Export clang-format16 via ydblib project

6e6be3a95868fde888d801b7590af4044049563f

1 files changed, 972 insertions, 0 deletions

diff --git a/contrib/libs/clang16/tools/extra/clang-tidy/modernize/LoopConvertCheck.cpp b/contrib/libs/clang16/tools/extra/clang-tidy/modernize/LoopConvertCheck.cpp
new file mode 100644
index 0000000000..fe9412f8d0
--- /dev/null
+++ b/contrib/libs/clang16/tools/extra/clang-tidy/modernize/LoopConvertCheck.cpp
@@ -0,0 +1,972 @@
+//===--- LoopConvertCheck.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 "LoopConvertCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+#include <cstring>
+#include <optional>
+#include <utility>
+
+using namespace clang::ast_matchers;
+using namespace llvm;
+
+namespace clang::tidy {
+
+template <> struct OptionEnumMapping<modernize::Confidence::Level> {
+  static llvm::ArrayRef<std::pair<modernize::Confidence::Level, StringRef>>
+  getEnumMapping() {
+    static constexpr std::pair<modernize::Confidence::Level, StringRef>
+        Mapping[] = {{modernize::Confidence::CL_Reasonable, "reasonable"},
+                     {modernize::Confidence::CL_Safe, "safe"},
+                     {modernize::Confidence::CL_Risky, "risky"}};
+    return ArrayRef(Mapping);
+  }
+};
+
+template <> struct OptionEnumMapping<modernize::VariableNamer::NamingStyle> {
+  static llvm::ArrayRef<
+      std::pair<modernize::VariableNamer::NamingStyle, StringRef>>
+  getEnumMapping() {
+    static constexpr std::pair<modernize::VariableNamer::NamingStyle, StringRef>
+        Mapping[] = {{modernize::VariableNamer::NS_CamelCase, "CamelCase"},
+                     {modernize::VariableNamer::NS_CamelBack, "camelBack"},
+                     {modernize::VariableNamer::NS_LowerCase, "lower_case"},
+                     {modernize::VariableNamer::NS_UpperCase, "UPPER_CASE"}};
+    return ArrayRef(Mapping);
+  }
+};
+
+namespace modernize {
+
+static const char LoopNameArray[] = "forLoopArray";
+static const char LoopNameIterator[] = "forLoopIterator";
+static const char LoopNameReverseIterator[] = "forLoopReverseIterator";
+static const char LoopNamePseudoArray[] = "forLoopPseudoArray";
+static const char ConditionBoundName[] = "conditionBound";
+static const char InitVarName[] = "initVar";
+static const char BeginCallName[] = "beginCall";
+static const char EndCallName[] = "endCall";
+static const char EndVarName[] = "endVar";
+static const char DerefByValueResultName[] = "derefByValueResult";
+static const char DerefByRefResultName[] = "derefByRefResult";
+
+static const StatementMatcher integerComparisonMatcher() {
+  return expr(ignoringParenImpCasts(
+      declRefExpr(to(varDecl(equalsBoundNode(InitVarName))))));
+}
+
+static const DeclarationMatcher initToZeroMatcher() {
+  return varDecl(
+             hasInitializer(ignoringParenImpCasts(integerLiteral(equals(0)))))
+      .bind(InitVarName);
+}
+
+static const StatementMatcher incrementVarMatcher() {
+  return declRefExpr(to(varDecl(equalsBoundNode(InitVarName))));
+}
+
+static StatementMatcher
+arrayConditionMatcher(internal::Matcher<Expr> LimitExpr) {
+  return binaryOperator(
+      anyOf(allOf(hasOperatorName("<"), hasLHS(integerComparisonMatcher()),
+                  hasRHS(LimitExpr)),
+            allOf(hasOperatorName(">"), hasLHS(LimitExpr),
+                  hasRHS(integerComparisonMatcher())),
+            allOf(hasOperatorName("!="),
+                  hasOperands(integerComparisonMatcher(), LimitExpr))));
+}
+
+/// The matcher for loops over arrays.
+/// \code
+///   for (int i = 0; i < 3 + 2; ++i) { ... }
+/// \endcode
+/// The following string identifiers are bound to these parts of the AST:
+///   ConditionBoundName: '3 + 2' (as an Expr)
+///   InitVarName: 'i' (as a VarDecl)
+///   LoopName: The entire for loop (as a ForStmt)
+///
+/// Client code will need to make sure that:
+///   - The index variable is only used as an array index.
+///   - All arrays indexed by the loop are the same.
+StatementMatcher makeArrayLoopMatcher() {
+  StatementMatcher ArrayBoundMatcher =
+      expr(hasType(isInteger())).bind(ConditionBoundName);
+
+  return forStmt(unless(isInTemplateInstantiation()),
+                 hasLoopInit(declStmt(hasSingleDecl(initToZeroMatcher()))),
+                 hasCondition(arrayConditionMatcher(ArrayBoundMatcher)),
+                 hasIncrement(
+                     unaryOperator(hasOperatorName("++"),
+                                   hasUnaryOperand(incrementVarMatcher()))))
+      .bind(LoopNameArray);
+}
+
+/// The matcher used for iterator-based for loops.
+///
+/// This matcher is more flexible than array-based loops. It will match
+/// catch loops of the following textual forms (regardless of whether the
+/// iterator type is actually a pointer type or a class type):
+///
+/// \code
+///   for (containerType::iterator it = container.begin(),
+///        e = createIterator(); it != e; ++it) { ... }
+///   for (containerType::iterator it = container.begin();
+///        it != anotherContainer.end(); ++it) { ... }
+/// \endcode
+/// The following string identifiers are bound to the parts of the AST:
+///   InitVarName: 'it' (as a VarDecl)
+///   LoopName: The entire for loop (as a ForStmt)
+///   In the first example only:
+///     EndVarName: 'e' (as a VarDecl)
+///   In the second example only:
+///     EndCallName: 'container.end()' (as a CXXMemberCallExpr)
+///
+/// Client code will need to make sure that:
+///   - The two containers on which 'begin' and 'end' are called are the same.
