[clang][NFC] Refactor `Sema::TagUseKind` (#92689)

This patch makes `TagUseKind` a scoped enumeration, and moves it outside
of `Sema` class, making it eligible for forward declaring.

7 files changed, 160 insertions, 150 deletions

diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 3c4ab64..cc6d933 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -2814,7 +2814,7 @@ private:
                                        SourceLocation CorrectLocation);
 
   void stripTypeAttributesOffDeclSpec(ParsedAttributes &Attrs, DeclSpec &DS,
-                                      Sema::TagUseKind TUK);
+                                      TagUseKind TUK);
 
   // FixItLoc = possible correct location for the attributes
   void ProhibitAttributes(ParsedAttributes &Attrs,
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 01ddba5..8eaf569 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -447,6 +447,13 @@ enum class CheckedConversionKind {
   ForBuiltinOverloadedOp
 };
 
+enum class TagUseKind {
+  Reference,   // Reference to a tag:  'struct foo *X;'
+  Declaration, // Fwd decl of a tag:   'struct foo;'
+  Definition,  // Definition of a tag: 'struct foo { int X; } Y;'
+  Friend       // Friend declaration:  'friend struct foo;'
+};
+
 /// Sema - This implements semantic analysis and AST building for C.
 /// \nosubgrouping
 class Sema final : public SemaBase {
@@ -3168,13 +3175,6 @@ public:
                                     bool isDefinition, SourceLocation NewTagLoc,
                                     const IdentifierInfo *Name);
 
-  enum TagUseKind {
-    TUK_Reference,   // Reference to a tag:  'struct foo *X;'
-    TUK_Declaration, // Fwd decl of a tag:   'struct foo;'
-    TUK_Definition,  // Definition of a tag: 'struct foo { int X; } Y;'
-    TUK_Friend       // Friend declaration:  'friend struct foo;'
-  };
-
   enum OffsetOfKind {
     // Not parsing a type within __builtin_offsetof.
     OOK_Outside,
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 445d3fd..651ef7b 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -1923,9 +1923,8 @@ void Parser::DiagnoseCXX11AttributeExtension(ParsedAttributes &Attrs) {
 // variable.
 // This function moves attributes that should apply to the type off DS to Attrs.
 void Parser::stripTypeAttributesOffDeclSpec(ParsedAttributes &Attrs,
-                                            DeclSpec &DS,
-                                            Sema::TagUseKind TUK) {
-  if (TUK == Sema::TUK_Reference)
+                                            DeclSpec &DS, TagUseKind TUK) {
+  if (TUK == TagUseKind::Reference)
     return;
 
   llvm::SmallVector<ParsedAttr *, 1> ToBeMoved;
@@ -5287,9 +5286,9 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   // enum foo {..};  void bar() { enum foo; }    <- new foo in bar.
   // enum foo {..};  void bar() { enum foo x; }  <- use of old foo.
   //
-  Sema::TagUseKind TUK;
+  TagUseKind TUK;
   if (AllowEnumSpecifier == AllowDefiningTypeSpec::No)
-    TUK = Sema::TUK_Reference;
+    TUK = TagUseKind::Reference;
   else if (Tok.is(tok::l_brace)) {
     if (DS.isFriendSpecified()) {
       Diag(Tok.getLocation(), diag::err_friend_decl_defines_type)
@@ -5301,9 +5300,9 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
       ScopedEnumKWLoc = SourceLocation();
       IsScopedUsingClassTag = false;
       BaseType = TypeResult();
-      TUK = Sema::TUK_Friend;
+      TUK = TagUseKind::Friend;
     } else {
-      TUK = Sema::TUK_Definition;
+      TUK = TagUseKind::Definition;
     }
   } else if (!isTypeSpecifier(DSC) &&
              (Tok.is(tok::semi) ||
@@ -5312,7 +5311,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     // An opaque-enum-declaration is required to be standalone (no preceding or
     // following tokens in the declaration). Sema enforces this separately by
     // diagnosing anything else in the DeclSpec.
-    TUK = DS.isFriendSpecified() ? Sema::TUK_Friend : Sema::TUK_Declaration;
+    TUK = DS.isFriendSpecified() ? TagUseKind::Friend : TagUseKind::Declaration;
     if (Tok.isNot(tok::semi)) {
       // A semicolon was missing after this declaration. Diagnose and recover.
       ExpectAndConsume(tok::semi, diag::err_expected_after, "enum");
@@ -5320,21 +5319,21 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
       Tok.setKind(tok::semi);
     }
   } else {
-    TUK = Sema::TUK_Reference;
+    TUK = TagUseKind::Reference;
   }
 
   bool IsElaboratedTypeSpecifier =
-      TUK == Sema::TUK_Reference || TUK == Sema::TUK_Friend;
+      TUK == TagUseKind::Reference || TUK == TagUseKind::Friend;
 
   // If this is an elaborated type specifier nested in a larger declaration,
   // and we delayed diagnostics before, just merge them into the current pool.
-  if (TUK == Sema::TUK_Reference && shouldDelayDiagsInTag) {
+  if (TUK == TagUseKind::Reference && shouldDelayDiagsInTag) {
     diagsFromTag.redelay();
   }
 
   MultiTemplateParamsArg TParams;
   if (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
-      TUK != Sema::TUK_Reference) {
+      TUK != TagUseKind::Reference) {
     if (!getLangOpts().CPlusPlus11 || !SS.isSet()) {
       // Skip the rest of this declarator, up until the comma or semicolon.
       Diag(Tok, diag::err_enum_template);
@@ -5355,7 +5354,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     SS.setTemplateParamLists(TParams);
   }
 
-  if (!Name && TUK != Sema::TUK_Definition) {
+  if (!Name && TUK != TagUseKind::Definition) {
     Diag(Tok, diag::err_enumerator_unnamed_no_def);
 
     DS.SetTypeSpecError();
@@ -5388,7 +5387,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   stripTypeAttributesOffDeclSpec(attrs, DS, TUK);
 
   SkipBodyInfo SkipBody;
-  if (!Name && TUK == Sema::TUK_Definition && Tok.is(tok::l_brace) &&
+  if (!Name && TUK == TagUseKind::Definition && Tok.is(tok::l_brace) &&
       NextToken().is(tok::identifier))
     SkipBody = Actions.shouldSkipAnonEnumBody(getCurScope(),
                                               NextToken().getIdentifierInfo(),
@@ -5409,7 +5408,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
                     OffsetOfState, &SkipBody).get();
 
   if (SkipBody.ShouldSkip) {
-    assert(TUK == Sema::TUK_Definition && "can only skip a definition");
+    assert(TUK == TagUseKind::Definition && "can only skip a definition");
 
