[clang] NFC: change more places to use Type::getAsTagDecl and friends (#155313)

This changes a bunch of places which use getAs<TagType>, including
derived types, just to obtain the tag definition.

This is preparation for #155028, offloading all the changes that PR used
to introduce which don't depend on any new helpers.

Author: mizvekov

clang-tools-extra/clang-doc/Serialize.cpp

@@ -901,9 +901,8 @@ parseBases(RecordInfo &I, const CXXRecordDecl *D, bool IsFileInRootDir,
   if (!D->isThisDeclarationADefinition())
     return;
   for (const CXXBaseSpecifier &B : D->bases()) {
-    if (const RecordType *Ty = B.getType()->getAs<RecordType>()) {
-      if (const CXXRecordDecl *Base = cast_or_null<CXXRecordDecl>(
-              Ty->getOriginalDecl()->getDefinition())) {
+    if (const auto *Base = B.getType()->getAsCXXRecordDecl()) {
+      if (Base->isCompleteDefinition()) {
         // Initialized without USR and name, this will be set in the following
         // if-else stmt.
         BaseRecordInfo BI(

clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp

@@ -31,7 +31,7 @@ void DefaultOperatorNewAlignmentCheck::check(
     return;
   const TagDecl *D = T->getAsTagDecl();
   // Alignment can not be obtained for undefined type.
-  if (!D || !D->getDefinition() || !D->isCompleteDefinition())
+  if (!D || !D->isCompleteDefinition())
     return;
 
   ASTContext &Context = D->getASTContext();

clang-tools-extra/clang-tidy/cppcoreguidelines/SlicingCheck.cpp

@@ -90,9 +90,8 @@ void SlicingCheck::diagnoseSlicedOverriddenMethods(
   }
   // Recursively process bases.
   for (const auto &Base : DerivedDecl.bases()) {
-    if (const auto *BaseRecordType = Base.getType()->getAs<RecordType>()) {
-      if (const auto *BaseRecord = cast_or_null<CXXRecordDecl>(
-              BaseRecordType->getOriginalDecl()->getDefinition()))
+    if (const auto *BaseRecord = Base.getType()->getAsCXXRecordDecl()) {
+      if (BaseRecord->isCompleteDefinition())
         diagnoseSlicedOverriddenMethods(Call, *BaseRecord, BaseDecl);
     }
   }

clang-tools-extra/clang-tidy/fuchsia/MultipleInheritanceCheck.cpp

@@ -71,13 +71,10 @@ bool MultipleInheritanceCheck::isInterface(const CXXRecordDecl *Node) {
   for (const auto &I : Node->bases()) {
     if (I.isVirtual())
       continue;
-    const auto *Ty = I.getType()->getAs<RecordType>();
-    if (!Ty)
+    const auto *Base = I.getType()->getAsCXXRecordDecl();
+    if (!Base)
       continue;
-    const RecordDecl *D = Ty->getOriginalDecl()->getDefinition();
-    if (!D)
-      continue;
-    const auto *Base = cast<CXXRecordDecl>(D);
+    assert(Base->isCompleteDefinition());
     if (!isInterface(Base)) {
       addNodeToInterfaceMap(Node, false);
       return false;
@@ -103,23 +100,21 @@ void MultipleInheritanceCheck::check(const MatchFinder::MatchResult &Result) {
     for (const auto &I : D->bases()) {
       if (I.isVirtual())
         continue;
-      const auto *Ty = I.getType()->getAs<RecordType>();
-      if (!Ty)
+      const auto *Base = I.getType()->getAsCXXRecordDecl();
+      if (!Base)
         continue;
-      const auto *Base =
-          cast<CXXRecordDecl>(Ty->getOriginalDecl()->getDefinition());
+      assert(Base->isCompleteDefinition());
       if (!isInterface(Base))
         NumConcrete++;
     }
 
     // Check virtual bases to see if there is more than one concrete
     // non-virtual base.
     for (const auto &V : D->vbases()) {
-      const auto *Ty = V.getType()->getAs<RecordType>();
-      if (!Ty)
+      const auto *Base = V.getType()->getAsCXXRecordDecl();
+      if (!Base)
         continue;
-      const auto *Base =
-          cast<CXXRecordDecl>(Ty->getOriginalDecl()->getDefinition());
+      assert(Base->isCompleteDefinition());
       if (!isInterface(Base))
         NumConcrete++;
     }

clang-tools-extra/clang-tidy/utils/TypeTraits.cpp

@@ -119,9 +119,8 @@ bool isTriviallyDefaultConstructible(QualType Type, const ASTContext &Context) {
   if (CanonicalType->isScalarType() || CanonicalType->isVectorType())
     return true;
 
-  if (const auto *RT = CanonicalType->getAs<RecordType>()) {
-    return recordIsTriviallyDefaultConstructible(
-        *RT->getOriginalDecl()->getDefinitionOrSelf(), Context);
+  if (const auto *RD = CanonicalType->getAsRecordDecl()) {
+    return recordIsTriviallyDefaultConstructible(*RD, Context);
   }
 
   // No other types can match.