+StatementMatcher makeIteratorLoopMatcher(bool IsReverse) {
+
+  auto BeginNameMatcher = IsReverse ? hasAnyName("rbegin", "crbegin")
+                                    : hasAnyName("begin", "cbegin");
+
+  auto EndNameMatcher =
+      IsReverse ? hasAnyName("rend", "crend") : hasAnyName("end", "cend");
+
+  StatementMatcher BeginCallMatcher =
+      cxxMemberCallExpr(argumentCountIs(0),
+                        callee(cxxMethodDecl(BeginNameMatcher)))
+          .bind(BeginCallName);
+
+  DeclarationMatcher InitDeclMatcher =
+      varDecl(hasInitializer(anyOf(ignoringParenImpCasts(BeginCallMatcher),
+                                   materializeTemporaryExpr(
+                                       ignoringParenImpCasts(BeginCallMatcher)),
+                                   hasDescendant(BeginCallMatcher))))
+          .bind(InitVarName);
+
+  DeclarationMatcher EndDeclMatcher =
+      varDecl(hasInitializer(anything())).bind(EndVarName);
+
+  StatementMatcher EndCallMatcher = cxxMemberCallExpr(
+      argumentCountIs(0), callee(cxxMethodDecl(EndNameMatcher)));
+
+  StatementMatcher IteratorBoundMatcher =
+      expr(anyOf(ignoringParenImpCasts(
+                     declRefExpr(to(varDecl(equalsBoundNode(EndVarName))))),
+                 ignoringParenImpCasts(expr(EndCallMatcher).bind(EndCallName)),
+                 materializeTemporaryExpr(ignoringParenImpCasts(
+                     expr(EndCallMatcher).bind(EndCallName)))));
+
+  StatementMatcher IteratorComparisonMatcher = expr(ignoringParenImpCasts(
+      declRefExpr(to(varDecl(equalsBoundNode(InitVarName))))));
+
+  // This matcher tests that a declaration is a CXXRecordDecl that has an
+  // overloaded operator*(). If the operator*() returns by value instead of by
+  // reference then the return type is tagged with DerefByValueResultName.
+  internal::Matcher<VarDecl> TestDerefReturnsByValue =
+      hasType(hasUnqualifiedDesugaredType(
+          recordType(hasDeclaration(cxxRecordDecl(hasMethod(cxxMethodDecl(
+              hasOverloadedOperatorName("*"),
+              anyOf(
+                  // Tag the return type if it's by value.
+                  returns(qualType(unless(hasCanonicalType(referenceType())))
+                              .bind(DerefByValueResultName)),
+                  returns(
+                      // Skip loops where the iterator's operator* returns an
+                      // rvalue reference. This is just weird.
+                      qualType(unless(hasCanonicalType(rValueReferenceType())))
+                          .bind(DerefByRefResultName))))))))));
+
+  return forStmt(
+             unless(isInTemplateInstantiation()),
+             hasLoopInit(anyOf(declStmt(declCountIs(2),
+                                        containsDeclaration(0, InitDeclMatcher),
+                                        containsDeclaration(1, EndDeclMatcher)),
+                               declStmt(hasSingleDecl(InitDeclMatcher)))),
+             hasCondition(ignoringImplicit(binaryOperation(
+                 hasOperatorName("!="), hasOperands(IteratorComparisonMatcher,
+                                                    IteratorBoundMatcher)))),
+             hasIncrement(anyOf(
+                 unaryOperator(hasOperatorName("++"),
+                               hasUnaryOperand(declRefExpr(
+                                   to(varDecl(equalsBoundNode(InitVarName)))))),
+                 cxxOperatorCallExpr(
+                     hasOverloadedOperatorName("++"),
+                     hasArgument(0, declRefExpr(to(
+                                        varDecl(equalsBoundNode(InitVarName),
+                                                TestDerefReturnsByValue))))))))
+      .bind(IsReverse ? LoopNameReverseIterator : LoopNameIterator);
+}
+
+/// The matcher used for array-like containers (pseudoarrays).
+///
+/// This matcher is more flexible than array-based loops. It will match
+/// loops of the following textual forms (regardless of whether the
+/// iterator type is actually a pointer type or a class type):
+///
+/// \code
+///   for (int i = 0, j = container.size(); i < j; ++i) { ... }
+///   for (int i = 0; i < container.size(); ++i) { ... }
+/// \endcode
+/// The following string identifiers are bound to the parts of the AST:
+///   InitVarName: 'i' (as a VarDecl)
+///   LoopName: The entire for loop (as a ForStmt)
+///   In the first example only:
+///     EndVarName: 'j' (as a VarDecl)
+///   In the second example only:
+///     EndCallName: 'container.size()' (as a CXXMemberCallExpr)
+///
+/// Client code will need to make sure that:
+///   - The containers on which 'size()' is called is the container indexed.
+///   - The index variable is only used in overloaded operator[] or
+///     container.at().
+///   - The container's iterators would not be invalidated during the loop.
+StatementMatcher makePseudoArrayLoopMatcher() {
+  // Test that the incoming type has a record declaration that has methods
+  // called 'begin' and 'end'. If the incoming type is const, then make sure
+  // these methods are also marked const.
