diff --git a/bolt/lib/Rewrite/DWARFRewriter.cpp b/bolt/lib/Rewrite/DWARFRewriter.cpp
@@ -184,7 +184,7 @@ namespace bolt {
 /// Emits debug information into .debug_info or .debug_types section.
 class DIEStreamer : public DwarfStreamer {
   DIEBuilder *DIEBldr;
-  DWARFRewriter &Rewriter;
+  GDBIndex &GDBIndexSection;
 
 private:
   /// Emit the compilation unit header for \p Unit in the debug_info
@@ -247,7 +247,7 @@ class DIEStreamer : public DwarfStreamer {
     const uint64_t TypeSignature = cast<DWARFTypeUnit>(Unit).getTypeHash();
     DIE *TypeDIE = DIEBldr->getTypeDIE(Unit);
     const DIEBuilder::DWARFUnitInfo &UI = DIEBldr->getUnitInfoByDwarfUnit(Unit);
-    Rewriter.addGDBTypeUnitEntry(
+    GDBIndexSection.addGDBTypeUnitEntry(
         {UI.UnitOffset, TypeSignature, TypeDIE->getOffset()});
     if (Unit.getVersion() < 5) {
       // Switch the section to .debug_types section.
@@ -278,12 +278,12 @@ class DIEStreamer : public DwarfStreamer {
   }
 
 public:
-  DIEStreamer(DIEBuilder *DIEBldr, DWARFRewriter &Rewriter,
+  DIEStreamer(DIEBuilder *DIEBldr, GDBIndex &GDBIndexSection,
               DWARFLinkerBase::OutputFileType OutFileType,
               raw_pwrite_stream &OutFile,
               DWARFLinkerBase::MessageHandlerTy Warning)
       : DwarfStreamer(OutFileType, OutFile, Warning), DIEBldr(DIEBldr),
-        Rewriter(Rewriter){};
+        GDBIndexSection(GDBIndexSection) {};
 
   using DwarfStreamer::emitCompileUnitHeader;
 
@@ -326,12 +326,11 @@ static cl::opt<bool> KeepARanges(
         "keep or generate .debug_aranges section if .gdb_index is written"),
     cl::Hidden, cl::cat(BoltCategory));
 
-static cl::opt<bool>
-DeterministicDebugInfo("deterministic-debuginfo",
-  cl::desc("disables parallel execution of tasks that may produce "
-           "nondeterministic debug info"),
-  cl::init(true),
-  cl::cat(BoltCategory));
+static cl::opt<bool> DeterministicDebugInfo(
+    "deterministic-debuginfo",
+    cl::desc("disables parallel execution of tasks that may produce "
+             "nondeterministic debug info"),
+    cl::init(true), cl::cat(BoltCategory));
 
 static cl::opt<std::string> DwarfOutputPath(
     "dwarf-output-path",
@@ -460,10 +459,11 @@ static std::optional<uint64_t> getAsAddress(const DWARFUnit &DU,
 static std::unique_ptr<DIEStreamer>
 createDIEStreamer(const Triple &TheTriple, raw_pwrite_stream &OutFile,
                   StringRef Swift5ReflectionSegmentName, DIEBuilder &DIEBldr,
-                  DWARFRewriter &Rewriter) {
+                  GDBIndex &GDBIndexSection) {
 
   std::unique_ptr<DIEStreamer> Streamer = std::make_unique<DIEStreamer>(
-      &DIEBldr, Rewriter, DWARFLinkerBase::OutputFileType::Object, OutFile,
+      &DIEBldr, GDBIndexSection, DWARFLinkerBase::OutputFileType::Object,
+      OutFile,
       [&](const Twine &Warning, StringRef Context, const DWARFDie *) {});
   Error Err = Streamer->init(TheTriple, Swift5ReflectionSegmentName);
   if (Err)
@@ -484,13 +484,12 @@ emitUnit(DIEBuilder &DIEBldr, DIEStreamer &Streamer, DWARFUnit &Unit) {
   return {U.UnitOffset, U.UnitLength, TypeHash};
 }
 
-static void emitDWOBuilder(const std::string &DWOName,
-                           DIEBuilder &DWODIEBuilder, DWARFRewriter &Rewriter,
-                           DWARFUnit &SplitCU, DWARFUnit &CU,
-                           DWARFRewriter::DWPState &State,
-                           DebugLocWriter &LocWriter,
-                           DebugStrOffsetsWriter &StrOffstsWriter,
-                           DebugStrWriter &StrWriter) {
+static void
+emitDWOBuilder(const std::string &DWOName, DIEBuilder &DWODIEBuilder,
+               DWARFRewriter &Rewriter, DWARFUnit &SplitCU, DWARFUnit &CU,
+               DWARFRewriter::DWPState &State, DebugLocWriter &LocWriter,
+               DebugStrOffsetsWriter &StrOffstsWriter,
+               DebugStrWriter &StrWriter, GDBIndex &GDBIndexSection) {
   // Populate debug_info and debug_abbrev for current dwo into StringRef.
   DWODIEBuilder.generateAbbrevs();
   DWODIEBuilder.finish();
@@ -500,8 +499,9 @@ static void emitDWOBuilder(const std::string &DWOName,
       std::make_shared<raw_svector_ostream>(OutBuffer);
   const object::ObjectFile *File = SplitCU.getContext().getDWARFObj().getFile();
   auto TheTriple = std::make_unique<Triple>(File->makeTriple());
-  std::unique_ptr<DIEStreamer> Streamer = createDIEStreamer(
-      *TheTriple, *ObjOS, "DwoStreamerInitAug2", DWODIEBuilder, Rewriter);
+  std::unique_ptr<DIEStreamer> Streamer =
+      createDIEStreamer(*TheTriple, *ObjOS, "DwoStreamerInitAug2",
+                        DWODIEBuilder, GDBIndexSection);
   DWARFRewriter::UnitMetaVectorType TUMetaVector;
   DWARFRewriter::UnitMeta CUMI = {0, 0, 0};
   if (SplitCU.getContext().getMaxDWOVersion() >= 5) {
@@ -652,6 +652,7 @@ void DWARFRewriter::updateDebugInfo() {
 
   DWARF5AcceleratorTable DebugNamesTable(opts::CreateDebugNames, BC,
                                          *StrWriter);
+  GDBIndex GDBIndexSection(BC);
   DWPState State;
   if (opts::WriteDWP)
     initDWPState(State);
@@ -704,7 +705,8 @@ void DWARFRewriter::updateDebugInfo() {
         TempRangesSectionWriter->finalizeSection();
 
       emitDWOBuilder(DWOName, DWODIEBuilder, *this, **SplitCU, *Unit, State,
-                     DebugLocDWoWriter, DWOStrOffstsWriter, DWOStrWriter);
+                     DebugLocDWoWriter, DWOStrOffstsWriter, DWOStrWriter,
+                     GDBIndexSection);
     }
 
     if (Unit->getVersion() >= 5) {
@@ -729,9 +731,10 @@ void DWARFRewriter::updateDebugInfo() {
       std::make_unique<raw_svector_ostream>(OutBuffer);
   const object::ObjectFile *File = BC.DwCtx->getDWARFObj().getFile();
   auto TheTriple = std::make_unique<Triple>(File->makeTriple());
-  std::unique_ptr<DIEStreamer> Streamer =
-      createDIEStreamer(*TheTriple, *ObjOS, "TypeStreamer", DIEBlder, *this);
-  CUOffsetMap OffsetMap = finalizeTypeSections(DIEBlder, *Streamer);
+  std::unique_ptr<DIEStreamer> Streamer = createDIEStreamer(
+      *TheTriple, *ObjOS, "TypeStreamer", DIEBlder, GDBIndexSection);
+  CUOffsetMap OffsetMap =
+      finalizeTypeSections(DIEBlder, *Streamer, GDBIndexSection);
 
   const bool SingleThreadedMode =
       opts::NoThreads || opts::DeterministicDebugInfo;
@@ -761,7 +764,8 @@ void DWARFRewriter::updateDebugInfo() {
 
   finalizeDebugSections(DIEBlder, DebugNamesTable, *Streamer, *ObjOS,
                         OffsetMap);
-  updateGdbIndexSection(OffsetMap, CUIndex);
+  GDBIndexSection.updateGdbIndexSection(OffsetMap, CUIndex,
+                                        *ARangesSectionWriter);
 }
 
 void DWARFRewriter::updateUnitDebugInfo(
@@ -1429,7 +1433,8 @@ void DWARFRewriter::updateLineTableOffsets(const MCAsmLayout &Layout) {
 }
 
 CUOffsetMap DWARFRewriter::finalizeTypeSections(DIEBuilder &DIEBlder,
-                                                DIEStreamer &Streamer) {
+                                                DIEStreamer &Streamer,
+                                                GDBIndex &GDBIndexSection) {
   // update TypeUnit DW_AT_stmt_list with new .debug_line information.
   auto updateLineTable = [&](const DWARFUnit &Unit) -> void {
     DIE *UnitDIE = DIEBlder.getUnitDIEbyUnit(Unit);
@@ -1449,8 +1454,8 @@ CUOffsetMap DWARFRewriter::finalizeTypeSections(DIEBuilder &DIEBlder,
       std::make_shared<raw_svector_ostream>(OutBuffer);
   const object::ObjectFile *File = BC.DwCtx->getDWARFObj().getFile();
   auto TheTriple = std::make_unique<Triple>(File->makeTriple());
-  std::unique_ptr<DIEStreamer> TypeStreamer =
-      createDIEStreamer(*TheTriple, *ObjOS, "TypeStreamer", DIEBlder, *this);
+  std::unique_ptr<DIEStreamer> TypeStreamer = createDIEStreamer(
+      *TheTriple, *ObjOS, "TypeStreamer", DIEBlder, GDBIndexSection);
 
   // generate debug_info and CUMap
   CUOffsetMap CUMap;

diff --git a/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp b/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
@@ -616,7 +616,7 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     return getTargetAddend(Op.getExpr());
   }
 
-  bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                            MCContext *Ctx) const override {
     assert((isCall(Inst) || isBranch(Inst)) && !isIndirectBranch(Inst) &&
            "Invalid instruction");
@@ -638,7 +638,6 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
 
     *OI = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   /// Matches indirect branch patterns in AArch64 related to a jump table (JT),
@@ -969,7 +968,7 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                               MCContext *Ctx) const override {
     if (isTB(Inst) || isCB(Inst)) {
       Inst.setOpcode(getInvertedBranchOpcode(Inst.getOpcode()));
@@ -984,7 +983,7 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
       LLVM_DEBUG(Inst.dump());
       llvm_unreachable("Unrecognized branch instruction");
     }
-    return replaceBranchTarget(Inst, TBB, Ctx);
+    replaceBranchTarget(Inst, TBB, Ctx);
   }
 
   int getPCRelEncodingSize(const MCInst &Inst) const override {

diff --git a/bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp b/bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
@@ -151,14 +151,14 @@ class RISCVMCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                               MCContext *Ctx) const override {
     auto Opcode = getInvertedBranchOpcode(Inst.getOpcode());
     Inst.setOpcode(Opcode);
-    return replaceBranchTarget(Inst, TBB, Ctx);
+    replaceBranchTarget(Inst, TBB, Ctx);
   }
 
-  bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                            MCContext *Ctx) const override {
     assert((isCall(Inst) || isBranch(Inst)) && !isIndirectBranch(Inst) &&
            "Invalid instruction");
@@ -170,7 +170,6 @@ class RISCVMCPlusBuilder : public MCPlusBuilder {
 
     Inst.getOperand(SymOpIndex) = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   IndirectBranchType analyzeIndirectBranch(

diff --git a/bolt/lib/Target/X86/X86MCPlusBuilder.cpp b/bolt/lib/Target/X86/X86MCPlusBuilder.cpp
@@ -2794,14 +2794,13 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     Inst.addOperand(MCOperand::createImm(CC));
   }
 
-  bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                               MCContext *Ctx) const override {
     unsigned InvCC = getInvertedCondCode(getCondCode(Inst));
     assert(InvCC != X86::COND_INVALID && "invalid branch instruction");
     Inst.getOperand(Info->get(Inst.getOpcode()).NumOperands - 1).setImm(InvCC);
     Inst.getOperand(0) = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   bool replaceBranchCondition(MCInst &Inst, const MCSymbol *TBB, MCContext *Ctx,
@@ -2844,13 +2843,12 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                            MCContext *Ctx) const override {
     assert((isCall(Inst) || isBranch(Inst)) && !isIndirectBranch(Inst) &&
            "Invalid instruction");
     Inst.getOperand(0) = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   MCPhysReg getX86R11() const override { return X86::R11; }

diff --git a/clang-tools-extra/clang-query/QueryParser.cpp b/clang-tools-extra/clang-query/QueryParser.cpp
@@ -144,13 +144,11 @@ QueryRef QueryParser::endQuery(QueryRef Q) {
   StringRef Extra = Line;
   StringRef ExtraTrimmed = Extra.ltrim(" \t\v\f\r");
 
-  if ((!ExtraTrimmed.empty() && ExtraTrimmed[0] == '\n') ||
-      (ExtraTrimmed.size() >= 2 && ExtraTrimmed[0] == '\r' &&
-       ExtraTrimmed[1] == '\n'))
+  if (ExtraTrimmed.starts_with('\n') || ExtraTrimmed.starts_with("\r\n"))
     Q->RemainingContent = Extra;
   else {
     StringRef TrailingWord = lexWord();
-    if (!TrailingWord.empty() && TrailingWord.front() == '#') {
+    if (TrailingWord.starts_with('#')) {
       Line = Line.drop_until([](char c) { return c == '\n'; });
       Line = Line.drop_while([](char c) { return c == '\n'; });
       return endQuery(Q);

diff --git a/clang-tools-extra/clang-tidy/bugprone/MultiLevelImplicitPointerConversionCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/MultiLevelImplicitPointerConversionCheck.cpp
@@ -48,12 +48,21 @@ AST_MATCHER(ImplicitCastExpr, isMultiLevelPointerConversion) {
   return SourcePtrLevel != TargetPtrLevel;
 }
 
+AST_MATCHER(QualType, isPointerType) {
+  const QualType Type =
+      Node.getCanonicalType().getNonReferenceType().getUnqualifiedType();
+
+  return !Type.isNull() && Type->isPointerType();
+}
+
 } // namespace
 
 void MultiLevelImplicitPointerConversionCheck::registerMatchers(
     MatchFinder *Finder) {
   Finder->addMatcher(
-      implicitCastExpr(hasCastKind(CK_BitCast), isMultiLevelPointerConversion())
+      implicitCastExpr(hasCastKind(CK_BitCast), isMultiLevelPointerConversion(),
+                       unless(hasParent(explicitCastExpr(
+                           hasDestinationType(isPointerType())))))
           .bind("expr"),
       this);
 }

diff --git a/clang-tools-extra/clang-tidy/misc/CMakeLists.txt b/clang-tools-extra/clang-tidy/misc/CMakeLists.txt
@@ -41,6 +41,7 @@ add_clang_library(clangTidyMiscModule
   UnusedParametersCheck.cpp
   UnusedUsingDeclsCheck.cpp
   UseAnonymousNamespaceCheck.cpp
+  UseInternalLinkageCheck.cpp
 
