[clang] Use {} instead of std::nullopt to initialize empty ArrayRef

clang/include/clang/AST/CommentSema.h

@@ -80,7 +80,7 @@ class Sema {
   ArrayRef<T> copyArray(ArrayRef<T> Source) {
     if (!Source.empty())
       return Source.copy(Allocator);
-    return std::nullopt;
+    return {};
   }
 
   ParagraphComment *actOnParagraphComment(

clang/include/clang/AST/DeclFriend.h

@@ -115,7 +115,7 @@ class FriendDecl final
   static FriendDecl *
   Create(ASTContext &C, DeclContext *DC, SourceLocation L, FriendUnion Friend_,
          SourceLocation FriendL, SourceLocation EllipsisLoc = {},
-         ArrayRef<TemplateParameterList *> FriendTypeTPLists = std::nullopt);
+         ArrayRef<TemplateParameterList *> FriendTypeTPLists = {});
   static FriendDecl *CreateDeserialized(ASTContext &C, GlobalDeclID ID,
                                         unsigned FriendTypeNumTPLists);
 

clang/include/clang/AST/DeclObjC.h

@@ -386,7 +386,7 @@ class ObjCMethodDecl : public NamedDecl, public DeclContext {
   /// If the method is implicit (not coming from source) \p SelLocs is
   /// ignored.
   void setMethodParams(ASTContext &C, ArrayRef<ParmVarDecl *> Params,
-                       ArrayRef<SourceLocation> SelLocs = std::nullopt);
+                       ArrayRef<SourceLocation> SelLocs = {});
 
   // Iterator access to parameter types.
   struct GetTypeFn {

clang/include/clang/AST/DeclOpenMP.h

@@ -34,7 +34,7 @@ template <typename U> class OMPDeclarativeDirective : public U {
   /// Get the clauses storage.
   MutableArrayRef<OMPClause *> getClauses() {
     if (!Data)
-      return std::nullopt;
+      return {};
     return Data->getClauses();
   }
 
@@ -90,7 +90,7 @@ template <typename U> class OMPDeclarativeDirective : public U {
 
   ArrayRef<OMPClause *> clauses() const {
     if (!Data)
-      return std::nullopt;
+      return {};
     return Data->getClauses();
   }
 };

clang/include/clang/AST/ExprCXX.h

@@ -4306,11 +4306,11 @@ class SizeOfPackExpr final
       : Expr(SizeOfPackExprClass, Empty), Length(NumPartialArgs) {}
 
 public:
-  static SizeOfPackExpr *
-  Create(ASTContext &Context, SourceLocation OperatorLoc, NamedDecl *Pack,
-         SourceLocation PackLoc, SourceLocation RParenLoc,
-         std::optional<unsigned> Length = std::nullopt,
-         ArrayRef<TemplateArgument> PartialArgs = std::nullopt);
+  static SizeOfPackExpr *Create(ASTContext &Context, SourceLocation OperatorLoc,
+                                NamedDecl *Pack, SourceLocation PackLoc,
+                                SourceLocation RParenLoc,
+                                std::optional<unsigned> Length = std::nullopt,
+                                ArrayRef<TemplateArgument> PartialArgs = {});
   static SizeOfPackExpr *CreateDeserialized(ASTContext &Context,
                                             unsigned NumPartialArgs);
 

clang/include/clang/AST/OpenMPClause.h

@@ -6108,14 +6108,14 @@ class OMPMappableExprListClause : public OMPVarListClause<T>,
     return const_component_lists_iterator(
         getUniqueDeclsRef(), getDeclNumListsRef(), getComponentListSizesRef(),
         getComponentsRef(), SupportsMapper,
-        SupportsMapper ? getUDMapperRefs() : std::nullopt);
+        SupportsMapper ? getUDMapperRefs() : ArrayRef<Expr *>());
   }
   const_component_lists_iterator component_lists_end() const {
     return const_component_lists_iterator(
         ArrayRef<ValueDecl *>(), ArrayRef<unsigned>(), ArrayRef<unsigned>(),
         MappableExprComponentListRef(getComponentsRef().end(),
                                      getComponentsRef().end()),
-        SupportsMapper, std::nullopt);
+        SupportsMapper, {});
   }
   const_component_lists_range component_lists() const {
     return {component_lists_begin(), component_lists_end()};
@@ -6128,7 +6128,7 @@ class OMPMappableExprListClause : public OMPVarListClause<T>,
     return const_component_lists_iterator(
         VD, getUniqueDeclsRef(), getDeclNumListsRef(),
         getComponentListSizesRef(), getComponentsRef(), SupportsMapper,
-        SupportsMapper ? getUDMapperRefs() : std::nullopt);
+        SupportsMapper ? getUDMapperRefs() : ArrayRef<Expr *>());
   }
   const_component_lists_iterator decl_component_lists_end() const {
     return component_lists_end();

clang/include/clang/AST/StmtOpenMP.h

@@ -277,7 +277,7 @@ class OMPExecutableDirective : public Stmt {
   /// Get the clauses storage.
   MutableArrayRef<OMPClause *> getClauses() {
     if (!Data)
-      return std::nullopt;
+      return {};
     return Data->getClauses();
   }
 
