Removed unused function argument. NFC.

include/clang/Sema/Sema.h

public:
   /// semantically correct CUDA programs, but only if they're never codegen'ed.
   bool IsAllowedCUDACall(const FunctionDecl *Caller,
                          const FunctionDecl *Callee) {
     return IdentifyCUDAPreference(Caller, Callee) != CFP_Never;
   }
 
   /// May add implicit CUDAHostAttr and CUDADeviceAttr attributes to FD,
   /// depending on FD and the current compilation settings.
-  void maybeAddCUDAHostDeviceAttrs(Scope *S, FunctionDecl *FD,
+  void maybeAddCUDAHostDeviceAttrs(FunctionDecl *FD,
                                    const LookupResult &Previous);
 
 public:
   /// Check whether we're allowed to call Callee from the current context.
   ///
   /// - If the call is never allowed in a semantically-correct program
   ///   (CFP_Never), emits an error and returns false.
   ///

lib/Sema/SemaCUDA.cpp

 //  * a __device__ function with this signature was already declared, in which
 //    case in which case we output an error, unless the __device__ decl is in a
 //    system header, in which case we leave the constexpr function unattributed.
 //
 // In addition, all function decls are treated as __host__ __device__ when
 // ForceCUDAHostDeviceDepth > 0 (corresponding to code within a
 //   #pragma clang force_cuda_host_device_begin/end
 // pair).
-void Sema::maybeAddCUDAHostDeviceAttrs(Scope *S, FunctionDecl *NewD,
+void Sema::maybeAddCUDAHostDeviceAttrs(FunctionDecl *NewD,
                                        const LookupResult &Previous) {
   assert(getLangOpts().CUDA && "Should only be called during CUDA compilation");
 
   if (ForceCUDAHostDeviceDepth > 0) {
     if (!NewD->hasAttr<CUDAHostAttr>())
       NewD->addAttr(CUDAHostAttr::CreateImplicit(Context));
     if (!NewD->hasAttr<CUDADeviceAttr>())
       NewD->addAttr(CUDADeviceAttr::CreateImplicit(Context));

lib/Sema/SemaDecl.cpp

if (UnifySection(CodeSegStack.CurrentValue->getString(),
                      NewFD))
       NewFD->dropAttr<SectionAttr>();
   }
 
   // Handle attributes.
   ProcessDeclAttributes(S, NewFD, D);
 
   if (getLangOpts().CUDA)
-    maybeAddCUDAHostDeviceAttrs(S, NewFD, Previous);
+    maybeAddCUDAHostDeviceAttrs(NewFD, Previous);
 
   if (getLangOpts().OpenCL) {
     // OpenCL v1.1 s6.5: Using an address space qualifier in a function return
     // type declaration will generate a compilation error.
     unsigned AddressSpace = NewFD->getReturnType().getAddressSpace();
     if (AddressSpace == LangAS::opencl_local ||
         AddressSpace == LangAS::opencl_global ||
         AddressSpace == LangAS::opencl_constant) {