remove unneeded function

Author: bob80905

clang/lib/Sema/SemaDeclAttr.cpp

@@ -7334,19 +7334,6 @@ static void handleHLSLShaderAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
     D->addAttr(NewAttr);
 }
 
-HLSLShaderAttr *
-Sema::mergeHLSLShaderAttr(Decl *D, const AttributeCommonInfo &AL,
-                          HLSLShaderAttr::ShaderType ShaderType) {
-  if (HLSLShaderAttr *NT = D->getAttr<HLSLShaderAttr>()) {
-    if (NT->getType() != ShaderType) {
-      Diag(NT->getLocation(), diag::err_hlsl_attribute_param_mismatch) << AL;
-      Diag(AL.getLoc(), diag::note_conflicting_attribute);
-    }
-    return nullptr;
-  }
-  return HLSLShaderAttr::Create(Context, ShaderType, AL);
-}
-
 static void DiagnoseHLSLResourceRegType(Sema &S, SourceLocation &ArgLoc,
                                         Decl *D, StringRef &Slot) {
   // Samplers, UAVs, and SRVs are VarDecl types