     BalancedDelimiterTracker T(*this, tok::l_brace);
     T.consumeOpen();
@@ -5451,7 +5450,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   if (!TagDecl) {
     // The action failed to produce an enumeration tag. If this is a
     // definition, consume the entire definition.
-    if (Tok.is(tok::l_brace) && TUK != Sema::TUK_Reference) {
+    if (Tok.is(tok::l_brace) && TUK != TagUseKind::Reference) {
       ConsumeBrace();
       SkipUntil(tok::r_brace, StopAtSemi);
     }
@@ -5460,7 +5459,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     return;
   }
 
-  if (Tok.is(tok::l_brace) && TUK == Sema::TUK_Definition) {
+  if (Tok.is(tok::l_brace) && TUK == TagUseKind::Definition) {
     Decl *D = SkipBody.CheckSameAsPrevious ? SkipBody.New : TagDecl;
     ParseEnumBody(StartLoc, D);
     if (SkipBody.CheckSameAsPrevious &&
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 5eaec2b..805651e 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -1961,11 +1961,11 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   MaybeParseCXX11Attributes(Attributes);
 
   const PrintingPolicy &Policy = Actions.getASTContext().getPrintingPolicy();
-  Sema::TagUseKind TUK;
+  TagUseKind TUK;
   if (isDefiningTypeSpecifierContext(DSC, getLangOpts().CPlusPlus) ==
           AllowDefiningTypeSpec::No ||
       (getLangOpts().OpenMP && OpenMPDirectiveParsing))
-    TUK = Sema::TUK_Reference;
+    TUK = TagUseKind::Reference;
   else if (Tok.is(tok::l_brace) ||
            (DSC != DeclSpecContext::DSC_association &&
             getLangOpts().CPlusPlus && Tok.is(tok::colon)) ||
@@ -1980,10 +1980,10 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
       // Skip everything up to the semicolon, so that this looks like a proper
       // friend class (or template thereof) declaration.
       SkipUntil(tok::semi, StopBeforeMatch);
-      TUK = Sema::TUK_Friend;
+      TUK = TagUseKind::Friend;
     } else {
       // Okay, this is a class definition.
-      TUK = Sema::TUK_Definition;
+      TUK = TagUseKind::Definition;
     }
   } else if (isClassCompatibleKeyword() &&
              (NextToken().is(tok::l_square) ||
@@ -2024,15 +2024,15 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     }
 
     if (Tok.isOneOf(tok::l_brace, tok::colon))
-      TUK = Sema::TUK_Definition;
+      TUK = TagUseKind::Definition;
     else
-      TUK = Sema::TUK_Reference;
+      TUK = TagUseKind::Reference;
 
     PA.Revert();
   } else if (!isTypeSpecifier(DSC) &&
              (Tok.is(tok::semi) ||
               (Tok.isAtStartOfLine() && !isValidAfterTypeSpecifier(false)))) {
-    TUK = DS.isFriendSpecified() ? Sema::TUK_Friend : Sema::TUK_Declaration;
+    TUK = DS.isFriendSpecified() ? TagUseKind::Friend : TagUseKind::Declaration;
     if (Tok.isNot(tok::semi)) {
       const PrintingPolicy &PPol = Actions.getASTContext().getPrintingPolicy();
       // A semicolon was missing after this declaration. Diagnose and recover.
@@ -2042,11 +2042,11 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
       Tok.setKind(tok::semi);
     }
   } else
-    TUK = Sema::TUK_Reference;
+    TUK = TagUseKind::Reference;
 
   // Forbid misplaced attributes. In cases of a reference, we pass attributes
   // to caller to handle.
-  if (TUK != Sema::TUK_Reference) {
+  if (TUK != TagUseKind::Reference) {
     // If this is not a reference, then the only possible
     // valid place for C++11 attributes to appear here
     // is between class-key and class-name. If there are
@@ -2072,7 +2072,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
 
   if (!Name && !TemplateId &&
       (DS.getTypeSpecType() == DeclSpec::TST_error ||
-       TUK != Sema::TUK_Definition)) {
+       TUK != TagUseKind::Definition)) {
     if (DS.getTypeSpecType() != DeclSpec::TST_error) {
       // We have a declaration or reference to an anonymous class.
       Diag(StartLoc, diag::err_anon_type_definition)
@@ -2082,7 +2082,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     // If we are parsing a definition and stop at a base-clause, continue on
     // until the semicolon.  Continuing from the comma will just trick us into
     // thinking we are seeing a variable declaration.
-    if (TUK == Sema::TUK_Definition && Tok.is(tok::colon))
+    if (TUK == TagUseKind::Definition && Tok.is(tok::colon))
       SkipUntil(tok::semi, StopBeforeMatch);
     else
       SkipUntil(tok::comma, StopAtSemi);
@@ -2103,7 +2103,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     if (TemplateId->isInvalid()) {
       // Can't build the declaration.
     } else if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation &&
-               TUK == Sema::TUK_Declaration) {
+               TUK == TagUseKind::Declaration) {
       // This is an explicit instantiation of a class template.
       ProhibitCXX11Attributes(attrs, diag::err_attributes_not_allowed,
                               diag::err_keyword_not_allowed,
@@ -2119,8 +2119,8 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
       // they have template headers, in which case they're ill-formed
       // (FIXME: "template <class T> friend class A<T>::B<int>;").
       // We diagnose this error in ActOnClassTemplateSpecialization.
-    } else if (TUK == Sema::TUK_Reference ||
-               (TUK == Sema::TUK_Friend &&
+    } else if (TUK == TagUseKind::Reference ||
+               (TUK == TagUseKind::Friend &&
                 TemplateInfo.Kind == ParsedTemplateInfo::NonTemplate)) {
       ProhibitCXX11Attributes(attrs, diag::err_attributes_not_allowed,
                               diag::err_keyword_not_allowed,
@@ -2145,10 +2145,10 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
         // It this is friend declaration however, since it cannot have a
         // template header, it is most likely that the user meant to
         // remove the 'template' keyword.
-        assert((TUK == Sema::TUK_Definition || TUK == Sema::TUK_Friend) &&
+        assert((TUK == TagUseKind::Definition || TUK == TagUseKind::Friend) &&
                "Expected a definition here");
 
