YQ Connector: support managed ClickHouse

Со стороны dqrun можно обратиться к инстансу коннектора, который работает на streaming стенде, и извлечь данные из облачного CH.

1 files changed, 915 insertions, 0 deletions

diff --git a/contrib/libs/clang14/tools/extra/clang-tidy/modernize/LoopConvertUtils.cpp b/contrib/libs/clang14/tools/extra/clang-tidy/modernize/LoopConvertUtils.cpp
new file mode 100644
index 0000000000..d29e631641
--- /dev/null
+++ b/contrib/libs/clang14/tools/extra/clang-tidy/modernize/LoopConvertUtils.cpp
@@ -0,0 +1,915 @@
+//===--- LoopConvertUtils.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 "LoopConvertUtils.h"
+#include "clang/Basic/IdentifierTable.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/Lambda.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/TokenKinds.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/APSInt.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Casting.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <string>
+#include <utility>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace modernize {
+
+/// Tracks a stack of parent statements during traversal.
+///
+/// All this really does is inject push_back() before running
+/// RecursiveASTVisitor::TraverseStmt() and pop_back() afterwards. The Stmt atop
+/// the stack is the parent of the current statement (NULL for the topmost
+/// statement).
+bool StmtAncestorASTVisitor::TraverseStmt(Stmt *Statement) {
+  StmtAncestors.insert(std::make_pair(Statement, StmtStack.back()));
+  StmtStack.push_back(Statement);
+  RecursiveASTVisitor<StmtAncestorASTVisitor>::TraverseStmt(Statement);
+  StmtStack.pop_back();
+  return true;
+}
+
+/// Keep track of the DeclStmt associated with each VarDecl.
+///
+/// Combined with StmtAncestors, this provides roughly the same information as
+/// Scope, as we can map a VarDecl to its DeclStmt, then walk up the parent tree
+/// using StmtAncestors.
+bool StmtAncestorASTVisitor::VisitDeclStmt(DeclStmt *Decls) {
+  for (const auto *Decl : Decls->decls()) {
+    if (const auto *V = dyn_cast<VarDecl>(Decl))
+      DeclParents.insert(std::make_pair(V, Decls));
+  }
+  return true;
+}
+
+/// record the DeclRefExpr as part of the parent expression.
+bool ComponentFinderASTVisitor::VisitDeclRefExpr(DeclRefExpr *E) {
+  Components.push_back(E);
+  return true;
+}
+
+/// record the MemberExpr as part of the parent expression.
+bool ComponentFinderASTVisitor::VisitMemberExpr(MemberExpr *Member) {
+  Components.push_back(Member);
+  return true;
+}
+
+/// Forward any DeclRefExprs to a check on the referenced variable
+/// declaration.
+bool DependencyFinderASTVisitor::VisitDeclRefExpr(DeclRefExpr *DeclRef) {
+  if (auto *V = dyn_cast_or_null<VarDecl>(DeclRef->getDecl()))
+    return VisitVarDecl(V);
+  return true;
+}
+
+/// Determine if any this variable is declared inside the ContainingStmt.
+bool DependencyFinderASTVisitor::VisitVarDecl(VarDecl *V) {
+  const Stmt *Curr = DeclParents->lookup(V);
+  // First, see if the variable was declared within an inner scope of the loop.
+  while (Curr != nullptr) {
+    if (Curr == ContainingStmt) {
+      DependsOnInsideVariable = true;
+      return false;
+    }
+    Curr = StmtParents->lookup(Curr);
+  }
+
+  // Next, check if the variable was removed from existence by an earlier
+  // iteration.
+  for (const auto &I : *ReplacedVars) {
+    if (I.second == V) {
+      DependsOnInsideVariable = true;
+      return false;
+    }
+  }
+  return true;
+}
+
+/// If we already created a variable for TheLoop, check to make sure
+/// that the name was not already taken.
+bool DeclFinderASTVisitor::VisitForStmt(ForStmt *TheLoop) {
+  StmtGeneratedVarNameMap::const_iterator I = GeneratedDecls->find(TheLoop);
+  if (I != GeneratedDecls->end() && I->second == Name) {
+    Found = true;
+    return false;
+  }
+  return true;
+}
+
+/// If any named declaration within the AST subtree has the same name,
+/// then consider Name already taken.
+bool DeclFinderASTVisitor::VisitNamedDecl(NamedDecl *D) {
+  const IdentifierInfo *Ident = D->getIdentifier();
+  if (Ident && Ident->getName() == Name) {
+    Found = true;
+    return false;
+  }
+  return true;
+}
+
+/// Forward any declaration references to the actual check on the
+/// referenced declaration.
