diff --git a/clang/include/clang/Analysis/FlowSensitive/ASTOps.h b/clang/include/clang/Analysis/FlowSensitive/ASTOps.h
@@ -56,6 +56,7 @@ class RecordInitListHelper {
 public:
   // `InitList` must have record type.
   RecordInitListHelper(const InitListExpr *InitList);
+  RecordInitListHelper(const CXXParenListInitExpr *ParenInitList);
 
   // Base classes with their associated initializer expressions.
   ArrayRef<std::pair<const CXXBaseSpecifier *, Expr *>> base_inits() const {
@@ -68,6 +69,9 @@ class RecordInitListHelper {
   }
 
 private:
+  RecordInitListHelper(QualType Ty, std::vector<const FieldDecl *> Fields,
+                       ArrayRef<Expr *> Inits);
+
   SmallVector<std::pair<const CXXBaseSpecifier *, Expr *>> BaseInits;
   SmallVector<std::pair<const FieldDecl *, Expr *>> FieldInits;
 
@@ -92,6 +96,9 @@ struct ReferencedDecls {
 /// Returns declarations that are declared in or referenced from `FD`.
 ReferencedDecls getReferencedDecls(const FunctionDecl &FD);
 
+/// Returns declarations that are declared in or referenced from `S`.
+ReferencedDecls getReferencedDecls(const Stmt &S);
+
 } // namespace dataflow
 } // namespace clang
 

diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h b/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
@@ -84,7 +84,7 @@ class Environment {
     virtual ComparisonResult compare(QualType Type, const Value &Val1,
                                      const Environment &Env1, const Value &Val2,
                                      const Environment &Env2) {
-      // FIXME: Consider adding QualType to RecordValue and removing the Type
+      // FIXME: Consider adding `QualType` to `Value` and removing the `Type`
       // argument here.
       return ComparisonResult::Unknown;
     }
@@ -244,6 +244,21 @@ class Environment {
                           Environment::ValueModel &Model,
                           ExprJoinBehavior ExprBehavior);
 
+  /// Returns a value that approximates both `Val1` and `Val2`, or null if no
+  /// such value can be produced.
+  ///
+  /// `Env1` and `Env2` can be used to query child values and path condition
+  /// implications of `Val1` and `Val2` respectively. The joined value will be
+  /// produced in `JoinedEnv`.
+  ///
+  /// Requirements:
+  ///
+  ///  `Val1` and `Val2` must model values of type `Type`.
+  static Value *joinValues(QualType Ty, Value *Val1, const Environment &Env1,
+                           Value *Val2, const Environment &Env2,
+                           Environment &JoinedEnv,
+                           Environment::ValueModel &Model);
+
   /// Widens the environment point-wise, using `PrevEnv` as needed to inform the
   /// approximation.
   ///
@@ -407,20 +422,15 @@ class Environment {
   /// storage locations and values for indirections until it finds a
   /// non-pointer/non-reference type.
   ///
-  /// If `Type` is a class, struct, or union type, creates values for all
-  /// modeled fields (including synthetic fields) and calls `setValue()` to
-  /// associate the `RecordValue` with its storage location
-  /// (`RecordValue::getLoc()`).
-  ///
   /// If `Type` is one of the following types, this function will always return
   /// a non-null pointer:
   /// - `bool`
   /// - Any integer type
-  /// - Any class, struct, or union type
   ///
   /// Requirements:
   ///
-  ///  `Type` must not be null.
+  ///  - `Type` must not be null.
+  ///  - `Type` must not be a reference type or record type.
   Value *createValue(QualType Type);
 
   /// Creates an object (i.e. a storage location with an associated value) of
@@ -452,6 +462,7 @@ class Environment {
   /// Initializes the fields (including synthetic fields) of `Loc` with values,
   /// unless values of the field type are not supported or we hit one of the
   /// limits at which we stop producing values.
+  /// If a field already has a value, that value is preserved.
   /// If `Type` is provided, initializes only those fields that are modeled for
   /// `Type`; this is intended for use in cases where `Loc` is a derived type
   /// and we only want to initialize the fields of a base type.
@@ -461,6 +472,10 @@ class Environment {
   }
 
   /// Assigns `Val` as the value of `Loc` in the environment.
+  ///
+  /// Requirements:
+  ///
+  ///  `Loc` must not be a `RecordStorageLocation`.
   void setValue(const StorageLocation &Loc, Value &Val);
 
   /// Clears any association between `Loc` and a value in the environment.
@@ -470,20 +485,24 @@ class Environment {
   ///
   /// Requirements:
   ///
-  ///  - `E` must be a prvalue
-  ///  - If `Val` is a `RecordValue`, its `RecordStorageLocation` must be
-  ///    `getResultObjectLocation(E)`. An exception to this is if `E` is an
-  ///    expression that originally creates a `RecordValue` (such as a
-  ///    `CXXConstructExpr` or `CallExpr`), as these establish the location of
-  ///    the result object in the first place.
+  ///  - `E` must be a prvalue.
+  ///  - `E` must not have record type.
   void setValue(const Expr &E, Value &Val);
 
   /// Returns the value assigned to `Loc` in the environment or null if `Loc`
   /// isn't assigned a value in the environment.
+  ///
+  /// Requirements:
+  ///
+  ///  `Loc` must not be a `RecordStorageLocation`.
   Value *getValue(const StorageLocation &Loc) const;
 
   /// Equivalent to `getValue(getStorageLocation(D))` if `D` is assigned a
   /// storage location in the environment, otherwise returns null.
+  ///
+  /// Requirements:
+  ///
+  ///  `D` must not have record type.
   Value *getValue(const ValueDecl &D) const;
 
   /// Equivalent to `getValue(getStorageLocation(E, SP))` if `E` is assigned a
@@ -775,12 +794,6 @@ RecordStorageLocation *getImplicitObjectLocation(const CXXMemberCallExpr &MCE,
 RecordStorageLocation *getBaseObjectLocation(const MemberExpr &ME,
                                              const Environment &Env);
 
-/// Associates a new `RecordValue` with `Loc` and returns the new value.
-RecordValue &refreshRecordValue(RecordStorageLocation &Loc, Environment &Env);
-
-/// Associates a new `RecordValue` with `Expr` and returns the new value.
-RecordValue &refreshRecordValue(const Expr &Expr, Environment &Env);
-
 } // namespace dataflow
 } // namespace clang
 

diff --git a/clang/include/clang/Analysis/FlowSensitive/Transfer.h b/clang/include/clang/Analysis/FlowSensitive/Transfer.h
@@ -53,7 +53,8 @@ class StmtToEnvMap {
 /// Requirements:
 ///
 ///  `S` must not be `ParenExpr` or `ExprWithCleanups`.
-void transfer(const StmtToEnvMap &StmtToEnv, const Stmt &S, Environment &Env);
+void transfer(const StmtToEnvMap &StmtToEnv, const Stmt &S, Environment &Env,
+              Environment::ValueModel &Model);
 
 } // namespace dataflow
 } // namespace clang

diff --git a/clang/include/clang/Analysis/FlowSensitive/Value.h b/clang/include/clang/Analysis/FlowSensitive/Value.h
@@ -35,7 +35,6 @@ class Value {
   enum class Kind {
     Integer,
     Pointer,
-    Record,
 
     // TODO: Top values should not be need to be type-specific.
     TopBool,
@@ -67,7 +66,6 @@ class Value {
   /// Properties may not be set on `RecordValue`s; use synthetic fields instead
   /// (for details, see documentation for `RecordStorageLocation`).
   void setProperty(llvm::StringRef Name, Value &Val) {
-    assert(getKind() != Kind::Record);
     Properties.insert_or_assign(Name, &Val);
   }
 
@@ -184,45 +182,6 @@ class PointerValue final : public Value {
   StorageLocation &PointeeLoc;
 };
 
-/// Models a value of `struct` or `class` type.
-/// In C++, prvalues of class type serve only a limited purpose: They can only
-/// be used to initialize a result object. It is not possible to access member
-/// variables or call member functions on a prvalue of class type.
-/// Correspondingly, `RecordValue` also serves only a limited purpose: It
-/// conveys a prvalue of class type from the place where the object is
-/// constructed to the result object that it initializes.
-///
-/// When creating a prvalue of class type, we already need a storage location
-/// for `this`, even though prvalues are otherwise not associated with storage
-/// locations. `RecordValue` is therefore essentially a wrapper for a storage
-/// location, which is then used to set the storage location for the result
-/// object when we process the AST node for that result object.
-///
-/// For example:
-///    MyStruct S = MyStruct(3);
-///
-/// In this example, `MyStruct(3) is a prvalue, which is modeled as a
-/// `RecordValue` that wraps a `RecordStorageLocation`. This
-/// `RecordStorageLocation` is then used as the storage location for `S`.
-///
-/// Over time, we may eliminate `RecordValue` entirely. See also the discussion
-/// here: https://reviews.llvm.org/D155204#inline-1503204
-class RecordValue final : public Value {
-public:
-  explicit RecordValue(RecordStorageLocation &Loc)
-      : Value(Kind::Record), Loc(Loc) {}
-
-  static bool classof(const Value *Val) {
-    return Val->getKind() == Kind::Record;
-  }
-
-  /// Returns the storage location that this `RecordValue` is associated with.
-  RecordStorageLocation &getLoc() const { return Loc; }
-
-private:
-  RecordStorageLocation &Loc;
-};
-
 raw_ostream &operator<<(raw_ostream &OS, const Value &Val);
 
 } // namespace dataflow

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
@@ -368,8 +368,8 @@ class Clang<string name, bit allowInC = 1, int version = 1>
   bit AllowInC = allowInC;
 }
 
-// HLSL Semantic spellings
-class HLSLSemantic<string name> : Spelling<name, "HLSLSemantic">;
+// HLSL Annotation spellings
+class HLSLAnnotation<string name> : Spelling<name, "HLSLAnnotation">;
 
 class Accessor<string name, list<Spelling> spellings> {
   string Name = name;
@@ -4358,22 +4358,22 @@ def HLSLNumThreads: InheritableAttr {
 }
 
 def HLSLSV_GroupIndex: HLSLAnnotationAttr {
-  let Spellings = [HLSLSemantic<"SV_GroupIndex">];
+  let Spellings = [HLSLAnnotation<"SV_GroupIndex">];
   let Subjects = SubjectList<[ParmVar, GlobalVar]>;
   let LangOpts = [HLSL];
   let Documentation = [HLSLSV_GroupIndexDocs];
 }
 
 def HLSLResourceBinding: InheritableAttr {
-  let Spellings = [HLSLSemantic<"register">];
+  let Spellings = [HLSLAnnotation<"register">];
   let Subjects = SubjectList<[HLSLBufferObj, ExternalGlobalVar]>;
   let LangOpts = [HLSL];
   let Args = [StringArgument<"Slot">, StringArgument<"Space", 1>];
   let Documentation = [HLSLResourceBindingDocs];
 }
 
 def HLSLSV_DispatchThreadID: HLSLAnnotationAttr {
-  let Spellings = [HLSLSemantic<"SV_DispatchThreadID">];
+  let Spellings = [HLSLAnnotation<"SV_DispatchThreadID">];
   let Subjects = SubjectList<[ParmVar, Field]>;
   let LangOpts = [HLSL];
   let Documentation = [HLSLSV_DispatchThreadIDDocs];

diff --git a/clang/include/clang/Basic/AttributeCommonInfo.h b/clang/include/clang/Basic/AttributeCommonInfo.h
@@ -52,8 +52,8 @@ class AttributeCommonInfo {
     /// Context-sensitive version of a keyword attribute.
     AS_ContextSensitiveKeyword,
 
-    /// <vardecl> : <semantic>
-    AS_HLSLSemantic,
+    /// <vardecl> : <annotation>
+    AS_HLSLAnnotation,
 
     /// The attibute has no source code manifestation and is only created
     /// implicitly.
@@ -120,7 +120,7 @@ class AttributeCommonInfo {
     }
     static Form Pragma() { return AS_Pragma; }
     static Form ContextSensitiveKeyword() { return AS_ContextSensitiveKeyword; }
-    static Form HLSLSemantic() { return AS_HLSLSemantic; }
+    static Form HLSLAnnotation() { return AS_HLSLAnnotation; }
     static Form Implicit() { return AS_Implicit; }
 
   private:

diff --git a/clang/include/clang/Basic/DebugOptions.def b/clang/include/clang/Basic/DebugOptions.def
@@ -129,6 +129,9 @@ DEBUGOPT(CodeViewCommandLine, 1, 0)
 /// Whether emit extra debug info for sample pgo profile collection.
 DEBUGOPT(DebugInfoForProfiling, 1, 0)
 