-        if (TUK == Sema::TUK_Friend) {
+        if (TUK == TagUseKind::Friend) {
           Diag(DS.getFriendSpecLoc(), diag::err_friend_explicit_instantiation);
           TemplateParams = nullptr;
         } else {
@@ -2179,7 +2179,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
           &SkipBody);
     }
   } else if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation &&
-             TUK == Sema::TUK_Declaration) {
+             TUK == TagUseKind::Declaration) {
     // Explicit instantiation of a member of a class template
     // specialization, e.g.,
     //
@@ -2190,7 +2190,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     TagOrTempResult = Actions.ActOnExplicitInstantiation(
         getCurScope(), TemplateInfo.ExternLoc, TemplateInfo.TemplateLoc,
         TagType, StartLoc, SS, Name, NameLoc, attrs);
-  } else if (TUK == Sema::TUK_Friend &&
+  } else if (TUK == TagUseKind::Friend &&
              TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate) {
     ProhibitCXX11Attributes(attrs, diag::err_attributes_not_allowed,
                             diag::err_keyword_not_allowed,
@@ -2202,12 +2202,12 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
         MultiTemplateParamsArg(TemplateParams ? &(*TemplateParams)[0] : nullptr,
                                TemplateParams ? TemplateParams->size() : 0));
   } else {
-    if (TUK != Sema::TUK_Declaration && TUK != Sema::TUK_Definition)
+    if (TUK != TagUseKind::Declaration && TUK != TagUseKind::Definition)
       ProhibitCXX11Attributes(attrs, diag::err_attributes_not_allowed,
                               diag::err_keyword_not_allowed,
                               /* DiagnoseEmptyAttrs=*/true);
 
-    if (TUK == Sema::TUK_Definition &&
+    if (TUK == TagUseKind::Definition &&
         TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
       // If the declarator-id is not a template-id, issue a diagnostic and
       // recover by ignoring the 'template' keyword.
@@ -2222,7 +2222,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     // reference.  For example, we don't need the template parameters here:
     //   template <class T> class A *makeA(T t);
     MultiTemplateParamsArg TParams;
-    if (TUK != Sema::TUK_Reference && TemplateParams)
+    if (TUK != TagUseKind::Reference && TemplateParams)
       TParams =
           MultiTemplateParamsArg(&(*TemplateParams)[0], TemplateParams->size());
 
@@ -2241,7 +2241,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     // If ActOnTag said the type was dependent, try again with the
     // less common call.
     if (IsDependent) {
-      assert(TUK == Sema::TUK_Reference || TUK == Sema::TUK_Friend);
+      assert(TUK == TagUseKind::Reference || TUK == TagUseKind::Friend);
       TypeResult = Actions.ActOnDependentTag(getCurScope(), TagType, TUK, SS,
                                              Name, StartLoc, NameLoc);
     }
@@ -2252,13 +2252,13 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   // just merge them into the current pool.
   if (shouldDelayDiagsInTag) {
     diagsFromTag.done();
-    if (TUK == Sema::TUK_Reference &&
+    if (TUK == TagUseKind::Reference &&
         TemplateInfo.Kind == ParsedTemplateInfo::Template)
       diagsFromTag.redelay();
   }
 
   // If there is a body, parse it and inform the actions module.
-  if (TUK == Sema::TUK_Definition) {
+  if (TUK == TagUseKind::Definition) {
     assert(Tok.is(tok::l_brace) ||
            (getLangOpts().CPlusPlus && Tok.is(tok::colon)) ||
            isClassCompatibleKeyword());
@@ -2316,7 +2316,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   //
   // After a type-specifier, we don't expect a semicolon. This only happens in
   // C, since definitions are not permitted in this context in C++.
-  if (TUK == Sema::TUK_Definition &&
+  if (TUK == TagUseKind::Definition &&
       (getLangOpts().CPlusPlus || !isTypeSpecifier(DSC)) &&
       (TemplateInfo.Kind || !isValidAfterTypeSpecifier(false))) {
     if (Tok.isNot(tok::semi)) {
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 7f6921e..6e60ec7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -4989,7 +4989,7 @@ void Sema::setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
   if (TagFromDeclSpec->hasNameForLinkage())
     return;
 
-  // A well-formed anonymous tag must always be a TUK_Definition.
+  // A well-formed anonymous tag must always be a TagUseKind::Definition.
   assert(TagFromDeclSpec->isThisDeclarationADefinition());
 
   // The type must match the tag exactly;  no qualifiers allowed.
@@ -17242,9 +17242,9 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
                OffsetOfKind OOK, SkipBodyInfo *SkipBody) {
   // If this is not a definition, it must have a name.
   IdentifierInfo *OrigName = Name;
-  assert((Name != nullptr || TUK == TUK_Definition) &&
+  assert((Name != nullptr || TUK == TagUseKind::Definition) &&
          "Nameless record must be a definition!");
-  assert(TemplateParameterLists.size() == 0 || TUK != TUK_Reference);
+  assert(TemplateParameterLists.size() == 0 || TUK != TagUseKind::Reference);
 
   OwnedDecl = false;
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
@@ -17258,11 +17258,11 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   // or a scope specifier, which also conveniently avoids this work
   // for non-C++ cases.
   if (TemplateParameterLists.size() > 0 ||
-      (SS.isNotEmpty() && TUK != TUK_Reference)) {
+      (SS.isNotEmpty() && TUK != TagUseKind::Reference)) {
     TemplateParameterList *TemplateParams =
         MatchTemplateParametersToScopeSpecifier(
             KWLoc, NameLoc, SS, nullptr, TemplateParameterLists,
-            TUK == TUK_Friend, isMemberSpecialization, Invalid);
+            TUK == TagUseKind::Friend, isMemberSpecialization, Invalid);
 
     // C++23 [dcl.type.elab] p2:
     //   If an elaborated-type-specifier is the sole constituent of a
@@ -17277,7 +17277,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     // FIXME: Class template partial specializations can be forward declared
     // per CWG2213, but the resolution failed to allow qualified forward
     // declarations. This is almost certainly unintentional, so we allow them.
-    if (TUK == TUK_Declaration && SS.isNotEmpty() && !isMemberSpecialization)
+    if (TUK == TagUseKind::Declaration && SS.isNotEmpty() &&
+        !isMemberSpecialization)
       Diag(SS.getBeginLoc(), diag::err_standalone_class_nested_name_specifier)
           << TypeWithKeyword::getTagTypeKindName(Kind) << SS.getRange();
 
@@ -17314,7 +17315,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       return true;
   }
 
-  if (TUK == TUK_Friend && Kind == TagTypeKind::Enum) {
+  if (TUK == TagUseKind::Friend && Kind == TagTypeKind::Enum) {
     // C++23 [dcl.type.elab]p4:
     //   If an elaborated-type-specifier appears with the friend specifier as
     //   an entire member-declaration, the member-declaration shall have one
@@ -17365,7 +17366,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       // of 'int'. However, if this is an unfixed forward declaration, don't set
       // the underlying type unless the user enables -fms-compatibility. This
       // makes unfixed forward declared enums incomplete and is more conforming.
-      if (TUK == TUK_Definition || getLangOpts().MSVCCompat)
+      if (TUK == TagUseKind::Definition || getLangOpts().MSVCCompat)
         EnumUnderlying = Context.IntTy.getTypePtr();
     }
   }
@@ -17376,7 +17377,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   bool isStdAlignValT = false;
 