+bool DeclFinderASTVisitor::VisitDeclRefExpr(DeclRefExpr *DeclRef) {
+  if (auto *D = dyn_cast<NamedDecl>(DeclRef->getDecl()))
+    return VisitNamedDecl(D);
+  return true;
+}
+
+/// If the new variable name conflicts with any type used in the loop,
+/// then we mark that variable name as taken.
+bool DeclFinderASTVisitor::VisitTypeLoc(TypeLoc TL) {
+  QualType QType = TL.getType();
+
+  // Check if our name conflicts with a type, to handle for typedefs.
+  if (QType.getAsString() == Name) {
+    Found = true;
+    return false;
+  }
+  // Check for base type conflicts. For example, when a struct is being
+  // referenced in the body of the loop, the above getAsString() will return the
+  // whole type (ex. "struct s"), but will be caught here.
+  if (const IdentifierInfo *Ident = QType.getBaseTypeIdentifier()) {
+    if (Ident->getName() == Name) {
+      Found = true;
+      return false;
+    }
+  }
+  return true;
+}
+
+/// Look through conversion/copy constructors and member functions to find the
+/// explicit initialization expression, returning it is found.
+///
+/// The main idea is that given
+///   vector<int> v;
+/// we consider either of these initializations
+///   vector<int>::iterator it = v.begin();
+///   vector<int>::iterator it(v.begin());
+///   vector<int>::const_iterator it(v.begin());
+/// and retrieve `v.begin()` as the expression used to initialize `it` but do
+/// not include
+///   vector<int>::iterator it;
+///   vector<int>::iterator it(v.begin(), 0); // if this constructor existed
+/// as being initialized from `v.begin()`
+const Expr *digThroughConstructorsConversions(const Expr *E) {
+  if (!E)
+    return nullptr;
+  E = E->IgnoreImplicit();
+  if (const auto *ConstructExpr = dyn_cast<CXXConstructExpr>(E)) {
+    // The initial constructor must take exactly one parameter, but base class
+    // and deferred constructors can take more.
+    if (ConstructExpr->getNumArgs() != 1 ||
+        ConstructExpr->getConstructionKind() != CXXConstructExpr::CK_Complete)
+      return nullptr;
+    E = ConstructExpr->getArg(0);
+    if (const auto *Temp = dyn_cast<MaterializeTemporaryExpr>(E))
+      E = Temp->getSubExpr();
+    return digThroughConstructorsConversions(E);
+  }
+  // If this is a conversion (as iterators commonly convert into their const
+  // iterator counterparts), dig through that as well.
+  if (const auto *ME = dyn_cast<CXXMemberCallExpr>(E))
+    if (isa<CXXConversionDecl>(ME->getMethodDecl()))
+      return digThroughConstructorsConversions(ME->getImplicitObjectArgument());
+  return E;
+}
+
+/// Returns true when two Exprs are equivalent.
+bool areSameExpr(ASTContext *Context, const Expr *First, const Expr *Second) {
+  if (!First || !Second)
+    return false;
+
+  llvm::FoldingSetNodeID FirstID, SecondID;
+  First->Profile(FirstID, *Context, true);
+  Second->Profile(SecondID, *Context, true);
+  return FirstID == SecondID;
+}
+
+/// Returns the DeclRefExpr represented by E, or NULL if there isn't one.
+const DeclRefExpr *getDeclRef(const Expr *E) {
+  return dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts());
+}
+
+/// Returns true when two ValueDecls are the same variable.
+bool areSameVariable(const ValueDecl *First, const ValueDecl *Second) {
+  return First && Second &&
+         First->getCanonicalDecl() == Second->getCanonicalDecl();
+}
+
+/// Determines if an expression is a declaration reference to a
+/// particular variable.
+static bool exprReferencesVariable(const ValueDecl *Target, const Expr *E) {
+  if (!Target || !E)
+    return false;
+  const DeclRefExpr *Decl = getDeclRef(E);
+  return Decl && areSameVariable(Target, Decl->getDecl());
+}
+
+/// If the expression is a dereference or call to operator*(), return the
+/// operand. Otherwise, return NULL.
+static const Expr *getDereferenceOperand(const Expr *E) {
+  if (const auto *Uop = dyn_cast<UnaryOperator>(E))
+    return Uop->getOpcode() == UO_Deref ? Uop->getSubExpr() : nullptr;
+
+  if (const auto *OpCall = dyn_cast<CXXOperatorCallExpr>(E)) {
+    return OpCall->getOperator() == OO_Star && OpCall->getNumArgs() == 1
+               ? OpCall->getArg(0)
+               : nullptr;
+  }
+
+  return nullptr;
+}
+
+/// Returns true when the Container contains an Expr equivalent to E.