   LINK_LIBS
   clangTidy

diff --git a/clang-tools-extra/clang-tidy/misc/HeaderIncludeCycleCheck.cpp b/clang-tools-extra/clang-tidy/misc/HeaderIncludeCycleCheck.cpp
@@ -130,20 +130,15 @@ class CyclicDependencyCallbacks : public PPCallbacks {
         << FileName;
 
     const bool IsIncludePathValid =
-        std::all_of(Files.rbegin(), It, [](const Include &Elem) {
+        std::all_of(Files.rbegin(), It + 1, [](const Include &Elem) {
           return !Elem.Name.empty() && Elem.Loc.isValid();
         });
-
     if (!IsIncludePathValid)
       return;
 
-    auto CurrentIt = Files.rbegin();
-    do {
-      if (CurrentIt->Loc.isValid())
-        Check.diag(CurrentIt->Loc, "'%0' included from here",
-                   DiagnosticIDs::Note)
-            << CurrentIt->Name;
-    } while (CurrentIt++ != It);
+    for (const Include &I : llvm::make_range(Files.rbegin(), It + 1))
+      Check.diag(I.Loc, "'%0' included from here", DiagnosticIDs::Note)
+          << I.Name;
   }
 
   bool isFileIgnored(StringRef FileName) const {

diff --git a/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp b/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
@@ -31,6 +31,7 @@
 #include "UnusedParametersCheck.h"
 #include "UnusedUsingDeclsCheck.h"
 #include "UseAnonymousNamespaceCheck.h"
+#include "UseInternalLinkageCheck.h"
 
 namespace clang::tidy {
 namespace misc {
@@ -78,6 +79,8 @@ class MiscModule : public ClangTidyModule {
         "misc-unused-using-decls");
     CheckFactories.registerCheck<UseAnonymousNamespaceCheck>(
         "misc-use-anonymous-namespace");
+    CheckFactories.registerCheck<UseInternalLinkageCheck>(
+        "misc-use-internal-linkage");
   }
 };
 

diff --git a/clang-tools-extra/clang-tidy/misc/UseInternalLinkageCheck.cpp b/clang-tools-extra/clang-tidy/misc/UseInternalLinkageCheck.cpp
@@ -0,0 +1,95 @@
+//===--- UseInternalLinkageCheck.cpp - clang-tidy--------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "UseInternalLinkageCheck.h"
+#include "../utils/FileExtensionsUtils.h"
+#include "clang/AST/Decl.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/Specifiers.h"
+#include "llvm/ADT/STLExtras.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::misc {
+
+namespace {
+
+AST_MATCHER(Decl, isFirstDecl) { return Node.isFirstDecl(); }
+
+static bool isInMainFile(SourceLocation L, SourceManager &SM,
+                         const FileExtensionsSet &HeaderFileExtensions) {
+  for (;;) {
+    if (utils::isSpellingLocInHeaderFile(L, SM, HeaderFileExtensions))
+      return false;
+    if (SM.isInMainFile(L))
+      return true;
+    // not in header file but not in main file
+    L = SM.getIncludeLoc(SM.getFileID(L));
+    if (L.isValid())
+      continue;
+    // Conservative about the unknown
+    return false;
+  }
+}
+
+AST_MATCHER_P(Decl, isAllRedeclsInMainFile, FileExtensionsSet,
+              HeaderFileExtensions) {
+  return llvm::all_of(Node.redecls(), [&](const Decl *D) {
+    return isInMainFile(D->getLocation(),
+                        Finder->getASTContext().getSourceManager(),
+                        HeaderFileExtensions);
+  });
+}
+
+AST_POLYMORPHIC_MATCHER(isExternStorageClass,
+                        AST_POLYMORPHIC_SUPPORTED_TYPES(FunctionDecl,
+                                                        VarDecl)) {
+  return Node.getStorageClass() == SC_Extern;
+}
+
+} // namespace
+
+void UseInternalLinkageCheck::registerMatchers(MatchFinder *Finder) {
+  auto Common =
+      allOf(isFirstDecl(), isAllRedeclsInMainFile(HeaderFileExtensions),
+            unless(anyOf(
+                // 1. internal linkage
+                isStaticStorageClass(), isInAnonymousNamespace(),
+                // 2. explicit external linkage
+                isExternStorageClass(), isExternC(),
+                // 3. template
+                isExplicitTemplateSpecialization(),
+                // 4. friend
+                hasAncestor(friendDecl()))));
+  Finder->addMatcher(
+      functionDecl(Common, unless(cxxMethodDecl()), unless(isMain()))
+          .bind("fn"),
+      this);
+  Finder->addMatcher(varDecl(Common, hasGlobalStorage()).bind("var"), this);
+}
+
+static constexpr StringRef Message =
+    "%0 %1 can be made static or moved into an anonymous namespace "
+    "to enforce internal linkage";
+
+void UseInternalLinkageCheck::check(const MatchFinder::MatchResult &Result) {
+  if (const auto *FD = Result.Nodes.getNodeAs<FunctionDecl>("fn")) {
+    diag(FD->getLocation(), Message) << "function" << FD;
+    return;
+  }
+  if (const auto *VD = Result.Nodes.getNodeAs<VarDecl>("var")) {
+    diag(VD->getLocation(), Message) << "variable" << VD;
+    return;
+  }
+  llvm_unreachable("");
+}
+
+} // namespace clang::tidy::misc
diff --git a/clang-tools-extra/clang-tidy/misc/UseInternalLinkageCheck.h b/clang-tools-extra/clang-tidy/misc/UseInternalLinkageCheck.h
@@ -0,0 +1,38 @@
+//===--- UseInternalLinkageCheck.h - clang-tidy -----------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_USEINTERNALLINKAGECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_USEINTERNALLINKAGECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::misc {
+
+/// Detects variables and functions that can be marked as static or moved into
+/// an anonymous namespace to enforce internal linkage.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc/use-internal-linkage.html
+class UseInternalLinkageCheck : public ClangTidyCheck {
+public:
+  UseInternalLinkageCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context),
+        HeaderFileExtensions(Context->getHeaderFileExtensions()) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  std::optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
+
+private:
+  FileExtensionsSet HeaderFileExtensions;
+};
+
+} // namespace clang::tidy::misc
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_USEINTERNALLINKAGECHECK_H
diff --git a/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp
@@ -32,6 +32,14 @@ static constexpr bool RestrictToPODTypesDefault = false;
 static constexpr char IgnoreMacrosName[] = "IgnoreMacros";
 static constexpr bool IgnoreMacrosDefault = true;
 
+static constexpr char StrictCStandardComplianceName[] =
+    "StrictCStandardCompliance";
+static constexpr bool StrictCStandardComplianceDefault = true;
+
+static constexpr char StrictCppStandardComplianceName[] =
+    "StrictCppStandardCompliance";
+static constexpr bool StrictCppStandardComplianceDefault = true;
+
 namespace {
 
 struct Designators {
@@ -97,7 +105,12 @@ UseDesignatedInitializersCheck::UseDesignatedInitializersCheck(
       RestrictToPODTypes(
           Options.get(RestrictToPODTypesName, RestrictToPODTypesDefault)),
       IgnoreMacros(
-          Options.getLocalOrGlobal(IgnoreMacrosName, IgnoreMacrosDefault)) {}
+          Options.getLocalOrGlobal(IgnoreMacrosName, IgnoreMacrosDefault)),
+      StrictCStandardCompliance(Options.get(StrictCStandardComplianceName,
+                                            StrictCStandardComplianceDefault)),
+      StrictCppStandardCompliance(
+          Options.get(StrictCppStandardComplianceName,
+                      StrictCppStandardComplianceDefault)) {}
 
 void UseDesignatedInitializersCheck::registerMatchers(MatchFinder *Finder) {
   const auto HasBaseWithFields =
@@ -179,6 +192,9 @@ void UseDesignatedInitializersCheck::storeOptions(
                 IgnoreSingleElementAggregates);
   Options.store(Opts, RestrictToPODTypesName, RestrictToPODTypes);
   Options.store(Opts, IgnoreMacrosName, IgnoreMacros);
+  Options.store(Opts, StrictCStandardComplianceName, StrictCStandardCompliance);
+  Options.store(Opts, StrictCppStandardComplianceName,
+                StrictCppStandardCompliance);
 }
 
 } // namespace clang::tidy::modernize
diff --git a/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h
@@ -29,10 +29,19 @@ class UseDesignatedInitializersCheck : public ClangTidyCheck {
     return TK_IgnoreUnlessSpelledInSource;
   }
 
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus20 || LangOpts.C99 ||
+           (LangOpts.CPlusPlus && !StrictCppStandardCompliance) ||
+           (!LangOpts.CPlusPlus && !LangOpts.ObjC &&
+            !StrictCStandardCompliance);
+  }
+
 private:
   bool IgnoreSingleElementAggregates;
   bool RestrictToPODTypes;
   bool IgnoreMacros;
+  bool StrictCStandardCompliance;
+  bool StrictCppStandardCompliance;
 };
 
 } // namespace clang::tidy::modernize

diff --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -75,16 +75,16 @@ void recordRemoval(const DeclStmt &Stmt, ASTContext &Context,
   }
 }
 
-AST_MATCHER_FUNCTION_P(StatementMatcher, isConstRefReturningMethodCall,
+AST_MATCHER_FUNCTION_P(StatementMatcher,
+                       isRefReturningMethodCallWithConstOverloads,
                        std::vector<StringRef>, ExcludedContainerTypes) {
   // Match method call expressions where the `this` argument is only used as
-  // const, this will be checked in `check()` part. This returned const
-  // reference is highly likely to outlive the local const reference of the
-  // variable being declared. The assumption is that the const reference being
-  // returned either points to a global static variable or to a member of the
-  // called object.
+  // const, this will be checked in `check()` part. This returned reference is
+  // highly likely to outlive the local const reference of the variable being
+  // declared. The assumption is that the reference being returned either points
+  // to a global static variable or to a member of the called object.
   const auto MethodDecl =
-      cxxMethodDecl(returns(hasCanonicalType(matchers::isReferenceToConst())))
+      cxxMethodDecl(returns(hasCanonicalType(referenceType())))
           .bind(MethodDeclId);
   const auto ReceiverExpr =
       ignoringParenImpCasts(declRefExpr(to(varDecl().bind(ObjectArgId))));
@@ -121,7 +121,7 @@ AST_MATCHER_FUNCTION_P(StatementMatcher, initializerReturnsReferenceToConst,
       declRefExpr(to(varDecl(hasLocalStorage()).bind(OldVarDeclId)));
   return expr(
       anyOf(isConstRefReturningFunctionCall(),
-            isConstRefReturningMethodCall(ExcludedContainerTypes),
+            isRefReturningMethodCallWithConstOverloads(ExcludedContainerTypes),
             ignoringImpCasts(OldVarDeclRef),
             ignoringImpCasts(unaryOperator(hasOperatorName("&"),
                                            hasUnaryOperand(OldVarDeclRef)))));
@@ -259,10 +259,11 @@ void UnnecessaryCopyInitialization::registerMatchers(MatchFinder *Finder) {
         .bind("blockStmt");
   };
 
-  Finder->addMatcher(LocalVarCopiedFrom(anyOf(isConstRefReturningFunctionCall(),
-                                              isConstRefReturningMethodCall(
-                                                  ExcludedContainerTypes))),
-                     this);
+  Finder->addMatcher(
+      LocalVarCopiedFrom(anyOf(
+          isConstRefReturningFunctionCall(),
+          isRefReturningMethodCallWithConstOverloads(ExcludedContainerTypes))),
+      this);
 
   Finder->addMatcher(LocalVarCopiedFrom(declRefExpr(
                          to(varDecl(hasLocalStorage()).bind(OldVarDeclId)))),

diff --git a/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp b/clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp
@@ -279,6 +279,9 @@ void ImplicitBoolConversionCheck::registerMatchers(MatchFinder *Finder) {
       hasParent(callExpr()),
       hasSourceExpression(binaryOperator(hasAnyOperatorName("==", "!="))));
 
+  auto IsInCompilerGeneratedFunction = hasAncestor(namedDecl(anyOf(
+      isImplicit(), functionDecl(isDefaulted()), functionTemplateDecl())));
+
   Finder->addMatcher(
       traverse(TK_AsIs,
                implicitCastExpr(
@@ -299,7 +302,7 @@ void ImplicitBoolConversionCheck::registerMatchers(MatchFinder *Finder) {
                    // additional parens in replacement.
                    optionally(hasParent(stmt().bind("parentStmt"))),
                    unless(isInTemplateInstantiation()),
-                   unless(hasAncestor(functionTemplateDecl())))
+                   unless(IsInCompilerGeneratedFunction))
                    .bind("implicitCastToBool")),
       this);
 
@@ -331,7 +334,7 @@ void ImplicitBoolConversionCheck::registerMatchers(MatchFinder *Finder) {
               anyOf(hasParent(implicitCastExpr().bind("furtherImplicitCast")),
                     anything()),
               unless(isInTemplateInstantiation()),
-              unless(hasAncestor(functionTemplateDecl())))),
+              unless(IsInCompilerGeneratedFunction))),
       this);
 }
 

diff --git a/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp b/clang-tools-extra/clang-tidy/readability/MathMissingParenthesesCheck.cpp
@@ -57,7 +57,8 @@ static void addParantheses(const BinaryOperator *BinOp,
   int Precedence1 = getPrecedence(BinOp);
   int Precedence2 = getPrecedence(ParentBinOp);
 
-  if (ParentBinOp != nullptr && Precedence1 != Precedence2) {
+  if (ParentBinOp != nullptr && Precedence1 != Precedence2 && Precedence1 > 0 &&
+      Precedence2 > 0) {
     const clang::SourceLocation StartLoc = BinOp->getBeginLoc();
     const clang::SourceLocation EndLoc =
         clang::Lexer::getLocForEndOfToken(BinOp->getEndLoc(), 0, SM, LangOpts);

diff --git a/clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py b/clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
@@ -242,7 +242,7 @@ def main():
     filename = None
     lines_by_file = {}
     for line in sys.stdin:
-        match = re.search('^\+\+\+\ "?(.*?/){%s}([^ \t\n"]*)' % args.p, line)
+        match = re.search('^\\+\\+\\+\\ "?(.*?/){%s}([^ \t\n"]*)' % args.p, line)
         if match:
             filename = match.group(2)
         if filename is None:
@@ -255,7 +255,7 @@ def main():
             if not re.match("^%s$" % args.iregex, filename, re.IGNORECASE):
                 continue
 
-        match = re.search("^@@.*\+(\d+)(,(\d+))?", line)
+        match = re.search(r"^@@.*\+(\d+)(,(\d+))?", line)
         if match:
             start_line = int(match.group(1))
             line_count = 1

diff --git a/clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp b/clang-tools-extra/clang-tidy/utils/DeclRefExprUtils.cpp
@@ -36,6 +36,116 @@ void extractNodesByIdTo(ArrayRef<BoundNodes> Matches, StringRef ID,
     Nodes.insert(Match.getNodeAs<Node>(ID));
 }
 