   RedeclarationKind Redecl = forRedeclarationInCurContext();
-  if (TUK == TUK_Friend || TUK == TUK_Reference)
+  if (TUK == TagUseKind::Friend || TUK == TagUseKind::Reference)
     Redecl = RedeclarationKind::NotForRedeclaration;
 
   /// Create a new tag decl in C/ObjC. Since the ODR-like semantics for ObjC/C
@@ -17394,7 +17395,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       New = EnumDecl::Create(Context, SearchDC, KWLoc, Loc, Name, nullptr,
                              ScopedEnum, ScopedEnumUsesClassTag, IsFixed);
       // If this is an undefined enum, bail.
-      if (TUK != TUK_Definition && !Invalid)
+      if (TUK != TagUseKind::Definition && !Invalid)
         return nullptr;
       if (EnumUnderlying) {
         EnumDecl *ED = cast<EnumDecl>(New);
@@ -17422,7 +17423,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       // many points during the parsing of a struct declaration (because
       // the #pragma tokens are effectively skipped over during the
       // parsing of the struct).
-      if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
+      if (TUK == TagUseKind::Definition &&
+          (!SkipBody || !SkipBody->ShouldSkip)) {
         AddAlignmentAttributesForRecord(RD);
         AddMsStructLayoutForRecord(RD);
       }
@@ -17443,7 +17445,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
 
     // If this is a friend or a reference to a class in a dependent
     // context, don't try to make a decl for it.
-    if (TUK == TUK_Friend || TUK == TUK_Reference) {
+    if (TUK == TagUseKind::Friend || TUK == TagUseKind::Reference) {
       DC = computeDeclContext(SS, false);
       if (!DC) {
         IsDependent = true;
@@ -17476,7 +17478,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       // this as a dependent elaborated-type-specifier.
       // But this only makes any sense for reference-like lookups.
       if (Previous.wasNotFoundInCurrentInstantiation() &&
-          (TUK == TUK_Reference || TUK == TUK_Friend)) {
+          (TUK == TagUseKind::Reference || TUK == TagUseKind::Friend)) {
         IsDependent = true;
         return true;
       }
@@ -17493,7 +17495,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     //   If T is the name of a class, then each of the following shall have a
     //   name different from T:
     //    -- every member of class T that is itself a type
-    if (TUK != TUK_Reference && TUK != TUK_Friend &&
+    if (TUK != TagUseKind::Reference && TUK != TagUseKind::Friend &&
         DiagnoseClassNameShadow(SearchDC, DeclarationNameInfo(Name, NameLoc)))
       return true;
 
@@ -17507,7 +17509,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     // When declaring or defining a tag, ignore ambiguities introduced
     // by types using'ed into this scope.
     if (Previous.isAmbiguous() &&
-        (TUK == TUK_Definition || TUK == TUK_Declaration)) {
+        (TUK == TagUseKind::Definition || TUK == TagUseKind::Declaration)) {
       LookupResult::Filter F = Previous.makeFilter();
       while (F.hasNext()) {
         NamedDecl *ND = F.next();
@@ -17531,7 +17533,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     //
     // Does it matter that this should be by scope instead of by
     // semantic context?
-    if (!Previous.empty() && TUK == TUK_Friend) {
+    if (!Previous.empty() && TUK == TagUseKind::Friend) {
       DeclContext *EnclosingNS = SearchDC->getEnclosingNamespaceContext();
       LookupResult::Filter F = Previous.makeFilter();
       bool FriendSawTagOutsideEnclosingNamespace = false;
@@ -17561,7 +17563,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     if (Previous.isAmbiguous())
       return true;
 
-    if (!getLangOpts().CPlusPlus && TUK != TUK_Reference) {
+    if (!getLangOpts().CPlusPlus && TUK != TagUseKind::Reference) {
       // FIXME: This makes sure that we ignore the contexts associated
       // with C structs, unions, and enums when looking for a matching
       // tag declaration or definition. See the similar lookup tweak
@@ -17613,11 +17615,12 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   // also need to do a redeclaration lookup there, just in case
   // there's a shadow friend decl.
   if (Name && Previous.empty() &&
-      (TUK == TUK_Reference || TUK == TUK_Friend || IsTemplateParamOrArg)) {
+      (TUK == TagUseKind::Reference || TUK == TagUseKind::Friend ||
+       IsTemplateParamOrArg)) {
     if (Invalid) goto CreateNewDecl;
     assert(SS.isEmpty());
 
-    if (TUK == TUK_Reference || IsTemplateParamOrArg) {
+    if (TUK == TagUseKind::Reference || IsTemplateParamOrArg) {
       // C++ [basic.scope.pdecl]p5:
       //   -- for an elaborated-type-specifier of the form
       //
@@ -17651,7 +17654,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       // Find the scope where we'll be declaring the tag.
       S = getTagInjectionScope(S, getLangOpts());
     } else {
-      assert(TUK == TUK_Friend);
+      assert(TUK == TagUseKind::Friend);
       CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(SearchDC);
 
       // C++ [namespace.memdef]p3:
@@ -17716,7 +17719,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     // redefinition if either context is within the other.
     if (auto *Shadow = dyn_cast<UsingShadowDecl>(DirectPrevDecl)) {
       auto *OldTag = dyn_cast<TagDecl>(PrevDecl);
-      if (SS.isEmpty() && TUK != TUK_Reference && TUK != TUK_Friend &&
+      if (SS.isEmpty() && TUK != TagUseKind::Reference &&
+          TUK != TagUseKind::Friend &&
           isDeclInScope(Shadow, SearchDC, S, isMemberSpecialization) &&
           !(OldTag && isAcceptableTagRedeclContext(
                           *this, OldTag->getDeclContext(), SearchDC))) {
@@ -17735,13 +17739,13 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       // If this is a use of a previous tag, or if the tag is already declared
       // in the same scope (so that the definition/declaration completes or
       // rementions the tag), reuse the decl.
-      if (TUK == TUK_Reference || TUK == TUK_Friend ||
+      if (TUK == TagUseKind::Reference || TUK == TagUseKind::Friend ||
           isDeclInScope(DirectPrevDecl, SearchDC, S,
                         SS.isNotEmpty() || isMemberSpecialization)) {
         // Make sure that this wasn't declared as an enum and now used as a
         // struct or something similar.
         if (!isAcceptableTagRedeclaration(PrevTagDecl, Kind,
-                                          TUK == TUK_Definition, KWLoc,
+                                          TUK == TagUseKind::Definition, KWLoc,
                                           Name)) {
           bool SafeToContinue =
               (PrevTagDecl->getTagKind() != TagTypeKind::Enum &&
@@ -17768,7 +17772,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
         if (Kind == TagTypeKind::Enum &&
             PrevTagDecl->getTagKind() == TagTypeKind::Enum) {
           const EnumDecl *PrevEnum = cast<EnumDecl>(PrevTagDecl);
-          if (TUK == TUK_Reference || TUK == TUK_Friend)
+          if (TUK == TagUseKind::Reference || TUK == TagUseKind::Friend)
             return PrevTagDecl;
 