+  //
+  // FIXME: To be completely thorough this matcher should also ensure the
+  // return type of begin/end is an iterator that dereferences to the same as
+  // what operator[] or at() returns. Such a test isn't likely to fail except
+  // for pathological cases.
+  //
+  // FIXME: Also, a record doesn't necessarily need begin() and end(). Free
+  // functions called begin() and end() taking the container as an argument
+  // are also allowed.
+  TypeMatcher RecordWithBeginEnd = qualType(anyOf(
+      qualType(isConstQualified(),
+               hasUnqualifiedDesugaredType(recordType(hasDeclaration(
+                   cxxRecordDecl(isSameOrDerivedFrom(cxxRecordDecl(
+                       hasMethod(cxxMethodDecl(hasName("begin"), isConst())),
+                       hasMethod(cxxMethodDecl(hasName("end"),
+                                               isConst())))))) // hasDeclaration
+                                                      ))),     // qualType
+      qualType(unless(isConstQualified()),
+               hasUnqualifiedDesugaredType(recordType(hasDeclaration(
+                   cxxRecordDecl(isSameOrDerivedFrom(cxxRecordDecl(
+                       hasMethod(hasName("begin")),
+                       hasMethod(hasName("end"))))))))) // qualType
+      ));
+
+  StatementMatcher SizeCallMatcher = cxxMemberCallExpr(
+      argumentCountIs(0), callee(cxxMethodDecl(hasAnyName("size", "length"))),
+      on(anyOf(hasType(pointsTo(RecordWithBeginEnd)),
+               hasType(RecordWithBeginEnd))));
+
+  StatementMatcher EndInitMatcher =
+      expr(anyOf(ignoringParenImpCasts(expr(SizeCallMatcher).bind(EndCallName)),
+                 explicitCastExpr(hasSourceExpression(ignoringParenImpCasts(
+                     expr(SizeCallMatcher).bind(EndCallName))))));
+
+  DeclarationMatcher EndDeclMatcher =
+      varDecl(hasInitializer(EndInitMatcher)).bind(EndVarName);
+
+  StatementMatcher IndexBoundMatcher =
+      expr(anyOf(ignoringParenImpCasts(
+                     declRefExpr(to(varDecl(equalsBoundNode(EndVarName))))),
+                 EndInitMatcher));
+
+  return forStmt(unless(isInTemplateInstantiation()),
+                 hasLoopInit(
+                     anyOf(declStmt(declCountIs(2),
+                                    containsDeclaration(0, initToZeroMatcher()),
+                                    containsDeclaration(1, EndDeclMatcher)),
+                           declStmt(hasSingleDecl(initToZeroMatcher())))),
+                 hasCondition(arrayConditionMatcher(IndexBoundMatcher)),
+                 hasIncrement(
+                     unaryOperator(hasOperatorName("++"),
+                                   hasUnaryOperand(incrementVarMatcher()))))
+      .bind(LoopNamePseudoArray);
+}
+
+/// Determine whether Init appears to be an initializing an iterator.
+///
+/// If it is, returns the object whose begin() or end() method is called, and
+/// the output parameter isArrow is set to indicate whether the initialization
+/// is called via . or ->.
+static const Expr *getContainerFromBeginEndCall(const Expr *Init, bool IsBegin,
+                                                bool *IsArrow, bool IsReverse) {
+  // FIXME: Maybe allow declaration/initialization outside of the for loop.
+  const auto *TheCall = dyn_cast_or_null<CXXMemberCallExpr>(
+      digThroughConstructorsConversions(Init));
+  if (!TheCall || TheCall->getNumArgs() != 0)
+    return nullptr;
+
+  const auto *Member = dyn_cast<MemberExpr>(TheCall->getCallee());
+  if (!Member)
+    return nullptr;
+  StringRef Name = Member->getMemberDecl()->getName();
+  if (!Name.consume_back(IsBegin ? "begin" : "end"))
+    return nullptr;
+  if (IsReverse && !Name.consume_back("r"))
+    return nullptr;
+  if (!Name.empty() && !Name.equals("c"))
+    return nullptr;
+
+  const Expr *SourceExpr = Member->getBase();
+  if (!SourceExpr)
+    return nullptr;
+
+  *IsArrow = Member->isArrow();
+  return SourceExpr;
+}
+
+/// Determines the container whose begin() and end() functions are called
+/// for an iterator-based loop.
+///
+/// BeginExpr must be a member call to a function named "begin()", and EndExpr
+/// must be a member.
+static const Expr *findContainer(ASTContext *Context, const Expr *BeginExpr,
+                                 const Expr *EndExpr,
+                                 bool *ContainerNeedsDereference,
+                                 bool IsReverse) {
+  // Now that we know the loop variable and test expression, make sure they are
+  // valid.
+  bool BeginIsArrow = false;
+  bool EndIsArrow = false;
+  const Expr *BeginContainerExpr = getContainerFromBeginEndCall(
+      BeginExpr, /*IsBegin=*/true, &BeginIsArrow, IsReverse);
+  if (!BeginContainerExpr)
+    return nullptr;
+
+  const Expr *EndContainerExpr = getContainerFromBeginEndCall(
+      EndExpr, /*IsBegin=*/false, &EndIsArrow, IsReverse);
+  // Disallow loops that try evil things like this (note the dot and arrow):
+  //  for (IteratorType It = Obj.begin(), E = Obj->end(); It != E; ++It) { }
+  if (!EndContainerExpr || BeginIsArrow != EndIsArrow ||
+      !areSameExpr(Context, EndContainerExpr, BeginContainerExpr))
+    return nullptr;
+
+  *ContainerNeedsDereference = BeginIsArrow;
+  return BeginContainerExpr;
+}
+
+/// Obtain the original source code text from a SourceRange.