@@ -572,7 +572,7 @@ class OMPExecutableDirective : public Stmt {
 
   ArrayRef<OMPClause *> clauses() const {
     if (!Data)
-      return std::nullopt;
+      return {};
     return Data->getClauses();
   }
 

clang/include/clang/AST/TemplateBase.h

@@ -283,7 +283,7 @@ class TemplateArgument {
   }
 
   static TemplateArgument getEmptyPack() {
-    return TemplateArgument(std::nullopt);
+    return TemplateArgument(ArrayRef<TemplateArgument>());
   }
 
   /// Create a new template argument pack by copying the given set of

clang/include/clang/ASTMatchers/ASTMatchersInternal.h

@@ -121,7 +121,7 @@ template <typename T> struct TypeListContainsSuperOf<EmptyTypeList, T> {
 template <typename ResultT, typename ArgT,
           ResultT (*Func)(ArrayRef<const ArgT *>)>
 struct VariadicFunction {
-  ResultT operator()() const { return Func(std::nullopt); }
+  ResultT operator()() const { return Func({}); }
 
   template <typename... ArgsT>
   ResultT operator()(const ArgT &Arg1, const ArgsT &... Args) const {
@@ -1949,35 +1949,35 @@ inline ArrayRef<TemplateArgument>
 getTemplateSpecializationArgs(const FunctionDecl &FD) {
   if (const auto* TemplateArgs = FD.getTemplateSpecializationArgs())
     return TemplateArgs->asArray();
-  return std::nullopt;
+  return {};
 }
 
 inline ArrayRef<TemplateArgumentLoc>
 getTemplateArgsWritten(const ClassTemplateSpecializationDecl &D) {
   if (const ASTTemplateArgumentListInfo *Args = D.getTemplateArgsAsWritten())
     return Args->arguments();
-  return std::nullopt;
+  return {};
 }
 
 inline ArrayRef<TemplateArgumentLoc>
 getTemplateArgsWritten(const VarTemplateSpecializationDecl &D) {
   if (const ASTTemplateArgumentListInfo *Args = D.getTemplateArgsAsWritten())
     return Args->arguments();
-  return std::nullopt;
+  return {};
 }
 
 inline ArrayRef<TemplateArgumentLoc>
 getTemplateArgsWritten(const FunctionDecl &FD) {
   if (const auto *Args = FD.getTemplateSpecializationArgsAsWritten())
     return Args->arguments();
-  return std::nullopt;
+  return {};
 }
 
 inline ArrayRef<TemplateArgumentLoc>
 getTemplateArgsWritten(const DeclRefExpr &DRE) {
   if (const auto *Args = DRE.getTemplateArgs())
     return {Args, DRE.getNumTemplateArgs()};
-  return std::nullopt;
+  return {};
 }
 
 inline SmallVector<TemplateArgumentLoc>

clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h

@@ -1470,7 +1470,7 @@ class Return : public Terminator {
   static bool classof(const SExpr *E) { return E->opcode() == COP_Return; }
 
   /// Return an empty list.
-  ArrayRef<BasicBlock *> successors() { return std::nullopt; }
+  ArrayRef<BasicBlock *> successors() { return {}; }
 
   SExpr *returnValue() { return Retval; }
   const SExpr *returnValue() const { return Retval; }
@@ -1496,7 +1496,7 @@ inline ArrayRef<BasicBlock*> Terminator::successors() {
     case COP_Branch: return cast<Branch>(this)->successors();
     case COP_Return: return cast<Return>(this)->successors();
     default:
-      return std::nullopt;
+      return {};
   }
 }
 

clang/include/clang/Analysis/AnyCall.h

@@ -143,7 +143,7 @@ class AnyCall {
   /// \returns formal parameters for direct calls (including virtual calls)
   ArrayRef<ParmVarDecl *> parameters() const {
     if (!D)
-      return std::nullopt;
+      return {};
 
     if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
       return FD->parameters();
@@ -152,7 +152,7 @@ class AnyCall {
     } else if (const auto *BD = dyn_cast<BlockDecl>(D)) {
       return BD->parameters();
     } else {
-      return std::nullopt;
+      return {};
     }
   }
 

clang/include/clang/Basic/TargetInfo.h

@@ -1858,11 +1858,9 @@ class TargetInfo : public TransferrableTargetInfo,
   }
   virtual ArrayRef<const char *> getGCCRegNames() const = 0;
   virtual ArrayRef<GCCRegAlias> getGCCRegAliases() const = 0;
-  virtual ArrayRef<AddlRegName> getGCCAddlRegNames() const {
-    return std::nullopt;
-  }
+  virtual ArrayRef<AddlRegName> getGCCAddlRegNames() const { return {}; }
 