+/// Whether to emit DW_TAG_template_alias for template aliases.
+DEBUGOPT(DebugTemplateAlias, 1, 0)
+
 /// Whether to emit .debug_gnu_pubnames section instead of .debug_pubnames.
 DEBUGOPT(DebugNameTable, 2, 0)
 

diff --git a/clang/include/clang/Basic/DiagnosticCommonKinds.td b/clang/include/clang/Basic/DiagnosticCommonKinds.td
@@ -234,6 +234,9 @@ def err_cxx23_size_t_suffix: Error<
 def err_size_t_literal_too_large: Error<
   "%select{signed |}0'size_t' literal is out of range of possible "
   "%select{signed |}0'size_t' values">;
+def ext_cxx_bitint_suffix : Extension<
+  "'_BitInt' suffix for literals is a Clang extension">,
+  InGroup<BitIntExtension>;
 def ext_c23_bitint_suffix : ExtWarn<
   "'_BitInt' suffix for literals is a C23 extension">,
   InGroup<C23>;

diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -1520,5 +1520,8 @@ def UnsafeBufferUsage : DiagGroup<"unsafe-buffer-usage", [UnsafeBufferUsageInCon
 // Warnings and notes InstallAPI verification.
 def InstallAPIViolation : DiagGroup<"installapi-violation">;
 
+// Warnings related to _BitInt extension
+def BitIntExtension : DiagGroup<"bit-int-extension">;
+
 // Warnings about misuse of ExtractAPI options.
 def ExtractAPIMisuse : DiagGroup<"extractapi-misuse">;
diff --git a/clang/include/clang/Basic/DiagnosticInstallAPIKinds.td b/clang/include/clang/Basic/DiagnosticInstallAPIKinds.td
@@ -24,6 +24,7 @@ def err_no_matching_target : Error<"no matching target found for target variant
 def err_unsupported_vendor : Error<"vendor '%0' is not supported: '%1'">;
 def err_unsupported_environment : Error<"environment '%0' is not supported: '%1'">;
 def err_unsupported_os : Error<"os '%0' is not supported: '%1'">;
+def err_cannot_read_alias_list : Error<"could not read alias list '%0': %1">;
 } // end of command line category.
 
 let CategoryName = "Verification" in {

diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -863,6 +863,8 @@ def err_empty_requires_expr : Error<
   "a requires expression must contain at least one requirement">;
 def err_requires_expr_parameter_list_ellipsis : Error<
   "varargs not allowed in requires expression">;
+def err_requires_expr_explicit_object_parameter: Error<
+  "a requires expression cannot have an explicit object parameter">;
 def err_expected_semi_requirement : Error<
   "expected ';' at end of requirement">;
 def err_requires_expr_missing_arrow : Error<
@@ -1652,7 +1654,7 @@ def warn_ext_int_deprecated : Warning<
   "'_ExtInt' is deprecated; use '_BitInt' instead">, InGroup<DeprecatedType>;
 def ext_bit_int : Extension<
   "'_BitInt' in %select{C17 and earlier|C++}0 is a Clang extension">,
-  InGroup<DiagGroup<"bit-int-extension">>;
+  InGroup<BitIntExtension>;
 } // end of Parse Issue category.
 
 let CategoryName = "Modules Issue" in {

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -87,9 +87,9 @@ def err_expr_not_cce : Error<
   "call to 'size()'|call to 'data()'}0 is not a constant expression">;
 def ext_cce_narrowing : ExtWarn<
   "%select{case value|enumerator value|non-type template argument|"
-  "array size|explicit specifier argument|noexcept specifier argument}0 "
-  "%select{cannot be narrowed from type %2 to %3|"
-  "evaluates to %2, which cannot be narrowed to type %3}1">,
+  "array size|explicit specifier argument|noexcept specifier argument|"
+  "call to 'size()'|call to 'data()'}0 %select{cannot be narrowed from "
+  "type %2 to %3|evaluates to %2, which cannot be narrowed to type %3}1">,
   InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
 def err_ice_not_integral : Error<
   "%select{integer|integral}1 constant expression must have "
@@ -3669,6 +3669,9 @@ def warn_attribute_dllexport_explicit_instantiation_decl : Warning<
 def warn_attribute_dllexport_explicit_instantiation_def : Warning<
   "'dllexport' attribute ignored on explicit instantiation definition">,
   InGroup<IgnoredAttributes>;
+def warn_attribute_exclude_from_explicit_instantiation_local_class : Warning<
+  "%0 attribute ignored on local class%select{| member}1">,
+  InGroup<IgnoredAttributes>;
 def warn_invalid_initializer_from_system_header : Warning<
   "invalid constructor from class in system header, should not be explicit">,
   InGroup<DiagGroup<"invalid-initializer-from-system-header">>;
@@ -12278,4 +12281,21 @@ def warn_acc_if_self_conflict
     : Warning<"OpenACC construct 'self' has no effect when an 'if' clause "
               "evaluates to true">,
       InGroup<DiagGroup<"openacc-self-if-potential-conflict">>;
+def err_acc_int_expr_requires_integer
+    : Error<"OpenACC %select{clause|directive}0 '%1' requires expression of "
+            "integer type (%2 invalid)">;
+def err_acc_int_expr_incomplete_class_type
+    : Error<"OpenACC integer expression has incomplete class type %0">;
+def err_acc_int_expr_explicit_conversion
+    : Error<"OpenACC integer expression type %0 requires explicit conversion "
+            "to %1">;
+def note_acc_int_expr_conversion
+    : Note<"conversion to %select{integral|enumeration}0 type %1">;
+def err_acc_int_expr_multiple_conversions
+    : Error<"multiple conversions from expression type %0 to an integral type">;
+def err_acc_num_gangs_num_args
+    : Error<"%select{no|too many}0 integer expression arguments provided to "
+            "OpenACC 'num_gangs' "
+            "%select{|clause: '%1' directive expects maximum of %2, %3 were "
+            "provided}0">;
 } // end of sema component.
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
@@ -224,6 +224,11 @@ class LangOptionsBase {
     ///   - the parameter list of a template template parameter
     Ver17,
 
+    /// Attempt to be ABI-compatible with code generated by Clang 18.0.x.
+    /// This causes clang to revert some fixes to the mangling of lambdas
+    /// in the initializers of members of local classes.
+    Ver18,
+
     /// Conform to the underlying platform's C and C++ ABIs as closely
     /// as we can.
     Latest
@@ -873,6 +878,8 @@ class FPOptions {
   /// Return difference with the given option set.
   FPOptionsOverride getChangesFrom(const FPOptions &Base) const;
 
+  void applyChanges(FPOptionsOverride FPO);
+
   // We can define most of the accessors automatically:
 #define OPTION(NAME, TYPE, WIDTH, PREVIOUS)                                    \
   TYPE get##NAME() const {                                                     \
@@ -954,6 +961,11 @@ class FPOptionsOverride {
       setAllowFPContractAcrossStatement();
   }
 
+  void setDisallowOptimizations() {
+    setFPPreciseEnabled(true);
+    setDisallowFPContract();
+  }
+
   storage_type getAsOpaqueInt() const {
     return (static_cast<storage_type>(Options.getAsOpaqueInt())
             << FPOptions::StorageBitSize) |
@@ -1010,6 +1022,10 @@ inline FPOptionsOverride FPOptions::getChangesFrom(const FPOptions &Base) const
   return getChangesSlow(Base);
 }
 
+inline void FPOptions::applyChanges(FPOptionsOverride FPO) {
+  *this = FPO.applyOverrides(*this);
+}
+
 /// Describes the kind of translation unit being processed.
 enum TranslationUnitKind {
   /// The translation unit is a complete translation unit.

diff --git a/clang/include/clang/Basic/OpenACCClauses.def b/clang/include/clang/Basic/OpenACCClauses.def
@@ -18,5 +18,8 @@
 VISIT_CLAUSE(Default)
 VISIT_CLAUSE(If)
 VISIT_CLAUSE(Self)
+VISIT_CLAUSE(NumGangs)
+VISIT_CLAUSE(NumWorkers)
+VISIT_CLAUSE(VectorLength)
 
 #undef VISIT_CLAUSE
diff --git a/clang/include/clang/Basic/riscv_vector.td b/clang/include/clang/Basic/riscv_vector.td
diff --git a/clang/include/clang/Driver/OffloadBundler.h b/clang/include/clang/Driver/OffloadBundler.h
@@ -100,6 +100,7 @@ struct OffloadTargetInfo {
 // - Version (2 bytes)
 // - Compression Method (2 bytes) - Uses the values from
 // llvm::compression::Format.
+// - Total file size (4 bytes). Available in version 2 and above.
 // - Uncompressed Size (4 bytes).
 // - Truncated MD5 Hash (8 bytes).
 // - Compressed Data (variable length).
@@ -109,13 +110,17 @@ class CompressedOffloadBundle {
   static inline const size_t MagicSize = 4;
   static inline const size_t VersionFieldSize = sizeof(uint16_t);
   static inline const size_t MethodFieldSize = sizeof(uint16_t);
-  static inline const size_t SizeFieldSize = sizeof(uint32_t);
-  static inline const size_t HashFieldSize = 8;
-  static inline const size_t HeaderSize = MagicSize + VersionFieldSize +
-                                          MethodFieldSize + SizeFieldSize +
-                                          HashFieldSize;
+  static inline const size_t FileSizeFieldSize = sizeof(uint32_t);
+  static inline const size_t UncompressedSizeFieldSize = sizeof(uint32_t);
+  static inline const size_t HashFieldSize = sizeof(uint64_t);
+  static inline const size_t V1HeaderSize =
+      MagicSize + VersionFieldSize + MethodFieldSize +
+      UncompressedSizeFieldSize + HashFieldSize;
+  static inline const size_t V2HeaderSize =
+      MagicSize + VersionFieldSize + FileSizeFieldSize + MethodFieldSize +
+      UncompressedSizeFieldSize + HashFieldSize;
   static inline const llvm::StringRef MagicNumber = "CCOB";
-  static inline const uint16_t Version = 1;
+  static inline const uint16_t Version = 2;
 
 public:
   static llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -807,8 +807,12 @@ def gcc_install_dir_EQ : Joined<["--"], "gcc-install-dir=">,
   "Note: executables (e.g. ld) used by the compiler are not overridden by the selected GCC installation">;
 def gcc_toolchain : Joined<["--"], "gcc-toolchain=">, Flags<[NoXarchOption]>,
   Visibility<[ClangOption, FlangOption]>,
-  HelpText<"Specify a directory where Clang can find 'include' and 'lib{,32,64}/gcc{,-cross}/$triple/$version'. "
-  "Clang will use the GCC installation with the largest version">;
+  HelpText<
+    "Specify a directory where Clang can find 'include' and 'lib{,32,64}/gcc{,-cross}/$triple/$version'. "
+    "Clang will use the GCC installation with the largest version">,
+  HelpTextForVariants<[FlangOption],
+    "Specify a directory where Flang can find 'lib{,32,64}/gcc{,-cross}/$triple/$version'. "
+    "Flang will use the GCC installation with the largest version">;
 def gcc_triple_EQ : Joined<["--"], "gcc-triple=">,
   HelpText<"Search for the GCC installation with the specified triple.">;
 def CC : Flag<["-"], "CC">, Visibility<[ClangOption, CC1Option]>,
@@ -1505,6 +1509,7 @@ def end_no_unused_arguments : Flag<["--"], "end-no-unused-arguments">,
 def interface_stub_version_EQ : JoinedOrSeparate<["-"], "interface-stub-version=">,
   Visibility<[ClangOption, CC1Option]>;
 def exported__symbols__list : Separate<["-"], "exported_symbols_list">;
+def alias_list : Separate<["-"], "alias_list">, Flags<[LinkerInput]>;
 def extract_api : Flag<["-"], "extract-api">,
   Visibility<[ClangOption, CC1Option]>, Group<Action_Group>,
   HelpText<"Extract API information">;
@@ -3099,6 +3104,11 @@ defm modules_skip_header_search_paths : BoolFOption<"modules-skip-header-search-
     HeaderSearchOpts<"ModulesSkipHeaderSearchPaths">, DefaultFalse,
     PosFlag<SetTrue, [], [], "Disable writing header search paths">,
     NegFlag<SetFalse>, BothFlags<[], [CC1Option]>>;
+def fno_modules_prune_non_affecting_module_map_files :
+    Flag<["-"], "fno-modules-prune-non-affecting-module-map-files">,
+    Group<f_Group>, Flags<[]>, Visibility<[CC1Option]>,
+    MarshallingInfoNegativeFlag<HeaderSearchOpts<"ModulesPruneNonAffectingModuleMaps">>,
+    HelpText<"Do not prune non-affecting module map files when writing module files">;
 
