diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -3254,8 +3254,7 @@
   /// Perform ODR-like check for C/ObjC when merging tag types from modules.
   /// Differently from C++, actually parse the body and reject / error out
   /// in case of a structural mismatch.
-  bool ActOnDuplicateDefinition(DeclSpec &DS, Decl *Prev,
-                                SkipBodyInfo &SkipBody);
+  bool ActOnDuplicateDefinition(Decl *Prev, SkipBodyInfo &SkipBody);
 
   typedef void *SkippedDefinitionContext;
 
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4870,7 +4870,7 @@
     Decl *D = SkipBody.CheckSameAsPrevious ? SkipBody.New : TagDecl;
     ParseEnumBody(StartLoc, D);
     if (SkipBody.CheckSameAsPrevious &&
-        !Actions.ActOnDuplicateDefinition(DS, TagDecl, SkipBody)) {
+        !Actions.ActOnDuplicateDefinition(TagDecl, SkipBody)) {
       DS.SetTypeSpecError();
       return;
     }
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2049,8 +2049,7 @@
       // Parse the definition body.
       ParseStructUnionBody(StartLoc, TagType, cast<RecordDecl>(D));
       if (SkipBody.CheckSameAsPrevious &&
-          !Actions.ActOnDuplicateDefinition(DS, TagOrTempResult.get(),
-                                            SkipBody)) {
+          !Actions.ActOnDuplicateDefinition(TagOrTempResult.get(), SkipBody)) {
         DS.SetTypeSpecError();
         return;
       }
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16698,8 +16698,7 @@
   AddPushedVisibilityAttribute(Tag);
 }
 
-bool Sema::ActOnDuplicateDefinition(DeclSpec &DS, Decl *Prev,
-                                    SkipBodyInfo &SkipBody) {
+bool Sema::ActOnDuplicateDefinition(Decl *Prev, SkipBodyInfo &SkipBody) {
   if (!hasStructuralCompatLayout(Prev, SkipBody.New))
     return false;