+// Returns true if both types refer to the same type,
+// ignoring the const-qualifier.
+bool isSameTypeIgnoringConst(QualType A, QualType B) {
+  A = A.getCanonicalType();
+  B = B.getCanonicalType();
+  A.addConst();
+  B.addConst();
+  return A == B;
+}
+
+// Returns true if `D` and `O` have the same parameter types.
+bool hasSameParameterTypes(const CXXMethodDecl &D, const CXXMethodDecl &O) {
+  if (D.getNumParams() != O.getNumParams())
+    return false;
+  for (int I = 0, E = D.getNumParams(); I < E; ++I) {
+    if (!isSameTypeIgnoringConst(D.getParamDecl(I)->getType(),
+                                 O.getParamDecl(I)->getType()))
+      return false;
+  }
+  return true;
+}
+
+// If `D` has a const-qualified overload with otherwise identical
+// ref-qualifiers and parameter types, returns that overload.
+const CXXMethodDecl *findConstOverload(const CXXMethodDecl &D) {
+  assert(!D.isConst());
+
+  DeclContext::lookup_result LookupResult =
+      D.getParent()->lookup(D.getNameInfo().getName());
+  if (LookupResult.isSingleResult()) {
+    // No overload.
+    return nullptr;
+  }
+  for (const Decl *Overload : LookupResult) {
+    const auto *O = dyn_cast<CXXMethodDecl>(Overload);
+    if (O && !O->isDeleted() && O->isConst() &&
+        O->getRefQualifier() == D.getRefQualifier() &&
+        hasSameParameterTypes(D, *O))
+      return O;
+  }
+  return nullptr;
+}
+
+// Returns true if both types are pointers or reference to the same type,
+// ignoring the const-qualifier.
+bool pointsToSameTypeIgnoringConst(QualType A, QualType B) {
+  assert(A->isPointerType() || A->isReferenceType());
+  assert(B->isPointerType() || B->isReferenceType());
+  return isSameTypeIgnoringConst(A->getPointeeType(), B->getPointeeType());
+}
+
+// Return true if non-const member function `M` likely does not mutate `*this`.
+//
+// Note that if the member call selects a method/operator `f` that
+// is not const-qualified, then we also consider that the object is
+// not mutated if:
+//  - (A) there is a const-qualified overload `cf` of `f` that has
+//  the
+//    same ref-qualifiers;
+//  - (B) * `f` returns a value, or
+//        * if `f` returns a `T&`, `cf` returns a `const T&` (up to
+//          possible aliases such as `reference` and
+//          `const_reference`), or
+//        * if `f` returns a `T*`, `cf` returns a `const T*` (up to
+//          possible aliases).
+//  - (C) the result of the call is not mutated.
+//
+// The assumption that `cf` has the same semantics as `f`.
+// For example:
+//   - In `std::vector<T> v; const T t = v[...];`, we consider that
+//     expression `v[...]` does not mutate `v` as
+//    `T& std::vector<T>::operator[]` has a const overload
+//     `const T& std::vector<T>::operator[] const`, and the
+//     result expression of type `T&` is only used as a `const T&`;
+//   - In `std::map<K, V> m; V v = m.at(...);`, we consider
+//     `m.at(...)` to be an immutable access for the same reason.
+// However:
+//   - In `std::map<K, V> m; const V v = m[...];`, We consider that
+//     `m[...]` mutates `m` as `V& std::map<K, V>::operator[]` does
+//     not have a const overload.
+//   - In `std::vector<T> v; T& t = v[...];`, we consider that
+//     expression `v[...]` mutates `v` as the result is kept as a
+//     mutable reference.
+//
+// This function checks (A) ad (B), but the caller should make sure that the
+// object is not mutated through the return value.
+bool isLikelyShallowConst(const CXXMethodDecl &M) {
+  assert(!M.isConst());
+  // The method can mutate our variable.
+
+  // (A)
+  const CXXMethodDecl *ConstOverload = findConstOverload(M);
+  if (ConstOverload == nullptr) {
+    return false;
+  }
+
+  // (B)
+  const QualType CallTy = M.getReturnType().getCanonicalType();
+  const QualType OverloadTy = ConstOverload->getReturnType().getCanonicalType();
+  if (CallTy->isReferenceType()) {
+    return OverloadTy->isReferenceType() &&
+           pointsToSameTypeIgnoringConst(CallTy, OverloadTy);
+  }
+  if (CallTy->isPointerType()) {
+    return OverloadTy->isPointerType() &&
+           pointsToSameTypeIgnoringConst(CallTy, OverloadTy);
+  }
+  return isSameTypeIgnoringConst(CallTy, OverloadTy);
+}
+
 // A matcher that matches DeclRefExprs that are used in ways such that the
 // underlying declaration is not modified.
 // If the declaration is of pointer type, `Indirections` specifies the level
@@ -54,16 +164,15 @@ void extractNodesByIdTo(ArrayRef<BoundNodes> Matches, StringRef ID,
 //  matches (A).
 //
 AST_MATCHER_P(DeclRefExpr, doesNotMutateObject, int, Indirections) {
-  // We walk up the parents of the DeclRefExpr recursively until we end up on a
-  // parent that cannot modify the underlying object. There are a few kinds of
-  // expressions:
-  //  - Those that cannot be used to mutate the underlying object. We can stop
+  // We walk up the parents of the DeclRefExpr recursively. There are a few
+  // kinds of expressions:
+  //  - Those that cannot be used to mutate the underlying variable. We can stop
   //    recursion there.
-  //  - Those that can be used to mutate the underlying object in analyzable
+  //  - Those that can be used to mutate the underlying variable in analyzable
   //    ways (such as taking the address or accessing a subobject). We have to
   //    examine the parents.
   //  - Those that we don't know how to analyze. In that case we stop there and
-  //    we assume that they can mutate the underlying expression.
+  //    we assume that they can modify the expression.
 
   struct StackEntry {
     StackEntry(const Expr *E, int Indirections)
@@ -90,7 +199,7 @@ AST_MATCHER_P(DeclRefExpr, doesNotMutateObject, int, Indirections) {
       assert(Ty->isPointerType());
       Ty = Ty->getPointeeType().getCanonicalType();
     }
-    if (Ty.isConstQualified())
+    if (Ty->isVoidType() || Ty.isConstQualified())
       continue;
 
     // Otherwise we have to look at the parents to see how the expression is
@@ -159,11 +268,56 @@ AST_MATCHER_P(DeclRefExpr, doesNotMutateObject, int, Indirections) {
             // The method call cannot mutate our variable.
             continue;
           }
+          if (isLikelyShallowConst(*Method)) {
+            // We still have to check that the object is not modified through
+            // the method's return value (C).
+            const auto MemberParents = Ctx.getParents(*Member);
+            assert(MemberParents.size() == 1);
+            const auto *Call = MemberParents[0].get<CallExpr>();
+            // If `o` is an object of class type and `f` is a member function,
+            // then `o.f` has to be used as part of a call expression.
+            assert(Call != nullptr && "member function has to be called");
+            Stack.emplace_back(
+                Call,
+                Method->getReturnType().getCanonicalType()->isPointerType()
+                    ? 1
+                    : 0);
+            continue;
+          }
           return false;
         }
         Stack.emplace_back(Member, 0);
         continue;
       }
+      if (const auto *const OpCall = dyn_cast<CXXOperatorCallExpr>(P)) {
+        // Operator calls have function call syntax. The `*this` parameter
+        // is the first parameter.
+        if (OpCall->getNumArgs() == 0 || OpCall->getArg(0) != Entry.E) {
+          return false;
+        }
+        const auto *const Method =
+            dyn_cast<CXXMethodDecl>(OpCall->getDirectCallee());
+
+        if (Method == nullptr) {
+          // This is not a member operator. Typically, a friend operator. These
+          // are handled like function calls.
+          return false;
+        }
+
+        if (Method->isConst() || Method->isStatic()) {
+          continue;
+        }
+        if (isLikelyShallowConst(*Method)) {
+          // We still have to check that the object is not modified through
+          // the operator's return value (C).
+          Stack.emplace_back(
+              OpCall,
+              Method->getReturnType().getCanonicalType()->isPointerType() ? 1
+                                                                          : 0);
+          continue;
+        }
+        return false;
+      }
 
       if (const auto *const Op = dyn_cast<UnaryOperator>(P)) {
         switch (Op->getOpcode()) {

diff --git a/clang-tools-extra/clangd/FindSymbols.cpp b/clang-tools-extra/clangd/FindSymbols.cpp
@@ -454,7 +454,7 @@ class DocumentOutline {
       if (!MacroName.isValid() || !MacroName.isFileID())
         continue;
       // All conditions satisfied, add the macro.
-      if (auto *Tok = AST.getTokens().spelledTokenAt(MacroName))
+      if (auto *Tok = AST.getTokens().spelledTokenContaining(MacroName))
         CurParent = &CurParent->inMacro(
             *Tok, SM, AST.getTokens().expansionStartingAt(Tok));
     }

diff --git a/clang-tools-extra/clangd/IncludeCleaner.cpp b/clang-tools-extra/clangd/IncludeCleaner.cpp
@@ -303,7 +303,7 @@ collectMacroReferences(ParsedAST &AST) {
   for (const auto &[_, Refs] : AST.getMacros().MacroRefs) {
     for (const auto &Ref : Refs) {
       auto Loc = SM.getComposedLoc(SM.getMainFileID(), Ref.StartOffset);
-      const auto *Tok = AST.getTokens().spelledTokenAt(Loc);
+      const auto *Tok = AST.getTokens().spelledTokenContaining(Loc);
       if (!Tok)
         continue;
       auto Macro = locateMacroAt(*Tok, PP);

diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -447,11 +447,10 @@ class HighlightingsBuilder {
     if (!RLoc.isValid())
       return;
 
-    const auto *RTok = TB.spelledTokenAt(RLoc);
-    // Handle `>>`. RLoc is always pointing at the right location, just change
-    // the end to be offset by 1.
-    // We'll either point at the beginning of `>>`, hence get a proper spelled
-    // or point in the middle of `>>` hence get no spelled tok.
+    const auto *RTok = TB.spelledTokenContaining(RLoc);
+    // Handle `>>`. RLoc is either part of `>>` or a spelled token on its own
+    // `>`. If it's the former, slice to have length of 1, if latter use the
+    // token as-is.
     if (!RTok || RTok->kind() == tok::greatergreater) {
       Position Begin = sourceLocToPosition(SourceMgr, RLoc);
       Position End = sourceLocToPosition(SourceMgr, RLoc.getLocWithOffset(1));
@@ -577,7 +576,7 @@ class HighlightingsBuilder {
       return std::nullopt;
     // We might have offsets in the main file that don't correspond to any
     // spelled tokens.
-    const auto *Tok = TB.spelledTokenAt(Loc);
+    const auto *Tok = TB.spelledTokenContaining(Loc);
     if (!Tok)
       return std::nullopt;
     return halfOpenToRange(SourceMgr,

diff --git a/clang-tools-extra/clangd/XRefs.cpp b/clang-tools-extra/clangd/XRefs.cpp
@@ -844,7 +844,7 @@ std::vector<DocumentLink> getDocumentLinks(ParsedAST &AST) {
     if (Inc.Resolved.empty())
       continue;
     auto HashLoc = SM.getComposedLoc(SM.getMainFileID(), Inc.HashOffset);
-    const auto *HashTok = AST.getTokens().spelledTokenAt(HashLoc);
+    const auto *HashTok = AST.getTokens().spelledTokenContaining(HashLoc);
     assert(HashTok && "got inclusion at wrong offset");
     const auto *IncludeTok = std::next(HashTok);
     const auto *FileTok = std::next(IncludeTok);
@@ -938,7 +938,7 @@ class ReferenceFinder : public index::IndexDataConsumer {
     CollectorOpts.CollectMainFileSymbols = true;
     for (SourceLocation L : Locs) {
       L = SM.getFileLoc(L);
-      if (const auto *Tok = TB.spelledTokenAt(L))
+      if (const auto *Tok = TB.spelledTokenContaining(L))
         References.push_back(
             {*Tok, Roles,
              SymbolCollector::getRefContainer(ASTNode.Parent, CollectorOpts)});
@@ -1216,7 +1216,7 @@ DocumentHighlight toHighlight(const ReferenceFinder::Reference &Ref,
 std::optional<DocumentHighlight> toHighlight(SourceLocation Loc,
                                              const syntax::TokenBuffer &TB) {
   Loc = TB.sourceManager().getFileLoc(Loc);
-  if (const auto *Tok = TB.spelledTokenAt(Loc)) {
+  if (const auto *Tok = TB.spelledTokenContaining(Loc)) {
     DocumentHighlight Result;
     Result.range = halfOpenToRange(
         TB.sourceManager(),
@@ -1353,7 +1353,8 @@ maybeFindIncludeReferences(ParsedAST &AST, Position Pos,
           Loc = SM.getIncludeLoc(SM.getFileID(Loc));
 
         ReferencesResult::Reference Result;
-        const auto *Token = AST.getTokens().spelledTokenAt(Loc);
+        const auto *Token = AST.getTokens().spelledTokenContaining(Loc);
+        assert(Token && "references expected token here");
         Result.Loc.range = Range{sourceLocToPosition(SM, Token->location()),
                                  sourceLocToPosition(SM, Token->endLocation())};
         Result.Loc.uri = URIMainFile;

diff --git a/clang-tools-extra/clangd/index/remote/CMakeLists.txt b/clang-tools-extra/clangd/index/remote/CMakeLists.txt
@@ -26,7 +26,6 @@ if (CLANGD_ENABLE_REMOTE)
     clangdRemoteIndexProto
     clangdRemoteIndexServiceProto
     clangdRemoteMarshalling
-    clangBasic
     clangDaemon
     clangdSupport
 
@@ -35,6 +34,11 @@ if (CLANGD_ENABLE_REMOTE)
     clangdRemoteIndexServiceProto
     )
 
+  clang_target_link_libraries(clangdRemoteIndex
+    PRIVATE
+    clangBasic
+    )
+
   add_subdirectory(marshalling)
   add_subdirectory(server)
   add_subdirectory(monitor)

diff --git a/clang-tools-extra/clangd/refactor/Rename.cpp b/clang-tools-extra/clangd/refactor/Rename.cpp
@@ -748,7 +748,7 @@ std::vector<SymbolRange> collectRenameIdentifierRanges(
 clangd::Range tokenRangeForLoc(ParsedAST &AST, SourceLocation TokLoc,
                                const SourceManager &SM,
                                const LangOptions &LangOpts) {
-  const auto *Token = AST.getTokens().spelledTokenAt(TokLoc);
+  const auto *Token = AST.getTokens().spelledTokenContaining(TokLoc);
   assert(Token && "rename expects spelled tokens");
   clangd::Range Result;
   Result.start = sourceLocToPosition(SM, Token->location());

diff --git a/clang-tools-extra/clangd/unittests/PreambleTests.cpp b/clang-tools-extra/clangd/unittests/PreambleTests.cpp
@@ -417,7 +417,7 @@ TEST(PreamblePatchTest, LocateMacroAtWorks) {
     ASSERT_TRUE(AST);
 
     const auto &SM = AST->getSourceManager();
-    auto *MacroTok = AST->getTokens().spelledTokenAt(
+    auto *MacroTok = AST->getTokens().spelledTokenContaining(
         SM.getComposedLoc(SM.getMainFileID(), Modified.point("use")));
     ASSERT_TRUE(MacroTok);
 