 def fincremental_extensions :
   Flag<["-"], "fincremental-extensions">,
@@ -4308,6 +4318,8 @@ def gsplit_dwarf_EQ : Joined<["-"], "gsplit-dwarf=">, Group<g_flags_Group>,
   Values<"split,single">;
 def gno_split_dwarf : Flag<["-"], "gno-split-dwarf">, Group<g_flags_Group>,
   Visibility<[ClangOption, CLOption, DXCOption]>;
+def gtemplate_alias : Flag<["-"], "gtemplate-alias">, Group<g_flags_Group>, Visibility<[ClangOption, CC1Option]>;
+def gno_template_alias : Flag<["-"], "gno-template-alias">, Group<g_flags_Group>, Visibility<[ClangOption]>;
 def gsimple_template_names : Flag<["-"], "gsimple-template-names">, Group<g_flags_Group>;
 def gsimple_template_names_EQ
     : Joined<["-"], "gsimple-template-names=">,
@@ -4744,9 +4756,9 @@ def munaligned_symbols : Flag<["-"], "munaligned-symbols">, Group<m_Group>,
   HelpText<"Expect external char-aligned symbols to be without ABI alignment (SystemZ only)">;
 def mno_unaligned_symbols : Flag<["-"], "mno-unaligned-symbols">, Group<m_Group>,
   HelpText<"Expect external char-aligned symbols to be without ABI alignment (SystemZ only)">;
-def mstrict_align : Flag<["-"], "mstrict-align">,
+def mstrict_align : Flag<["-"], "mstrict-align">, Group<m_Group>,
   HelpText<"Force all memory accesses to be aligned (AArch64/LoongArch/RISC-V only)">;
-def mno_strict_align : Flag<["-"], "mno-strict-align">,
+def mno_strict_align : Flag<["-"], "mno-strict-align">, Group<m_Group>,
   HelpText<"Allow memory accesses to be unaligned (AArch64/LoongArch/RISC-V only)">;
 def mno_thumb : Flag<["-"], "mno-thumb">, Group<m_arm_Features_Group>;
 def mrestrict_it: Flag<["-"], "mrestrict-it">, Group<m_arm_Features_Group>,
@@ -5029,6 +5041,12 @@ def maix_small_local_exec_tls : Flag<["-"], "maix-small-local-exec-tls">,
            "where the offset from the TLS base is encoded as an "
            "immediate operand (AIX 64-bit only). "
            "This access sequence is not used for variables larger than 32KB.">;
+def maix_small_local_dynamic_tls : Flag<["-"], "maix-small-local-dynamic-tls">,
+  Group<m_ppc_Features_Group>,
+  HelpText<"Produce a faster access sequence for local-dynamic TLS variables "
+           "where the offset from the TLS base is encoded as an "
+           "immediate operand (AIX 64-bit only). "
+           "This access sequence is not used for variables larger than 32KB.">;
 def maix_struct_return : Flag<["-"], "maix-struct-return">,
   Group<m_Group>, Visibility<[ClangOption, CC1Option]>,
   HelpText<"Return all structs in memory (PPC32 only)">,
@@ -5490,6 +5508,14 @@ def fno_rtlib_add_rpath: Flag<["-"], "fno-rtlib-add-rpath">,
   Visibility<[ClangOption, FlangOption]>,
   HelpText<"Do not add -rpath with architecture-specific resource directory to the linker flags. "
   "When --hip-link is specified, do not add -rpath with HIP runtime library directory to the linker flags">;
+def frtlib_defaultlib : Flag<["-"], "frtlib-defaultlib">,
+                      Visibility<[ClangOption, CLOption]>,
+                      Group<f_Group>,
+                      HelpText<"On Windows, emit /defaultlib: directives to link compiler-rt libraries (default)">;
+def fno_rtlib_defaultlib : Flag<["-"], "fno-rtlib-defaultlib">,
+                      Visibility<[ClangOption, CLOption]>,
+                      Group<f_Group>,
+                      HelpText<"On Windows, do not emit /defaultlib: directives to link compiler-rt libraries">;
 def offload_add_rpath: Flag<["--"], "offload-add-rpath">,
   Flags<[NoArgumentUnused]>,
   Alias<frtlib_add_rpath>;
@@ -8343,14 +8369,15 @@ def _SLASH_FI : CLJoinedOrSeparate<"FI">,
 def _SLASH_Fe : CLJoined<"Fe">,
   HelpText<"Set output executable file name">,
   MetaVarName<"<file or dir/>">;
-def _SLASH_Fe_COLON : CLJoined<"Fe:">, Alias<_SLASH_Fe>;
+def _SLASH_Fe_COLON : CLJoinedOrSeparate<"Fe:">, Alias<_SLASH_Fe>;
 def _SLASH_Fi : CLCompileJoined<"Fi">,
   HelpText<"Set preprocess output file name (with /P)">,
   MetaVarName<"<file>">;
+def _SLASH_Fi_COLON : CLJoinedOrSeparate<"Fi:">, Alias<_SLASH_Fi>;
 def _SLASH_Fo : CLCompileJoined<"Fo">,
   HelpText<"Set output object file (with /c)">,
   MetaVarName<"<file or dir/>">;
-def _SLASH_Fo_COLON : CLCompileJoined<"Fo:">, Alias<_SLASH_Fo>;
+def _SLASH_Fo_COLON : CLCompileJoinedOrSeparate<"Fo:">, Alias<_SLASH_Fo>;
 def _SLASH_guard : CLJoined<"guard:">,
   HelpText<"Enable Control Flow Guard with /guard:cf, or only the table with /guard:cf,nochecks. "
            "Enable EH Continuation Guard with /guard:ehcont">;
@@ -8445,6 +8472,7 @@ def _SLASH_Zc_dllexportInlines_ : CLFlag<"Zc:dllexportInlines-">,
   HelpText<"Do not dllexport/dllimport inline member functions of dllexport/import classes">;
 def _SLASH_Fp : CLJoined<"Fp">,
   HelpText<"Set pch file name (with /Yc and /Yu)">, MetaVarName<"<file>">;
+def _SLASH_Fp_COLON : CLJoinedOrSeparate<"Fp:">, Alias<_SLASH_Fp>;
 
 def _SLASH_Gd : CLFlag<"Gd">,
   HelpText<"Set __cdecl as a default calling convention">;

diff --git a/clang/include/clang/InstallAPI/DylibVerifier.h b/clang/include/clang/InstallAPI/DylibVerifier.h
@@ -78,10 +78,12 @@ class DylibVerifier : llvm::MachO::RecordVisitor {
   DylibVerifier() = default;
 
   DylibVerifier(llvm::MachO::Records &&Dylib, ReexportedInterfaces &&Reexports,
-                DiagnosticsEngine *Diag, VerificationMode Mode, bool Zippered,
-                bool Demangle, StringRef DSYMPath)
-      : Dylib(std::move(Dylib)), Reexports(std::move(Reexports)), Mode(Mode),
-        Zippered(Zippered), Demangle(Demangle), DSYMPath(DSYMPath),
+                AliasMap Aliases, DiagnosticsEngine *Diag,
+                VerificationMode Mode, bool Zippered, bool Demangle,
+                StringRef DSYMPath)
+      : Dylib(std::move(Dylib)), Reexports(std::move(Reexports)),
+        Aliases(std::move(Aliases)), Mode(Mode), Zippered(Zippered),
+        Demangle(Demangle), DSYMPath(DSYMPath),
         Exports(std::make_unique<SymbolSet>()), Ctx(VerifierContext{Diag}) {}
 
   Result verify(GlobalRecord *R, const FrontendAttrs *FA);
@@ -104,7 +106,7 @@ class DylibVerifier : llvm::MachO::RecordVisitor {
   void setTarget(const Target &T);
 
   /// Release ownership over exports.
-  std::unique_ptr<SymbolSet> getExports() { return std::move(Exports); }
+  std::unique_ptr<SymbolSet> takeExports();
 
   /// Get result of verification.
   Result getState() const { return Ctx.FrontendState; }
@@ -189,6 +191,9 @@ class DylibVerifier : llvm::MachO::RecordVisitor {
   // Reexported interfaces apart of the library.
   ReexportedInterfaces Reexports;
 
+  // Symbol aliases.
+  AliasMap Aliases;
+
   // Controls what class of violations to report.
   VerificationMode Mode = VerificationMode::Invalid;
 

diff --git a/clang/include/clang/InstallAPI/MachO.h b/clang/include/clang/InstallAPI/MachO.h
@@ -23,6 +23,7 @@
 #include "llvm/TextAPI/TextAPIWriter.h"
 #include "llvm/TextAPI/Utils.h"
 
+using AliasMap = llvm::MachO::AliasMap;
 using Architecture = llvm::MachO::Architecture;
 using ArchitectureSet = llvm::MachO::ArchitectureSet;
 using SymbolFlags = llvm::MachO::SymbolFlags;

diff --git a/clang/include/clang/Lex/HeaderSearchOptions.h b/clang/include/clang/Lex/HeaderSearchOptions.h
@@ -252,6 +252,10 @@ class HeaderSearchOptions {
   LLVM_PREFERRED_TYPE(bool)
   unsigned ModulesSkipPragmaDiagnosticMappings : 1;
 
+  /// Whether to prune non-affecting module map files from PCM files.
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned ModulesPruneNonAffectingModuleMaps : 1;
+
   LLVM_PREFERRED_TYPE(bool)
   unsigned ModulesHashContent : 1;
 
@@ -280,7 +284,8 @@ class HeaderSearchOptions {
         ModulesValidateDiagnosticOptions(true),
         ModulesSkipDiagnosticOptions(false),
         ModulesSkipHeaderSearchPaths(false),
-        ModulesSkipPragmaDiagnosticMappings(false), ModulesHashContent(false),
+        ModulesSkipPragmaDiagnosticMappings(false),
+        ModulesPruneNonAffectingModuleMaps(true), ModulesHashContent(false),
         ModulesStrictContextHash(false), ModulesIncludeVFSUsage(false) {}
 
   /// AddPath - Add the \p Path path to the specified \p Group list.

diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
@@ -80,7 +80,8 @@ class NumericLiteralParser {
   bool isFloat128 : 1;      // 1.0q
   bool isFract : 1;         // 1.0hr/r/lr/uhr/ur/ulr
   bool isAccum : 1;         // 1.0hk/k/lk/uhk/uk/ulk
-  bool isBitInt : 1;        // 1wb, 1uwb (C23)
+  bool isBitInt : 1;        // 1wb, 1uwb (C23) or 1__wb, 1__uwb (Clang extension in C++
+                            // mode)
   uint8_t MicrosoftInteger; // Microsoft suffix extension i8, i16, i32, or i64.
 
 

diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
@@ -313,7 +313,15 @@ class Parser : public CodeCompletionHandler {
   /// top-level declaration is finished.
   SmallVector<TemplateIdAnnotation *, 16> TemplateIds;
 
+  /// Don't destroy template annotations in MaybeDestroyTemplateIds even if
+  /// we're at the end of a declaration. Instead, we defer the destruction until
+  /// after a top-level declaration.
+  /// Use DelayTemplateIdDestructionRAII rather than setting it directly.
+  bool DelayTemplateIdDestruction = false;
+
   void MaybeDestroyTemplateIds() {
+    if (DelayTemplateIdDestruction)
+      return;
     if (!TemplateIds.empty() &&
         (Tok.is(tok::eof) || !PP.mightHavePendingAnnotationTokens()))
       DestroyTemplateIds();
@@ -329,6 +337,22 @@ class Parser : public CodeCompletionHandler {
     ~DestroyTemplateIdAnnotationsRAIIObj() { Self.MaybeDestroyTemplateIds(); }
   };
 
+  struct DelayTemplateIdDestructionRAII {
+    Parser &Self;
+    bool PrevDelayTemplateIdDestruction;
+
+    DelayTemplateIdDestructionRAII(Parser &Self,
+                                   bool DelayTemplateIdDestruction) noexcept
+        : Self(Self),
+          PrevDelayTemplateIdDestruction(Self.DelayTemplateIdDestruction) {
+      Self.DelayTemplateIdDestruction = DelayTemplateIdDestruction;
+    }
+
+    ~DelayTemplateIdDestructionRAII() noexcept {
+      Self.DelayTemplateIdDestruction = PrevDelayTemplateIdDestruction;
+    }
+  };
+
   /// Identifiers which have been declared within a tentative parse.
   SmallVector<const IdentifierInfo *, 8> TentativelyDeclaredIdentifiers;
 
@@ -2967,25 +2991,25 @@ class Parser : public CodeCompletionHandler {
       Sema::AttributeCompletion Completion = Sema::AttributeCompletion::None,
       const IdentifierInfo *EnclosingScope = nullptr);
 
-  void MaybeParseHLSLSemantics(Declarator &D,
-                               SourceLocation *EndLoc = nullptr) {
-    assert(getLangOpts().HLSL && "MaybeParseHLSLSemantics is for HLSL only");
+  void MaybeParseHLSLAnnotations(Declarator &D,
+                                 SourceLocation *EndLoc = nullptr) {
+    assert(getLangOpts().HLSL && "MaybeParseHLSLAnnotations is for HLSL only");
     if (Tok.is(tok::colon)) {
       ParsedAttributes Attrs(AttrFactory);
-      ParseHLSLSemantics(Attrs, EndLoc);
+      ParseHLSLAnnotations(Attrs, EndLoc);
       D.takeAttributes(Attrs);
     }
   }
 