+static StringRef getStringFromRange(SourceManager &SourceMgr,
+                                    const LangOptions &LangOpts,
+                                    SourceRange Range) {
+  if (SourceMgr.getFileID(Range.getBegin()) !=
+      SourceMgr.getFileID(Range.getEnd())) {
+    return StringRef(); // Empty string.
+  }
+
+  return Lexer::getSourceText(CharSourceRange(Range, true), SourceMgr,
+                              LangOpts);
+}
+
+/// If the given expression is actually a DeclRefExpr or a MemberExpr,
+/// find and return the underlying ValueDecl; otherwise, return NULL.
+static const ValueDecl *getReferencedVariable(const Expr *E) {
+  if (const DeclRefExpr *DRE = getDeclRef(E))
+    return dyn_cast<VarDecl>(DRE->getDecl());
+  if (const auto *Mem = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))
+    return dyn_cast<FieldDecl>(Mem->getMemberDecl());
+  return nullptr;
+}
+
+/// Returns true when the given expression is a member expression
+/// whose base is `this` (implicitly or not).
+static bool isDirectMemberExpr(const Expr *E) {
+  if (const auto *Member = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))
+    return isa<CXXThisExpr>(Member->getBase()->IgnoreParenImpCasts());
+  return false;
+}
+
+/// Given an expression that represents an usage of an element from the
+/// containter that we are iterating over, returns false when it can be
+/// guaranteed this element cannot be modified as a result of this usage.
+static bool canBeModified(ASTContext *Context, const Expr *E) {
+  if (E->getType().isConstQualified())
+    return false;
+  auto Parents = Context->getParents(*E);
+  if (Parents.size() != 1)
+    return true;
+  if (const auto *Cast = Parents[0].get<ImplicitCastExpr>()) {
+    if ((Cast->getCastKind() == CK_NoOp &&
+         Context->hasSameType(Cast->getType(), E->getType().withConst())) ||
+        (Cast->getCastKind() == CK_LValueToRValue &&
+         !Cast->getType().isNull() && Cast->getType()->isFundamentalType()))
+      return false;
+  }
+  // FIXME: Make this function more generic.
+  return true;
+}
+
+/// Returns true when it can be guaranteed that the elements of the
+/// container are not being modified.
+static bool usagesAreConst(ASTContext *Context, const UsageResult &Usages) {
+  for (const Usage &U : Usages) {
+    // Lambda captures are just redeclarations (VarDecl) of the same variable,
+    // not expressions. If we want to know if a variable that is captured by
+    // reference can be modified in an usage inside the lambda's body, we need
+    // to find the expression corresponding to that particular usage, later in
+    // this loop.
+    if (U.Kind != Usage::UK_CaptureByCopy && U.Kind != Usage::UK_CaptureByRef &&
+        canBeModified(Context, U.Expression))
+      return false;
+  }
+  return true;
+}
+
+/// Returns true if the elements of the container are never accessed
+/// by reference.
+static bool usagesReturnRValues(const UsageResult &Usages) {
+  for (const auto &U : Usages) {
+    if (U.Expression && !U.Expression->isPRValue())
+      return false;
+  }
+  return true;
+}
+
+/// Returns true if the container is const-qualified.
+static bool containerIsConst(const Expr *ContainerExpr, bool Dereference) {
+  if (const auto *VDec = getReferencedVariable(ContainerExpr)) {
+    QualType CType = VDec->getType();
+    if (Dereference) {
+      if (!CType->isPointerType())
+        return false;
+      CType = CType->getPointeeType();
+    }
+    // If VDec is a reference to a container, Dereference is false,
+    // but we still need to check the const-ness of the underlying container
+    // type.
+    CType = CType.getNonReferenceType();
+    return CType.isConstQualified();
+  }
+  return false;
+}
+
+LoopConvertCheck::RangeDescriptor::RangeDescriptor()
+    : ContainerNeedsDereference(false), DerefByConstRef(false),
+      DerefByValue(false), NeedsReverseCall(false) {}
+
+LoopConvertCheck::LoopConvertCheck(StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context), TUInfo(new TUTrackingInfo),
+      MaxCopySize(Options.get("MaxCopySize", 16ULL)),
+      MinConfidence(Options.get("MinConfidence", Confidence::CL_Reasonable)),
+      NamingStyle(Options.get("NamingStyle", VariableNamer::NS_CamelCase)),
+      Inserter(Options.getLocalOrGlobal("IncludeStyle",
+                                        utils::IncludeSorter::IS_LLVM),
+               areDiagsSelfContained()),
+      UseCxx20IfAvailable(Options.get("UseCxx20ReverseRanges", true)),
+      ReverseFunction(Options.get("MakeReverseRangeFunction", "")),
+      ReverseHeader(Options.get("MakeReverseRangeHeader", "")) {
+
+  if (ReverseFunction.empty() && !ReverseHeader.empty()) {
+    configurationDiag(
+        "modernize-loop-convert: 'MakeReverseRangeHeader' is set but "
+        "'MakeReverseRangeFunction' is not, disabling reverse loop "
+        "transformation");
+    UseReverseRanges = false;
+  } else if (ReverseFunction.empty()) {
+    UseReverseRanges = UseCxx20IfAvailable && getLangOpts().CPlusPlus20;
+  } else {
+    UseReverseRanges = true;
+  }
+}
+
+void LoopConvertCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "MaxCopySize", MaxCopySize);
+  Options.store(Opts, "MinConfidence", MinConfidence);
+  Options.store(Opts, "NamingStyle", NamingStyle);
+  Options.store(Opts, "IncludeStyle", Inserter.getStyle());
+  Options.store(Opts, "UseCxx20ReverseRanges", UseCxx20IfAvailable);
+  Options.store(Opts, "MakeReverseRangeFunction", ReverseFunction);
+  Options.store(Opts, "MakeReverseRangeHeader", ReverseHeader);
+}
+
+void LoopConvertCheck::registerPPCallbacks(const SourceManager &SM,
+                                           Preprocessor *PP,
+                                           Preprocessor *ModuleExpanderPP) {
+  Inserter.registerPreprocessor(PP);
+}
+
+void LoopConvertCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(traverse(TK_AsIs, makeArrayLoopMatcher()), this);
+  Finder->addMatcher(traverse(TK_AsIs, makeIteratorLoopMatcher(false)), this);
+  Finder->addMatcher(traverse(TK_AsIs, makePseudoArrayLoopMatcher()), this);
+  if (UseReverseRanges)
+    Finder->addMatcher(traverse(TK_AsIs, makeIteratorLoopMatcher(true)), this);
+}
+
+/// Given the range of a single declaration, such as:
+/// \code
+///   unsigned &ThisIsADeclarationThatCanSpanSeveralLinesOfCode =
+///       InitializationValues[I];
+///   next_instruction;
+/// \endcode
+/// Finds the range that has to be erased to remove this declaration without
+/// leaving empty lines, by extending the range until the beginning of the
+/// next instruction.