+template <typename ContainerT>
+static bool containsExpr(ASTContext *Context, const ContainerT *Container,
+                         const Expr *E) {
+  llvm::FoldingSetNodeID ID;
+  E->Profile(ID, *Context, true);
+  for (const auto &I : *Container) {
+    if (ID == I.second)
+      return true;
+  }
+  return false;
+}
+
+/// Returns true when the index expression is a declaration reference to
+/// IndexVar.
+///
+/// If the index variable is `index`, this function returns true on
+///    arrayExpression[index];
+///    containerExpression[index];
+/// but not
+///    containerExpression[notIndex];
+static bool isIndexInSubscriptExpr(const Expr *IndexExpr,
+                                   const VarDecl *IndexVar) {
+  const DeclRefExpr *Idx = getDeclRef(IndexExpr);
+  return Idx && Idx->getType()->isIntegerType() &&
+         areSameVariable(IndexVar, Idx->getDecl());
+}
+
+/// Returns true when the index expression is a declaration reference to
+/// IndexVar, Obj is the same expression as SourceExpr after all parens and
+/// implicit casts are stripped off.
+///
+/// If PermitDeref is true, IndexExpression may
+/// be a dereference (overloaded or builtin operator*).
+///
+/// This function is intended for array-like containers, as it makes sure that
+/// both the container and the index match.
+/// If the loop has index variable `index` and iterates over `container`, then
+/// isIndexInSubscriptExpr returns true for
+/// \code
+///   container[index]
+///   container.at(index)
+///   container->at(index)
+/// \endcode
+/// but not for
+/// \code
+///   container[notIndex]
+///   notContainer[index]
+/// \endcode
+/// If PermitDeref is true, then isIndexInSubscriptExpr additionally returns
+/// true on these expressions:
+/// \code
+///   (*container)[index]
+///   (*container).at(index)
+/// \endcode
+static bool isIndexInSubscriptExpr(ASTContext *Context, const Expr *IndexExpr,
+                                   const VarDecl *IndexVar, const Expr *Obj,
+                                   const Expr *SourceExpr, bool PermitDeref) {
+  if (!SourceExpr || !Obj || !isIndexInSubscriptExpr(IndexExpr, IndexVar))
+    return false;
+
+  if (areSameExpr(Context, SourceExpr->IgnoreParenImpCasts(),
+                  Obj->IgnoreParenImpCasts()))
+    return true;
+
+  if (const Expr *InnerObj = getDereferenceOperand(Obj->IgnoreParenImpCasts()))
+    if (PermitDeref && areSameExpr(Context, SourceExpr->IgnoreParenImpCasts(),
+                                   InnerObj->IgnoreParenImpCasts()))
+      return true;
+
+  return false;
+}
+
+/// Returns true when Opcall is a call a one-parameter dereference of
+/// IndexVar.
+///
+/// For example, if the index variable is `index`, returns true for
+///   *index
+/// but not
+///   index
+///   *notIndex
+static bool isDereferenceOfOpCall(const CXXOperatorCallExpr *OpCall,
+                                  const VarDecl *IndexVar) {
+  return OpCall->getOperator() == OO_Star && OpCall->getNumArgs() == 1 &&
+         exprReferencesVariable(IndexVar, OpCall->getArg(0));
+}
+
+/// Returns true when Uop is a dereference of IndexVar.
+///
+/// For example, if the index variable is `index`, returns true for
+///   *index
+/// but not
+///   index
+///   *notIndex
+static bool isDereferenceOfUop(const UnaryOperator *Uop,
+                               const VarDecl *IndexVar) {
+  return Uop->getOpcode() == UO_Deref &&
+         exprReferencesVariable(IndexVar, Uop->getSubExpr());
+}
+
+/// Determines whether the given Decl defines a variable initialized to
+/// the loop object.
