ -746,10 +746,6 @@ namespace cling {
     return getCI()->getDiagnostics();
   }
 
-  IncrementalCUDADeviceCompiler* Interpreter::getCUDACompiler() const {
-    return m_CUDACompiler.get();
-  }
-
   CompilationOptions Interpreter::makeDefaultCompilationOpts() const {
     CompilationOptions CO;
     CO.DeclarationExtraction = 0;