-  void MaybeParseHLSLSemantics(ParsedAttributes &Attrs,
-                               SourceLocation *EndLoc = nullptr) {
-    assert(getLangOpts().HLSL && "MaybeParseHLSLSemantics is for HLSL only");
+  void MaybeParseHLSLAnnotations(ParsedAttributes &Attrs,
+                                 SourceLocation *EndLoc = nullptr) {
+    assert(getLangOpts().HLSL && "MaybeParseHLSLAnnotations is for HLSL only");
     if (getLangOpts().HLSL && Tok.is(tok::colon))
-      ParseHLSLSemantics(Attrs, EndLoc);
+      ParseHLSLAnnotations(Attrs, EndLoc);
   }
 
-  void ParseHLSLSemantics(ParsedAttributes &Attrs,
-                          SourceLocation *EndLoc = nullptr);
+  void ParseHLSLAnnotations(ParsedAttributes &Attrs,
+                            SourceLocation *EndLoc = nullptr);
   Decl *ParseHLSLBuffer(SourceLocation &DeclEnd);
 
   void MaybeParseMicrosoftAttributes(ParsedAttributes &Attrs) {
@@ -3640,13 +3664,26 @@ class Parser : public CodeCompletionHandler {
   /// Parses the clause-list for an OpenACC directive.
   SmallVector<OpenACCClause *>
   ParseOpenACCClauseList(OpenACCDirectiveKind DirKind);
-  bool ParseOpenACCWaitArgument();
+  bool ParseOpenACCWaitArgument(SourceLocation Loc, bool IsDirective);
   /// Parses the clause of the 'bind' argument, which can be a string literal or
   /// an ID expression.
   ExprResult ParseOpenACCBindClauseArgument();
+
+  /// A type to represent the state of parsing after an attempt to parse an
+  /// OpenACC int-expr. This is useful to determine whether an int-expr list can
+  /// continue parsing after a failed int-expr.
+  using OpenACCIntExprParseResult =
+      std::pair<ExprResult, OpenACCParseCanContinue>;
   /// Parses the clause kind of 'int-expr', which can be any integral
   /// expression.
-  ExprResult ParseOpenACCIntExpr();
+  OpenACCIntExprParseResult ParseOpenACCIntExpr(OpenACCDirectiveKind DK,
+                                                OpenACCClauseKind CK,
+                                                SourceLocation Loc);
+  /// Parses the argument list for 'num_gangs', which allows up to 3
+  /// 'int-expr's.
+  bool ParseOpenACCIntExprList(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
+                               SourceLocation Loc,
+                               llvm::SmallVectorImpl<Expr *> &IntExprs);
   /// Parses the 'device-type-list', which is a list of identifiers.
   bool ParseOpenACCDeviceTypeList();
   /// Parses the 'async-argument', which is an integral value with two
@@ -3657,9 +3694,9 @@ class Parser : public CodeCompletionHandler {
   /// Parses a comma delimited list of 'size-expr's.
   bool ParseOpenACCSizeExprList();
   /// Parses a 'gang-arg-list', used for the 'gang' clause.
-  bool ParseOpenACCGangArgList();
+  bool ParseOpenACCGangArgList(SourceLocation GangLoc);
   /// Parses a 'gang-arg', used for the 'gang' clause.
-  bool ParseOpenACCGangArg();
+  bool ParseOpenACCGangArg(SourceLocation GangLoc);
   /// Parses a 'condition' expr, ensuring it results in a
   ExprResult ParseOpenACCConditionExpr();
 

diff --git a/clang/include/clang/Sema/Lookup.h b/clang/include/clang/Sema/Lookup.h
@@ -153,28 +153,30 @@ class LookupResult {
 
   using iterator = UnresolvedSetImpl::iterator;
 
-  LookupResult(Sema &SemaRef, const DeclarationNameInfo &NameInfo,
-               Sema::LookupNameKind LookupKind,
-               Sema::RedeclarationKind Redecl = Sema::NotForRedeclaration)
+  LookupResult(
+      Sema &SemaRef, const DeclarationNameInfo &NameInfo,
+      Sema::LookupNameKind LookupKind,
+      RedeclarationKind Redecl = RedeclarationKind::NotForRedeclaration)
       : SemaPtr(&SemaRef), NameInfo(NameInfo), LookupKind(LookupKind),
-        Redecl(Redecl != Sema::NotForRedeclaration),
-        ExternalRedecl(Redecl == Sema::ForExternalRedeclaration),
-        DiagnoseAccess(Redecl == Sema::NotForRedeclaration),
-        DiagnoseAmbiguous(Redecl == Sema::NotForRedeclaration) {
+        Redecl(Redecl != RedeclarationKind::NotForRedeclaration),
+        ExternalRedecl(Redecl == RedeclarationKind::ForExternalRedeclaration),
+        DiagnoseAccess(Redecl == RedeclarationKind::NotForRedeclaration),
+        DiagnoseAmbiguous(Redecl == RedeclarationKind::NotForRedeclaration) {
     configure();
   }
 
   // TODO: consider whether this constructor should be restricted to take
   // as input a const IdentifierInfo* (instead of Name),
   // forcing other cases towards the constructor taking a DNInfo.
-  LookupResult(Sema &SemaRef, DeclarationName Name, SourceLocation NameLoc,
-               Sema::LookupNameKind LookupKind,
-               Sema::RedeclarationKind Redecl = Sema::NotForRedeclaration)
+  LookupResult(
+      Sema &SemaRef, DeclarationName Name, SourceLocation NameLoc,
+      Sema::LookupNameKind LookupKind,
+      RedeclarationKind Redecl = RedeclarationKind::NotForRedeclaration)
       : SemaPtr(&SemaRef), NameInfo(Name, NameLoc), LookupKind(LookupKind),
-        Redecl(Redecl != Sema::NotForRedeclaration),
-        ExternalRedecl(Redecl == Sema::ForExternalRedeclaration),
-        DiagnoseAccess(Redecl == Sema::NotForRedeclaration),
-        DiagnoseAmbiguous(Redecl == Sema::NotForRedeclaration) {
+        Redecl(Redecl != RedeclarationKind::NotForRedeclaration),
+        ExternalRedecl(Redecl == RedeclarationKind::ForExternalRedeclaration),
+        DiagnoseAccess(Redecl == RedeclarationKind::NotForRedeclaration),
+        DiagnoseAmbiguous(Redecl == RedeclarationKind::NotForRedeclaration) {
     configure();
   }
 
@@ -285,9 +287,10 @@ class LookupResult {
     return ExternalRedecl;
   }
 
-  Sema::RedeclarationKind redeclarationKind() const {
-    return ExternalRedecl ? Sema::ForExternalRedeclaration :
-           Redecl ? Sema::ForVisibleRedeclaration : Sema::NotForRedeclaration;
+  RedeclarationKind redeclarationKind() const {
+    return ExternalRedecl ? RedeclarationKind::ForExternalRedeclaration
+           : Redecl       ? RedeclarationKind::ForVisibleRedeclaration
+                          : RedeclarationKind::NotForRedeclaration;
   }
 
   /// Specify whether hidden declarations are visible, e.g.,
@@ -615,9 +618,9 @@ class LookupResult {
   }
 
   /// Change this lookup's redeclaration kind.
-  void setRedeclarationKind(Sema::RedeclarationKind RK) {
-    Redecl = (RK != Sema::NotForRedeclaration);
-    ExternalRedecl = (RK == Sema::ForExternalRedeclaration);
+  void setRedeclarationKind(RedeclarationKind RK) {
+    Redecl = (RK != RedeclarationKind::NotForRedeclaration);
+    ExternalRedecl = (RK == RedeclarationKind::ForExternalRedeclaration);
     configure();
   }
 

diff --git a/clang/include/clang/Sema/MultiplexExternalSemaSource.h b/clang/include/clang/Sema/MultiplexExternalSemaSource.h
@@ -65,7 +65,7 @@ class MultiplexExternalSemaSource : public ExternalSemaSource {
 
   /// Resolve a declaration ID into a declaration, potentially
   /// building a new declaration.
-  Decl *GetExternalDecl(uint32_t ID) override;
+  Decl *GetExternalDecl(Decl::DeclID ID) override;
 
   /// Complete the redeclaration chain if it's been extended since the
   /// previous generation of the AST source.

diff --git a/clang/include/clang/Sema/ParsedAttr.h b/clang/include/clang/Sema/ParsedAttr.h
@@ -94,7 +94,7 @@ struct PropertyData {
       : GetterId(getterId), SetterId(setterId) {}
 };
 
-} // namespace
+} // namespace detail
 
 /// Wraps an identifier and optional source location for the identifier.
 struct IdentifierLoc {
@@ -743,11 +743,6 @@ class AttributePool {
                      IdentifierInfo *scopeName, SourceLocation scopeLoc,
                      ArgsUnion *args, unsigned numArgs, ParsedAttr::Form form,
                      SourceLocation ellipsisLoc = SourceLocation()) {
-    size_t temp =
-        ParsedAttr::totalSizeToAlloc<ArgsUnion, detail::AvailabilityData,
-                                     detail::TypeTagForDatatypeData, ParsedType,
-                                     detail::PropertyData>(numArgs, 0, 0, 0, 0);
-    (void)temp;
     void *memory = allocate(
         ParsedAttr::totalSizeToAlloc<ArgsUnion, detail::AvailabilityData,
                                      detail::TypeTagForDatatypeData, ParsedType,

diff --git a/clang/include/clang/Sema/Redeclaration.h b/clang/include/clang/Sema/Redeclaration.h
@@ -0,0 +1,31 @@
+//===- Redeclaration.h - Redeclarations--------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines RedeclarationKind enum.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SEMA_REDECLARATION_H
+#define LLVM_CLANG_SEMA_REDECLARATION_H
+
+/// Specifies whether (or how) name lookup is being performed for a
+/// redeclaration (vs. a reference).
+enum class RedeclarationKind {
+  /// The lookup is a reference to this name that is not for the
+  /// purpose of redeclaring the name.
+  NotForRedeclaration = 0,
+  /// The lookup results will be used for redeclaration of a name,
+  /// if an entity by that name already exists and is visible.
+  ForVisibleRedeclaration,
+  /// The lookup results will be used for redeclaration of a name
+  /// with external linkage; non-visible lookup results with external linkage
+  /// may also be found.
+  ForExternalRedeclaration
+};
+
+#endif // LLVM_CLANG_SEMA_REDECLARATION_H
diff --git a/clang/include/clang/Sema/Scope.h b/clang/include/clang/Sema/Scope.h
@@ -156,6 +156,9 @@ class Scope {
     /// This is the scope of an OpenACC Compute Construct, which restricts
     /// jumping into/out of it.
     OpenACCComputeConstructScope = 0x10000000,
+
+    /// This is a scope of type alias declaration.
+    TypeAliasScope = 0x20000000,
   };
 
 private:
@@ -580,6 +583,9 @@ class Scope {
   /// if/switch/while/for statement.
   bool isControlScope() const { return getFlags() & Scope::ControlScope; }
 
+  /// Determine whether this scope is a type alias scope.
+  bool isTypeAliasScope() const { return getFlags() & Scope::TypeAliasScope; }
+
   /// Returns if rhs has a higher scope depth than this.
   ///
   /// The caller is responsible for calling this only if one of the two scopes

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -52,6 +52,7 @@
 #include "clang/Sema/IdentifierResolver.h"
 #include "clang/Sema/ObjCMethodList.h"
 #include "clang/Sema/Ownership.h"
+#include "clang/Sema/Redeclaration.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/SemaBase.h"
 #include "clang/Sema/SemaConcept.h"
@@ -3083,6 +3084,7 @@ class Sema final : public SemaBase {
   Decl *ActOnStartOfFunctionDef(Scope *S, Decl *D,
                                 SkipBodyInfo *SkipBody = nullptr,
                                 FnBodyKind BodyKind = FnBodyKind::Other);
+  void applyFunctionAttributesBeforeParsingBody(Decl *FD);
 
   /// Determine whether we can delay parsing the body of a function or
   /// function template until it is used, assuming we don't care about emitting
@@ -5444,7 +5446,7 @@ class Sema final : public SemaBase {
   ExprResult ActOnPredefinedExpr(SourceLocation Loc, tok::TokenKind Kind);
   ExprResult ActOnIntegerConstant(SourceLocation Loc, uint64_t Val);
 
-  bool CheckLoopHintExpr(Expr *E, SourceLocation Loc);
+  bool CheckLoopHintExpr(Expr *E, SourceLocation Loc, bool AllowZero);
 
   ExprResult ActOnNumericConstant(const Token &Tok, Scope *UDLScope = nullptr);
   ExprResult ActOnCharacterConstant(const Token &Tok,
@@ -6526,7 +6528,10 @@ class Sema final : public SemaBase {
                             SourceLocation RParenLoc);
 