+///
+/// This is intended to find cases such as
+/// \code
+///   for (int i = 0; i < arraySize(arr); ++i) {
+///     T t = arr[i];
+///     // use t, do not use i
+///   }
+/// \endcode
+/// and
+/// \code
+///   for (iterator i = container.begin(), e = container.end(); i != e; ++i) {
+///     T t = *i;
+///     // use t, do not use i
+///   }
+/// \endcode
+static bool isAliasDecl(ASTContext *Context, const Decl *TheDecl,
+                        const VarDecl *IndexVar) {
+  const auto *VDecl = dyn_cast<VarDecl>(TheDecl);
+  if (!VDecl)
+    return false;
+  if (!VDecl->hasInit())
+    return false;
+
+  bool OnlyCasts = true;
+  const Expr *Init = VDecl->getInit()->IgnoreParenImpCasts();
+  if (isa_and_nonnull<CXXConstructExpr>(Init)) {
+    Init = digThroughConstructorsConversions(Init);
+    OnlyCasts = false;
+  }
+  if (!Init)
+    return false;
+
+  // Check that the declared type is the same as (or a reference to) the
+  // container type.
+  if (!OnlyCasts) {
+    QualType InitType = Init->getType();
+    QualType DeclarationType = VDecl->getType();
+    if (!DeclarationType.isNull() && DeclarationType->isReferenceType())
+      DeclarationType = DeclarationType.getNonReferenceType();
+
+    if (InitType.isNull() || DeclarationType.isNull() ||
+        !Context->hasSameUnqualifiedType(DeclarationType, InitType))
+      return false;
+  }
+
+  switch (Init->getStmtClass()) {
+  case Stmt::ArraySubscriptExprClass: {
+    const auto *E = cast<ArraySubscriptExpr>(Init);
+    // We don't really care which array is used here. We check to make sure
+    // it was the correct one later, since the AST will traverse it next.
+    return isIndexInSubscriptExpr(E->getIdx(), IndexVar);
+  }
+
+  case Stmt::UnaryOperatorClass:
+    return isDereferenceOfUop(cast<UnaryOperator>(Init), IndexVar);
+
+  case Stmt::CXXOperatorCallExprClass: {
+    const auto *OpCall = cast<CXXOperatorCallExpr>(Init);
+    if (OpCall->getOperator() == OO_Star)
+      return isDereferenceOfOpCall(OpCall, IndexVar);
+    if (OpCall->getOperator() == OO_Subscript) {
+      assert(OpCall->getNumArgs() == 2);
+      return isIndexInSubscriptExpr(OpCall->getArg(1), IndexVar);
+    }
+    break;
+  }
+
+  case Stmt::CXXMemberCallExprClass: {
+    const auto *MemCall = cast<CXXMemberCallExpr>(Init);
+    // This check is needed because getMethodDecl can return nullptr if the
+    // callee is a member function pointer.
+    const auto *MDecl = MemCall->getMethodDecl();
+    if (MDecl && !isa<CXXConversionDecl>(MDecl) &&
+        MDecl->getNameAsString() == "at" && MemCall->getNumArgs() == 1) {
+      return isIndexInSubscriptExpr(MemCall->getArg(0), IndexVar);
+    }
+    return false;
+  }
+
+  default:
+    break;
+  }
+  return false;
+}
+
+/// Determines whether the bound of a for loop condition expression is
+/// the same as the statically computable size of ArrayType.
+///
+/// Given
+/// \code
+///   const int N = 5;
+///   int arr[N];
+/// \endcode
+/// This is intended to permit
+/// \code
+///   for (int i = 0; i < N; ++i) {  /* use arr[i] */ }
+///   for (int i = 0; i < arraysize(arr); ++i) { /* use arr[i] */ }
+/// \endcode
+static bool arrayMatchesBoundExpr(ASTContext *Context,
+                                  const QualType &ArrayType,
+                                  const Expr *ConditionExpr) {
+  if (!ConditionExpr || ConditionExpr->isValueDependent())
+    return false;
+  const ConstantArrayType *ConstType =
+      Context->getAsConstantArrayType(ArrayType);
+  if (!ConstType)
+    return false;
+  Optional<llvm::APSInt> ConditionSize =
+      ConditionExpr->getIntegerConstantExpr(*Context);
+  if (!ConditionSize)
+    return false;
+  llvm::APSInt ArraySize(ConstType->getSize());
+  return llvm::APSInt::isSameValue(*ConditionSize, ArraySize);
+}
+
+ForLoopIndexUseVisitor::ForLoopIndexUseVisitor(ASTContext *Context,
+                                               const VarDecl *IndexVar,
+                                               const VarDecl *EndVar,
+                                               const Expr *ContainerExpr,
+                                               const Expr *ArrayBoundExpr,
+                                               bool ContainerNeedsDereference)
+    : Context(Context), IndexVar(IndexVar), EndVar(EndVar),
+      ContainerExpr(ContainerExpr), ArrayBoundExpr(ArrayBoundExpr),
+      ContainerNeedsDereference(ContainerNeedsDereference),
+      OnlyUsedAsIndex(true), AliasDecl(nullptr),
+      ConfidenceLevel(Confidence::CL_Safe), NextStmtParent(nullptr),
+      CurrStmtParent(nullptr), ReplaceWithAliasUse(false),
+      AliasFromForInit(false) {
+  if (ContainerExpr)
+    addComponent(ContainerExpr);
+}
+
+bool ForLoopIndexUseVisitor::findAndVerifyUsages(const Stmt *Body) {
+  TraverseStmt(const_cast<Stmt *>(Body));
+  return OnlyUsedAsIndex && ContainerExpr;
+}
+
+void ForLoopIndexUseVisitor::addComponents(const ComponentVector &Components) {
+  // FIXME: add sort(on ID)+unique to avoid extra work.