@@ -441,7 +441,7 @@ TEST(PreamblePatchTest, LocateMacroAtDeletion) {
     ASSERT_TRUE(AST);
 
     const auto &SM = AST->getSourceManager();
-    auto *MacroTok = AST->getTokens().spelledTokenAt(
+    auto *MacroTok = AST->getTokens().spelledTokenContaining(
         SM.getComposedLoc(SM.getMainFileID(), Modified.point()));
     ASSERT_TRUE(MacroTok);
 
@@ -512,9 +512,10 @@ TEST(PreamblePatchTest, RefsToMacros) {
       ExpectedLocations.push_back(referenceRangeIs(R));
 
     for (const auto &P : Modified.points()) {
-      auto *MacroTok = AST->getTokens().spelledTokenAt(SM.getComposedLoc(
-          SM.getMainFileID(),
-          llvm::cantFail(positionToOffset(Modified.code(), P))));
+      auto *MacroTok =
+          AST->getTokens().spelledTokenContaining(SM.getComposedLoc(
+              SM.getMainFileID(),
+              llvm::cantFail(positionToOffset(Modified.code(), P))));
       ASSERT_TRUE(MacroTok);
       EXPECT_THAT(findReferences(*AST, P, 0).References,
                   testing::ElementsAreArray(ExpectedLocations));

diff --git a/clang-tools-extra/clangd/unittests/XRefsTests.cpp b/clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -2173,6 +2173,11 @@ TEST(FindReferences, WithinAST) {
         using $def[[MyTypeD^ef]] = int;
         enum MyEnum : $(MyEnum)[[MyTy^peDef]] { };
       )cpp",
+      // UDL
+      R"cpp(
+        bool $decl[[operator]]"" _u^dl(unsigned long long value);
+        bool x = $(x)[[1_udl]];
+      )cpp",
   };
   for (const char *Test : Tests)
     checkFindRefs(Test);
@@ -2358,7 +2363,13 @@ TEST(FindReferences, UsedSymbolsFromInclude) {
 
       R"cpp([[#in^clude <vector>]]
         std::[[vector]]<int> vec;
-      )cpp"};
+      )cpp",
+
+      R"cpp(
+        [[#include ^"udl_header.h"]]
+        auto x = [[1_b]];
+      )cpp",
+  };
   for (const char *Test : Tests) {
     Annotations T(Test);
     auto TU = TestTU::withCode(T.code());
@@ -2375,6 +2386,9 @@ TEST(FindReferences, UsedSymbolsFromInclude) {
         class vector{};
       }
     )cpp");
+    TU.AdditionalFiles["udl_header.h"] = guard(R"cpp(
+      bool operator"" _b(unsigned long long value);
+    )cpp");
     TU.ExtraArgs.push_back("-isystem" + testPath("system"));
 
     auto AST = TU.build();

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -148,6 +148,12 @@ New checks
   to reading out-of-bounds data due to inadequate or incorrect string null
   termination.
 
+- New :doc:`misc-use-internal-linkage
+  <clang-tidy/checks/misc/use-internal-linkage>` check.
+
+  Detects variables and functions that can be marked as static or moved into
+  an anonymous namespace to enforce internal linkage.
+
 - New :doc:`modernize-min-max-use-initializer-list
   <clang-tidy/checks/modernize/min-max-use-initializer-list>` check.
 
@@ -218,6 +224,10 @@ Changes in existing checks
   check by ignoring ``__func__`` macro in lambda captures, initializers of
   default parameters and nested function declarations.
 
+- Improved :doc:`bugprone-multi-level-implicit-pointer-conversion
+  <clang-tidy/checks/bugprone/multi-level-implicit-pointer-conversion>` check
+  by ignoring implicit pointer conversions that are part of a cast expression.
+
 - Improved :doc:`bugprone-non-zero-enum-to-bool-conversion
   <clang-tidy/checks/bugprone/non-zero-enum-to-bool-conversion>` check by
   eliminating false positives resulting from direct usage of bitwise operators
@@ -366,8 +376,10 @@ Changes in existing checks
 - Improved :doc:`performance-unnecessary-copy-initialization
   <clang-tidy/checks/performance/unnecessary-copy-initialization>` check by
   detecting more cases of constant access. In particular, pointers can be
-  analyzed, se the check now handles the common patterns
+  analyzed, so the check now handles the common patterns
   `const auto e = (*vector_ptr)[i]` and `const auto e = vector_ptr->at(i);`.
+  Calls to mutable function where there exists a `const` overload are also
+  handled.
 
 - Improved :doc:`readability-avoid-return-with-void-value
   <clang-tidy/checks/readability/avoid-return-with-void-value>` check by adding
@@ -402,7 +414,8 @@ Changes in existing checks
   valid fix suggestions for ``static_cast`` without a preceding space and
   fixed problem with duplicate parentheses in double implicit casts. Corrected
   the fix suggestions for C23 and later by using C-style casts instead of
-  ``static_cast``.
+  ``static_cast``. Fixed false positives in C++20 spaceship operator by ignoring
+  casts in implicit and defaulted functions.
 
 - Improved :doc:`readability-redundant-inline-specifier
   <clang-tidy/checks/readability/redundant-inline-specifier>` check to properly

diff --git a/clang-tools-extra/docs/clang-tidy/checks/clang-analyzer/cplusplus.ArrayDelete.rst b/clang-tools-extra/docs/clang-tidy/checks/clang-analyzer/cplusplus.ArrayDelete.rst
@@ -0,0 +1,14 @@
+.. title:: clang-tidy - clang-analyzer-cplusplus.ArrayDelete
+.. meta::
+   :http-equiv=refresh: 5;URL=https://clang.llvm.org/docs/analyzer/checkers.html#cplusplus-arraydelete
+
+clang-analyzer-cplusplus.ArrayDelete
+====================================
+
+Reports destructions of arrays of polymorphic objects that are destructed as
+their base class.
+
+The `clang-analyzer-cplusplus.ArrayDelete` check is an alias, please see
+`Clang Static Analyzer Available Checkers
+<https://clang.llvm.org/docs/analyzer/checkers.html#cplusplus-arraydelete>`_
+for more information.
diff --git a/...ools-extra/docs/clang-tidy/checks/clang-analyzer/security.SetgidSetuidOrder.rst b/...ools-extra/docs/clang-tidy/checks/clang-analyzer/security.SetgidSetuidOrder.rst
@@ -0,0 +1,10 @@
+.. title:: clang-tidy - clang-analyzer-security.SetgidSetuidOrder
+
+clang-analyzer-security.SetgidSetuidOrder
+=========================================
+
+Warn on possible reversed order of 'setgid(getgid()))' and 'setuid(getuid())'
+(CERT: POS36-C).
+
+The clang-analyzer-security.SetgidSetuidOrder check is an alias of
+Clang Static Analyzer security.SetgidSetuidOrder.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/clang-analyzer/unix.Stream.rst b/clang-tools-extra/docs/clang-tidy/checks/clang-analyzer/unix.Stream.rst
@@ -0,0 +1,13 @@
+.. title:: clang-tidy - clang-analyzer-unix.Stream
+.. meta::
+   :http-equiv=refresh: 5;URL=https://clang.llvm.org/docs/analyzer/checkers.html#unix-stream
+
+clang-analyzer-unix.Stream
+==========================
+
+Check stream handling functions.
+
+The `clang-analyzer-unix.Stream` check is an alias, please see
+`Clang Static Analyzer Available Checkers
+<https://clang.llvm.org/docs/analyzer/checkers.html#unix-stream>`_
+for more information.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/gen-static-analyzer-docs.py b/clang-tools-extra/docs/clang-tidy/checks/gen-static-analyzer-docs.py
@@ -47,7 +47,7 @@ def get_checkers(checkers_td, checkers_rst):
         parent_package_ = package["ParentPackage"]
         hidden = (checker["Hidden"] != 0) or (package["Hidden"] != 0)
 
-        while parent_package_ != None:
+        while parent_package_ is not None:
             parent_package = table_entries[parent_package_["def"]]
             checker_package_prefix = (
                 parent_package["PackageName"] + "." + checker_package_prefix
@@ -59,7 +59,7 @@ def get_checkers(checkers_td, checkers_rst):
             "clang-analyzer-" + checker_package_prefix + "." + checker_name
         )
         anchor_url = re.sub(
-            "\.", "-", checker_package_prefix + "." + checker_name
+            r"\.", "-", checker_package_prefix + "." + checker_name
         ).lower()
 
         if not hidden and "alpha" not in full_package_name.lower():
@@ -130,7 +130,7 @@ def generate_documentation(checker, has_documentation):
 def update_documentation_list(checkers):
     with open(os.path.join(__location__, "list.rst"), "r+") as f:
         f_text = f.read()
-        check_text = f_text.split(".. csv-table:: Aliases..\n")[1]
+        check_text = f_text.split(':header: "Name", "Redirect", "Offers fixes"\n')[1]
         checks = [x for x in check_text.split("\n") if ":header:" not in x and x]
         old_check_text = "\n".join(checks)
         checks = [x for x in checks if "clang-analyzer-" not in x]

diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -267,6 +267,7 @@ Clang-Tidy Checks
    :doc:`misc-unused-parameters <misc/unused-parameters>`, "Yes"
    :doc:`misc-unused-using-decls <misc/unused-using-decls>`, "Yes"
    :doc:`misc-use-anonymous-namespace <misc/use-anonymous-namespace>`,
+   :doc:`misc-use-internal-linkage <misc/use-internal-linkage>`,
    :doc:`modernize-avoid-bind <modernize/avoid-bind>`, "Yes"
    :doc:`modernize-avoid-c-arrays <modernize/avoid-c-arrays>`,
    :doc:`modernize-concat-nested-namespaces <modernize/concat-nested-namespaces>`, "Yes"
@@ -442,6 +443,7 @@ Check aliases
    :doc:`clang-analyzer-core.uninitialized.CapturedBlockVariable <clang-analyzer/core.uninitialized.CapturedBlockVariable>`, `Clang Static Analyzer core.uninitialized.CapturedBlockVariable <https://clang.llvm.org/docs/analyzer/checkers.html#core-uninitialized-capturedblockvariable>`_,
    :doc:`clang-analyzer-core.uninitialized.NewArraySize <clang-analyzer/core.uninitialized.NewArraySize>`, `Clang Static Analyzer core.uninitialized.NewArraySize <https://clang.llvm.org/docs/analyzer/checkers.html#core-uninitialized-newarraysize>`_,
    :doc:`clang-analyzer-core.uninitialized.UndefReturn <clang-analyzer/core.uninitialized.UndefReturn>`, `Clang Static Analyzer core.uninitialized.UndefReturn <https://clang.llvm.org/docs/analyzer/checkers.html#core-uninitialized-undefreturn>`_,
+   :doc:`clang-analyzer-cplusplus.ArrayDelete <clang-analyzer/cplusplus.ArrayDelete>`, `Clang Static Analyzer cplusplus.ArrayDelete <https://clang.llvm.org/docs/analyzer/checkers.html#cplusplus-arraydelete>`_,
    :doc:`clang-analyzer-cplusplus.InnerPointer <clang-analyzer/cplusplus.InnerPointer>`, `Clang Static Analyzer cplusplus.InnerPointer <https://clang.llvm.org/docs/analyzer/checkers.html#cplusplus-innerpointer>`_,
    :doc:`clang-analyzer-cplusplus.Move <clang-analyzer/cplusplus.Move>`, Clang Static Analyzer cplusplus.Move,
    :doc:`clang-analyzer-cplusplus.NewDelete <clang-analyzer/cplusplus.NewDelete>`, `Clang Static Analyzer cplusplus.NewDelete <https://clang.llvm.org/docs/analyzer/checkers.html#cplusplus-newdelete>`_,
@@ -496,6 +498,7 @@ Check aliases
    :doc:`clang-analyzer-osx.coreFoundation.containers.OutOfBounds <clang-analyzer/osx.coreFoundation.containers.OutOfBounds>`, `Clang Static Analyzer osx.coreFoundation.containers.OutOfBounds <https://clang.llvm.org/docs/analyzer/checkers.html#osx-corefoundation-containers-outofbounds>`_,
    :doc:`clang-analyzer-osx.coreFoundation.containers.PointerSizedValues <clang-analyzer/osx.coreFoundation.containers.PointerSizedValues>`, `Clang Static Analyzer osx.coreFoundation.containers.PointerSizedValues <https://clang.llvm.org/docs/analyzer/checkers.html#osx-corefoundation-containers-pointersizedvalues>`_,
    :doc:`clang-analyzer-security.FloatLoopCounter <clang-analyzer/security.FloatLoopCounter>`, `Clang Static Analyzer security.FloatLoopCounter <https://clang.llvm.org/docs/analyzer/checkers.html#security-floatloopcounter>`_,
+   :doc:`clang-analyzer-security.SetgidSetuidOrder <clang-analyzer/security.SetgidSetuidOrder>`, Clang Static Analyzer security.SetgidSetuidOrder,
    :doc:`clang-analyzer-security.cert.env.InvalidPtr <clang-analyzer/security.cert.env.InvalidPtr>`, `Clang Static Analyzer security.cert.env.InvalidPtr <https://clang.llvm.org/docs/analyzer/checkers.html#security-cert-env-invalidptr>`_,
    :doc:`clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling <clang-analyzer/security.insecureAPI.DeprecatedOrUnsafeBufferHandling>`, `Clang Static Analyzer security.insecureAPI.DeprecatedOrUnsafeBufferHandling <https://clang.llvm.org/docs/analyzer/checkers.html#security-insecureapi-deprecatedorunsafebufferhandling>`_,
    :doc:`clang-analyzer-security.insecureAPI.UncheckedReturn <clang-analyzer/security.insecureAPI.UncheckedReturn>`, `Clang Static Analyzer security.insecureAPI.UncheckedReturn <https://clang.llvm.org/docs/analyzer/checkers.html#security-insecureapi-uncheckedreturn>`_,
@@ -516,6 +519,7 @@ Check aliases
    :doc:`clang-analyzer-unix.MallocSizeof <clang-analyzer/unix.MallocSizeof>`, `Clang Static Analyzer unix.MallocSizeof <https://clang.llvm.org/docs/analyzer/checkers.html#unix-mallocsizeof>`_,
    :doc:`clang-analyzer-unix.MismatchedDeallocator <clang-analyzer/unix.MismatchedDeallocator>`, `Clang Static Analyzer unix.MismatchedDeallocator <https://clang.llvm.org/docs/analyzer/checkers.html#unix-mismatcheddeallocator>`_,
    :doc:`clang-analyzer-unix.StdCLibraryFunctions <clang-analyzer/unix.StdCLibraryFunctions>`, `Clang Static Analyzer unix.StdCLibraryFunctions <https://clang.llvm.org/docs/analyzer/checkers.html#unix-stdclibraryfunctions>`_,
+   :doc:`clang-analyzer-unix.Stream <clang-analyzer/unix.Stream>`, `Clang Static Analyzer unix.Stream <https://clang.llvm.org/docs/analyzer/checkers.html#unix-stream>`_,
    :doc:`clang-analyzer-unix.Vfork <clang-analyzer/unix.Vfork>`, `Clang Static Analyzer unix.Vfork <https://clang.llvm.org/docs/analyzer/checkers.html#unix-vfork>`_,
    :doc:`clang-analyzer-unix.cstring.BadSizeArg <clang-analyzer/unix.cstring.BadSizeArg>`, `Clang Static Analyzer unix.cstring.BadSizeArg <https://clang.llvm.org/docs/analyzer/checkers.html#unix-cstring-badsizearg>`_,
    :doc:`clang-analyzer-unix.cstring.NullArg <clang-analyzer/unix.cstring.NullArg>`, `Clang Static Analyzer unix.cstring.NullArg <https://clang.llvm.org/docs/analyzer/checkers.html#unix-cstring-nullarg>`_,