   //// ActOnCXXThis -  Parse 'this' pointer.
-  ExprResult ActOnCXXThis(SourceLocation loc);
+  ExprResult ActOnCXXThis(SourceLocation Loc);
+
+  /// Check whether the type of 'this' is valid in the current context.
+  bool CheckCXXThisType(SourceLocation Loc, QualType Type);
 
   /// Build a CXXThisExpr and mark it referenced in the current context.
   Expr *BuildCXXThisExpr(SourceLocation Loc, QualType Type, bool IsImplicit);
@@ -6948,10 +6953,14 @@ class Sema final : public SemaBase {
   ///@{
 
 public:
+  /// Check whether an expression might be an implicit class member access.
+  bool isPotentialImplicitMemberAccess(const CXXScopeSpec &SS, LookupResult &R,
+                                       bool IsAddressOfOperand);
+
   ExprResult BuildPossibleImplicitMemberExpr(
       const CXXScopeSpec &SS, SourceLocation TemplateKWLoc, LookupResult &R,
-      const TemplateArgumentListInfo *TemplateArgs, const Scope *S,
-      UnresolvedLookupExpr *AsULE = nullptr);
+      const TemplateArgumentListInfo *TemplateArgs, const Scope *S);
+
   ExprResult
   BuildImplicitMemberExpr(const CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
                           LookupResult &R,
@@ -7443,40 +7452,17 @@ class Sema final : public SemaBase {
   typedef std::function<ExprResult(Sema &, TypoExpr *, TypoCorrection)>
       TypoRecoveryCallback;
 
-  /// Specifies whether (or how) name lookup is being performed for a
-  /// redeclaration (vs. a reference).
-  enum RedeclarationKind {
-    /// The lookup is a reference to this name that is not for the
-    /// purpose of redeclaring the name.
-    NotForRedeclaration = 0,
-    /// The lookup results will be used for redeclaration of a name,
-    /// if an entity by that name already exists and is visible.
-    ForVisibleRedeclaration,
-    /// The lookup results will be used for redeclaration of a name
-    /// with external linkage; non-visible lookup results with external linkage
-    /// may also be found.
-    ForExternalRedeclaration
-  };
-
-  RedeclarationKind forRedeclarationInCurContext() const {
-    // A declaration with an owning module for linkage can never link against
-    // anything that is not visible. We don't need to check linkage here; if
-    // the context has internal linkage, redeclaration lookup won't find things
-    // from other TUs, and we can't safely compute linkage yet in general.
-    if (cast<Decl>(CurContext)
-            ->getOwningModuleForLinkage(/*IgnoreLinkage*/ true))
-      return ForVisibleRedeclaration;
-    return ForExternalRedeclaration;
-  }
+  RedeclarationKind forRedeclarationInCurContext() const;
 
   /// Look up a name, looking for a single declaration.  Return
   /// null if the results were absent, ambiguous, or overloaded.
   ///
   /// It is preferable to use the elaborated form and explicitly handle
   /// ambiguity and overloaded.
-  NamedDecl *LookupSingleName(Scope *S, DeclarationName Name,
-                              SourceLocation Loc, LookupNameKind NameKind,
-                              RedeclarationKind Redecl = NotForRedeclaration);
+  NamedDecl *LookupSingleName(
+      Scope *S, DeclarationName Name, SourceLocation Loc,
+      LookupNameKind NameKind,
+      RedeclarationKind Redecl = RedeclarationKind::NotForRedeclaration);
   bool LookupBuiltin(LookupResult &R);
   void LookupNecessaryTypesForBuiltin(Scope *S, unsigned ID);
   bool LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation = false,
@@ -7488,9 +7474,9 @@ class Sema final : public SemaBase {
   bool LookupParsedName(LookupResult &R, Scope *S, CXXScopeSpec *SS,
                         bool AllowBuiltinCreation = false,
                         bool EnteringContext = false);
-  ObjCProtocolDecl *
-  LookupProtocol(IdentifierInfo *II, SourceLocation IdLoc,
-                 RedeclarationKind Redecl = NotForRedeclaration);
+  ObjCProtocolDecl *LookupProtocol(
+      IdentifierInfo *II, SourceLocation IdLoc,
+      RedeclarationKind Redecl = RedeclarationKind::NotForRedeclaration);
   bool LookupInSuper(LookupResult &R, CXXRecordDecl *Class);
 
   void LookupOverloadedOperatorName(OverloadedOperatorKind Op, Scope *S,

diff --git a/clang/include/clang/Sema/SemaOpenACC.h b/clang/include/clang/Sema/SemaOpenACC.h
@@ -44,8 +44,13 @@ class SemaOpenACC : public SemaBase {
       Expr *ConditionExpr;
     };
 
-    std::variant<std::monostate, DefaultDetails, ConditionDetails> Details =
-        std::monostate{};
+    struct IntExprDetails {
+      SmallVector<Expr *> IntExprs;
+    };
+
+    std::variant<std::monostate, DefaultDetails, ConditionDetails,
+                 IntExprDetails>
+        Details = std::monostate{};
 
   public:
     OpenACCParsedClause(OpenACCDirectiveKind DirKind,
@@ -87,6 +92,26 @@ class SemaOpenACC : public SemaBase {
       return std::get<ConditionDetails>(Details).ConditionExpr;
     }
 
+    unsigned getNumIntExprs() const {
+      assert((ClauseKind == OpenACCClauseKind::NumGangs ||
+              ClauseKind == OpenACCClauseKind::NumWorkers ||
+              ClauseKind == OpenACCClauseKind::VectorLength) &&
+             "Parsed clause kind does not have a int exprs");
+      return std::get<IntExprDetails>(Details).IntExprs.size();
+    }
+
+    ArrayRef<Expr *> getIntExprs() {
+      assert((ClauseKind == OpenACCClauseKind::NumGangs ||
+              ClauseKind == OpenACCClauseKind::NumWorkers ||
+              ClauseKind == OpenACCClauseKind::VectorLength) &&
+             "Parsed clause kind does not have a int exprs");
+      return std::get<IntExprDetails>(Details).IntExprs;
+    }
+
+    ArrayRef<Expr *> getIntExprs() const {
+      return const_cast<OpenACCParsedClause *>(this)->getIntExprs();
+    }
+
     void setLParenLoc(SourceLocation EndLoc) { LParenLoc = EndLoc; }
     void setEndLoc(SourceLocation EndLoc) { ClauseRange.setEnd(EndLoc); }
 
@@ -109,6 +134,21 @@ class SemaOpenACC : public SemaBase {
 
       Details = ConditionDetails{ConditionExpr};
     }
+
+    void setIntExprDetails(ArrayRef<Expr *> IntExprs) {
+      assert((ClauseKind == OpenACCClauseKind::NumGangs ||
+              ClauseKind == OpenACCClauseKind::NumWorkers ||
+              ClauseKind == OpenACCClauseKind::VectorLength) &&
+             "Parsed clause kind does not have a int exprs");
+      Details = IntExprDetails{{IntExprs.begin(), IntExprs.end()}};
+    }
+    void setIntExprDetails(llvm::SmallVector<Expr *> &&IntExprs) {
+      assert((ClauseKind == OpenACCClauseKind::NumGangs ||
+              ClauseKind == OpenACCClauseKind::NumWorkers ||
+              ClauseKind == OpenACCClauseKind::VectorLength) &&
+             "Parsed clause kind does not have a int exprs");
+      Details = IntExprDetails{IntExprs};
+    }
   };
 
   SemaOpenACC(Sema &S);
@@ -148,6 +188,11 @@ class SemaOpenACC : public SemaBase {
   /// Called after the directive has been completely parsed, including the
   /// declaration group or associated statement.
   DeclGroupRef ActOnEndDeclDirective();
+
+  /// Called when encountering an 'int-expr' for OpenACC, and manages
+  /// conversions and diagnostics to 'int'.
+  ExprResult ActOnIntExpr(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
+                          SourceLocation Loc, Expr *IntExpr);
 };
 
 } // namespace clang

diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -65,12 +65,85 @@ using IdentifierID = uint32_t;
 /// discovery), with values below NUM_PREDEF_DECL_IDS being reserved.
 /// At the start of a chain of precompiled headers, declaration ID 1 is
 /// used for the translation unit declaration.
+///
+/// FIXME: Merge with Decl::DeclID
 using DeclID = uint32_t;
 
-// FIXME: Turn these into classes so we can have some type safety when
-// we go from local ID to global and vice-versa.
-using LocalDeclID = DeclID;
-using GlobalDeclID = DeclID;
+class LocalDeclID {
+public:
+  explicit LocalDeclID(DeclID ID) : ID(ID) {}
+
+  DeclID get() const { return ID; }
+
+private:
+  DeclID ID;
+};
+
+/// Wrapper class for DeclID. This is helpful to not mix the use of LocalDeclID
+/// and GlobalDeclID to improve the type safety.
+class GlobalDeclID {
+public:
+  GlobalDeclID() : ID(0) {}
+  explicit GlobalDeclID(DeclID ID) : ID(ID) {}
+
+  DeclID get() const { return ID; }
+
+  explicit operator DeclID() const { return ID; }
+
+  friend bool operator==(const GlobalDeclID &LHS, const GlobalDeclID &RHS) {
+    return LHS.ID == RHS.ID;
+  }
+  friend bool operator!=(const GlobalDeclID &LHS, const GlobalDeclID &RHS) {
+    return LHS.ID != RHS.ID;
+  }
+  // We may sort the global decl ID.
+  friend bool operator<(const GlobalDeclID &LHS, const GlobalDeclID &RHS) {
+    return LHS.ID < RHS.ID;
+  }
+  friend bool operator>(const GlobalDeclID &LHS, const GlobalDeclID &RHS) {
+    return LHS.ID > RHS.ID;
+  }
+  friend bool operator<=(const GlobalDeclID &LHS, const GlobalDeclID &RHS) {
+    return LHS.ID <= RHS.ID;
+  }
+  friend bool operator>=(const GlobalDeclID &LHS, const GlobalDeclID &RHS) {
+    return LHS.ID >= RHS.ID;
+  }
+
+private:
+  DeclID ID;
+};
+
+/// A helper iterator adaptor to convert the iterators to `SmallVector<DeclID>`
+/// to the iterators to `SmallVector<GlobalDeclID>`.
+class GlobalDeclIDIterator
+    : public llvm::iterator_adaptor_base<GlobalDeclIDIterator, const DeclID *,
+                                         std::forward_iterator_tag,
+                                         GlobalDeclID> {
+public:
+  GlobalDeclIDIterator() : iterator_adaptor_base(nullptr) {}
+
+  GlobalDeclIDIterator(const DeclID *ID) : iterator_adaptor_base(ID) {}
+
+  value_type operator*() const { return GlobalDeclID(*I); }
+
+  bool operator==(const GlobalDeclIDIterator &RHS) const { return I == RHS.I; }
+};
+
+/// A helper iterator adaptor to convert the iterators to
+/// `SmallVector<GlobalDeclID>` to the iterators to `SmallVector<DeclID>`.
+class DeclIDIterator
+    : public llvm::iterator_adaptor_base<DeclIDIterator, const GlobalDeclID *,
+                                         std::forward_iterator_tag, DeclID> {
+public:
+  DeclIDIterator() : iterator_adaptor_base(nullptr) {}
+
+  DeclIDIterator(const GlobalDeclID *ID) : iterator_adaptor_base(ID) {}
+
+  value_type operator*() const { return DeclID(*I); }
+
+  bool operator==(const DeclIDIterator &RHS) const { return I == RHS.I; }
+};
 
 /// An ID number that refers to a type in an AST file.
 ///
@@ -2056,35 +2129,6 @@ enum CtorInitializerType {
 /// Kinds of cleanup objects owned by ExprWithCleanups.
 enum CleanupObjectKind { COK_Block, COK_CompoundLiteral };
 
-/// Describes the redeclarations of a declaration.
-struct LocalRedeclarationsInfo {
-  // The ID of the first declaration
-  DeclID FirstID;
-
-  // Offset into the array of redeclaration chains.
-  unsigned Offset;
-
-  friend bool operator<(const LocalRedeclarationsInfo &X,
-                        const LocalRedeclarationsInfo &Y) {
-    return X.FirstID < Y.FirstID;
-  }
-
-  friend bool operator>(const LocalRedeclarationsInfo &X,
-                        const LocalRedeclarationsInfo &Y) {
-    return X.FirstID > Y.FirstID;
-  }
-
-  friend bool operator<=(const LocalRedeclarationsInfo &X,
-                         const LocalRedeclarationsInfo &Y) {
-    return X.FirstID <= Y.FirstID;
-  }
-
-  friend bool operator>=(const LocalRedeclarationsInfo &X,
-                         const LocalRedeclarationsInfo &Y) {
-    return X.FirstID >= Y.FirstID;
-  }
-};
-
 /// Describes the categories of an Objective-C class.
 struct ObjCCategoriesInfo {
   // The ID of the definition
@@ -2187,6 +2231,27 @@ template <> struct DenseMapInfo<clang::serialization::DeclarationNameKey> {
   }
 };
 