+  for (const auto &I : Components)
+    addComponent(I);
+}
+
+void ForLoopIndexUseVisitor::addComponent(const Expr *E) {
+  llvm::FoldingSetNodeID ID;
+  const Expr *Node = E->IgnoreParenImpCasts();
+  Node->Profile(ID, *Context, true);
+  DependentExprs.push_back(std::make_pair(Node, ID));
+}
+
+void ForLoopIndexUseVisitor::addUsage(const Usage &U) {
+  SourceLocation Begin = U.Range.getBegin();
+  if (Begin.isMacroID())
+    Begin = Context->getSourceManager().getSpellingLoc(Begin);
+
+  if (UsageLocations.insert(Begin).second)
+    Usages.push_back(U);
+}
+
+/// If the unary operator is a dereference of IndexVar, include it
+/// as a valid usage and prune the traversal.
+///
+/// For example, if container.begin() and container.end() both return pointers
+/// to int, this makes sure that the initialization for `k` is not counted as an
+/// unconvertible use of the iterator `i`.
+/// \code
+///   for (int *i = container.begin(), *e = container.end(); i != e; ++i) {
+///     int k = *i + 2;
+///   }
+/// \endcode
+bool ForLoopIndexUseVisitor::TraverseUnaryOperator(UnaryOperator *Uop) {
+  // If we dereference an iterator that's actually a pointer, count the
+  // occurrence.
+  if (isDereferenceOfUop(Uop, IndexVar)) {
+    addUsage(Usage(Uop));
+    return true;
+  }
+
+  return VisitorBase::TraverseUnaryOperator(Uop);
+}
+
+/// If the member expression is operator-> (overloaded or not) on
+/// IndexVar, include it as a valid usage and prune the traversal.
+///
+/// For example, given
+/// \code
+///   struct Foo { int bar(); int x; };
+///   vector<Foo> v;
+/// \endcode
+/// the following uses will be considered convertible:
+/// \code
+///   for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
+///     int b = i->bar();
+///     int k = i->x + 1;
+///   }
+/// \endcode
+/// though
+/// \code
+///   for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
+///     int k = i.insert(1);
+///   }
+///   for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
+///     int b = e->bar();
+///   }
+/// \endcode
+/// will not.
+bool ForLoopIndexUseVisitor::TraverseMemberExpr(MemberExpr *Member) {
+  const Expr *Base = Member->getBase();
+  const DeclRefExpr *Obj = getDeclRef(Base);
+  const Expr *ResultExpr = Member;
+  QualType ExprType;
+  if (const auto *Call =
+          dyn_cast<CXXOperatorCallExpr>(Base->IgnoreParenImpCasts())) {
+    // If operator->() is a MemberExpr containing a CXXOperatorCallExpr, then
+    // the MemberExpr does not have the expression we want. We therefore catch
+    // that instance here.
+    // For example, if vector<Foo>::iterator defines operator->(), then the
+    // example `i->bar()` at the top of this function is a CXXMemberCallExpr
+    // referring to `i->` as the member function called. We want just `i`, so
+    // we take the argument to operator->() as the base object.
+    if (Call->getOperator() == OO_Arrow) {
+      assert(Call->getNumArgs() == 1 &&
+             "Operator-> takes more than one argument");
+      Obj = getDeclRef(Call->getArg(0));
+      ResultExpr = Obj;
+      ExprType = Call->getCallReturnType(*Context);
+    }
+  }
+
+  if (Obj && exprReferencesVariable(IndexVar, Obj)) {
+    // Member calls on the iterator with '.' are not allowed.
+    if (!Member->isArrow()) {
+      OnlyUsedAsIndex = false;
+      return true;
+    }
+
+    if (ExprType.isNull())
+      ExprType = Obj->getType();
+
+    if (!ExprType->isPointerType())
+      return false;
+
+    // FIXME: This works around not having the location of the arrow operator.