           QualType EnumUnderlyingTy;
@@ -17783,14 +17787,14 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
           if (CheckEnumRedeclaration(NameLoc.isValid() ? NameLoc : KWLoc,
                                      ScopedEnum, EnumUnderlyingTy,
                                      IsFixed, PrevEnum))
-            return TUK == TUK_Declaration ? PrevTagDecl : nullptr;
+            return TUK == TagUseKind::Declaration ? PrevTagDecl : nullptr;
         }
 
         // C++11 [class.mem]p1:
         //   A member shall not be declared twice in the member-specification,
         //   except that a nested class or member class template can be declared
         //   and then later defined.
-        if (TUK == TUK_Declaration && PrevDecl->isCXXClassMember() &&
+        if (TUK == TagUseKind::Declaration && PrevDecl->isCXXClassMember() &&
             S->isDeclScope(PrevDecl)) {
           Diag(NameLoc, diag::ext_member_redeclared);
           Diag(PrevTagDecl->getLocation(), diag::note_previous_declaration);
@@ -17799,11 +17803,11 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
         if (!Invalid) {
           // If this is a use, just return the declaration we found, unless
           // we have attributes.
-          if (TUK == TUK_Reference || TUK == TUK_Friend) {
+          if (TUK == TagUseKind::Reference || TUK == TagUseKind::Friend) {
             if (!Attrs.empty()) {
               // FIXME: Diagnose these attributes. For now, we create a new
               // declaration to hold them.
-            } else if (TUK == TUK_Reference &&
+            } else if (TUK == TagUseKind::Reference &&
                        (PrevTagDecl->getFriendObjectKind() ==
                             Decl::FOK_Undeclared ||
                         PrevDecl->getOwningModule() != getCurrentModule()) &&
@@ -17827,7 +17831,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
           }
 
           // Diagnose attempts to redefine a tag.
-          if (TUK == TUK_Definition) {
+          if (TUK == TagUseKind::Definition) {
             if (NamedDecl *Def = PrevTagDecl->getDefinition()) {
               // If we're defining a specialization and the previous definition
               // is from an implicit instantiation, don't emit an error
@@ -17907,7 +17911,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
           // Okay, we're going to make a redeclaration.  If this is some kind
           // of reference, make sure we build the redeclaration in the same DC
           // as the original, and ignore the current access specifier.
-          if (TUK == TUK_Friend || TUK == TUK_Reference) {
+          if (TUK == TagUseKind::Friend || TUK == TagUseKind::Reference) {
             SearchDC = PrevTagDecl->getDeclContext();
             AS = AS_none;
           }
@@ -17933,7 +17937,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       // Use a better diagnostic if an elaborated-type-specifier
       // found the wrong kind of type on the first
       // (non-redeclaration) lookup.
-      if ((TUK == TUK_Reference || TUK == TUK_Friend) &&
+      if ((TUK == TagUseKind::Reference || TUK == TagUseKind::Friend) &&
           !Previous.isForRedeclaration()) {
         NonTagKind NTK = getNonTagTypeDeclKind(PrevDecl, Kind);
         Diag(NameLoc, diag::err_tag_reference_non_tag)
@@ -17947,7 +17951,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
         // do nothing
 
       // Diagnose implicit declarations introduced by elaborated types.
-      } else if (TUK == TUK_Reference || TUK == TUK_Friend) {
+      } else if (TUK == TagUseKind::Reference || TUK == TagUseKind::Friend) {
         NonTagKind NTK = getNonTagTypeDeclKind(PrevDecl, Kind);
         Diag(NameLoc, diag::err_tag_reference_conflict) << NTK;
         Diag(PrevDecl->getLocation(), diag::note_previous_decl) << PrevDecl;
@@ -18006,7 +18010,7 @@ CreateNewDecl:
       StdAlignValT = cast<EnumDecl>(New);
 
     // If this is an undefined enum, warn.
-    if (TUK != TUK_Definition && !Invalid) {
+    if (TUK != TagUseKind::Definition && !Invalid) {
       TagDecl *Def;
       if (IsFixed && cast<EnumDecl>(New)->isFixed()) {
         // C++0x: 7.2p2: opaque-enum-declaration.
@@ -18056,21 +18060,22 @@ CreateNewDecl:
   }
 
   // Only C23 and later allow defining new types in 'offsetof()'.
-  if (OOK != OOK_Outside && TUK == TUK_Definition && !getLangOpts().CPlusPlus &&
-      !getLangOpts().C23)
+  if (OOK != OOK_Outside && TUK == TagUseKind::Definition &&
+      !getLangOpts().CPlusPlus && !getLangOpts().C23)
     Diag(New->getLocation(), diag::ext_type_defined_in_offsetof)
         << (OOK == OOK_Macro) << New->getSourceRange();
 
   // C++11 [dcl.type]p3:
   //   A type-specifier-seq shall not define a class or enumeration [...].
   if (!Invalid && getLangOpts().CPlusPlus &&
-      (IsTypeSpecifier || IsTemplateParamOrArg) && TUK == TUK_Definition) {
+      (IsTypeSpecifier || IsTemplateParamOrArg) &&
+      TUK == TagUseKind::Definition) {
     Diag(New->getLocation(), diag::err_type_defined_in_type_specifier)
       << Context.getTagDeclType(New);
     Invalid = true;
   }
 