diff --git a/clang-tools-extra/docs/clang-tidy/checks/misc/use-internal-linkage.rst b/clang-tools-extra/docs/clang-tidy/checks/misc/use-internal-linkage.rst
@@ -0,0 +1,27 @@
+.. title:: clang-tidy - misc-use-internal-linkage
+
+misc-use-internal-linkage
+=========================
+
+Detects variables and functions that can be marked as static or moved into
+an anonymous namespace to enforce internal linkage.
+
+Static functions and variables are scoped to a single file. Marking functions
+and variables as static helps to better remove dead code. In addition, it gives
+the compiler more information and allows for more aggressive optimizations.
+
+Example:
+
+.. code-block:: c++
+
+  int v1; // can be marked as static
+
+  void fn1(); // can be marked as static
+
+  namespace {
+    // already in anonymous namespace
+    int v2;
+    void fn2();
+  }
+  // already declared as extern
+  extern int v2;
diff --git a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst
@@ -37,7 +37,7 @@ declaration of ``S``.
 
 Even when compiling in a language version older than C++20, depending on your
 compiler, designated initializers are potentially supported. Therefore, the
-check is not restricted to C++20 and newer versions. Check out the options
+check is by default restricted to C99/C++20 and above. Check out the options
 ``-Wc99-designator`` to get support for mixed designators in initializer list in
 C and ``-Wc++20-designator`` for support of designated initializers in older C++
 language modes.
@@ -60,3 +60,13 @@ Options
     The value `true` specifies that only Plain Old Data (POD) types shall be
     checked. This makes the check applicable to even older C++ standards. The
     default value is `false`.
+
+.. option:: StrictCStandardCompliance
+
+   When set to `false`, the check will not restrict itself to C99 and above.
+   The default value is `true`.
+
+.. option:: StrictCppStandardCompliance
+
+   When set to `false`, the check will not restrict itself to C++20 and above.
+   The default value is `true`.
diff --git a/clang-tools-extra/pseudo/lib/CMakeLists.txt b/clang-tools-extra/pseudo/lib/CMakeLists.txt
@@ -14,8 +14,6 @@ add_clang_library(clangPseudo
   Token.cpp
 
   LINK_LIBS
-  clangBasic
-  clangLex
   clangPseudoGrammar
 
   DEPENDS
@@ -25,3 +23,9 @@ add_clang_library(clangPseudo
   target_include_directories(clangPseudo INTERFACE
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../include>
   )
+
+clang_target_link_libraries(clangPseudo
+  PRIVATE
+  clangBasic
+  clangLex
+  )
diff --git a/clang-tools-extra/pseudo/lib/cxx/CMakeLists.txt b/clang-tools-extra/pseudo/lib/cxx/CMakeLists.txt
@@ -9,7 +9,11 @@ add_clang_library(clangPseudoCXX
   cxx_gen
 
   LINK_LIBS
-  clangBasic
   clangPseudo
   clangPseudoGrammar
   )
+
+clang_target_link_libraries(clangPseudoCXX
+  PRIVATE
+  clangBasic
+  )
diff --git a/...tools-extra/test/clang-tidy/checkers/bugprone/multi-level-implicit-pointer-conversion.cpp b/...tools-extra/test/clang-tidy/checkers/bugprone/multi-level-implicit-pointer-conversion.cpp
@@ -63,3 +63,15 @@ void test()
 
   takeSecondLevelVoidPtr(getSecondLevelVoidPtr());
 }
+
+namespace PR93959 {
+  void free(void*);
+
+  void test() {
+    char **p = nullptr;
+    free(p);
+    // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: multilevel pointer conversion from 'char **' to 'void *', please use explicit cast [bugprone-multi-level-implicit-pointer-conversion]
+    free((void *)p);
+    free(static_cast<void *>(p));
+  }
+}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func.h b/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func.h
@@ -0,0 +1,5 @@
+#pragma once
+
+void func_header();
+
+#include "func_h.inc"
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func_cpp.inc b/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func_cpp.inc
@@ -0,0 +1 @@
+void func_cpp_inc();
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func_h.inc b/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func_h.inc
@@ -0,0 +1 @@
+void func_h_inc();
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/var.h b/clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/var.h
@@ -0,0 +1,3 @@
+#pragma once
+
+extern int gloabl_header;
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/use-internal-linkage-func.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/use-internal-linkage-func.cpp
@@ -0,0 +1,37 @@
+// RUN: %check_clang_tidy %s misc-use-internal-linkage %t -- -- -I%S/Inputs/use-internal-linkage
+
+#include "func.h"
+
+void func() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func'
+
+template<class T>
+void func_template() {}
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func_template'
+
+void func_cpp_inc();
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func_cpp_inc'
+
+#include "func_cpp.inc"
+
+void func_h_inc();
+
+struct S {
+  void method();
+};
+void S::method() {}
+
+void func_header();
+extern void func_extern();
+static void func_static();
+namespace {
+void func_anonymous_ns();
+} // namespace
+
+int main(int argc, const char*argv[]) {}
+
+extern "C" {
+void func_extern_c_1() {}
+}
+
+extern "C" void func_extern_c_2() {}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/use-internal-linkage-var.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/use-internal-linkage-var.cpp
@@ -0,0 +1,40 @@
+// RUN: %check_clang_tidy %s misc-use-internal-linkage %t -- -- -I%S/Inputs/use-internal-linkage
+
+#include "var.h"
+
+int global;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: variable 'global'
+
+template<class T>
+T global_template;
+// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: variable 'global_template'
+
+int gloabl_header;
+
+extern int global_extern;
+
+static int global_static;
+
+namespace {
+static int global_anonymous_ns;
+namespace NS {
+static int global_anonymous_ns;
+}
+}
+
+static void f(int para) {
+  int local;
+  static int local_static;
+}
+
+struct S {
+  int m1;
+  static int m2;
+};
+int S::m2;
+
+extern "C" {
+int global_in_extern_c_1;
+}
+
+extern "C" int global_in_extern_c_2;
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp
@@ -1,13 +1,13 @@
-// RUN: %check_clang_tidy -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN: %check_clang_tidy -std=c++20 %s modernize-use-designated-initializers %t \
 // RUN:     -- \
 // RUN:     -- -fno-delayed-template-parsing
-// RUN: %check_clang_tidy -check-suffixes=,SINGLE-ELEMENT -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN: %check_clang_tidy -check-suffixes=,SINGLE-ELEMENT -std=c++20 %s modernize-use-designated-initializers %t \
 // RUN:     -- -config="{CheckOptions: {modernize-use-designated-initializers.IgnoreSingleElementAggregates: false}}" \
 // RUN:     -- -fno-delayed-template-parsing
-// RUN: %check_clang_tidy -check-suffixes=POD -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN: %check_clang_tidy -check-suffixes=POD -std=c++20 %s modernize-use-designated-initializers %t \
 // RUN:     -- -config="{CheckOptions: {modernize-use-designated-initializers.RestrictToPODTypes: true}}" \
 // RUN:     -- -fno-delayed-template-parsing
-// RUN: %check_clang_tidy -check-suffixes=,MACROS -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN: %check_clang_tidy -check-suffixes=,MACROS -std=c++20 %s modernize-use-designated-initializers %t \
 // RUN:     -- -config="{CheckOptions: {modernize-use-designated-initializers.IgnoreMacros: false}}" \
 // RUN:     -- -fno-delayed-template-parsing
 

diff --git a/clang-tools-extra/test/clang-tidy/checkers/performance/unnecessary-copy-initialization.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/unnecessary-copy-initialization.cpp
@@ -32,6 +32,9 @@ struct ExpensiveToCopyType {
 
 template <typename T>
 struct Container {
+  using reference = T&;
+  using const_reference = const T&;
+
   bool empty() const;
   const T& operator[](int) const;
   const T& operator[](int);
@@ -42,8 +45,8 @@ struct Container {
   void nonConstMethod();
   bool constMethod() const;
 
-  const T& at(int) const;
-  T& at(int);
+  reference at(int) const;
+  const_reference at(int);
 
 };
 
@@ -207,6 +210,28 @@ void PositiveOperatorCallConstValueParam(const Container<ExpensiveToCopyType> C)
   VarCopyConstructed.constMethod();
 }
 
+void PositiveOperatorValueParam(Container<ExpensiveToCopyType> C) {
+  const auto AutoAssigned = C[42];
+  // CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'
+  // CHECK-FIXES: const auto& AutoAssigned = C[42];
+  AutoAssigned.constMethod();
+
+  const auto AutoCopyConstructed(C[42]);
+  // CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoCopyConstructed'
+  // CHECK-FIXES: const auto& AutoCopyConstructed(C[42]);
+  AutoCopyConstructed.constMethod();
+
+  const ExpensiveToCopyType VarAssigned = C.at(42);
+  // CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarAssigned'
+  // CHECK-FIXES: const ExpensiveToCopyType& VarAssigned = C.at(42);
+  VarAssigned.constMethod();
+
+  const ExpensiveToCopyType VarCopyConstructed(C.at(42));
+  // CHECK-MESSAGES: [[@LINE-1]]:29: warning: the const qualified variable 'VarCopyConstructed'
+  // CHECK-FIXES: const ExpensiveToCopyType& VarCopyConstructed(C.at(42));
+  VarCopyConstructed.constMethod();
+}
+
 void PositiveOperatorCallConstValueParamAlias(const ExpensiveToCopyContainerAlias C) {
   const auto AutoAssigned = C[42];
   // CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'AutoAssigned'

diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion-cxx20.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion-cxx20.cpp
@@ -0,0 +1,31 @@
+// RUN: %check_clang_tidy -std=c++20 %s readability-implicit-bool-conversion %t
+
+namespace std {
+struct strong_ordering {
+  int n;
+  constexpr operator int() const { return n; }
+  static const strong_ordering equal, greater, less;
+};
+constexpr strong_ordering strong_ordering::equal = {0};
+constexpr strong_ordering strong_ordering::greater = {1};
+constexpr strong_ordering strong_ordering::less = {-1};
+} // namespace std
+
+namespace PR93409 {
+  struct X
+  {
+      auto operator<=>(const X&) const = default;
+      bool m_b;
+  };
+
+  struct Y
+  {
+      auto operator<=>(const Y&) const = default;
+      X m_x;
+  };
+
+  bool compare(const Y& y1, const Y& y2)
+  {
+     return y1 == y2 || y1 < y2 || y1 > y2;
+  }
+}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/math-missing-parentheses.cpp
@@ -140,3 +140,20 @@ void f(){
     //CHECK-MESSAGES: :[[@LINE+1]]:13: warning: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses]
     int v = FUN5(0 + 1);
 }
+
+namespace PR92516 {
+  void f(int i) {
+    int j, k;
+    for (j = i + 1, k = 0; j < 1; ++j) {}
+  }
+
+  void f2(int i) {
+    int j;
+    for (j = i + 1; j < 1; ++j) {}
+  }
+
+  void f3(int i) {
+    int j;
+    for (j = i + 1, 2; j < 1; ++j) {}
+  }
+}
diff --git a/clang-tools-extra/unittests/clang-tidy/DeclRefExprUtilsTest.cpp b/clang-tools-extra/unittests/clang-tidy/DeclRefExprUtilsTest.cpp
@@ -46,6 +46,7 @@ template <int Indirections> void RunTest(StringRef Snippet) {
   StringRef CommonCode = R"(
     struct ConstTag{};
     struct NonConstTag{};
+    struct Tag1{};
 
     struct S {
       void constMethod() const;
@@ -59,6 +60,13 @@ template <int Indirections> void RunTest(StringRef Snippet) {
       void operator[](int);
       void operator[](int) const;
 
+      int& at(int);
+      const int& at(int) const;
+      const int& at(Tag1);
+
+      int& weird_overload();
+      const double& weird_overload() const;
+
       bool operator==(const S&) const;
 
       int int_member;
@@ -161,9 +169,11 @@ TEST(ConstReferenceDeclRefExprsTest, ConstRefVar) {
       useIntConstRef(/*const*/target.int_member);
       useIntPtr(/*const*/target.ptr_member);
       useIntConstPtr(&/*const*/target.int_member);
+      (void)/*const*/target.at(3);
 
       const S& const_target_ref = /*const*/target;
       const S* const_target_ptr = &/*const*/target;
+      (void)/*const*/target.at(3);
     }
 )");
 }
@@ -187,7 +197,7 @@ TEST(ConstReferenceDeclRefExprsTest, ValueVar) {
       /*const*/target.staticMethod();
       target.nonConstMethod();
       /*const*/target(ConstTag{});
-      target[42];
+      /*const*/target[42];
       /*const*/target(ConstTag{});
       target(NonConstTag{});
       useRef(target);
@@ -211,6 +221,14 @@ TEST(ConstReferenceDeclRefExprsTest, ValueVar) {
       const S& const_target_ref = /*const*/target;
       const S* const_target_ptr = &/*const*/target;
       S* target_ptr = &target;
+
+      (void)/*const*/target.at(3);
+      ++target.at(3);
+      const int civ = /*const*/target.at(3);
+      const int& cir = /*const*/target.at(3);
+      int& ir = target.at(3);
+      target.at(Tag1{});
+      target.weird_overload();
     }
 )");
 }
@@ -227,7 +245,7 @@ TEST(ConstReferenceDeclRefExprsTest, RefVar) {
       /*const*/target.staticMethod();
       target.nonConstMethod();
       /*const*/target(ConstTag{});
-      target[42];
+      /*const*/target[42];
       useConstRef((/*const*/target));
       (/*const*/target).constMethod();
       (void)(/*const*/target == /*const*/target);
@@ -249,6 +267,14 @@ TEST(ConstReferenceDeclRefExprsTest, RefVar) {
       const S& const_target_ref = /*const*/target;
       const S* const_target_ptr = &/*const*/target;
       S* target_ptr = &target;
+
+      (void)/*const*/target.at(3);
+      ++target.at(3);
+      const int civ = /*const*/target.at(3);
+      const int& cir = /*const*/target.at(3);
+      int& ir = target.at(3);
+      target.at(Tag1{});
+      target.weird_overload();
     }
 )");
 }
@@ -266,8 +292,8 @@ TEST(ConstReferenceDeclRefExprsTest, PtrVar) {
       /*const*/target->staticMethod();
       target->nonConstMethod();
       (*/*const*/target)(ConstTag{});
-      (*target)[42];
-      target->operator[](42);
+      (*/*const*/target)[42];
+      /*const*/target->operator[](42);
       useConstRef((*/*const*/target));
       (/*const*/target)->constMethod();
       (void)(*/*const*/target == */*const*/target);
@@ -284,7 +310,15 @@ TEST(ConstReferenceDeclRefExprsTest, PtrVar) {
 
       const S& const_target_ref = */*const*/target;
       const S* const_target_ptr = /*const*/target;
-      S* target_ptr = target;  // FIXME: we could chect const usage of `target_ptr`.
+      S* target_ptr = target;  // FIXME: we could chect const usage of `target_ptr`
+
+      (void)/*const*/target->at(3);
+      ++target->at(3);
+      const int civ = /*const*/target->at(3);
+      const int& cir = /*const*/target->at(3);
+      int& ir = target->at(3);
+      target->at(Tag1{});
+      target->weird_overload();
     }
 )");
 }
@@ -319,6 +353,10 @@ TEST(ConstReferenceDeclRefExprsTest, ConstPtrVar) {
 
       const S& const_target_ref = */*const*/target;
       const S* const_target_ptr = /*const*/target;
+
+      (void)/*const*/target->at(3);
+      const int civ = /*const*/target->at(3);
+      const int& cir = /*const*/target->at(3);
     }
 )");
 }

diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
@@ -350,7 +350,9 @@ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic -Wno-long-long")
   endif ()
 