+///
+/// We need to delete a potential newline after the deleted alias, as
+/// clang-format will leave empty lines untouched. For all other formatting we
+/// rely on clang-format to fix it.
+void LoopConvertCheck::getAliasRange(SourceManager &SM, SourceRange &Range) {
+  bool Invalid = false;
+  const char *TextAfter =
+      SM.getCharacterData(Range.getEnd().getLocWithOffset(1), &Invalid);
+  if (Invalid)
+    return;
+  unsigned Offset = std::strspn(TextAfter, " \t\r\n");
+  Range =
+      SourceRange(Range.getBegin(), Range.getEnd().getLocWithOffset(Offset));
+}
+
+/// Computes the changes needed to convert a given for loop, and
+/// applies them.
+void LoopConvertCheck::doConversion(
+    ASTContext *Context, const VarDecl *IndexVar,
+    const ValueDecl *MaybeContainer, const UsageResult &Usages,
+    const DeclStmt *AliasDecl, bool AliasUseRequired, bool AliasFromForInit,
+    const ForStmt *Loop, RangeDescriptor Descriptor) {
+  std::string VarName;
+  bool VarNameFromAlias = (Usages.size() == 1) && AliasDecl;
+  bool AliasVarIsRef = false;
+  bool CanCopy = true;
+  std::vector<FixItHint> FixIts;
+  if (VarNameFromAlias) {
+    const auto *AliasVar = cast<VarDecl>(AliasDecl->getSingleDecl());
+    VarName = AliasVar->getName().str();
+
+    // Use the type of the alias if it's not the same
+    QualType AliasVarType = AliasVar->getType();
+    assert(!AliasVarType.isNull() && "Type in VarDecl is null");
+    if (AliasVarType->isReferenceType()) {
+      AliasVarType = AliasVarType.getNonReferenceType();
+      AliasVarIsRef = true;
+    }
+    if (Descriptor.ElemType.isNull() ||
+        !Context->hasSameUnqualifiedType(AliasVarType, Descriptor.ElemType))
+      Descriptor.ElemType = AliasVarType;
+
+    // We keep along the entire DeclStmt to keep the correct range here.
+    SourceRange ReplaceRange = AliasDecl->getSourceRange();
+
+    std::string ReplacementText;
+    if (AliasUseRequired) {
+      ReplacementText = VarName;
+    } else if (AliasFromForInit) {
+      // FIXME: Clang includes the location of the ';' but only for DeclStmt's
+      // in a for loop's init clause. Need to put this ';' back while removing
+      // the declaration of the alias variable. This is probably a bug.
+      ReplacementText = ";";
+    } else {
+      // Avoid leaving empty lines or trailing whitespaces.
+      getAliasRange(Context->getSourceManager(), ReplaceRange);
+    }
+
+    FixIts.push_back(FixItHint::CreateReplacement(
+        CharSourceRange::getTokenRange(ReplaceRange), ReplacementText));
+    // No further replacements are made to the loop, since the iterator or index
+    // was used exactly once - in the initialization of AliasVar.
+  } else {
+    VariableNamer Namer(&TUInfo->getGeneratedDecls(),
+                        &TUInfo->getParentFinder().getStmtToParentStmtMap(),
+                        Loop, IndexVar, MaybeContainer, Context, NamingStyle);
+    VarName = Namer.createIndexName();
+    // First, replace all usages of the array subscript expression with our new
+    // variable.
+    for (const auto &Usage : Usages) {
+      std::string ReplaceText;
+      SourceRange Range = Usage.Range;
+      if (Usage.Expression) {
+        // If this is an access to a member through the arrow operator, after
+        // the replacement it must be accessed through the '.' operator.
+        ReplaceText = Usage.Kind == Usage::UK_MemberThroughArrow ? VarName + "."
+                                                                 : VarName;
+        auto Parents = Context->getParents(*Usage.Expression);
+        if (Parents.size() == 1) {
+          if (const auto *Paren = Parents[0].get<ParenExpr>()) {
+            // Usage.Expression will be replaced with the new index variable,
+            // and parenthesis around a simple DeclRefExpr can always be
+            // removed.
+            Range = Paren->getSourceRange();
+          } else if (const auto *UOP = Parents[0].get<UnaryOperator>()) {
+            // If we are taking the address of the loop variable, then we must
+            // not use a copy, as it would mean taking the address of the loop's
+            // local index instead.