-  if (!Invalid && getLangOpts().CPlusPlus && TUK == TUK_Definition &&
+  if (!Invalid && getLangOpts().CPlusPlus && TUK == TagUseKind::Definition &&
       DC->getDeclKind() == Decl::Enum) {
     Diag(New->getLocation(), diag::err_type_defined_in_enum)
       << Context.getTagDeclType(New);
@@ -18082,7 +18087,7 @@ CreateNewDecl:
     if (SS.isSet()) {
       // If this is either a declaration or a definition, check the
       // nested-name-specifier against the current context.
-      if ((TUK == TUK_Definition || TUK == TUK_Declaration) &&
+      if ((TUK == TagUseKind::Definition || TUK == TagUseKind::Declaration) &&
           diagnoseQualifiedDeclaration(SS, DC, OrigName, Loc,
                                        /*TemplateId=*/nullptr,
                                        isMemberSpecialization))
@@ -18107,7 +18112,7 @@ CreateNewDecl:
     // many points during the parsing of a struct declaration (because
     // the #pragma tokens are effectively skipped over during the
     // parsing of the struct).
-    if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
+    if (TUK == TagUseKind::Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
       AddAlignmentAttributesForRecord(RD);
       AddMsStructLayoutForRecord(RD);
     }
@@ -18138,7 +18143,7 @@ CreateNewDecl:
     if (getLangOpts().CPlusPlus) {
       // C++ [dcl.fct]p6:
       //   Types shall not be defined in return or parameter types.
-      if (TUK == TUK_Definition && !IsTypeSpecifier) {
+      if (TUK == TagUseKind::Definition && !IsTypeSpecifier) {
         Diag(Loc, diag::err_type_defined_in_param_type)
             << Name;
         Invalid = true;
@@ -18159,7 +18164,7 @@ CreateNewDecl:
   // In Microsoft mode, a friend declaration also acts as a forward
   // declaration so we always pass true to setObjectOfFriendDecl to make
   // the tag name visible.
-  if (TUK == TUK_Friend)
+  if (TUK == TagUseKind::Friend)
     New->setObjectOfFriendDecl(getLangOpts().MSVCCompat);
 
   // Set the access specifier.
@@ -18169,14 +18174,14 @@ CreateNewDecl:
   if (PrevDecl)
     CheckRedeclarationInModule(New, PrevDecl);
 
-  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
+  if (TUK == TagUseKind::Definition && (!SkipBody || !SkipBody->ShouldSkip))
     New->startDefinition();
 
   ProcessDeclAttributeList(S, New, Attrs);
   AddPragmaAttributes(S, New);
 
   // If this has an identifier, add it to the scope stack.
-  if (TUK == TUK_Friend) {
+  if (TUK == TagUseKind::Friend) {
     // We might be replacing an existing declaration in the lookup tables;
     // if so, borrow its access specifier.
     if (PrevDecl)
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 104e271..8ab429e 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -17580,11 +17580,12 @@ DeclResult Sema::ActOnTemplatedFriendTag(
       if (Invalid)
         return true;
 
-      return CheckClassTemplate(S, TagSpec, TUK_Friend, TagLoc, SS, Name,
-                                NameLoc, Attr, TemplateParams, AS_public,
+      return CheckClassTemplate(S, TagSpec, TagUseKind::Friend, TagLoc, SS,
+                                Name, NameLoc, Attr, TemplateParams, AS_public,
                                 /*ModulePrivateLoc=*/SourceLocation(),
                                 FriendLoc, TempParamLists.size() - 1,
-                                TempParamLists.data()).get();
+                                TempParamLists.data())
+          .get();
     } else {
       // The "template<>" header is extraneous.
       Diag(TemplateParams->getTemplateLoc(), diag::err_template_tag_noparams)
@@ -17612,8 +17613,8 @@ DeclResult Sema::ActOnTemplatedFriendTag(
     if (SS.isEmpty()) {
       bool Owned = false;
       bool IsDependent = false;
-      return ActOnTag(S, TagSpec, TUK_Friend, TagLoc, SS, Name, NameLoc, Attr,
-                      AS_public,
+      return ActOnTag(S, TagSpec, TagUseKind::Friend, TagLoc, SS, Name, NameLoc,
+                      Attr, AS_public,
                       /*ModulePrivateLoc=*/SourceLocation(),
                       MultiTemplateParamsArg(), Owned, IsDependent,
                       /*ScopedEnumKWLoc=*/SourceLocation(),
@@ -17728,7 +17729,7 @@ Decl *Sema::ActOnFriendTypeDecl(Scope *S, const DeclSpec &DS,
 
   // Try to convert the decl specifier to a type.  This works for
   // friend templates because ActOnTag never produces a ClassTemplateDecl
-  // for a TUK_Friend.
+  // for a TagUseKind::Friend.
   Declarator TheDeclarator(DS, ParsedAttributesView::none(),
                            DeclaratorContext::Member);
   TypeSourceInfo *TSI = GetTypeForDeclarator(TheDeclarator);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 02d9b64..8b82348 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1839,7 +1839,8 @@ DeclResult Sema::CheckClassTemplate(
     TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
   assert(TemplateParams && TemplateParams->size() > 0 &&
          "No template parameters");
-  assert(TUK != TUK_Reference && "Can only declare or define class templates");
+  assert(TUK != TagUseKind::Reference &&
+         "Can only declare or define class templates");
   bool Invalid = false;
 
   // Check that we can declare a template here.
@@ -1861,8 +1862,9 @@ DeclResult Sema::CheckClassTemplate(
   // C++11 [basic.lookup.elab]p2).
   DeclContext *SemanticContext;
   LookupResult Previous(*this, Name, NameLoc,
-                        (SS.isEmpty() && TUK == TUK_Friend)
-                          ? LookupTagName : LookupOrdinaryName,
+                        (SS.isEmpty() && TUK == TagUseKind::Friend)
+                            ? LookupTagName
+                            : LookupOrdinaryName,
                         forRedeclarationInCurContext());
   if (SS.isNotEmpty() && !SS.isInvalid()) {
     SemanticContext = computeDeclContext(SS, true);
@@ -1870,11 +1872,11 @@ DeclResult Sema::CheckClassTemplate(
       // FIXME: Horrible, horrible hack! We can't currently represent this
       // in the AST, and historically we have just ignored such friend
       // class templates, so don't complain here.
-      Diag(NameLoc, TUK == TUK_Friend
+      Diag(NameLoc, TUK == TagUseKind::Friend
                         ? diag::warn_template_qualified_friend_ignored
                         : diag::err_template_qualified_declarator_no_match)
           << SS.getScopeRep() << SS.getRange();
-      return TUK != TUK_Friend;
+      return TUK != TagUseKind::Friend;
     }
 
     if (RequireCompleteDeclContext(SS, SemanticContext))
@@ -1889,7 +1891,7 @@ DeclResult Sema::CheckClassTemplate(
         Invalid = true;
     }
 
-    if (TUK != TUK_Friend && TUK != TUK_Reference)
+    if (TUK != TagUseKind::Friend && TUK != TagUseKind::Reference)
       diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc,
                                    /*TemplateId-*/ nullptr,
                                    /*IsMemberSpecialization*/ false);
@@ -1902,7 +1904,7 @@ DeclResult Sema::CheckClassTemplate(
     //   If T is the name of a class, then each of the following shall have a
     //   name different from T:
     //    -- every member template of class T
-    if (TUK != TUK_Friend &&
+    if (TUK != TagUseKind::Friend &&
         DiagnoseClassNameShadow(SemanticContext,
                                 DeclarationNameInfo(Name, NameLoc)))
       return true;
@@ -1944,7 +1946,7 @@ DeclResult Sema::CheckClassTemplate(
     }
   }
 