+    // Consider adding OperatorLoc to MemberExpr?
+    SourceLocation ArrowLoc = Lexer::getLocForEndOfToken(
+        Base->getExprLoc(), 0, Context->getSourceManager(),
+        Context->getLangOpts());
+    // If something complicated is happening (i.e. the next token isn't an
+    // arrow), give up on making this work.
+    if (ArrowLoc.isValid()) {
+      addUsage(Usage(ResultExpr, Usage::UK_MemberThroughArrow,
+                     SourceRange(Base->getExprLoc(), ArrowLoc)));
+      return true;
+    }
+  }
+  return VisitorBase::TraverseMemberExpr(Member);
+}
+
+/// If a member function call is the at() accessor on the container with
+/// IndexVar as the single argument, include it as a valid usage and prune
+/// the traversal.
+///
+/// Member calls on other objects will not be permitted.
+/// Calls on the iterator object are not permitted, unless done through
+/// operator->(). The one exception is allowing vector::at() for pseudoarrays.
+bool ForLoopIndexUseVisitor::TraverseCXXMemberCallExpr(
+    CXXMemberCallExpr *MemberCall) {
+  auto *Member =
+      dyn_cast<MemberExpr>(MemberCall->getCallee()->IgnoreParenImpCasts());
+  if (!Member)
+    return VisitorBase::TraverseCXXMemberCallExpr(MemberCall);
+
+  // We specifically allow an accessor named "at" to let STL in, though
+  // this is restricted to pseudo-arrays by requiring a single, integer
+  // argument.
+  const IdentifierInfo *Ident = Member->getMemberDecl()->getIdentifier();
+  if (Ident && Ident->isStr("at") && MemberCall->getNumArgs() == 1) {
+    if (isIndexInSubscriptExpr(Context, MemberCall->getArg(0), IndexVar,
+                               Member->getBase(), ContainerExpr,
+                               ContainerNeedsDereference)) {
+      addUsage(Usage(MemberCall));
+      return true;
+    }
+  }
+
+  if (containsExpr(Context, &DependentExprs, Member->getBase()))
+    ConfidenceLevel.lowerTo(Confidence::CL_Risky);
+
+  return VisitorBase::TraverseCXXMemberCallExpr(MemberCall);
+}
+
+/// If an overloaded operator call is a dereference of IndexVar or
+/// a subscript of the container with IndexVar as the single argument,
+/// include it as a valid usage and prune the traversal.
+///
+/// For example, given
+/// \code
+///   struct Foo { int bar(); int x; };
+///   vector<Foo> v;
+///   void f(Foo);
+/// \endcode
+/// the following uses will be considered convertible:
+/// \code
+///   for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
+///     f(*i);
+///   }
+///   for (int i = 0; i < v.size(); ++i) {
+///      int i = v[i] + 1;
+///   }
+/// \endcode
+bool ForLoopIndexUseVisitor::TraverseCXXOperatorCallExpr(
+    CXXOperatorCallExpr *OpCall) {
+  switch (OpCall->getOperator()) {
+  case OO_Star:
+    if (isDereferenceOfOpCall(OpCall, IndexVar)) {
+      addUsage(Usage(OpCall));
+      return true;
+    }
+    break;
+
+  case OO_Subscript:
+    if (OpCall->getNumArgs() != 2)
+      break;
+    if (isIndexInSubscriptExpr(Context, OpCall->getArg(1), IndexVar,
+                               OpCall->getArg(0), ContainerExpr,
+                               ContainerNeedsDereference)) {
+      addUsage(Usage(OpCall));
+      return true;
+    }
+    break;
+
+  default:
+    break;
+  }
+  return VisitorBase::TraverseCXXOperatorCallExpr(OpCall);
+}
+
+/// If we encounter an array with IndexVar as the index of an
+/// ArraySubscriptExpression, note it as a consistent usage and prune the
+/// AST traversal.
+///
+/// For example, given
+/// \code
+///   const int N = 5;
+///   int arr[N];
+/// \endcode
+/// This is intended to permit
+/// \code
+///   for (int i = 0; i < N; ++i) {  /* use arr[i] */ }
+/// \endcode
+/// but not
+/// \code
+///   for (int i = 0; i < N; ++i) {  /* use notArr[i] */ }
+/// \endcode
+/// and further checking needs to be done later to ensure that exactly one array
+/// is referenced.