+template <> struct DenseMapInfo<clang::serialization::GlobalDeclID> {
+  using DeclID = clang::serialization::DeclID;
+  using GlobalDeclID = clang::serialization::GlobalDeclID;
+
+  static GlobalDeclID getEmptyKey() {
+    return GlobalDeclID(DenseMapInfo<DeclID>::getEmptyKey());
+  }
+
+  static GlobalDeclID getTombstoneKey() {
+    return GlobalDeclID(DenseMapInfo<DeclID>::getTombstoneKey());
+  }
+
+  static unsigned getHashValue(const GlobalDeclID &Key) {
+    return DenseMapInfo<DeclID>::getHashValue(Key.get());
+  }
+
+  static bool isEqual(const GlobalDeclID &L, const GlobalDeclID &R) {
+    return L == R;
+  }
+};
+
 } // namespace llvm
 
 #endif // LLVM_CLANG_SERIALIZATION_ASTBITCODES_H
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
@@ -501,8 +501,10 @@ class ASTReader
   /// = I + 1 has already been loaded.
   llvm::PagedVector<Decl *> DeclsLoaded;
 
+  static_assert(std::is_same_v<serialization::DeclID, Decl::DeclID>);
+
   using GlobalDeclMapType =
-      ContinuousRangeMap<serialization::DeclID, ModuleFile *, 4>;
+      ContinuousRangeMap<serialization::GlobalDeclID, ModuleFile *, 4>;
 
   /// Mapping from global declaration IDs to the module in which the
   /// declaration resides.
@@ -511,14 +513,14 @@ class ASTReader
   using FileOffset = std::pair<ModuleFile *, uint64_t>;
   using FileOffsetsTy = SmallVector<FileOffset, 2>;
   using DeclUpdateOffsetsMap =
-      llvm::DenseMap<serialization::DeclID, FileOffsetsTy>;
+      llvm::DenseMap<serialization::GlobalDeclID, FileOffsetsTy>;
 
   /// Declarations that have modifications residing in a later file
   /// in the chain.
   DeclUpdateOffsetsMap DeclUpdateOffsets;
 
   using DelayedNamespaceOffsetMapTy = llvm::DenseMap<
-      serialization::DeclID,
+      serialization::GlobalDeclID,
       std::pair</*LexicalOffset*/ uint64_t, /*VisibleOffset*/ uint64_t>>;
 
   /// Mapping from global declaration IDs to the lexical and visible block
@@ -604,7 +606,11 @@ class ASTReader
 
   /// An array of lexical contents of a declaration context, as a sequence of
   /// Decl::Kind, DeclID pairs.
-  using LexicalContents = ArrayRef<llvm::support::unaligned_uint32_t>;
+  using unalighed_decl_id_t =
+      llvm::support::detail::packed_endian_specific_integral<
+          serialization::DeclID, llvm::endianness::native,
+          llvm::support::unaligned>;
+  using LexicalContents = ArrayRef<unalighed_decl_id_t>;
 
   /// Map from a DeclContext to its lexical contents.
   llvm::DenseMap<const DeclContext*, std::pair<ModuleFile*, LexicalContents>>
@@ -629,7 +635,7 @@ class ASTReader
 
   /// Updates to the visible declarations of declaration contexts that
   /// haven't been loaded yet.
-  llvm::DenseMap<serialization::DeclID, DeclContextVisibleUpdates>
+  llvm::DenseMap<serialization::GlobalDeclID, DeclContextVisibleUpdates>
       PendingVisibleUpdates;
 
   /// The set of C++ or Objective-C classes that have forward
@@ -656,7 +662,8 @@ class ASTReader
   /// Read the record that describes the visible contents of a DC.
   bool ReadVisibleDeclContextStorage(ModuleFile &M,
                                      llvm::BitstreamCursor &Cursor,
-                                     uint64_t Offset, serialization::DeclID ID);
+                                     uint64_t Offset,
+                                     serialization::GlobalDeclID ID);
 
   /// A vector containing identifiers that have already been
   /// loaded.
@@ -809,29 +816,38 @@ class ASTReader
   /// This contains the data loaded from all EAGERLY_DESERIALIZED_DECLS blocks
   /// in the chain. The referenced declarations are deserialized and passed to
   /// the consumer eagerly.
-  SmallVector<serialization::DeclID, 16> EagerlyDeserializedDecls;
+  SmallVector<serialization::GlobalDeclID, 16> EagerlyDeserializedDecls;
 
   /// The IDs of all tentative definitions stored in the chain.
   ///
   /// Sema keeps track of all tentative definitions in a TU because it has to
   /// complete them and pass them on to CodeGen. Thus, tentative definitions in
   /// the PCH chain must be eagerly deserialized.
-  SmallVector<serialization::DeclID, 16> TentativeDefinitions;
+  SmallVector<serialization::GlobalDeclID, 16> TentativeDefinitions;
 
   /// The IDs of all CXXRecordDecls stored in the chain whose VTables are
   /// used.
   ///
   /// CodeGen has to emit VTables for these records, so they have to be eagerly
   /// deserialized.
-  SmallVector<serialization::DeclID, 64> VTableUses;
+  struct VTableUse {
+    serialization::GlobalDeclID ID;
+    SourceLocation::UIntTy RawLoc;
+    bool Used;
+  };
+  SmallVector<VTableUse> VTableUses;
 
   /// A snapshot of the pending instantiations in the chain.
   ///
   /// This record tracks the instantiations that Sema has to perform at the
   /// end of the TU. It consists of a pair of values for every pending
   /// instantiation where the first value is the ID of the decl and the second
   /// is the instantiation location.
-  SmallVector<serialization::DeclID, 64> PendingInstantiations;
+  struct PendingInstantiation {
+    serialization::GlobalDeclID ID;
+    SourceLocation::UIntTy RawLoc;
+  };
+  SmallVector<PendingInstantiation, 64> PendingInstantiations;
 
   //@}
 
@@ -841,11 +857,11 @@ class ASTReader
 
   /// A snapshot of Sema's unused file-scoped variable tracking, for
   /// generating warnings.
-  SmallVector<serialization::DeclID, 16> UnusedFileScopedDecls;
+  SmallVector<serialization::GlobalDeclID, 16> UnusedFileScopedDecls;
 
   /// A list of all the delegating constructors we've seen, to diagnose
   /// cycles.
-  SmallVector<serialization::DeclID, 4> DelegatingCtorDecls;
+  SmallVector<serialization::GlobalDeclID, 4> DelegatingCtorDecls;
 
   /// Method selectors used in a @selector expression. Used for
   /// implementation of -Wselector.
@@ -858,7 +874,7 @@ class ASTReader
   /// The IDs of type aliases for ext_vectors that exist in the chain.
   ///
   /// Used by Sema for finding sugared names for ext_vectors in diagnostics.
-  SmallVector<serialization::DeclID, 4> ExtVectorDecls;
+  SmallVector<serialization::GlobalDeclID, 4> ExtVectorDecls;
 
   //@}
 
@@ -869,7 +885,7 @@ class ASTReader
   /// The IDs of all potentially unused typedef names in the chain.
   ///
   /// Sema tracks these to emit warnings.
-  SmallVector<serialization::DeclID, 16> UnusedLocalTypedefNameCandidates;
+  SmallVector<serialization::GlobalDeclID, 16> UnusedLocalTypedefNameCandidates;
 
   /// Our current depth in #pragma cuda force_host_device begin/end
   /// macros.
@@ -878,7 +894,7 @@ class ASTReader
   /// The IDs of the declarations Sema stores directly.
   ///
   /// Sema tracks a few important decls, such as namespace std, directly.
-  SmallVector<serialization::DeclID, 4> SemaDeclRefs;
+  SmallVector<serialization::GlobalDeclID, 4> SemaDeclRefs;
 
   /// The IDs of the types ASTContext stores directly.
   ///
@@ -889,7 +905,7 @@ class ASTReader
   ///
   /// The AST context tracks a few important decls, currently cudaConfigureCall,
   /// directly.
-  SmallVector<serialization::DeclID, 2> CUDASpecialDeclRefs;
+  SmallVector<serialization::GlobalDeclID, 2> CUDASpecialDeclRefs;
 
   /// The floating point pragma option settings.
   SmallVector<uint64_t, 1> FPPragmaOptions;
@@ -938,11 +954,15 @@ class ASTReader
   llvm::DenseMap<const Decl *, std::set<std::string>> OpenCLDeclExtMap;
 
   /// A list of the namespaces we've seen.
-  SmallVector<serialization::DeclID, 4> KnownNamespaces;
+  SmallVector<serialization::GlobalDeclID, 4> KnownNamespaces;
 
   /// A list of undefined decls with internal linkage followed by the
   /// SourceLocation of a matching ODR-use.
-  SmallVector<serialization::DeclID, 8> UndefinedButUsed;
+  struct UndefinedButUsedDecl {
+    serialization::GlobalDeclID ID;
+    SourceLocation::UIntTy RawLoc;
+  };
+  SmallVector<UndefinedButUsedDecl, 8> UndefinedButUsed;
 
   /// Delete expressions to analyze at the end of translation unit.
   SmallVector<uint64_t, 8> DelayedDeleteExprs;
@@ -954,7 +974,8 @@ class ASTReader
   /// The IDs of all decls to be checked for deferred diags.
   ///
   /// Sema tracks these to emit deferred diags.
-  llvm::SmallSetVector<serialization::DeclID, 4> DeclsToCheckForDeferredDiags;
+  llvm::SmallSetVector<serialization::GlobalDeclID, 4>
+      DeclsToCheckForDeferredDiags;
 
 private:
   struct ImportedSubmodule {
@@ -1091,8 +1112,8 @@ class ASTReader
   ///
   /// The declarations on the identifier chain for these identifiers will be
   /// loaded once the recursive loading has completed.
-  llvm::MapVector<IdentifierInfo *, SmallVector<uint32_t, 4>>
-    PendingIdentifierInfos;
+  llvm::MapVector<IdentifierInfo *, SmallVector<serialization::GlobalDeclID, 4>>
+      PendingIdentifierInfos;
 
   /// The set of lookup results that we have faked in order to support
   /// merging of partially deserialized decls but that we have not yet removed.
@@ -1219,7 +1240,7 @@ class ASTReader
   SmallVector<ObjCInterfaceDecl *, 16> ObjCClassesLoaded;
 
   using KeyDeclsMap =
-      llvm::DenseMap<Decl *, SmallVector<serialization::DeclID, 2>>;
+      llvm::DenseMap<Decl *, SmallVector<serialization::GlobalDeclID, 2>>;
 
   /// A mapping from canonical declarations to the set of global
   /// declaration IDs for key declaration that have been merged with that
@@ -1428,15 +1449,15 @@ class ASTReader
   QualType readTypeRecord(unsigned Index);
   RecordLocation TypeCursorForIndex(unsigned Index);
   void LoadedDecl(unsigned Index, Decl *D);
-  Decl *ReadDeclRecord(serialization::DeclID ID);
+  Decl *ReadDeclRecord(serialization::GlobalDeclID ID);
   void markIncompleteDeclChain(Decl *D);
 
   /// Returns the most recent declaration of a declaration (which must be
   /// of a redeclarable kind) that is either local or has already been loaded
   /// merged into its redecl chain.
   Decl *getMostRecentExistingDecl(Decl *D);
 
-  RecordLocation DeclCursorForID(serialization::DeclID ID,
+  RecordLocation DeclCursorForID(serialization::GlobalDeclID ID,
                                  SourceLocation &Location);
   void loadDeclUpdateRecords(PendingUpdateRecord &Record);
   void loadPendingDeclChain(Decl *D, uint64_t LocalOffset);
@@ -1895,8 +1916,8 @@ class ASTReader
 
   /// Map from a local declaration ID within a given module to a
   /// global declaration ID.
-  serialization::DeclID getGlobalDeclID(ModuleFile &F,
-                                      serialization::LocalDeclID LocalID) const;
+  serialization::GlobalDeclID
+  getGlobalDeclID(ModuleFile &F, serialization::LocalDeclID LocalID) const;
 
   /// Returns true if global DeclID \p ID originated from module \p M.
   bool isDeclIDFromModule(serialization::GlobalDeclID ID, ModuleFile &M) const;
@@ -1910,23 +1931,23 @@ class ASTReader
 
   /// Resolve a declaration ID into a declaration, potentially
   /// building a new declaration.
-  Decl *GetDecl(serialization::DeclID ID);
-  Decl *GetExternalDecl(uint32_t ID) override;
+  Decl *GetDecl(serialization::GlobalDeclID ID);
+  Decl *GetExternalDecl(Decl::DeclID ID) override;
 