+            // FIXME: This won't catch cases where the address is taken outside
+            // of the loop's body (for instance, in a function that got the
+            // loop's index as a const reference parameter), or where we take
+            // the address of a member (like "&Arr[i].A.B.C").
+            if (UOP->getOpcode() == UO_AddrOf)
+              CanCopy = false;
+          }
+        }
+      } else {
+        // The Usage expression is only null in case of lambda captures (which
+        // are VarDecl). If the index is captured by value, add '&' to capture
+        // by reference instead.
+        ReplaceText =
+            Usage.Kind == Usage::UK_CaptureByCopy ? "&" + VarName : VarName;
+      }
+      TUInfo->getReplacedVars().insert(std::make_pair(Loop, IndexVar));
+      FixIts.push_back(FixItHint::CreateReplacement(
+          CharSourceRange::getTokenRange(Range), ReplaceText));
+    }
+  }
+
+  // Now, we need to construct the new range expression.
+  SourceRange ParenRange(Loop->getLParenLoc(), Loop->getRParenLoc());
+
+  QualType Type = Context->getAutoDeductType();
+  if (!Descriptor.ElemType.isNull() && Descriptor.ElemType->isFundamentalType())
+    Type = Descriptor.ElemType.getUnqualifiedType();
+  Type = Type.getDesugaredType(*Context);
+
+  // If the new variable name is from the aliased variable, then the reference
+  // type for the new variable should only be used if the aliased variable was
+  // declared as a reference.
+  bool IsCheapToCopy =
+      !Descriptor.ElemType.isNull() &&
+      Descriptor.ElemType.isTriviallyCopyableType(*Context) &&
+      // TypeInfo::Width is in bits.
+      Context->getTypeInfo(Descriptor.ElemType).Width <= 8 * MaxCopySize;
+  bool UseCopy = CanCopy && ((VarNameFromAlias && !AliasVarIsRef) ||
+                             (Descriptor.DerefByConstRef && IsCheapToCopy));
+
+  if (!UseCopy) {
+    if (Descriptor.DerefByConstRef) {
+      Type = Context->getLValueReferenceType(Context->getConstType(Type));
+    } else if (Descriptor.DerefByValue) {
+      if (!IsCheapToCopy)
+        Type = Context->getRValueReferenceType(Type);
+    } else {
+      Type = Context->getLValueReferenceType(Type);
+    }
+  }
+
+  SmallString<128> Range;
+  llvm::raw_svector_ostream Output(Range);
+  Output << '(';
+  Type.print(Output, getLangOpts());
+  Output << ' ' << VarName << " : ";
+  if (Descriptor.NeedsReverseCall)
+    Output << getReverseFunction() << '(';
+  if (Descriptor.ContainerNeedsDereference)
+    Output << '*';
+  Output << Descriptor.ContainerString;
+  if (Descriptor.NeedsReverseCall)
+    Output << "))";
+  else
+    Output << ')';
+  FixIts.push_back(FixItHint::CreateReplacement(
+      CharSourceRange::getTokenRange(ParenRange), Range));
+
+  if (Descriptor.NeedsReverseCall && !getReverseHeader().empty()) {
+    if (std::optional<FixItHint> Insertion = Inserter.createIncludeInsertion(
+            Context->getSourceManager().getFileID(Loop->getBeginLoc()),
+            getReverseHeader()))
+      FixIts.push_back(*Insertion);
+  }
+  diag(Loop->getForLoc(), "use range-based for loop instead") << FixIts;
+  TUInfo->getGeneratedDecls().insert(make_pair(Loop, VarName));
+}
+
+/// Returns a string which refers to the container iterated over.
+StringRef LoopConvertCheck::getContainerString(ASTContext *Context,
+                                               const ForStmt *Loop,
+                                               const Expr *ContainerExpr) {
+  StringRef ContainerString;
+  ContainerExpr = ContainerExpr->IgnoreParenImpCasts();
+  if (isa<CXXThisExpr>(ContainerExpr)) {
+    ContainerString = "this";
+  } else {
+    // For CXXOperatorCallExpr such as vector_ptr->size() we want the class
+    // object vector_ptr, but for vector[2] we need the whole expression.
+    if (const auto* E = dyn_cast<CXXOperatorCallExpr>(ContainerExpr))
+      if (E->getOperator() != OO_Subscript)
+        ContainerExpr = E->getArg(0);
+    ContainerString =
+        getStringFromRange(Context->getSourceManager(), Context->getLangOpts(),
+                           ContainerExpr->getSourceRange());
+  }
+
+  return ContainerString;
+}
+
+/// Determines what kind of 'auto' must be used after converting a for
+/// loop that iterates over an array or pseudoarray.
+void LoopConvertCheck::getArrayLoopQualifiers(ASTContext *Context,
+                                              const BoundNodes &Nodes,
+                                              const Expr *ContainerExpr,
+                                              const UsageResult &Usages,
+                                              RangeDescriptor &Descriptor) {
+  // On arrays and pseudoarrays, we must figure out the qualifiers from the
+  // usages.
+  if (usagesAreConst(Context, Usages) ||
+      containerIsConst(ContainerExpr, Descriptor.ContainerNeedsDereference)) {
+    Descriptor.DerefByConstRef = true;
+  }
+  if (usagesReturnRValues(Usages)) {
+    // If the index usages (dereference, subscript, at, ...) return rvalues,
+    // then we should not use a reference, because we need to keep the code
+    // correct if it mutates the returned objects.
+    Descriptor.DerefByValue = true;
+  }
+  // Try to find the type of the elements on the container, to check if
+  // they are trivially copyable.