+bool ForLoopIndexUseVisitor::TraverseArraySubscriptExpr(ArraySubscriptExpr *E) {
+  Expr *Arr = E->getBase();
+  if (!isIndexInSubscriptExpr(E->getIdx(), IndexVar))
+    return VisitorBase::TraverseArraySubscriptExpr(E);
+
+  if ((ContainerExpr &&
+       !areSameExpr(Context, Arr->IgnoreParenImpCasts(),
+                    ContainerExpr->IgnoreParenImpCasts())) ||
+      !arrayMatchesBoundExpr(Context, Arr->IgnoreImpCasts()->getType(),
+                             ArrayBoundExpr)) {
+    // If we have already discovered the array being indexed and this isn't it
+    // or this array doesn't match, mark this loop as unconvertible.
+    OnlyUsedAsIndex = false;
+    return VisitorBase::TraverseArraySubscriptExpr(E);
+  }
+
+  if (!ContainerExpr)
+    ContainerExpr = Arr;
+
+  addUsage(Usage(E));
+  return true;
+}
+
+/// If we encounter a reference to IndexVar in an unpruned branch of the
+/// traversal, mark this loop as unconvertible.
+///
+/// This determines the set of convertible loops: any usages of IndexVar
+/// not explicitly considered convertible by this traversal will be caught by
+/// this function.
+///
+/// Additionally, if the container expression is more complex than just a
+/// DeclRefExpr, and some part of it is appears elsewhere in the loop, lower
+/// our confidence in the transformation.
+///
+/// For example, these are not permitted:
+/// \code
+///   for (int i = 0; i < N; ++i) {  printf("arr[%d] = %d", i, arr[i]); }
+///   for (vector<int>::iterator i = container.begin(), e = container.end();
+///        i != e; ++i)
+///     i.insert(0);
+///   for (vector<int>::iterator i = container.begin(), e = container.end();
+///        i != e; ++i)
+///     if (i + 1 != e)
+///       printf("%d", *i);
+/// \endcode
+///
+/// And these will raise the risk level:
+/// \code
+///    int arr[10][20];
+///    int l = 5;
+///    for (int j = 0; j < 20; ++j)
+///      int k = arr[l][j] + l; // using l outside arr[l] is considered risky
+///    for (int i = 0; i < obj.getVector().size(); ++i)
+///      obj.foo(10); // using `obj` is considered risky
+/// \endcode
+bool ForLoopIndexUseVisitor::VisitDeclRefExpr(DeclRefExpr *E) {
+  const ValueDecl *TheDecl = E->getDecl();
+  if (areSameVariable(IndexVar, TheDecl) ||
+      exprReferencesVariable(IndexVar, E) || areSameVariable(EndVar, TheDecl) ||
+      exprReferencesVariable(EndVar, E))
+    OnlyUsedAsIndex = false;
+  if (containsExpr(Context, &DependentExprs, E))
+    ConfidenceLevel.lowerTo(Confidence::CL_Risky);
+  return true;
+}
+
+/// If the loop index is captured by a lambda, replace this capture
+/// by the range-for loop variable.
+///
+/// For example:
+/// \code
+///   for (int i = 0; i < N; ++i) {
+///     auto f = [v, i](int k) {
+///       printf("%d\n", v[i] + k);
+///     };
+///     f(v[i]);
+///   }
+/// \endcode
+///
+/// Will be replaced by:
+/// \code
+///   for (auto & elem : v) {
+///     auto f = [v, elem](int k) {
+///       printf("%d\n", elem + k);
+///     };
+///     f(elem);
+///   }
+/// \endcode
+bool ForLoopIndexUseVisitor::TraverseLambdaCapture(LambdaExpr *LE,
+                                                   const LambdaCapture *C,
+                                                   Expr *Init) {
+  if (C->capturesVariable()) {
+    const VarDecl *VDecl = C->getCapturedVar();
+    if (areSameVariable(IndexVar, cast<ValueDecl>(VDecl))) {
+      // FIXME: if the index is captured, it will count as an usage and the
+      // alias (if any) won't work, because it is only used in case of having
+      // exactly one usage.
+      addUsage(Usage(nullptr,
+                     C->getCaptureKind() == LCK_ByCopy ? Usage::UK_CaptureByCopy
+                                                       : Usage::UK_CaptureByRef,
+                     C->getLocation()));
+    }
+  }
+  return VisitorBase::TraverseLambdaCapture(LE, C, Init);
+}
+
+/// If we find that another variable is created just to refer to the loop
+/// element, note it for reuse as the loop variable.
+///
+/// See the comments for isAliasDecl.