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
+  if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
+  endif ()
 endif ()
 
 # Determine HOST_LINK_VERSION on Darwin.
@@ -848,23 +850,17 @@ if (CLANG_ENABLE_BOOTSTRAP)
     set(CLANG_BOOTSTRAP_TARGETS check-llvm check-clang check-all)
   endif()
   foreach(target ${CLANG_BOOTSTRAP_TARGETS})
-    # Install targets have side effects, so we always want to execute them.
-    # "install" is reserved by CMake and can't be used as a step name for
-    # ExternalProject_Add_Step, so we can match against "^install-" instead of
-    # "^install" to get a tighter match. CMake's installation scripts already
-    # skip up-to-date files, so there's no behavior change if you install to the
-    # same destination multiple times.
-    if(target MATCHES "^install-")
-      set(step_always ON)
-    else()
-      set(step_always OFF)
-    endif()
 
     ExternalProject_Add_Step(${NEXT_CLANG_STAGE} ${target}
       COMMAND ${CMAKE_COMMAND} --build <BINARY_DIR> --target ${target}
       COMMENT "Performing ${target} for '${NEXT_CLANG_STAGE}'"
       DEPENDEES configure
-      ALWAYS ${step_always}
+      # We need to set ALWAYS to ON here, otherwise these targets won't be
+      # built on a second invocation of ninja.  The targets have their own
+      # logic to determine if they should build or not so setting ALWAYS ON
+      # here does not mean the targets will always rebuild it just means that
+      # they will check their dependenices and see if they need to be built.
+      ALWAYS ON
       EXCLUDE_FROM_MAIN ON
       USES_TERMINAL 1
     )

diff --git a/clang/cmake/caches/CrossWinToARMLinux.cmake b/clang/cmake/caches/CrossWinToARMLinux.cmake
@@ -6,21 +6,23 @@
 # on Windows platform.
 #
 # NOTE: the build requires a development ARM Linux root filesystem to use
-# proper target platform depended library and header files:
-#  - create <full-path-to-clang-configs> directory and put the clang configuration
-#    file named <TOOLCHAIN_TARGET_TRIPLE>.cfg into it.
-#  - add the `--sysroot=<path-to-develop-arm-linux-root-fs>` argument into
-#    this configuration file.
-#  - add other necessary target depended clang arguments there, 
-#    such as '-mcpu=cortex-a78' & etc.
+# proper target platform depended library and header files.
+#
+# The build generates a proper clang configuration file with stored
+# --sysroot argument for specified target triple. Also it is possible
+# to specify configuration path via CMake arguments, such as
+#   -DCLANG_CONFIG_FILE_USER_DIR=<full-path-to-clang-configs>
+# and/or
+#   -DCLANG_CONFIG_FILE_SYSTEM_DIR=<full-path-to-clang-configs>
 #
 # See more details here: https://clang.llvm.org/docs/UsersManual.html#configuration-files
 #
 # Configure:
 #  cmake -G Ninja ^
 #       -DTOOLCHAIN_TARGET_TRIPLE=aarch64-unknown-linux-gnu ^
+#       -DTOOLCHAIN_TARGET_SYSROOTFS=<path-to-develop-arm-linux-root-fs> ^
+#       -DTOOLCHAIN_SHARED_LIBS=OFF ^ 
 #       -DCMAKE_INSTALL_PREFIX=../install ^
-#       -DCLANG_CONFIG_FILE_USER_DIR=<full-path-to-clang-configs> ^
 #       -DCMAKE_CXX_FLAGS="-D__OPTIMIZE__" ^
 #       -DREMOTE_TEST_HOST="<hostname>" ^
 #       -DREMOTE_TEST_USER="<ssh_user_name>" ^
@@ -81,6 +83,20 @@ endif()
 
 message(STATUS "Toolchain target triple: ${TOOLCHAIN_TARGET_TRIPLE}")
 
+if (DEFINED TOOLCHAIN_TARGET_SYSROOTFS)
+  message(STATUS "Toolchain target sysroot: ${TOOLCHAIN_TARGET_SYSROOTFS}")
+  # Store the --sysroot argument for the compiler-rt test flags.
+  set(sysroot_flags --sysroot='${TOOLCHAIN_TARGET_SYSROOTFS}')
+  # Generate the clang configuration file for the specified target triple
+  # and store --sysroot in this file.
+  file(WRITE "${CMAKE_BINARY_DIR}/bin/${TOOLCHAIN_TARGET_TRIPLE}.cfg" ${sysroot_flags})
+endif()
+
+# Build the shared libraries for libc++/libc++abi/libunwind.
+if (NOT DEFINED TOOLCHAIN_SHARED_LIBS)
+  set(TOOLCHAIN_SHARED_LIBS OFF)
+endif()
+
 if (NOT DEFINED LLVM_TARGETS_TO_BUILD)
   if ("${TOOLCHAIN_TARGET_TRIPLE}" MATCHES "^(armv|arm32)+")
     set(LLVM_TARGETS_TO_BUILD "ARM" CACHE STRING "")
@@ -183,20 +199,21 @@ set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_CAN_EXECUTE_TESTS
 
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_USE_BUILTINS_LIBRARY          ON CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_CXX_LIBRARY                   libcxx CACHE STRING "")
-# Tell Clang to seach C++ headers alongside with the just-built binaries for the C++ compiler-rt tests.
-set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_TEST_COMPILER_CFLAGS          "--stdlib=libc++" CACHE STRING "")
-
+# The compiler-rt tests disable the clang configuration files during the execution by setting CLANG_NO_DEFAULT_CONFIG=1
+# and drops out the --sysroot from there. Provide it explicity via the test flags here if target sysroot has been specified.
+set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_COMPILER_RT_TEST_COMPILER_CFLAGS          "--stdlib=libc++ ${sysroot_flags}" CACHE STRING "")
+
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBUNWIND_USE_COMPILER_RT                 ON CACHE BOOL "")
-set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBUNWIND_ENABLE_SHARED                   OFF CACHE BOOL "")
+set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBUNWIND_ENABLE_SHARED                   ${TOOLCHAIN_SHARED_LIBS} CACHE BOOL "")
 
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_USE_LLVM_UNWINDER               ON CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_ENABLE_STATIC_UNWINDER          ON CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_USE_COMPILER_RT                 ON CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS   OFF CACHE BOOL "")
-set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_ENABLE_SHARED                   OFF CACHE BOOL "")
+set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_ENABLE_SHARED                   ${TOOLCHAIN_SHARED_LIBS} CACHE BOOL "")
 
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_USE_COMPILER_RT                    ON CACHE BOOL "")
-set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_SHARED                      OFF CACHE BOOL "")
+set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_SHARED                      ${TOOLCHAIN_SHARED_LIBS} CACHE BOOL "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ABI_VERSION                        ${LIBCXX_ABI_VERSION} CACHE STRING "")
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_CXX_ABI                            "libcxxabi" CACHE STRING "")    #!!!
 set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS      ON CACHE BOOL "")

diff --git a/clang/cmake/caches/Release.cmake b/clang/cmake/caches/Release.cmake
@@ -30,7 +30,7 @@ endfunction()
 #
 # cmake -D LLVM_RELEASE_ENABLE_PGO=ON -C Release.cmake
 set(LLVM_RELEASE_ENABLE_LTO THIN CACHE STRING "")
-set(LLVM_RELEASE_ENABLE_PGO OFF CACHE BOOL "")
+set(LLVM_RELEASE_ENABLE_PGO ON CACHE BOOL "")
 set(LLVM_RELEASE_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")
 set(LLVM_RELEASE_ENABLE_PROJECTS "clang;lld;lldb;clang-tools-extra;bolt;polly;mlir;flang" CACHE STRING "")
 # Note we don't need to add install here, since it is one of the pre-defined
@@ -91,4 +91,6 @@ endif()
 # Final Stage Config (stage2)
 set_final_stage_var(LLVM_ENABLE_RUNTIMES "${LLVM_RELEASE_ENABLE_RUNTIMES}" STRING)
 set_final_stage_var(LLVM_ENABLE_PROJECTS "${LLVM_RELEASE_ENABLE_PROJECTS}" STRING)
+set_final_stage_var(CPACK_GENERATOR "TXZ" STRING)
+set_final_stage_var(CPACK_ARCHIVE_THREADS "0" STRING)
 
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -907,6 +907,7 @@ Arm and AArch64 Support
     * Arm Cortex-A520AE (cortex-a520ae).
     * Arm Cortex-A720AE (cortex-a720ae).
     * Arm Cortex-R82AE (cortex-r82ae).
+    * Arm Cortex-R52+ (cortex-r52plus).
     * Arm Neoverse-N3 (neoverse-n3).
     * Arm Neoverse-V3 (neoverse-v3).
     * Arm Neoverse-V3AE (neoverse-v3ae).

diff --git a/clang/docs/tools/clang-formatted-files.txt b/clang/docs/tools/clang-formatted-files.txt
@@ -622,6 +622,7 @@ clang/tools/libclang/CXCursor.h
 clang/tools/scan-build-py/tests/functional/src/include/clean-one.h
 clang/unittests/Analysis/CFGBuildResult.h
 clang/unittests/Analysis/MacroExpansionContextTest.cpp
+clang/unittests/Analysis/FlowSensitive/ASTOpsTest.cpp
 clang/unittests/Analysis/FlowSensitive/CNFFormula.cpp
 clang/unittests/Analysis/FlowSensitive/DataflowAnalysisContextTest.cpp
 clang/unittests/Analysis/FlowSensitive/DataflowEnvironmentTest.cpp

diff --git a/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp b/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp
@@ -72,7 +72,7 @@ class PrintFunctionsConsumer : public ASTConsumer {
           *sema.LateParsedTemplateMap.find(FD)->second;
       sema.LateTemplateParser(sema.OpaqueParser, LPT);
       llvm::errs() << "late-parsed-decl: \"" << FD->getNameAsString() << "\"\n";
-    }   
+    }
   }
 };
 

diff --git a/clang/include/clang/AST/ASTUnresolvedSet.h b/clang/include/clang/AST/ASTUnresolvedSet.h
@@ -16,6 +16,7 @@
 
 #include "clang/AST/ASTVector.h"
 #include "clang/AST/DeclAccessPair.h"
+#include "clang/AST/DeclID.h"
 #include "clang/AST/UnresolvedSet.h"
 #include "clang/Basic/Specifiers.h"
 #include <cassert>
@@ -56,6 +57,10 @@ class ASTUnresolvedSet {
     Decls.push_back(DeclAccessPair::make(D, AS), C);
   }
 
+  void addLazyDecl(ASTContext &C, GlobalDeclID ID, AccessSpecifier AS) {
+    Decls.push_back(DeclAccessPair::makeLazy(ID.get(), AS), C);
+  }
+
   /// Replaces the given declaration with the new one, once.
   ///
   /// \return true if the set changed
@@ -109,10 +114,10 @@ class LazyASTUnresolvedSet {
 
   void reserve(ASTContext &C, unsigned N) { Impl.reserve(C, N); }
 
-  void addLazyDecl(ASTContext &C, uintptr_t ID, AccessSpecifier AS) {
+  void addLazyDecl(ASTContext &C, GlobalDeclID ID, AccessSpecifier AS) {
     assert(Impl.empty() || Impl.Decls.isLazy());
     Impl.Decls.setLazy(true);
-    Impl.addDecl(C, reinterpret_cast<NamedDecl *>(ID << 2), AS);
+    Impl.addLazyDecl(C, ID, AS);
   }
 };
 

diff --git a/clang/include/clang/AST/CommentCommands.td b/clang/include/clang/AST/CommentCommands.td
@@ -132,9 +132,9 @@ def Tparam : BlockCommand<"tparam"> { let IsTParamCommand = 1; }
 // HeaderDoc command for template parameter documentation.
 def Templatefield : BlockCommand<"templatefield"> { let IsTParamCommand = 1; }
 
-def Throws    : BlockCommand<"throws"> { let IsThrowsCommand = 1; }
-def Throw     : BlockCommand<"throw"> { let IsThrowsCommand = 1; }
-def Exception : BlockCommand<"exception"> { let IsThrowsCommand = 1; }
+def Throws    : BlockCommand<"throws"> { let IsThrowsCommand = 1; let NumArgs = 1; }
+def Throw     : BlockCommand<"throw"> { let IsThrowsCommand = 1; let NumArgs = 1; }
+def Exception : BlockCommand<"exception"> { let IsThrowsCommand = 1; let NumArgs = 1;}
 
 def Deprecated : BlockCommand<"deprecated"> {
   let IsEmptyParagraphAllowed = 1;

diff --git a/clang/include/clang/AST/CommentParser.h b/clang/include/clang/AST/CommentParser.h
@@ -100,6 +100,11 @@ class Parser {
   ArrayRef<Comment::Argument>
   parseCommandArgs(TextTokenRetokenizer &Retokenizer, unsigned NumArgs);
 