-  if (TUK == TUK_Friend) {
+  if (TUK == TagUseKind::Friend) {
     // C++ [namespace.memdef]p3:
     //   [...] When looking for a prior declaration of a class or a function
     //   declared as a friend, and when the name of the friend class or
@@ -1981,9 +1983,8 @@ DeclResult Sema::CheckClassTemplate(
           PrevDecl = (*Previous.begin())->getUnderlyingDecl();
       }
     }
-  } else if (PrevDecl &&
-             !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
-                            S, SS.isValid()))
+  } else if (PrevDecl && !isDeclInScope(Previous.getRepresentativeDecl(),
+                                        SemanticContext, S, SS.isValid()))
     PrevDecl = PrevClassTemplate = nullptr;
 
   if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
@@ -2005,7 +2006,7 @@ DeclResult Sema::CheckClassTemplate(
     // Ensure that the template parameter lists are compatible. Skip this check
     // for a friend in a dependent context: the template parameter list itself
     // could be dependent.
-    if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
+    if (!(TUK == TagUseKind::Friend && CurContext->isDependentContext()) &&
         !TemplateParameterListsAreEqual(
             TemplateCompareNewDeclInfo(SemanticContext ? SemanticContext
                                                        : CurContext,
@@ -2021,8 +2022,8 @@ DeclResult Sema::CheckClassTemplate(
     //   the class-key shall agree in kind with the original class
     //   template declaration (7.1.5.3).
     RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
-    if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
-                                      TUK == TUK_Definition,  KWLoc, Name)) {
+    if (!isAcceptableTagRedeclaration(
+            PrevRecordDecl, Kind, TUK == TagUseKind::Definition, KWLoc, Name)) {
       Diag(KWLoc, diag::err_use_with_wrong_tag)
         << Name
         << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
@@ -2031,7 +2032,7 @@ DeclResult Sema::CheckClassTemplate(
     }
 
     // Check for redefinition of this class template.
-    if (TUK == TUK_Definition) {
+    if (TUK == TagUseKind::Definition) {
       if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
         // If we have a prior definition that is not visible, treat this as
         // simply making that previous definition visible.
@@ -2068,7 +2069,7 @@ DeclResult Sema::CheckClassTemplate(
   // merging in the template parameter list from the previous class
   // template declaration. Skip this check for a friend in a dependent
   // context, because the template parameter list might be dependent.
-  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
+  if (!(TUK == TagUseKind::Friend && CurContext->isDependentContext()) &&
       CheckTemplateParameterList(
           TemplateParams,
           PrevClassTemplate ? GetTemplateParameterList(PrevClassTemplate)
@@ -2076,8 +2077,8 @@ DeclResult Sema::CheckClassTemplate(
           (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
            SemanticContext->isDependentContext())
               ? TPC_ClassTemplateMember
-          : TUK == TUK_Friend ? TPC_FriendClassTemplate
-                              : TPC_ClassTemplate,
+          : TUK == TagUseKind::Friend ? TPC_FriendClassTemplate
+                                      : TPC_ClassTemplate,
           SkipBody))
     Invalid = true;
 
@@ -2085,9 +2086,10 @@ DeclResult Sema::CheckClassTemplate(
     // If the name of the template was qualified, we must be defining the
     // template out-of-line.
     if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
-      Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
-                                      : diag::err_member_decl_does_not_match)
-        << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
+      Diag(NameLoc, TUK == TagUseKind::Friend
+                        ? diag::err_friend_decl_does_not_match
+                        : diag::err_member_decl_does_not_match)
+          << Name << SemanticContext << /*IsDefinition*/ true << SS.getRange();
       Invalid = true;
     }
   }
@@ -2097,8 +2099,8 @@ DeclResult Sema::CheckClassTemplate(
   // recent declaration tricking the template instantiator to make substitutions
   // there.
   // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
-  bool ShouldAddRedecl
-    = !(TUK == TUK_Friend && CurContext->isDependentContext());
+  bool ShouldAddRedecl =
+      !(TUK == TagUseKind::Friend && CurContext->isDependentContext());
 
   CXXRecordDecl *NewClass =
     CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
@@ -2113,7 +2115,7 @@ DeclResult Sema::CheckClassTemplate(
 
   // Add alignment attributes if necessary; these attributes are checked when
   // the ASTContext lays out the structure.
-  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
+  if (TUK == TagUseKind::Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
     AddAlignmentAttributesForRecord(NewClass);
     AddMsStructLayoutForRecord(NewClass);
   }
@@ -2144,14 +2146,15 @@ DeclResult Sema::CheckClassTemplate(
     PrevClassTemplate->setMemberSpecialization();
 
   // Set the access specifier.
-  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
+  if (!Invalid && TUK != TagUseKind::Friend &&
+      NewTemplate->getDeclContext()->isRecord())
     SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
 
   // Set the lexical context of these templates
   NewClass->setLexicalDeclContext(CurContext);
   NewTemplate->setLexicalDeclContext(CurContext);
 
-  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
+  if (TUK == TagUseKind::Definition && (!SkipBody || !SkipBody->ShouldSkip))
     NewClass->startDefinition();
 
   ProcessDeclAttributeList(S, NewClass, Attr);
@@ -2164,7 +2167,7 @@ DeclResult Sema::CheckClassTemplate(
   inferGslOwnerPointerAttribute(NewClass);
   inferNullableClassAttribute(NewClass);
 
-  if (TUK != TUK_Friend) {
+  if (TUK != TagUseKind::Friend) {
     // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
     Scope *Outer = S;
     while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
@@ -5015,7 +5018,7 @@ TypeResult Sema::ActOnTagTemplateIdType(TagUseKind TUK,
     IdentifierInfo *Id = D->getIdentifier();
     assert(Id && "templated class must have an identifier");
 
-    if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
+    if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TagUseKind::Definition,
                                       TagLoc, Id)) {
       Diag(TagLoc, diag::err_use_with_wrong_tag)
         << Result
@@ -9451,7 +9454,7 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
     SourceLocation ModulePrivateLoc, CXXScopeSpec &SS,
     TemplateIdAnnotation &TemplateId, const ParsedAttributesView &Attr,
     MultiTemplateParamsArg TemplateParameterLists, SkipBodyInfo *SkipBody) {
-  assert(TUK != TUK_Reference && "References are not specializations");
+  assert(TUK != TagUseKind::Reference && "References are not specializations");
 