+bool ForLoopIndexUseVisitor::VisitDeclStmt(DeclStmt *S) {
+  if (!AliasDecl && S->isSingleDecl() &&
+      isAliasDecl(Context, S->getSingleDecl(), IndexVar)) {
+    AliasDecl = S;
+    if (CurrStmtParent) {
+      if (isa<IfStmt>(CurrStmtParent) || isa<WhileStmt>(CurrStmtParent) ||
+          isa<SwitchStmt>(CurrStmtParent))
+        ReplaceWithAliasUse = true;
+      else if (isa<ForStmt>(CurrStmtParent)) {
+        if (cast<ForStmt>(CurrStmtParent)->getConditionVariableDeclStmt() == S)
+          ReplaceWithAliasUse = true;
+        else
+          // It's assumed S came the for loop's init clause.
+          AliasFromForInit = true;
+      }
+    }
+  }
+
+  return true;
+}
+
+bool ForLoopIndexUseVisitor::TraverseStmt(Stmt *S) {
+  // If this is an initialization expression for a lambda capture, prune the
+  // traversal so that we don't end up diagnosing the contained DeclRefExpr as
+  // inconsistent usage. No need to record the usage here -- this is done in
+  // TraverseLambdaCapture().
+  if (const auto *LE = dyn_cast_or_null<LambdaExpr>(NextStmtParent)) {
+    // Any child of a LambdaExpr that isn't the body is an initialization
+    // expression.
+    if (S != LE->getBody()) {
+      return true;
+    }
+  }
+
+  // All this pointer swapping is a mechanism for tracking immediate parentage
+  // of Stmts.
+  const Stmt *OldNextParent = NextStmtParent;
+  CurrStmtParent = NextStmtParent;
+  NextStmtParent = S;
+  bool Result = VisitorBase::TraverseStmt(S);
+  NextStmtParent = OldNextParent;
+  return Result;
+}
+
+std::string VariableNamer::createIndexName() {
+  // FIXME: Add in naming conventions to handle:
+  //  - How to handle conflicts.
+  //  - An interactive process for naming.
+  std::string IteratorName;
+  StringRef ContainerName;
+  if (TheContainer)
+    ContainerName = TheContainer->getName();
+
+  size_t Len = ContainerName.size();
+  if (Len > 1 && ContainerName.endswith(Style == NS_UpperCase ? "S" : "s")) {
+    IteratorName = std::string(ContainerName.substr(0, Len - 1));
+    // E.g.: (auto thing : things)
+    if (!declarationExists(IteratorName) || IteratorName == OldIndex->getName())
+      return IteratorName;
+  }
+
+  if (Len > 2 && ContainerName.endswith(Style == NS_UpperCase ? "S_" : "s_")) {
+    IteratorName = std::string(ContainerName.substr(0, Len - 2));
+    // E.g.: (auto thing : things_)
+    if (!declarationExists(IteratorName) || IteratorName == OldIndex->getName())
+      return IteratorName;
+  }
+
+  return std::string(OldIndex->getName());
+}
+
+/// Determines whether or not the name \a Symbol conflicts with
+/// language keywords or defined macros. Also checks if the name exists in
+/// LoopContext, any of its parent contexts, or any of its child statements.
+///
+/// We also check to see if the same identifier was generated by this loop
+/// converter in a loop nested within SourceStmt.
+bool VariableNamer::declarationExists(StringRef Symbol) {
+  assert(Context != nullptr && "Expected an ASTContext");
+  IdentifierInfo &Ident = Context->Idents.get(Symbol);
+
+  // Check if the symbol is not an identifier (ie. is a keyword or alias).
+  if (!isAnyIdentifier(Ident.getTokenID()))
+    return true;
+
+  // Check for conflicting macro definitions.
+  if (Ident.hasMacroDefinition())
+    return true;
+
+  // Determine if the symbol was generated in a parent context.
+  for (const Stmt *S = SourceStmt; S != nullptr; S = ReverseAST->lookup(S)) {
+    StmtGeneratedVarNameMap::const_iterator I = GeneratedDecls->find(S);
+    if (I != GeneratedDecls->end() && I->second == Symbol)
+      return true;
+  }
+
+  // FIXME: Rather than detecting conflicts at their usages, we should check the
+  // parent context.
+  // For some reason, lookup() always returns the pair (NULL, NULL) because its
+  // StoredDeclsMap is not initialized (i.e. LookupPtr.getInt() is false inside
+  // of DeclContext::lookup()). Why is this?
+
+  // Finally, determine if the symbol was used in the loop or a child context.
+  DeclFinderASTVisitor DeclFinder(std::string(Symbol), GeneratedDecls);
+  return DeclFinder.findUsages(SourceStmt);
+}
+
+} // namespace modernize
+} // namespace tidy
+} // namespace clang