clang/include/clang/AST/AbstractBasicReader.h

@@ -193,7 +193,7 @@ class DataStreamBasicReader : public BasicReaderBase<Impl> {
     auto elemTy = origTy;
     unsigned pathLength = asImpl().readUInt32();
     for (unsigned i = 0; i < pathLength; ++i) {
-      if (elemTy->template getAs<RecordType>()) {
+      if (elemTy->isRecordType()) {
         unsigned int_ = asImpl().readUInt32();
         Decl *decl = asImpl().template readDeclAs<Decl>();
         if (auto *recordDecl = dyn_cast<CXXRecordDecl>(decl))

clang/include/clang/AST/AbstractBasicWriter.h

@@ -176,7 +176,7 @@ class DataStreamBasicWriter : public BasicWriterBase<Impl> {
     asImpl().writeUInt32(path.size());
     auto &ctx = ((BasicWriterBase<Impl> *)this)->getASTContext();
     for (auto elem : path) {
-      if (elemTy->getAs<RecordType>()) {
+      if (elemTy->isRecordType()) {
         asImpl().writeUInt32(elem.getAsBaseOrMember().getInt());
         const Decl *baseOrMember = elem.getAsBaseOrMember().getPointer();
         if (const auto *recordDecl = dyn_cast<CXXRecordDecl>(baseOrMember)) {

clang/include/clang/AST/DeclCXX.h

@@ -3825,7 +3825,9 @@ class UsingEnumDecl : public BaseUsingDecl, public Mergeable<UsingEnumDecl> {
   void setEnumType(TypeSourceInfo *TSI) { EnumType = TSI; }
 
 public:
-  EnumDecl *getEnumDecl() const { return cast<EnumDecl>(EnumType->getType()->getAsTagDecl()); }
+  EnumDecl *getEnumDecl() const {
+    return cast<clang::EnumType>(EnumType->getType())->getOriginalDecl();
+  }
 
   static UsingEnumDecl *Create(ASTContext &C, DeclContext *DC,
                                SourceLocation UsingL, SourceLocation EnumL,

clang/include/clang/Sema/Sema.h

@@ -5404,7 +5404,7 @@ class Sema final : public SemaBase {
 
   /// FinalizeVarWithDestructor - Prepare for calling destructor on the
   /// constructed variable.
-  void FinalizeVarWithDestructor(VarDecl *VD, const RecordType *DeclInitType);
+  void FinalizeVarWithDestructor(VarDecl *VD, CXXRecordDecl *DeclInit);
 
   /// Helper class that collects exception specifications for
   /// implicitly-declared special member functions.

clang/lib/AST/ASTContext.cpp

@@ -654,9 +654,9 @@ comments::FullComment *ASTContext::getCommentForDecl(
       // does not have one of its own.
       QualType QT = TD->getUnderlyingType();
       if (const auto *TT = QT->getAs<TagType>())
-        if (const Decl *TD = TT->getOriginalDecl())
-          if (comments::FullComment *FC = getCommentForDecl(TD, PP))
-            return cloneFullComment(FC, D);
+        if (comments::FullComment *FC =
+                getCommentForDecl(TT->getOriginalDecl(), PP))
+          return cloneFullComment(FC, D);
     }
     else if (const auto *IC = dyn_cast<ObjCInterfaceDecl>(D)) {
       while (IC->getSuperClass()) {
@@ -1933,12 +1933,9 @@ TypeInfoChars ASTContext::getTypeInfoDataSizeInChars(QualType T) const {
   // of a base-class subobject.  We decide whether that's possible
   // during class layout, so here we can just trust the layout results.
   if (getLangOpts().CPlusPlus) {
-    if (const auto *RT = T->getAs<RecordType>()) {
-      const auto *RD = RT->getOriginalDecl()->getDefinitionOrSelf();
-      if (!RD->isInvalidDecl()) {
-        const ASTRecordLayout &layout = getASTRecordLayout(RD);
-        Info.Width = layout.getDataSize();
-      }
+    if (const auto *RD = T->getAsCXXRecordDecl(); RD && !RD->isInvalidDecl()) {
+      const ASTRecordLayout &layout = getASTRecordLayout(RD);
+      Info.Width = layout.getDataSize();
     }
   }
 
@@ -2694,9 +2691,7 @@ unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
   if (!Target->allowsLargerPreferedTypeAlignment())
     return ABIAlign;
 
-  if (const auto *RT = T->getAs<RecordType>()) {
-    const RecordDecl *RD = RT->getOriginalDecl()->getDefinitionOrSelf();
-
+  if (const auto *RD = T->getAsRecordDecl()) {
     // When used as part of a typedef, or together with a 'packed' attribute,
     // the 'aligned' attribute can be used to decrease alignment. Note that the
     // 'packed' case is already taken into consideration when computing the
@@ -2887,12 +2882,10 @@ structHasUniqueObjectRepresentations(const ASTContext &Context,
 static std::optional<int64_t>
 getSubobjectSizeInBits(const FieldDecl *Field, const ASTContext &Context,
                        bool CheckIfTriviallyCopyable) {
-  if (Field->getType()->isRecordType()) {
-    const RecordDecl *RD = Field->getType()->getAsRecordDecl();
-    if (!RD->isUnion())
-      return structHasUniqueObjectRepresentations(Context, RD,
-                                                  CheckIfTriviallyCopyable);
-  }
+  if (const auto *RD = Field->getType()->getAsRecordDecl();
+      RD && !RD->isUnion())
+    return structHasUniqueObjectRepresentations(Context, RD,
+                                                CheckIfTriviallyCopyable);
 
   // A _BitInt type may not be unique if it has padding bits
   // but if it is a bitfield the padding bits are not used.
@@ -3047,10 +3040,7 @@ bool ASTContext::hasUniqueObjectRepresentations(
   if (const auto *MPT = Ty->getAs<MemberPointerType>())
     return !ABI->getMemberPointerInfo(MPT).HasPadding;
 
-  if (Ty->isRecordType()) {
-    const RecordDecl *Record =
-        Ty->castAs<RecordType>()->getOriginalDecl()->getDefinitionOrSelf();
-
+  if (const auto *Record = Ty->getAsRecordDecl()) {
     if (Record->isInvalidDecl())
       return false;