   SourceLocation TemplateNameLoc = TemplateId.TemplateNameLoc;
   SourceLocation LAngleLoc = TemplateId.LAngleLoc;
@@ -9473,7 +9476,7 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   bool isPartialSpecialization = false;
 
   if (SS.isSet()) {
-    if (TUK != TUK_Reference && TUK != TUK_Friend &&
+    if (TUK != TagUseKind::Reference && TUK != TagUseKind::Friend &&
         diagnoseQualifiedDeclaration(SS, ClassTemplate->getDeclContext(),
                                      ClassTemplate->getDeclName(),
                                      TemplateNameLoc, &TemplateId,
@@ -9488,9 +9491,8 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   bool Invalid = false;
   TemplateParameterList *TemplateParams =
       MatchTemplateParametersToScopeSpecifier(
-          KWLoc, TemplateNameLoc, SS, &TemplateId,
-          TemplateParameterLists, TUK == TUK_Friend, isMemberSpecialization,
-          Invalid);
+          KWLoc, TemplateNameLoc, SS, &TemplateId, TemplateParameterLists,
+          TUK == TagUseKind::Friend, isMemberSpecialization, Invalid);
   if (Invalid)
     return true;
 
@@ -9501,7 +9503,7 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   if (TemplateParams && TemplateParams->size() > 0) {
     isPartialSpecialization = true;
 
-    if (TUK == TUK_Friend) {
+    if (TUK == TagUseKind::Friend) {
       Diag(KWLoc, diag::err_partial_specialization_friend)
         << SourceRange(LAngleLoc, RAngleLoc);
       return true;
@@ -9537,14 +9539,15 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
       }
     }
   } else if (TemplateParams) {
-    if (TUK == TUK_Friend)
+    if (TUK == TagUseKind::Friend)
       Diag(KWLoc, diag::err_template_spec_friend)
         << FixItHint::CreateRemoval(
                                 SourceRange(TemplateParams->getTemplateLoc(),
                                             TemplateParams->getRAngleLoc()))
         << SourceRange(LAngleLoc, RAngleLoc);
   } else {
-    assert(TUK == TUK_Friend && "should have a 'template<>' for this decl");
+    assert(TUK == TagUseKind::Friend &&
+           "should have a 'template<>' for this decl");
   }
 
   // Check that the specialization uses the same tag kind as the
@@ -9552,8 +9555,8 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
   assert(Kind != TagTypeKind::Enum &&
          "Invalid enum tag in class template spec!");
-  if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(),
-                                    Kind, TUK == TUK_Definition, KWLoc,
+  if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(), Kind,
+                                    TUK == TagUseKind::Definition, KWLoc,
                                     ClassTemplate->getIdentifier())) {
     Diag(KWLoc, diag::err_use_with_wrong_tag)
       << ClassTemplate
@@ -9617,7 +9620,7 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
 
   // Check whether we can declare a class template specialization in
   // the current scope.
-  if (TUK != TUK_Friend &&
+  if (TUK != TagUseKind::Friend &&
       CheckTemplateSpecializationScope(*this, ClassTemplate, PrevDecl,
                                        TemplateNameLoc,
                                        isPartialSpecialization))
@@ -9644,8 +9647,8 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
       // This rule has since been removed, because it's redundant given DR1495,
       // but we keep it because it produces better diagnostics and recovery.
       Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
-        << /*class template*/0 << (TUK == TUK_Definition)
-        << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
+          << /*class template*/ 0 << (TUK == TagUseKind::Definition)
+          << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
       return CheckClassTemplate(S, TagSpec, TUK, KWLoc, SS,
                                 ClassTemplate->getIdentifier(),
                                 TemplateNameLoc,
@@ -9737,11 +9740,11 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   }
 
   // If this is not a friend, note that this is an explicit specialization.
-  if (TUK != TUK_Friend)
+  if (TUK != TagUseKind::Friend)
     Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
 
   // Check that this isn't a redefinition of this specialization.
-  if (TUK == TUK_Definition) {
+  if (TUK == TagUseKind::Definition) {
     RecordDecl *Def = Specialization->getDefinition();
     NamedDecl *Hidden = nullptr;
     if (Def && SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
@@ -9762,7 +9765,7 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
 
   // Add alignment attributes if necessary; these attributes are checked when
   // the ASTContext lays out the structure.
-  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
+  if (TUK == TagUseKind::Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
     AddAlignmentAttributesForRecord(Specialization);
     AddMsStructLayoutForRecord(Specialization);
   }
@@ -9783,10 +9786,10 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   Specialization->setLexicalDeclContext(CurContext);
 
   // We may be starting the definition of this specialization.
-  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
+  if (TUK == TagUseKind::Definition && (!SkipBody || !SkipBody->ShouldSkip))
     Specialization->startDefinition();
 
-  if (TUK == TUK_Friend) {
+  if (TUK == TagUseKind::Friend) {
     // Build the fully-sugared type for this class template
     // specialization as the user wrote in the specialization
     // itself. This means that we'll pretty-print the type retrieved
@@ -11160,11 +11163,13 @@ Sema::ActOnExplicitInstantiation(Scope *S, SourceLocation ExternLoc,
 
   bool Owned = false;
   bool IsDependent = false;
-  Decl *TagD = ActOnTag(S, TagSpec, Sema::TUK_Reference, KWLoc, SS, Name,
-               NameLoc, Attr, AS_none, /*ModulePrivateLoc=*/SourceLocation(),
+  Decl *TagD =
+      ActOnTag(S, TagSpec, TagUseKind::Reference, KWLoc, SS, Name, NameLoc,
+               Attr, AS_none, /*ModulePrivateLoc=*/SourceLocation(),
                MultiTemplateParamsArg(), Owned, IsDependent, SourceLocation(),
                false, TypeResult(), /*IsTypeSpecifier*/ false,
-               /*IsTemplateParamOrArg*/ false, /*OOK=*/OOK_Outside).get();
+               /*IsTemplateParamOrArg*/ false, /*OOK=*/OOK_Outside)
+          .get();
   assert(!IsDependent && "explicit instantiation of dependent name not yet handled");
 
   if (!TagD)
@@ -11695,9 +11700,9 @@ TypeResult Sema::ActOnDependentTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
 
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
 
-  if (TUK == TUK_Declaration || TUK == TUK_Definition) {
+  if (TUK == TagUseKind::Declaration || TUK == TagUseKind::Definition) {
     Diag(NameLoc, diag::err_dependent_tag_decl)
-        << (TUK == TUK_Definition) << llvm::to_underlying(Kind)
+        << (TUK == TagUseKind::Definition) << llvm::to_underlying(Kind)
         << SS.getRange();
     return true;
   }