+  for (const Usage &U : Usages) {
+    if (!U.Expression || U.Expression->getType().isNull())
+      continue;
+    QualType Type = U.Expression->getType().getCanonicalType();
+    if (U.Kind == Usage::UK_MemberThroughArrow) {
+      if (!Type->isPointerType()) {
+        continue;
+      }
+      Type = Type->getPointeeType();
+    }
+    Descriptor.ElemType = Type;
+  }
+}
+
+/// Determines what kind of 'auto' must be used after converting an
+/// iterator based for loop.
+void LoopConvertCheck::getIteratorLoopQualifiers(ASTContext *Context,
+                                                 const BoundNodes &Nodes,
+                                                 RangeDescriptor &Descriptor) {
+  // The matchers for iterator loops provide bound nodes to obtain this
+  // information.
+  const auto *InitVar = Nodes.getNodeAs<VarDecl>(InitVarName);
+  QualType CanonicalInitVarType = InitVar->getType().getCanonicalType();
+  const auto *DerefByValueType =
+      Nodes.getNodeAs<QualType>(DerefByValueResultName);
+  Descriptor.DerefByValue = DerefByValueType;
+
+  if (Descriptor.DerefByValue) {
+    // If the dereference operator returns by value then test for the
+    // canonical const qualification of the init variable type.
+    Descriptor.DerefByConstRef = CanonicalInitVarType.isConstQualified();
+    Descriptor.ElemType = *DerefByValueType;
+  } else {
+    if (const auto *DerefType =
+            Nodes.getNodeAs<QualType>(DerefByRefResultName)) {
+      // A node will only be bound with DerefByRefResultName if we're dealing
+      // with a user-defined iterator type. Test the const qualification of
+      // the reference type.
+      auto ValueType = DerefType->getNonReferenceType();
+
+      Descriptor.DerefByConstRef = ValueType.isConstQualified();
+      Descriptor.ElemType = ValueType;
+    } else {
+      // By nature of the matcher this case is triggered only for built-in
+      // iterator types (i.e. pointers).
+      assert(isa<PointerType>(CanonicalInitVarType) &&
+             "Non-class iterator type is not a pointer type");
+
+      // We test for const qualification of the pointed-at type.
+      Descriptor.DerefByConstRef =
+          CanonicalInitVarType->getPointeeType().isConstQualified();
+      Descriptor.ElemType = CanonicalInitVarType->getPointeeType();
+    }
+  }
+}
+
+/// Determines the parameters needed to build the range replacement.
+void LoopConvertCheck::determineRangeDescriptor(
+    ASTContext *Context, const BoundNodes &Nodes, const ForStmt *Loop,
+    LoopFixerKind FixerKind, const Expr *ContainerExpr,
+    const UsageResult &Usages, RangeDescriptor &Descriptor) {
+  Descriptor.ContainerString =
+      std::string(getContainerString(Context, Loop, ContainerExpr));
+  Descriptor.NeedsReverseCall = (FixerKind == LFK_ReverseIterator);
+
+  if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator)
+    getIteratorLoopQualifiers(Context, Nodes, Descriptor);
+  else
+    getArrayLoopQualifiers(Context, Nodes, ContainerExpr, Usages, Descriptor);
+}
+
+/// Check some of the conditions that must be met for the loop to be
+/// convertible.
+bool LoopConvertCheck::isConvertible(ASTContext *Context,
+                                     const ast_matchers::BoundNodes &Nodes,
+                                     const ForStmt *Loop,
+                                     LoopFixerKind FixerKind) {
+  // In self contained diagnosics mode we don't want dependancies on other
+  // loops, otherwise, If we already modified the range of this for loop, don't
+  // do any further updates on this iteration.
+  if (areDiagsSelfContained())
+    TUInfo = std::make_unique<TUTrackingInfo>();
+  else if (TUInfo->getReplacedVars().count(Loop))
+    return false;
+
+  // Check that we have exactly one index variable and at most one end variable.
+  const auto *InitVar = Nodes.getNodeAs<VarDecl>(InitVarName);
+
+  // FIXME: Try to put most of this logic inside a matcher.
+  if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator) {
+    QualType InitVarType = InitVar->getType();
+    QualType CanonicalInitVarType = InitVarType.getCanonicalType();
+
+    const auto *BeginCall = Nodes.getNodeAs<CXXMemberCallExpr>(BeginCallName);
+    assert(BeginCall && "Bad Callback. No begin call expression");
+    QualType CanonicalBeginType =
+        BeginCall->getMethodDecl()->getReturnType().getCanonicalType();
+    if (CanonicalBeginType->isPointerType() &&
+        CanonicalInitVarType->isPointerType()) {
+      // If the initializer and the variable are both pointers check if the
+      // un-qualified pointee types match, otherwise we don't use auto.
+      if (!Context->hasSameUnqualifiedType(
+              CanonicalBeginType->getPointeeType(),
+              CanonicalInitVarType->getPointeeType()))
+        return false;
+    }
+  } else if (FixerKind == LFK_PseudoArray) {
+    // This call is required to obtain the container.