   /// Resolve a declaration ID into a declaration. Return 0 if it's not
   /// been loaded yet.
-  Decl *GetExistingDecl(serialization::DeclID ID);
+  Decl *GetExistingDecl(serialization::GlobalDeclID ID);
 
   /// Reads a declaration with the given local ID in the given module.
-  Decl *GetLocalDecl(ModuleFile &F, uint32_t LocalID) {
+  Decl *GetLocalDecl(ModuleFile &F, serialization::LocalDeclID LocalID) {
     return GetDecl(getGlobalDeclID(F, LocalID));
   }
 
   /// Reads a declaration with the given local ID in the given module.
   ///
   /// \returns The requested declaration, casted to the given return type.
-  template<typename T>
-  T *GetLocalDeclAs(ModuleFile &F, uint32_t LocalID) {
+  template <typename T>
+  T *GetLocalDeclAs(ModuleFile &F, serialization::LocalDeclID LocalID) {
     return cast_or_null<T>(GetLocalDecl(F, LocalID));
   }
 
@@ -1937,14 +1958,14 @@ class ASTReader
   /// module file.
   serialization::DeclID
   mapGlobalIDToModuleFileGlobalID(ModuleFile &M,
-                                  serialization::DeclID GlobalID);
+                                  serialization::GlobalDeclID GlobalID);
 
   /// Reads a declaration ID from the given position in a record in the
   /// given module.
   ///
   /// \returns The declaration ID read from the record, adjusted to a global ID.
-  serialization::DeclID ReadDeclID(ModuleFile &F, const RecordData &Record,
-                                   unsigned &Idx);
+  serialization::GlobalDeclID
+  ReadDeclID(ModuleFile &F, const RecordData &Record, unsigned &Idx);
 
   /// Reads a declaration from the given position in a record in the
   /// given module.
@@ -2118,9 +2139,10 @@ class ASTReader
   void LoadSelector(Selector Sel);
 
   void SetIdentifierInfo(unsigned ID, IdentifierInfo *II);
-  void SetGloballyVisibleDecls(IdentifierInfo *II,
-                               const SmallVectorImpl<uint32_t> &DeclIDs,
-                               SmallVectorImpl<Decl *> *Decls = nullptr);
+  void SetGloballyVisibleDecls(
+      IdentifierInfo *II,
+      const SmallVectorImpl<serialization::GlobalDeclID> &DeclIDs,
+      SmallVectorImpl<Decl *> *Decls = nullptr);
 
   /// Report a diagnostic.
   DiagnosticBuilder Diag(unsigned DiagID) const;
@@ -2361,7 +2383,7 @@ class ASTReader
 
   // Contains the IDs for declarations that were requested before we have
   // access to a Sema object.
-  SmallVector<uint64_t, 16> PreloadedDeclIDs;
+  SmallVector<serialization::GlobalDeclID, 16> PreloadedDeclIDs;
 
   /// Retrieve the semantic analysis object used to analyze the
   /// translation unit in which the precompiled header is being

diff --git a/clang/include/clang/Serialization/ASTRecordReader.h b/clang/include/clang/Serialization/ASTRecordReader.h
@@ -103,13 +103,6 @@ class ASTRecordReader
                                                  DC);
   }
 
-  /// Read the record that describes the visible contents of a DC.
-  bool readVisibleDeclContextStorage(uint64_t Offset,
-                                     serialization::DeclID ID) {
-    return Reader->ReadVisibleDeclContextStorage(*F, F->DeclsCursor, Offset,
-                                                 ID);
-  }
-
   ExplicitSpecifier readExplicitSpec() {
     uint64_t Kind = readInt();
     bool HasExpr = Kind & 0x1;
@@ -143,8 +136,7 @@ class ASTRecordReader
   /// Reads a declaration with the given local ID in the given module.
   ///
   /// \returns The requested declaration, casted to the given return type.
-  template<typename T>
-  T *GetLocalDeclAs(uint32_t LocalID) {
+  template <typename T> T *GetLocalDeclAs(serialization::LocalDeclID LocalID) {
     return cast_or_null<T>(Reader->GetLocalDecl(*F, LocalID));
   }
 
@@ -190,7 +182,7 @@ class ASTRecordReader
   /// Reads a declaration ID from the given position in this record.
   ///
   /// \returns The declaration ID read from the record, adjusted to a global ID.
-  serialization::DeclID readDeclID() {
+  serialization::GlobalDeclID readDeclID() {
     return Reader->ReadDeclID(*F, Record, Idx);
   }
 

diff --git a/clang/include/clang/Serialization/ASTWriter.h b/clang/include/clang/Serialization/ASTWriter.h
@@ -399,6 +399,11 @@ class ASTWriter : public ASTDeserializationListener,
   /// record containing modifications to them.
   DeclUpdateMap DeclUpdates;
 
+  /// DeclUpdates added during parsing the GMF. We split these from
+  /// DeclUpdates since we want to add these updates in GMF on need.
+  /// Only meaningful for reduced BMI.
+  DeclUpdateMap DeclUpdatesFromGMF;
+
   using FirstLatestDeclMap = llvm::DenseMap<Decl *, Decl *>;
 
   /// Map of first declarations from a chained PCH that point to the
@@ -554,6 +559,8 @@ class ASTWriter : public ASTDeserializationListener,
   void WriteIdentifierTable(Preprocessor &PP, IdentifierResolver &IdResolver,
                             bool IsModule);
   void WriteDeclAndTypes(ASTContext &Context);
+  void PrepareWritingSpecialDecls(Sema &SemaRef);
+  void WriteSpecialDeclRecords(Sema &SemaRef);
   void WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord);
   void WriteDeclContextVisibleUpdate(const DeclContext *DC);
   void WriteFPPragmaOptions(const FPOptionsOverride &Opts);
@@ -707,6 +714,8 @@ class ASTWriter : public ASTDeserializationListener,
 
   /// Emit a reference to a declaration.
   void AddDeclRef(const Decl *D, RecordDataImpl &Record);
+  // Emit a reference to a declaration if the declaration was emitted.
+  void AddEmittedDeclRef(const Decl *D, RecordDataImpl &Record);
 
   /// Force a declaration to be emitted and get its ID.
   serialization::DeclID GetDeclRef(const Decl *D);
@@ -866,6 +875,11 @@ class ASTWriter : public ASTDeserializationListener,
   void RedefinedHiddenDefinition(const NamedDecl *D, Module *M) override;
   void AddedAttributeToRecord(const Attr *Attr,
                               const RecordDecl *Record) override;
+  void EnteringModulePurview() override;
+  void AddedManglingNumber(const Decl *D, unsigned) override;
+  void AddedStaticLocalNumbers(const Decl *D, unsigned) override;
+  void AddedAnonymousNamespace(const TranslationUnitDecl *,
+                               NamespaceDecl *AnonNamespace) override;
 };
 
 /// AST and semantic-analysis consumer that generates a

diff --git a/clang/include/clang/Serialization/ModuleFile.h b/clang/include/clang/Serialization/ModuleFile.h
@@ -462,7 +462,7 @@ class ModuleFile {
   serialization::DeclID BaseDeclID = 0;
 
   /// Remapping table for declaration IDs in this module.
-  ContinuousRangeMap<uint32_t, int, 2> DeclRemap;
+  ContinuousRangeMap<serialization::DeclID, int, 2> DeclRemap;
 
   /// Mapping from the module files that this module file depends on
   /// to the base declaration ID for that module as it is understood within this
@@ -474,7 +474,7 @@ class ModuleFile {
   llvm::DenseMap<ModuleFile *, serialization::DeclID> GlobalToLocalDeclIDs;
 
   /// Array of file-level DeclIDs sorted by file.
-  const serialization::DeclID *FileSortedDecls = nullptr;
+  const serialization::LocalDeclID *FileSortedDecls = nullptr;
   unsigned NumFileSortedDecls = 0;
 
   /// Array of category list location information within this

diff --git a/clang/include/clang/Support/RISCVVIntrinsicUtils.h b/clang/include/clang/Support/RISCVVIntrinsicUtils.h
@@ -502,7 +502,8 @@ enum RVVRequire : uint32_t {
   RVV_REQ_Zvksed = 1 << 14,
   RVV_REQ_Zvksh = 1 << 15,
   RVV_REQ_Zvfbfwma = 1 << 16,
-  RVV_REQ_Experimental = 1 << 17,
+  RVV_REQ_Zvfbfmin = 1 << 17,
+  RVV_REQ_Experimental = 1 << 18,
 
   LLVM_MARK_AS_BITMASK_ENUM(RVV_REQ_Experimental)
 };

diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
@@ -908,7 +908,8 @@ void APValue::printPretty(raw_ostream &Out, const PrintingPolicy &Policy,
     for (const auto *FI : RD->fields()) {
       if (!First)
         Out << ", ";
-      if (FI->isUnnamedBitfield()) continue;
+      if (FI->isUnnamedBitField())
+        continue;
       getStructField(FI->getFieldIndex()).
         printPretty(Out, Policy, FI->getType(), Ctx);
       First = false;

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
@@ -1083,7 +1083,8 @@ void ASTContext::addModuleInitializer(Module *M, Decl *D) {
   Inits->Initializers.push_back(D);
 }
 
-void ASTContext::addLazyModuleInitializers(Module *M, ArrayRef<uint32_t> IDs) {
+void ASTContext::addLazyModuleInitializers(Module *M,
+                                           ArrayRef<Decl::DeclID> IDs) {
   auto *&Inits = ModuleInitializers[M];
   if (!Inits)
     Inits = new (*this) PerModuleInitializers;
@@ -2684,7 +2685,7 @@ getSubobjectSizeInBits(const FieldDecl *Field, const ASTContext &Context,
   if (Field->isBitField()) {
     // If we have explicit padding bits, they don't contribute bits
     // to the actual object representation, so return 0.
-    if (Field->isUnnamedBitfield())
+    if (Field->isUnnamedBitField())
       return 0;
 
     int64_t BitfieldSize = Field->getBitWidthValue(Context);
@@ -7241,6 +7242,14 @@ QualType ASTContext::isPromotableBitField(Expr *E) const {
   //        We perform that promotion here to match GCC and C++.
   // FIXME: C does not permit promotion of an enum bit-field whose rank is
   //        greater than that of 'int'. We perform that promotion to match GCC.
+  //
+  // C23 6.3.1.1p2:
+  //   The value from a bit-field of a bit-precise integer type is converted to
+  //   the corresponding bit-precise integer type. (The rest is the same as in
+  //   C11.)
+  if (QualType QT = Field->getType(); QT->isBitIntType())
+    return QT;
+
   if (BitWidth < IntSize)
     return IntTy;
 
@@ -12245,8 +12254,13 @@ QualType ASTContext::getRealTypeForBitwidth(unsigned DestWidth,
 }
 
 void ASTContext::setManglingNumber(const NamedDecl *ND, unsigned Number) {
-  if (Number > 1)
-    MangleNumbers[ND] = Number;
+  if (Number <= 1)
+    return;
+
+  MangleNumbers[ND] = Number;
+
+  if (Listener)
+    Listener->AddedManglingNumber(ND, Number);
 }
 
 unsigned ASTContext::getManglingNumber(const NamedDecl *ND,
@@ -12265,8 +12279,13 @@ unsigned ASTContext::getManglingNumber(const NamedDecl *ND,
 }
 
 void ASTContext::setStaticLocalNumber(const VarDecl *VD, unsigned Number) {
-  if (Number > 1)
-    StaticLocalNumbers[VD] = Number;
+  if (Number <= 1)
+    return;
+
+  StaticLocalNumbers[VD] = Number;
+
+  if (Listener)
+    Listener->AddedStaticLocalNumbers(VD, Number);
 }
 
 unsigned ASTContext::getStaticLocalNumber(const VarDecl *VD) const {

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
@@ -695,7 +695,7 @@ namespace clang {
     // Returns true if the given function has a placeholder return type and
     // that type is declared inside the body of the function.
     // E.g. auto f() { struct X{}; return X(); }
-    bool hasAutoReturnTypeDeclaredInside(FunctionDecl *D);
+    bool hasReturnTypeDeclaredInside(FunctionDecl *D);
   };
 
 template <typename InContainerTy>
@@ -3647,15 +3647,28 @@ class IsTypeDeclaredInsideVisitor
 };
 } // namespace
 
-/// This function checks if the function has 'auto' return type that contains
+/// This function checks if the given function has a return type that contains
 /// a reference (in any way) to a declaration inside the same function.
-bool ASTNodeImporter::hasAutoReturnTypeDeclaredInside(FunctionDecl *D) {
+bool ASTNodeImporter::hasReturnTypeDeclaredInside(FunctionDecl *D) {
   QualType FromTy = D->getType();
   const auto *FromFPT = FromTy->getAs<FunctionProtoType>();
   assert(FromFPT && "Must be called on FunctionProtoType");
 