+  /// Parse arguments for \throws command supported args are in form of class
+  /// or template.
+  ArrayRef<Comment::Argument>
+  parseThrowCommandArgs(TextTokenRetokenizer &Retokenizer, unsigned NumArgs);
+
   BlockCommandComment *parseBlockCommand();
   InlineCommandComment *parseInlineCommand();
 

diff --git a/clang/include/clang/AST/DeclAccessPair.h b/clang/include/clang/AST/DeclAccessPair.h
@@ -19,6 +19,7 @@
 
 #include "clang/Basic/Specifiers.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Endian.h"
 
 namespace clang {
 
@@ -27,9 +28,17 @@ class NamedDecl;
 /// A POD class for pairing a NamedDecl* with an access specifier.
 /// Can be put into unions.
 class DeclAccessPair {
-  uintptr_t Ptr; // we'd use llvm::PointerUnion, but it isn't trivial
+  /// Use the lower 2 bit to store AccessSpecifier. Use the higher
+  /// 61 bit to store the pointer to a NamedDecl or the DeclID to
+  /// a NamedDecl. If the 3rd bit is set, storing the DeclID, otherwise
+  /// storing the pointer.
+  llvm::support::detail::packed_endian_specific_integral<
+      uint64_t, llvm::endianness::native, alignof(void *)>
+      Ptr;
 
-  enum { Mask = 0x3 };
+  enum { ASMask = 0x3, Mask = 0x7 };
+
+  bool isDeclID() const { return (Ptr >> 2) & 0x1; }
 
 public:
   static DeclAccessPair make(NamedDecl *D, AccessSpecifier AS) {
@@ -38,12 +47,22 @@ class DeclAccessPair {
     return p;
   }
 
+  static DeclAccessPair makeLazy(uint64_t ID, AccessSpecifier AS) {
+    DeclAccessPair p;
+    p.Ptr = (ID << 3) | (0x1 << 2) | uint64_t(AS);
+    return p;
+  }
+
+  uint64_t getDeclID() const {
+    assert(isDeclID());
+    return (~Mask & Ptr) >> 3;
+  }
+
   NamedDecl *getDecl() const {
+    assert(!isDeclID());
     return reinterpret_cast<NamedDecl*>(~Mask & Ptr);
   }
-  AccessSpecifier getAccess() const {
-    return AccessSpecifier(Mask & Ptr);
-  }
+  AccessSpecifier getAccess() const { return AccessSpecifier(ASMask & Ptr); }
 
   void setDecl(NamedDecl *D) {
     set(D, getAccess());
@@ -52,12 +71,18 @@ class DeclAccessPair {
     set(getDecl(), AS);
   }
   void set(NamedDecl *D, AccessSpecifier AS) {
-    Ptr = uintptr_t(AS) | reinterpret_cast<uintptr_t>(D);
+    Ptr = uint64_t(AS) | reinterpret_cast<uint64_t>(D);
   }
 
   operator NamedDecl*() const { return getDecl(); }
   NamedDecl *operator->() const { return getDecl(); }
 };
+
+// Make sure DeclAccessPair is pointer-aligned types.
+static_assert(alignof(DeclAccessPair) == alignof(void *));
+// Make sure DeclAccessPair is still POD.
+static_assert(std::is_standard_layout_v<DeclAccessPair> &&
+              std::is_trivial_v<DeclAccessPair>);
 }
 
 #endif
diff --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
@@ -708,10 +708,7 @@ class alignas(8) Decl {
 
   /// Set the owning module ID.  This may only be called for
   /// deserialized Decls.
-  void setOwningModuleID(unsigned ID) {
-    assert(isFromASTFile() && "Only works on a deserialized declaration");
-    *((unsigned*)this - 2) = ID;
-  }
+  void setOwningModuleID(unsigned ID);
 
 public:
   /// Determine the availability of the given declaration.
@@ -784,19 +781,11 @@ class alignas(8) Decl {
 
   /// Retrieve the global declaration ID associated with this
   /// declaration, which specifies where this Decl was loaded from.
-  GlobalDeclID getGlobalID() const {
-    if (isFromASTFile())
-      return (*((const GlobalDeclID *)this - 1));
-    return GlobalDeclID();
-  }
+  GlobalDeclID getGlobalID() const;
 
   /// Retrieve the global ID of the module that owns this particular
   /// declaration.
-  unsigned getOwningModuleID() const {
-    if (isFromASTFile())
-      return *((const unsigned*)this - 2);
-    return 0;
-  }
+  unsigned getOwningModuleID() const;
 
 private:
   Module *getOwningModuleSlow() const;

diff --git a/clang/include/clang/AST/DeclID.h b/clang/include/clang/AST/DeclID.h
@@ -19,6 +19,8 @@
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/iterator.h"
 
+#include <climits>
+
 namespace clang {
 
 /// Predefined declaration IDs.
@@ -107,12 +109,16 @@ class DeclIDBase {
   ///
   /// DeclID should only be used directly in serialization. All other users
   /// should use LocalDeclID or GlobalDeclID.
-  using DeclID = uint32_t;
+  using DeclID = uint64_t;
 
 protected:
   DeclIDBase() : ID(PREDEF_DECL_NULL_ID) {}
   explicit DeclIDBase(DeclID ID) : ID(ID) {}
 
+  explicit DeclIDBase(unsigned LocalID, unsigned ModuleFileIndex) {
+    ID = (DeclID)LocalID | ((DeclID)ModuleFileIndex << 32);
+  }
+
 public:
   DeclID get() const { return ID; }
 
@@ -124,6 +130,10 @@ class DeclIDBase {
 
   bool isInvalid() const { return ID == PREDEF_DECL_NULL_ID; }
 
+  unsigned getModuleFileIndex() const { return ID >> 32; }
+
+  unsigned getLocalDeclIndex() const;
+
   friend bool operator==(const DeclIDBase &LHS, const DeclIDBase &RHS) {
     return LHS.ID == RHS.ID;
   }
@@ -156,6 +166,9 @@ class LocalDeclID : public DeclIDBase {
   LocalDeclID(PredefinedDeclIDs ID) : Base(ID) {}
   explicit LocalDeclID(DeclID ID) : Base(ID) {}
 
+  explicit LocalDeclID(unsigned LocalID, unsigned ModuleFileIndex)
+      : Base(LocalID, ModuleFileIndex) {}
+
   LocalDeclID &operator++() {
     ++ID;
     return *this;
@@ -175,6 +188,9 @@ class GlobalDeclID : public DeclIDBase {
   GlobalDeclID() : Base() {}
   explicit GlobalDeclID(DeclID ID) : Base(ID) {}
 
+  explicit GlobalDeclID(unsigned LocalID, unsigned ModuleFileIndex)
+      : Base(LocalID, ModuleFileIndex) {}
+
   // For DeclIDIterator<GlobalDeclID> to be able to convert a GlobalDeclID
   // to a LocalDeclID.
   explicit operator LocalDeclID() const { return LocalDeclID(this->ID); }

diff --git a/clang/include/clang/AST/TemplateBase.h b/clang/include/clang/AST/TemplateBase.h
@@ -459,7 +459,7 @@ class TemplateArgument {
              bool IncludeType) const;
 
   /// Debugging aid that dumps the template argument.
-  void dump(raw_ostream &Out) const;
+  void dump(raw_ostream &Out, const ASTContext &Context) const;
 
   /// Debugging aid that dumps the template argument to standard error.
   void dump() const;

diff --git a/clang/include/clang/AST/TemplateName.h b/clang/include/clang/AST/TemplateName.h
@@ -340,7 +340,7 @@ class TemplateName {
              Qualified Qual = Qualified::AsWritten) const;
 
   /// Debugging aid that dumps the template name.
-  void dump(raw_ostream &OS) const;
+  void dump(raw_ostream &OS, const ASTContext &Context) const;
 
   /// Debugging aid that dumps the template name to standard
   /// error.

diff --git a/clang/include/clang/AST/UnresolvedSet.h b/clang/include/clang/AST/UnresolvedSet.h
@@ -47,6 +47,7 @@ class UnresolvedSetIterator : public llvm::iterator_adaptor_base<
   // temporaries with defaulted ctors are not zero initialized.
   UnresolvedSetIterator() : iterator_adaptor_base(nullptr) {}
 
+  uint64_t getDeclID() const { return I->getDeclID(); }
   NamedDecl *getDecl() const { return I->getDecl(); }
   void setDecl(NamedDecl *ND) const { return I->setDecl(ND); }
   AccessSpecifier getAccess() const { return I->getAccess(); }

diff --git a/clang/include/clang/Analysis/Analyses/ThreadSafetyCommon.h b/clang/include/clang/Analysis/Analyses/ThreadSafetyCommon.h
@@ -330,9 +330,9 @@ class CapabilityExpr {
 
   bool shouldIgnore() const { return sexpr() == nullptr; }
 
-  bool isInvalid() const { return sexpr() && isa<til::Undefined>(sexpr()); }
+  bool isInvalid() const { return isa_and_nonnull<til::Undefined>(sexpr()); }
 
-  bool isUniversal() const { return sexpr() && isa<til::Wildcard>(sexpr()); }
+  bool isUniversal() const { return isa_and_nonnull<til::Wildcard>(sexpr()); }
 };
 
 // Translate clang::Expr to til::SExpr.

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
@@ -4470,37 +4470,20 @@ def HLSLShader : InheritableAttr {
   let Subjects = SubjectList<[HLSLEntry]>;
   let LangOpts = [HLSL];
   let Args = [
-    EnumArgument<"Type", "ShaderType", /*is_string=*/true,
+    EnumArgument<"Type", "llvm::Triple::EnvironmentType", /*is_string=*/true,
                  ["pixel", "vertex", "geometry", "hull", "domain", "compute",
                   "raygeneration", "intersection", "anyhit", "closesthit",
                   "miss", "callable", "mesh", "amplification"],
                  ["Pixel", "Vertex", "Geometry", "Hull", "Domain", "Compute",
                   "RayGeneration", "Intersection", "AnyHit", "ClosestHit",
-                  "Miss", "Callable", "Mesh", "Amplification"]>
+                  "Miss", "Callable", "Mesh", "Amplification"],
+                  /*opt=*/0, /*fake=*/0, /*isExternalType=*/1>
   ];
   let Documentation = [HLSLSV_ShaderTypeAttrDocs];
   let AdditionalMembers =
 [{
-  static const unsigned ShaderTypeMaxValue = (unsigned)HLSLShaderAttr::Amplification;
-
-  static llvm::Triple::EnvironmentType getTypeAsEnvironment(HLSLShaderAttr::ShaderType ShaderType) {
-    switch (ShaderType) {
-      case HLSLShaderAttr::Pixel:         return llvm::Triple::Pixel;
-      case HLSLShaderAttr::Vertex:        return llvm::Triple::Vertex;
-      case HLSLShaderAttr::Geometry:      return llvm::Triple::Geometry;
-      case HLSLShaderAttr::Hull:          return llvm::Triple::Hull;
-      case HLSLShaderAttr::Domain:        return llvm::Triple::Domain;
-      case HLSLShaderAttr::Compute:       return llvm::Triple::Compute;
-      case HLSLShaderAttr::RayGeneration: return llvm::Triple::RayGeneration;
-      case HLSLShaderAttr::Intersection:  return llvm::Triple::Intersection;
-      case HLSLShaderAttr::AnyHit:        return llvm::Triple::AnyHit;
-      case HLSLShaderAttr::ClosestHit:    return llvm::Triple::ClosestHit;
-      case HLSLShaderAttr::Miss:          return llvm::Triple::Miss;
-      case HLSLShaderAttr::Callable:      return llvm::Triple::Callable;
-      case HLSLShaderAttr::Mesh:          return llvm::Triple::Mesh;
-      case HLSLShaderAttr::Amplification: return llvm::Triple::Amplification;
-    }
-    llvm_unreachable("unknown enumeration value");
+  static bool isValidShaderType(llvm::Triple::EnvironmentType ShaderType) {
+    return ShaderType >= llvm::Triple::Pixel && ShaderType <= llvm::Triple::Amplification;
   }
 }];
 }

diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
@@ -482,11 +482,11 @@ def SqrtF16F128 : Builtin, F16F128MathTemplate {
   let Prototype = "T(T)";
 }
 
-def TanF128 : Builtin {
-  let Spellings = ["__builtin_tanf128"];
+def TanF16F128 : Builtin, F16F128MathTemplate {
+  let Spellings = ["__builtin_tan"];
   let Attributes = [FunctionWithBuiltinPrefix, NoThrow,
                     ConstIgnoringErrnoAndExceptions];
-  let Prototype = "__float128(__float128)";
+  let Prototype = "T(T)";
 }
 
 def TanhF128 : Builtin {

diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
@@ -61,7 +61,7 @@ CODEGENOPT(SeparateNamedSections, 1, 0) ///< Set for -fseparate-named-sections.
 CODEGENOPT(EnableAIXExtendedAltivecABI, 1, 0) ///< Set for -mabi=vec-extabi. Enables the extended Altivec ABI on AIX.
 CODEGENOPT(XCOFFReadOnlyPointers, 1, 0) ///< Set for -mxcoff-roptr.
 CODEGENOPT(AllTocData, 1, 0) ///< AIX -mtocdata
-ENUM_CODEGENOPT(FramePointer, FramePointerKind, 2, FramePointerKind::None) /// frame-pointer: all,non-leaf,none
+ENUM_CODEGENOPT(FramePointer, FramePointerKind, 2, FramePointerKind::None) /// frame-pointer: all,non-leaf,reserved,none
 
 CODEGENOPT(ClearASTBeforeBackend , 1, 0) ///< Free the AST before running backend code generation. Only works with -disable-free.
 CODEGENOPT(DisableFree       , 1, 0) ///< Don't free memory.

diff --git a/clang/include/clang/Basic/CodeGenOptions.h b/clang/include/clang/Basic/CodeGenOptions.h
@@ -127,15 +127,18 @@ class CodeGenOptions : public CodeGenOptionsBase {
   std::string BinutilsVersion;
 
   enum class FramePointerKind {
-    None,        // Omit all frame pointers.
-    NonLeaf,     // Keep non-leaf frame pointers.
-    All,         // Keep all frame pointers.
+    None,     // Omit all frame pointers.
+    Reserved, // Maintain valid frame pointer chain.
+    NonLeaf,  // Keep non-leaf frame pointers.
+    All,      // Keep all frame pointers.
   };
 
   static StringRef getFramePointerKindName(FramePointerKind Kind) {
     switch (Kind) {
     case FramePointerKind::None:
       return "none";
+    case FramePointerKind::Reserved:
+      return "reserved";
     case FramePointerKind::NonLeaf:
       return "non-leaf";
     case FramePointerKind::All:

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -607,6 +607,8 @@ def note_using_decl_class_member_workaround : Note<
   "a const variable|a constexpr variable}0 instead">;
 def err_using_decl_can_not_refer_to_namespace : Error<
   "using declaration cannot refer to a namespace">;
+def note_namespace_using_decl : Note<
+  "did you mean 'using namespace'?">;
 def warn_cxx17_compat_using_decl_scoped_enumerator: Warning<
   "using declaration naming a scoped enumerator is incompatible with "
   "C++ standards before C++20">, InGroup<CXXPre20Compat>, DefaultIgnore;
@@ -6088,9 +6090,9 @@ def err_redefinition_different_concept : Error<
   "redefinition of concept %0 with different template parameters or requirements">;
 def err_tag_reference_non_tag : Error<
   "%select{non-struct type|non-class type|non-union type|non-enum "
-  "type|typedef|type alias|template|type alias template|template "
-  "template argument}1 %0 cannot be referenced with a "
-  "%select{struct|interface|union|class|enum}2 specifier">;
+  "type|typedef|type alias|template|alias template|template "
+  "template argument}1 %0 cannot be referenced with the '"
+  "%select{struct|interface|union|class|enum}2' specifier">;
 def err_tag_reference_conflict : Error<
   "implicit declaration introduced by elaborated type conflicts with a "
   "%select{non-struct type|non-class type|non-union type|non-enum "
@@ -9013,6 +9015,11 @@ def err_cuda_ovl_target : Error<
   "cannot overload %select{__device__|__global__|__host__|__host__ __device__}2 function %3">;
 def note_cuda_ovl_candidate_target_mismatch : Note<
     "candidate template ignored: target attributes do not match">;
+def warn_offload_incompatible_redeclare : Warning<
+  "target-attribute based function overloads are not supported by NVCC and will be treated as a function redeclaration:"
+  "new declaration is %select{__device__|__global__|__host__|__host__ __device__}0 function, "
+  "old declaration is %select{__device__|__global__|__host__|__host__ __device__}1 function">,
+  InGroup<DiagGroup<"nvcc-compat">>, DefaultIgnore;
 
 def err_cuda_device_builtin_surftex_cls_template : Error<
     "illegal device builtin %select{surface|texture}0 reference "

diff --git a/clang/include/clang/Basic/Features.def b/clang/include/clang/Basic/Features.def
@@ -96,6 +96,7 @@ FEATURE(nullability, true)
 FEATURE(nullability_on_arrays, true)
 FEATURE(nullability_on_classes, true)
 FEATURE(nullability_nullable_result, true)
+FEATURE(numerical_stability_sanitizer, LangOpts.Sanitize.has(SanitizerKind::NumericalStability))
 FEATURE(memory_sanitizer,
         LangOpts.Sanitize.hasOneOf(SanitizerKind::Memory |
                                    SanitizerKind::KernelMemory))

diff --git a/clang/include/clang/Basic/Sanitizers.def b/clang/include/clang/Basic/Sanitizers.def
@@ -76,6 +76,9 @@ SANITIZER("fuzzer-no-link", FuzzerNoLink)
 // ThreadSanitizer
 SANITIZER("thread", Thread)
 
+// Numerical stability sanitizer.
+SANITIZER("numerical", NumericalStability)
+
 // LeakSanitizer
 SANITIZER("leak", Leak)
 

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -7724,8 +7724,8 @@ def pic_is_pie : Flag<["-"], "pic-is-pie">,
   MarshallingInfoFlag<LangOpts<"PIE">>;
 
 def mframe_pointer_EQ : Joined<["-"], "mframe-pointer=">,
-  HelpText<"Specify which frame pointers to retain.">, Values<"all,non-leaf,none">,
-  NormalizedValuesScope<"CodeGenOptions::FramePointerKind">, NormalizedValues<["All", "NonLeaf", "None"]>,
+  HelpText<"Specify which frame pointers to retain.">, Values<"all,non-leaf,reserved,none">,
+  NormalizedValuesScope<"CodeGenOptions::FramePointerKind">, NormalizedValues<["All", "NonLeaf", "Reserved", "None"]>,
   MarshallingInfoEnum<CodeGenOpts<"FramePointer">, "None">;
 
 

diff --git a/clang/include/clang/Driver/SanitizerArgs.h b/clang/include/clang/Driver/SanitizerArgs.h
@@ -103,6 +103,9 @@ class SanitizerArgs {
   bool needsCfiDiagRt() const;
   bool needsStatsRt() const { return Stats; }
   bool needsScudoRt() const { return Sanitizers.has(SanitizerKind::Scudo); }
+  bool needsNsanRt() const {
+    return Sanitizers.has(SanitizerKind::NumericalStability);
+  }
 
   bool hasMemTag() const {
     return hasMemtagHeap() || hasMemtagStack() || hasMemtagGlobals();

diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
@@ -205,7 +205,8 @@ class ToolChain {
 
   /// Executes the given \p Executable and returns the stdout.
   llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
-  executeToolChainProgram(StringRef Executable) const;
+  executeToolChainProgram(StringRef Executable,
+                          unsigned SecondsToWait = 0) const;
 
   void setTripleEnvironment(llvm::Triple::EnvironmentType Env);
 

diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
@@ -1360,7 +1360,7 @@ class Preprocessor {
 
     MacroState &S = CurSubmoduleState->Macros[II];
     auto *MD = S.getLatest();
-    while (MD && isa<VisibilityMacroDirective>(MD))
+    while (isa_and_nonnull<VisibilityMacroDirective>(MD))
       MD = MD->getPrevious();
     return MacroDefinition(dyn_cast_or_null<DefMacroDirective>(MD),
                            S.getActiveModuleMacros(*this, II),

diff --git a/clang/include/clang/Sema/Initialization.h b/clang/include/clang/Sema/Initialization.h
@@ -212,7 +212,7 @@ class alignas(8) InitializedEntity {
     struct C Capture;
   };
 
-  InitializedEntity() {};
+  InitializedEntity() {}
 
   /// Create the initialization entity for a variable.
   InitializedEntity(VarDecl *Var, EntityKind EK = EK_Variable)

diff --git a/clang/include/clang/Sema/SemaHLSL.h b/clang/include/clang/Sema/SemaHLSL.h
@@ -39,7 +39,7 @@ class SemaHLSL : public SemaBase {
                                           const AttributeCommonInfo &AL, int X,
                                           int Y, int Z);
   HLSLShaderAttr *mergeShaderAttr(Decl *D, const AttributeCommonInfo &AL,
-                                  HLSLShaderAttr::ShaderType ShaderType);
+                                  llvm::Triple::EnvironmentType ShaderType);
   HLSLParamModifierAttr *
   mergeParamModifierAttr(Decl *D, const AttributeCommonInfo &AL,
                          HLSLParamModifierAttr::Spelling Spelling);
@@ -48,8 +48,8 @@ class SemaHLSL : public SemaBase {
   void CheckSemanticAnnotation(FunctionDecl *EntryPoint, const Decl *Param,
                                const HLSLAnnotationAttr *AnnotationAttr);
   void DiagnoseAttrStageMismatch(
-      const Attr *A, HLSLShaderAttr::ShaderType Stage,
-      std::initializer_list<HLSLShaderAttr::ShaderType> AllowedStages);
+      const Attr *A, llvm::Triple::EnvironmentType Stage,
+      std::initializer_list<llvm::Triple::EnvironmentType> AllowedStages);
   void DiagnoseAvailabilityViolations(TranslationUnitDecl *TU);
 
   void handleNumThreadsAttr(Decl *D, const ParsedAttr &AL);

diff --git a/clang/include/clang/Sema/SemaObjC.h b/clang/include/clang/Sema/SemaObjC.h
@@ -383,7 +383,7 @@ class SemaObjC : public SemaBase {
   void AddAnyMethodToGlobalPool(Decl *D);
 
   void ActOnStartOfObjCMethodDef(Scope *S, Decl *D);
-  bool isObjCMethodDecl(Decl *D) { return D && isa<ObjCMethodDecl>(D); }
+  bool isObjCMethodDecl(Decl *D) { return isa_and_nonnull<ObjCMethodDecl>(D); }
 
   /// CheckImplementationIvars - This routine checks if the instance variables
   /// listed in the implelementation match those listed in the interface.

diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -255,6 +255,12 @@ class DeclOffset {
   }
 };
 
+// The unaligned decl ID used in the Blobs of bistreams.
+using unaligned_decl_id_t =
+    llvm::support::detail::packed_endian_specific_integral<
+        serialization::DeclID, llvm::endianness::native,
+        llvm::support::unaligned>;
+
 /// The number of predefined preprocessed entity IDs.
 const unsigned int NUM_PREDEF_PP_ENTITY_IDS = 1;
 
@@ -1980,33 +1986,44 @@ enum CleanupObjectKind { COK_Block, COK_CompoundLiteral };
 
 /// Describes the categories of an Objective-C class.
 struct ObjCCategoriesInfo {
-  // The ID of the definition
-  LocalDeclID DefinitionID;
+  // The ID of the definition. Use unaligned_decl_id_t to keep
+  // ObjCCategoriesInfo 32-bit aligned.
+  unaligned_decl_id_t DefinitionID;
 
   // Offset into the array of category lists.
   unsigned Offset;
 
+  ObjCCategoriesInfo() = default;
+  ObjCCategoriesInfo(LocalDeclID ID, unsigned Offset)
+      : DefinitionID(ID.get()), Offset(Offset) {}
+
+  LocalDeclID getDefinitionID() const { return LocalDeclID(DefinitionID); }
+
   friend bool operator<(const ObjCCategoriesInfo &X,
                         const ObjCCategoriesInfo &Y) {
-    return X.DefinitionID < Y.DefinitionID;
+    return X.getDefinitionID() < Y.getDefinitionID();
   }
 
   friend bool operator>(const ObjCCategoriesInfo &X,
                         const ObjCCategoriesInfo &Y) {
-    return X.DefinitionID > Y.DefinitionID;
+    return X.getDefinitionID() > Y.getDefinitionID();
   }
 
   friend bool operator<=(const ObjCCategoriesInfo &X,
                          const ObjCCategoriesInfo &Y) {
-    return X.DefinitionID <= Y.DefinitionID;
+    return X.getDefinitionID() <= Y.getDefinitionID();
   }
 
   friend bool operator>=(const ObjCCategoriesInfo &X,
                          const ObjCCategoriesInfo &Y) {
-    return X.DefinitionID >= Y.DefinitionID;
+    return X.getDefinitionID() >= Y.getDefinitionID();
   }
 };
 
+static_assert(alignof(ObjCCategoriesInfo) <= 4);
+static_assert(std::is_standard_layout_v<ObjCCategoriesInfo> &&
+              std::is_trivial_v<ObjCCategoriesInfo>);
+
 /// A key used when looking up entities by \ref DeclarationName.
 ///
 /// Different \ref DeclarationNames are mapped to different keys, but the

diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
@@ -504,12 +504,6 @@ class ASTReader
   /// = I + 1 has already been loaded.
   llvm::PagedVector<Decl *> DeclsLoaded;
 
-  using GlobalDeclMapType = ContinuousRangeMap<GlobalDeclID, ModuleFile *, 4>;
-
-  /// Mapping from global declaration IDs to the module in which the
-  /// declaration resides.
-  GlobalDeclMapType GlobalDeclMap;
-
   using FileOffset = std::pair<ModuleFile *, uint64_t>;
   using FileOffsetsTy = SmallVector<FileOffset, 2>;
   using DeclUpdateOffsetsMap = llvm::DenseMap<GlobalDeclID, FileOffsetsTy>;
@@ -592,10 +586,11 @@ class ASTReader
 
   struct FileDeclsInfo {
     ModuleFile *Mod = nullptr;
-    ArrayRef<LocalDeclID> Decls;
+    ArrayRef<serialization::unaligned_decl_id_t> Decls;
 
     FileDeclsInfo() = default;
-    FileDeclsInfo(ModuleFile *Mod, ArrayRef<LocalDeclID> Decls)
+    FileDeclsInfo(ModuleFile *Mod,
+                  ArrayRef<serialization::unaligned_decl_id_t> Decls)
         : Mod(Mod), Decls(Decls) {}
   };
 
@@ -604,11 +599,7 @@ class ASTReader
 
   /// An array of lexical contents of a declaration context, as a sequence of
   /// Decl::Kind, DeclID pairs.
-  using unaligned_decl_id_t =
-      llvm::support::detail::packed_endian_specific_integral<
-          serialization::DeclID, llvm::endianness::native,
-          llvm::support::unaligned>;
-  using LexicalContents = ArrayRef<unaligned_decl_id_t>;
+  using LexicalContents = ArrayRef<serialization::unaligned_decl_id_t>;
 
   /// Map from a DeclContext to its lexical contents.
   llvm::DenseMap<const DeclContext*, std::pair<ModuleFile*, LexicalContents>>
@@ -1489,22 +1480,23 @@ class ASTReader
                                unsigned ClientLoadCapabilities);
 
 public:
-  class ModuleDeclIterator : public llvm::iterator_adaptor_base<
-                                 ModuleDeclIterator, const LocalDeclID *,
-                                 std::random_access_iterator_tag, const Decl *,
-                                 ptrdiff_t, const Decl *, const Decl *> {
+  class ModuleDeclIterator
+      : public llvm::iterator_adaptor_base<
+            ModuleDeclIterator, const serialization::unaligned_decl_id_t *,
+            std::random_access_iterator_tag, const Decl *, ptrdiff_t,
+            const Decl *, const Decl *> {
     ASTReader *Reader = nullptr;
     ModuleFile *Mod = nullptr;
 
   public:
     ModuleDeclIterator() : iterator_adaptor_base(nullptr) {}
 
     ModuleDeclIterator(ASTReader *Reader, ModuleFile *Mod,
-                       const LocalDeclID *Pos)
+                       const serialization::unaligned_decl_id_t *Pos)
         : iterator_adaptor_base(Pos), Reader(Reader), Mod(Mod) {}
 
     value_type operator*() const {
-      return Reader->GetDecl(Reader->getGlobalDeclID(*Mod, *I));
+      return Reader->GetDecl(Reader->getGlobalDeclID(*Mod, (LocalDeclID)*I));
     }
 
     value_type operator->() const { return **this; }
@@ -1544,6 +1536,9 @@ class ASTReader
              StringRef Arg2 = StringRef(), StringRef Arg3 = StringRef()) const;
   void Error(llvm::Error &&Err) const;
 
+  /// Translate a \param GlobalDeclID to the index of DeclsLoaded array.
+  unsigned translateGlobalDeclIDToIndex(GlobalDeclID ID) const;
+
 public:
   /// Load the AST file and validate its contents against the given
   /// Preprocessor.
@@ -1915,7 +1910,8 @@ class ASTReader
 
   /// Retrieve the module file that owns the given declaration, or NULL
   /// if the declaration is not from a module file.
-  ModuleFile *getOwningModuleFile(const Decl *D);
+  ModuleFile *getOwningModuleFile(const Decl *D) const;
+  ModuleFile *getOwningModuleFile(GlobalDeclID ID) const;
 
   /// Returns the source location for the decl \p ID.
   SourceLocation getSourceLocationForDeclID(GlobalDeclID ID);
-Original file line number
+Diff line change
@@ Expand Up / @@ -72,7 +72,7 @@ class PrintFunctionsConsumer : public ASTConsumer { @@
               *sema.LateParsedTemplateMap.find(FD)->second;
           sema.LateTemplateParser(sema.OpaqueParser, LPT);
           llvm::errs() << "late-parsed-decl: \"" << FD->getNameAsString() << "\"\n";
-        }
+        }
       }
     };
@@ Expand Down @@