+    const auto *EndCall = Nodes.getNodeAs<CXXMemberCallExpr>(EndCallName);
+    if (!EndCall || !isa<MemberExpr>(EndCall->getCallee()))
+      return false;
+  }
+  return true;
+}
+
+void LoopConvertCheck::check(const MatchFinder::MatchResult &Result) {
+  const BoundNodes &Nodes = Result.Nodes;
+  Confidence ConfidenceLevel(Confidence::CL_Safe);
+  ASTContext *Context = Result.Context;
+
+  const ForStmt *Loop;
+  LoopFixerKind FixerKind;
+  RangeDescriptor Descriptor;
+
+  if ((Loop = Nodes.getNodeAs<ForStmt>(LoopNameArray))) {
+    FixerKind = LFK_Array;
+  } else if ((Loop = Nodes.getNodeAs<ForStmt>(LoopNameIterator))) {
+    FixerKind = LFK_Iterator;
+  } else if ((Loop = Nodes.getNodeAs<ForStmt>(LoopNameReverseIterator))) {
+    FixerKind = LFK_ReverseIterator;
+  } else {
+    Loop = Nodes.getNodeAs<ForStmt>(LoopNamePseudoArray);
+    assert(Loop && "Bad Callback. No for statement");
+    FixerKind = LFK_PseudoArray;
+  }
+
+  if (!isConvertible(Context, Nodes, Loop, FixerKind))
+    return;
+
+  const auto *LoopVar = Nodes.getNodeAs<VarDecl>(InitVarName);
+  const auto *EndVar = Nodes.getNodeAs<VarDecl>(EndVarName);
+
+  // If the loop calls end()/size() after each iteration, lower our confidence
+  // level.
+  if (FixerKind != LFK_Array && !EndVar)
+    ConfidenceLevel.lowerTo(Confidence::CL_Reasonable);
+
+  // If the end comparison isn't a variable, we can try to work with the
+  // expression the loop variable is being tested against instead.
+  const auto *EndCall = Nodes.getNodeAs<CXXMemberCallExpr>(EndCallName);
+  const auto *BoundExpr = Nodes.getNodeAs<Expr>(ConditionBoundName);
+
+  // Find container expression of iterators and pseudoarrays, and determine if
+  // this expression needs to be dereferenced to obtain the container.
+  // With array loops, the container is often discovered during the
+  // ForLoopIndexUseVisitor traversal.
+  const Expr *ContainerExpr = nullptr;
+  if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator) {
+    ContainerExpr = findContainer(
+        Context, LoopVar->getInit(), EndVar ? EndVar->getInit() : EndCall,
+        &Descriptor.ContainerNeedsDereference,
+        /*IsReverse=*/FixerKind == LFK_ReverseIterator);
+  } else if (FixerKind == LFK_PseudoArray) {
+    ContainerExpr = EndCall->getImplicitObjectArgument();
+    Descriptor.ContainerNeedsDereference =
+        dyn_cast<MemberExpr>(EndCall->getCallee())->isArrow();
+  }
+
+  // We must know the container or an array length bound.
+  if (!ContainerExpr && !BoundExpr)
+    return;
+
+  ForLoopIndexUseVisitor Finder(Context, LoopVar, EndVar, ContainerExpr,
+                                BoundExpr,
+                                Descriptor.ContainerNeedsDereference);
+
+  // Find expressions and variables on which the container depends.
+  if (ContainerExpr) {
+    ComponentFinderASTVisitor ComponentFinder;
+    ComponentFinder.findExprComponents(ContainerExpr->IgnoreParenImpCasts());
+    Finder.addComponents(ComponentFinder.getComponents());
+  }
+
+  // Find usages of the loop index. If they are not used in a convertible way,
+  // stop here.
+  if (!Finder.findAndVerifyUsages(Loop->getBody()))
+    return;
+  ConfidenceLevel.lowerTo(Finder.getConfidenceLevel());
+
+  // Obtain the container expression, if we don't have it yet.
+  if (FixerKind == LFK_Array) {
+    ContainerExpr = Finder.getContainerIndexed()->IgnoreParenImpCasts();
+
+    // Very few loops are over expressions that generate arrays rather than
+    // array variables. Consider loops over arrays that aren't just represented
+    // by a variable to be risky conversions.
+    if (!getReferencedVariable(ContainerExpr) &&
+        !isDirectMemberExpr(ContainerExpr))
+      ConfidenceLevel.lowerTo(Confidence::CL_Risky);
+  }
+
+  // Find out which qualifiers we have to use in the loop range.
+  TraversalKindScope RAII(*Context, TK_AsIs);
+  const UsageResult &Usages = Finder.getUsages();
+  determineRangeDescriptor(Context, Nodes, Loop, FixerKind, ContainerExpr,
+                           Usages, Descriptor);
+
+  // Ensure that we do not try to move an expression dependent on a local
+  // variable declared inside the loop outside of it.
+  // FIXME: Determine when the external dependency isn't an expression converted
+  // by another loop.
+  TUInfo->getParentFinder().gatherAncestors(*Context);
+  DependencyFinderASTVisitor DependencyFinder(
+      &TUInfo->getParentFinder().getStmtToParentStmtMap(),
+      &TUInfo->getParentFinder().getDeclToParentStmtMap(),
+      &TUInfo->getReplacedVars(), Loop);
+
+  if (DependencyFinder.dependsOnInsideVariable(ContainerExpr) ||
+      Descriptor.ContainerString.empty() || Usages.empty() ||
+      ConfidenceLevel.getLevel() < MinConfidence)
+    return;
+
+  doConversion(Context, LoopVar, getReferencedVariable(ContainerExpr), Usages,
+               Finder.getAliasDecl(), Finder.aliasUseRequired(),
+               Finder.aliasFromForInit(), Loop, Descriptor);
+}
+
+llvm::StringRef LoopConvertCheck::getReverseFunction() const {
+  if (!ReverseFunction.empty())
+    return ReverseFunction;
+  if (UseReverseRanges)
+    return "std::ranges::reverse_view";
+  return "";
+}
+
+llvm::StringRef LoopConvertCheck::getReverseHeader() const {
+  if (!ReverseHeader.empty())
+    return ReverseHeader;
+  if (UseReverseRanges && ReverseFunction.empty()) {
+    return "<ranges>";
+  }
+  return "";
+}
+
+} // namespace modernize
+} // namespace clang::tidy