+  auto IsCXX11LambdaWithouTrailingReturn = [&]() {
+    if (Importer.FromContext.getLangOpts().CPlusPlus14) // C++14 or later
+      return false;
+
+    if (FromFPT->hasTrailingReturn())
+      return false;
+
+    if (const auto *MD = dyn_cast<CXXMethodDecl>(D))
+      return cast<CXXRecordDecl>(MD->getDeclContext())->isLambda();
+
+    return false;
+  };
+
   QualType RetT = FromFPT->getReturnType();
-  if (isa<AutoType>(RetT.getTypePtr())) {
+  if (isa<AutoType>(RetT.getTypePtr()) || IsCXX11LambdaWithouTrailingReturn()) {
     FunctionDecl *Def = D->getDefinition();
     IsTypeDeclaredInsideVisitor Visitor(Def ? Def : D);
     return Visitor.CheckType(RetT);
@@ -3811,7 +3824,7 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
     // E.g.: auto foo() { struct X{}; return X(); }
     // To avoid an infinite recursion when importing, create the FunctionDecl
     // with a simplified return type.
-    if (hasAutoReturnTypeDeclaredInside(D)) {
+    if (hasReturnTypeDeclaredInside(D)) {
       FromReturnTy = Importer.getFromContext().VoidTy;
       UsedDifferentProtoType = true;
     }
@@ -8561,8 +8574,8 @@ ASTNodeImporter::VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E) {
 
   return UnresolvedLookupExpr::Create(
       Importer.getToContext(), *ToNamingClassOrErr, *ToQualifierLocOrErr,
-      ToNameInfo, E->requiresADL(), E->isOverloaded(), ToDecls.begin(),
-      ToDecls.end());
+      ToNameInfo, E->requiresADL(), ToDecls.begin(), ToDecls.end(),
+      /*KnownDependent=*/E->isTypeDependent());
 }
 
 ExpectedStmt

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
@@ -2151,7 +2151,7 @@ VarDecl *VarDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation StartL,
   return new (C, DC) VarDecl(Var, C, DC, StartL, IdL, Id, T, TInfo, S);
 }
 
-VarDecl *VarDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+VarDecl *VarDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID)
       VarDecl(Var, C, nullptr, SourceLocation(), SourceLocation(), nullptr,
               QualType(), nullptr, SC_None);
@@ -2929,7 +2929,7 @@ QualType ParmVarDecl::getOriginalType() const {
   return T;
 }
 
-ParmVarDecl *ParmVarDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+ParmVarDecl *ParmVarDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID)
       ParmVarDecl(ParmVar, C, nullptr, SourceLocation(), SourceLocation(),
                   nullptr, QualType(), nullptr, SC_None, nullptr);
@@ -4553,7 +4553,7 @@ FieldDecl *FieldDecl::Create(const ASTContext &C, DeclContext *DC,
                                BW, Mutable, InitStyle);
 }
 
-FieldDecl *FieldDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+FieldDecl *FieldDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) FieldDecl(Field, nullptr, SourceLocation(),
                                SourceLocation(), nullptr, QualType(), nullptr,
                                nullptr, false, ICIS_NoInit);
@@ -4597,7 +4597,7 @@ unsigned FieldDecl::getBitWidthValue(const ASTContext &Ctx) const {
 }
 
 bool FieldDecl::isZeroLengthBitField(const ASTContext &Ctx) const {
-  return isUnnamedBitfield() && !getBitWidth()->isValueDependent() &&
+  return isUnnamedBitField() && !getBitWidth()->isValueDependent() &&
          getBitWidthValue(Ctx) == 0;
 }
 
@@ -4863,7 +4863,7 @@ EnumDecl *EnumDecl::Create(ASTContext &C, DeclContext *DC,
   return Enum;
 }
 
-EnumDecl *EnumDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+EnumDecl *EnumDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   EnumDecl *Enum =
       new (C, ID) EnumDecl(C, nullptr, SourceLocation(), SourceLocation(),
                            nullptr, nullptr, false, false, false);
@@ -5025,7 +5025,7 @@ RecordDecl *RecordDecl::Create(const ASTContext &C, TagKind TK, DeclContext *DC,
   return R;
 }
 
-RecordDecl *RecordDecl::CreateDeserialized(const ASTContext &C, unsigned ID) {
+RecordDecl *RecordDecl::CreateDeserialized(const ASTContext &C, Decl::DeclID ID) {
   RecordDecl *R = new (C, ID)
       RecordDecl(Record, TagTypeKind::Struct, C, nullptr, SourceLocation(),
                  SourceLocation(), nullptr, nullptr);
@@ -5274,6 +5274,13 @@ TranslationUnitDecl *TranslationUnitDecl::Create(ASTContext &C) {
   return new (C, (DeclContext *)nullptr) TranslationUnitDecl(C);
 }
 
+void TranslationUnitDecl::setAnonymousNamespace(NamespaceDecl *D) {
+  AnonymousNamespace = D;
+
+  if (ASTMutationListener *Listener = Ctx.getASTMutationListener())
+    Listener->AddedAnonymousNamespace(this, D);
+}
+
 void PragmaCommentDecl::anchor() {}
 
 PragmaCommentDecl *PragmaCommentDecl::Create(const ASTContext &C,
@@ -5290,7 +5297,7 @@ PragmaCommentDecl *PragmaCommentDecl::Create(const ASTContext &C,
 }
 
 PragmaCommentDecl *PragmaCommentDecl::CreateDeserialized(ASTContext &C,
-                                                         unsigned ID,
+                                                         Decl::DeclID ID,
                                                          unsigned ArgSize) {
   return new (C, ID, additionalSizeToAlloc<char>(ArgSize + 1))
       PragmaCommentDecl(nullptr, SourceLocation(), PCK_Unknown);
@@ -5315,7 +5322,7 @@ PragmaDetectMismatchDecl::Create(const ASTContext &C, TranslationUnitDecl *DC,
 }
 
 PragmaDetectMismatchDecl *
-PragmaDetectMismatchDecl::CreateDeserialized(ASTContext &C, unsigned ID,
+PragmaDetectMismatchDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID,
                                              unsigned NameValueSize) {
   return new (C, ID, additionalSizeToAlloc<char>(NameValueSize + 1))
       PragmaDetectMismatchDecl(nullptr, SourceLocation(), 0);
@@ -5342,7 +5349,7 @@ LabelDecl *LabelDecl::Create(ASTContext &C, DeclContext *DC,
   return new (C, DC) LabelDecl(DC, IdentL, II, nullptr, GnuLabelL);
 }
 
-LabelDecl *LabelDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+LabelDecl *LabelDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) LabelDecl(nullptr, SourceLocation(), nullptr, nullptr,
                                SourceLocation());
 }
@@ -5383,7 +5390,7 @@ ImplicitParamDecl *ImplicitParamDecl::Create(ASTContext &C, QualType Type,
 }
 
 ImplicitParamDecl *ImplicitParamDecl::CreateDeserialized(ASTContext &C,
-                                                         unsigned ID) {
+                                                         Decl::DeclID ID) {
   return new (C, ID) ImplicitParamDecl(C, QualType(), ImplicitParamKind::Other);
 }
 
@@ -5401,7 +5408,7 @@ FunctionDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
   return New;
 }
 
-FunctionDecl *FunctionDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+FunctionDecl *FunctionDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) FunctionDecl(
       Function, C, nullptr, SourceLocation(), DeclarationNameInfo(), QualType(),
       nullptr, SC_None, false, false, ConstexprSpecKind::Unspecified, nullptr);
@@ -5411,7 +5418,7 @@ BlockDecl *BlockDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L) {
   return new (C, DC) BlockDecl(DC, L);
 }
 
-BlockDecl *BlockDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+BlockDecl *BlockDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) BlockDecl(nullptr, SourceLocation());
 }
 
@@ -5425,7 +5432,7 @@ CapturedDecl *CapturedDecl::Create(ASTContext &C, DeclContext *DC,
       CapturedDecl(DC, NumParams);
 }
 
-CapturedDecl *CapturedDecl::CreateDeserialized(ASTContext &C, unsigned ID,
+CapturedDecl *CapturedDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID,
                                                unsigned NumParams) {
   return new (C, ID, additionalSizeToAlloc<ImplicitParamDecl *>(NumParams))
       CapturedDecl(nullptr, NumParams);
@@ -5452,7 +5459,7 @@ EnumConstantDecl *EnumConstantDecl::Create(ASTContext &C, EnumDecl *CD,
 }
 
 EnumConstantDecl *
-EnumConstantDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+EnumConstantDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) EnumConstantDecl(C, nullptr, SourceLocation(), nullptr,
                                       QualType(), nullptr, llvm::APSInt());
 }
@@ -5479,7 +5486,7 @@ IndirectFieldDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L,
 }
 
 IndirectFieldDecl *IndirectFieldDecl::CreateDeserialized(ASTContext &C,
-                                                         unsigned ID) {
+                                                         Decl::DeclID ID) {
   return new (C, ID)
       IndirectFieldDecl(C, nullptr, SourceLocation(), DeclarationName(),
                         QualType(), std::nullopt);
@@ -5540,7 +5547,7 @@ bool TypedefNameDecl::isTransparentTagSlow() const {
   return isTransparent;
 }
 
-TypedefDecl *TypedefDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+TypedefDecl *TypedefDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) TypedefDecl(C, nullptr, SourceLocation(), SourceLocation(),
                                  nullptr, nullptr);
 }
@@ -5553,7 +5560,7 @@ TypeAliasDecl *TypeAliasDecl::Create(ASTContext &C, DeclContext *DC,
   return new (C, DC) TypeAliasDecl(C, DC, StartLoc, IdLoc, Id, TInfo);
 }
 
-TypeAliasDecl *TypeAliasDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+TypeAliasDecl *TypeAliasDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) TypeAliasDecl(C, nullptr, SourceLocation(),
                                    SourceLocation(), nullptr, nullptr);
 }
@@ -5584,7 +5591,7 @@ FileScopeAsmDecl *FileScopeAsmDecl::Create(ASTContext &C, DeclContext *DC,
 }
 
 FileScopeAsmDecl *FileScopeAsmDecl::CreateDeserialized(ASTContext &C,
-                                                       unsigned ID) {
+                                                       Decl::DeclID ID) {
   return new (C, ID) FileScopeAsmDecl(nullptr, nullptr, SourceLocation(),
                                       SourceLocation());
 }
@@ -5602,7 +5609,7 @@ TopLevelStmtDecl *TopLevelStmtDecl::Create(ASTContext &C, Stmt *Statement) {
 }
 
 TopLevelStmtDecl *TopLevelStmtDecl::CreateDeserialized(ASTContext &C,
-                                                       unsigned ID) {
+                                                       Decl::DeclID ID) {
   return new (C, ID)
       TopLevelStmtDecl(/*DC=*/nullptr, SourceLocation(), /*S=*/nullptr);
 }
@@ -5623,7 +5630,7 @@ EmptyDecl *EmptyDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L) {
   return new (C, DC) EmptyDecl(DC, L);
 }
 
-EmptyDecl *EmptyDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+EmptyDecl *EmptyDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) EmptyDecl(nullptr, SourceLocation());
 }
 
@@ -5656,7 +5663,7 @@ HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
   return Result;
 }
 
-HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) HLSLBufferDecl(nullptr, false, SourceLocation(), nullptr,
                                     SourceLocation(), SourceLocation());
 }
@@ -5712,7 +5719,7 @@ ImportDecl *ImportDecl::CreateImplicit(ASTContext &C, DeclContext *DC,
   return Import;
 }
 
-ImportDecl *ImportDecl::CreateDeserialized(ASTContext &C, unsigned ID,
+ImportDecl *ImportDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID,
                                            unsigned NumLocations) {
   return new (C, ID, additionalSizeToAlloc<SourceLocation>(NumLocations))
       ImportDecl(EmptyShell());
@@ -5745,6 +5752,6 @@ ExportDecl *ExportDecl::Create(ASTContext &C, DeclContext *DC,
   return new (C, DC) ExportDecl(DC, ExportLoc);
 }
 
-ExportDecl *ExportDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+ExportDecl *ExportDecl::CreateDeserialized(ASTContext &C, Decl::DeclID ID) {
   return new (C, ID) ExportDecl(nullptr, SourceLocation());
 }
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
@@ -71,7 +71,7 @@ void Decl::updateOutOfDate(IdentifierInfo &II) const {
 #include "clang/AST/DeclNodes.inc"
 
 void *Decl::operator new(std::size_t Size, const ASTContext &Context,
-                         unsigned ID, std::size_t Extra) {
+                         Decl::DeclID ID, std::size_t Extra) {
   // Allocate an extra 8 bytes worth of storage, which ensures that the
   // resulting pointer will still be 8-byte aligned.
   static_assert(sizeof(unsigned) * 2 >= alignof(Decl),