- private:
+private:
   // Assert the values for the fractional and integral bits for each fixed point
   // type follow the restrictions given in clause 6.2.6.3 of N1169.
   void CheckFixedPointBits() const;

clang/include/clang/Driver/Job.h

@@ -172,8 +172,7 @@ class Command {
   Command(const Action &Source, const Tool &Creator,
           ResponseFileSupport ResponseSupport, const char *Executable,
           const llvm::opt::ArgStringList &Arguments, ArrayRef<InputInfo> Inputs,
-          ArrayRef<InputInfo> Outputs = std::nullopt,
-          const char *PrependArg = nullptr);
+          ArrayRef<InputInfo> Outputs = {}, const char *PrependArg = nullptr);
   // FIXME: This really shouldn't be copyable, but is currently copied in some
   // error handling in Driver::generateCompilationDiagnostics.
   Command(const Command &) = default;
@@ -245,8 +244,7 @@ class CC1Command : public Command {
   CC1Command(const Action &Source, const Tool &Creator,
              ResponseFileSupport ResponseSupport, const char *Executable,
              const llvm::opt::ArgStringList &Arguments,
-             ArrayRef<InputInfo> Inputs,
-             ArrayRef<InputInfo> Outputs = std::nullopt,
+             ArrayRef<InputInfo> Inputs, ArrayRef<InputInfo> Outputs = {},
              const char *PrependArg = nullptr);
 
   void Print(llvm::raw_ostream &OS, const char *Terminator, bool Quote,

clang/include/clang/Frontend/ASTUnit.h

@@ -836,7 +836,7 @@ class ASTUnit {
       bool StorePreamblesInMemory = false,
       StringRef PreambleStoragePath = StringRef(), bool OnlyLocalDecls = false,
       CaptureDiagsKind CaptureDiagnostics = CaptureDiagsKind::None,
-      ArrayRef<RemappedFile> RemappedFiles = std::nullopt,
+      ArrayRef<RemappedFile> RemappedFiles = {},
       bool RemappedFilesKeepOriginalName = true,
       unsigned PrecompilePreambleAfterNParses = 0,
       TranslationUnitKind TUKind = TU_Complete,
@@ -864,7 +864,7 @@ class ASTUnit {
   /// \returns True if a failure occurred that causes the ASTUnit not to
   /// contain any translation-unit information, false otherwise.
   bool Reparse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
-               ArrayRef<RemappedFile> RemappedFiles = std::nullopt,
+               ArrayRef<RemappedFile> RemappedFiles = {},
                IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS = nullptr);
 
   /// Free data that will be re-generated on the next parse.

clang/include/clang/Lex/Preprocessor.h

@@ -911,7 +911,7 @@ class Preprocessor {
     getActiveModuleMacros(Preprocessor &PP, const IdentifierInfo *II) const {
       if (auto *Info = getModuleInfo(PP, II))
         return Info->ActiveModuleMacros;
-      return std::nullopt;
+      return {};
     }
 
     MacroDirective::DefInfo findDirectiveAtLoc(SourceLocation Loc,
@@ -935,7 +935,7 @@ class Preprocessor {
     ArrayRef<ModuleMacro*> getOverriddenMacros() const {
       if (auto *Info = State.dyn_cast<ModuleMacroInfo*>())
         return Info->OverriddenMacros;
-      return std::nullopt;
+      return {};
     }
 
     void setOverriddenMacros(Preprocessor &PP,
@@ -1444,7 +1444,7 @@ class Preprocessor {
     auto I = LeafModuleMacros.find(II);
     if (I != LeafModuleMacros.end())
       return I->second;
-    return std::nullopt;
+    return {};
   }
 
   /// Get the list of submodules that we're currently building.

clang/include/clang/Sema/CodeCompleteConsumer.h

@@ -375,12 +375,11 @@ class CodeCompletionContext {
 public:
   /// Construct a new code-completion context of the given kind.
   CodeCompletionContext(Kind CCKind)
-      : CCKind(CCKind), IsUsingDeclaration(false), SelIdents(std::nullopt) {}
+      : CCKind(CCKind), IsUsingDeclaration(false), SelIdents() {}
 
   /// Construct a new code-completion context of the given kind.
-  CodeCompletionContext(
-      Kind CCKind, QualType T,
-      ArrayRef<const IdentifierInfo *> SelIdents = std::nullopt)
+  CodeCompletionContext(Kind CCKind, QualType T,
+                        ArrayRef<const IdentifierInfo *> SelIdents = {})
       : CCKind(CCKind), IsUsingDeclaration(false), SelIdents(SelIdents) {
     if (CCKind == CCC_DotMemberAccess || CCKind == CCC_ArrowMemberAccess ||
         CCKind == CCC_ObjCPropertyAccess || CCKind == CCC_ObjCClassMessage ||

clang/include/clang/Sema/Overload.h

@@ -1206,9 +1206,8 @@ class Sema;
 
     /// Add a new candidate with NumConversions conversion sequence slots
     /// to the overload set.
-    OverloadCandidate &
-    addCandidate(unsigned NumConversions = 0,
-                 ConversionSequenceList Conversions = std::nullopt) {
+    OverloadCandidate &addCandidate(unsigned NumConversions = 0,
+                                    ConversionSequenceList Conversions = {}) {
       assert((Conversions.empty() || Conversions.size() == NumConversions) &&
              "preallocated conversion sequence has wrong length");