| //===--- LoopConvertCheck.cpp - clang-tidy---------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #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/SmallVector.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/ADT/StringSwitch.h" |
| #include "llvm/Support/Casting.h" |
| #include <cassert> |
| #include <cstring> |
| #include <utility> |
| |
| using namespace clang::ast_matchers; |
| using namespace llvm; |
| |
| namespace clang { |
| namespace tidy { |
| namespace modernize { |
| |
| static const char LoopNameArray[] = "forLoopArray"; |
| static const char LoopNameIterator[] = "forLoopIterator"; |
| static const char LoopNamePseudoArray[] = "forLoopPseudoArray"; |
| static const char ConditionBoundName[] = "conditionBound"; |
| static const char ConditionVarName[] = "conditionVar"; |
| static const char IncrementVarName[] = "incrementVar"; |
| static const char InitVarName[] = "initVar"; |
| static const char BeginCallName[] = "beginCall"; |
| static const char EndCallName[] = "endCall"; |
| static const char ConditionEndVarName[] = "conditionEndVar"; |
| static const char EndVarName[] = "endVar"; |
| static const char DerefByValueResultName[] = "derefByValueResult"; |
| static const char DerefByRefResultName[] = "derefByRefResult"; |
| |
| // shared matchers |
| static const TypeMatcher AnyType = anything(); |
| |
| static const StatementMatcher IntegerComparisonMatcher = |
| expr(ignoringParenImpCasts( |
| declRefExpr(to(varDecl(hasType(isInteger())).bind(ConditionVarName))))); |
| |
| static const DeclarationMatcher InitToZeroMatcher = |
| varDecl(hasInitializer(ignoringParenImpCasts(integerLiteral(equals(0))))) |
| .bind(InitVarName); |
| |
| static const StatementMatcher IncrementVarMatcher = |
| declRefExpr(to(varDecl(hasType(isInteger())).bind(IncrementVarName))); |
| |
| /// \brief The matcher for loops over arrays. |
| /// |
| /// In this general example, assuming 'j' and 'k' are of integral type: |
| /// \code |
| /// for (int i = 0; j < 3 + 2; ++k) { ... } |
| /// \endcode |
| /// The following string identifiers are bound to these parts of the AST: |
| /// ConditionVarName: 'j' (as a VarDecl) |
| /// ConditionBoundName: '3 + 2' (as an Expr) |
| /// InitVarName: 'i' (as a VarDecl) |
| /// IncrementVarName: 'k' (as a VarDecl) |
| /// LoopName: The entire for loop (as a ForStmt) |
| /// |
| /// Client code will need to make sure that: |
| /// - The three index variables identified by the matcher are the same |
| /// VarDecl. |
| /// - 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(anyOf( |
| binaryOperator(hasOperatorName("<"), |
| hasLHS(IntegerComparisonMatcher), |
| hasRHS(ArrayBoundMatcher)), |
| binaryOperator(hasOperatorName(">"), hasLHS(ArrayBoundMatcher), |
| hasRHS(IntegerComparisonMatcher)))), |
| hasIncrement(unaryOperator(hasOperatorName("++"), |
| hasUnaryOperand(IncrementVarMatcher)))) |
| .bind(LoopNameArray); |
| } |
| |
| /// \brief 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): |
| /// |
| /// Assuming f, g, and h are of type containerType::iterator, |
| /// \code |
| /// for (containerType::iterator it = container.begin(), |
| /// e = createIterator(); f != g; ++h) { ... } |
| /// for (containerType::iterator it = container.begin(); |
| /// f != anotherContainer.end(); ++h) { ... } |
| /// \endcode |
| /// The following string identifiers are bound to the parts of the AST: |
| /// InitVarName: 'it' (as a VarDecl) |
| /// ConditionVarName: 'f' (as a VarDecl) |
| /// LoopName: The entire for loop (as a ForStmt) |
| /// In the first example only: |
| /// EndVarName: 'e' (as a VarDecl) |
| /// ConditionEndVarName: 'g' (as a VarDecl) |
| /// In the second example only: |
| /// EndCallName: 'container.end()' (as a CXXMemberCallExpr) |
| /// |
| /// Client code will need to make sure that: |
| /// - The iterator variables 'it', 'f', and 'h' are the same. |
| /// - The two containers on which 'begin' and 'end' are called are the same. |
| /// - If the end iterator variable 'g' is defined, it is the same as 'f'. |
| StatementMatcher makeIteratorLoopMatcher() { |
| StatementMatcher BeginCallMatcher = |
| cxxMemberCallExpr( |
| argumentCountIs(0), |
| callee(cxxMethodDecl(anyOf(hasName("begin"), hasName("cbegin"))))) |
| .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(anyOf(hasName("end"), hasName("cend"))))); |
| |
| StatementMatcher IteratorBoundMatcher = |
| expr(anyOf(ignoringParenImpCasts( |
| declRefExpr(to(varDecl().bind(ConditionEndVarName)))), |
| ignoringParenImpCasts(expr(EndCallMatcher).bind(EndCallName)), |
| materializeTemporaryExpr(ignoringParenImpCasts( |
| expr(EndCallMatcher).bind(EndCallName))))); |
| |
| StatementMatcher IteratorComparisonMatcher = expr( |
| ignoringParenImpCasts(declRefExpr(to(varDecl().bind(ConditionVarName))))); |
| |
| auto OverloadedNEQMatcher = ignoringImplicit( |
| cxxOperatorCallExpr(hasOverloadedOperatorName("!="), argumentCountIs(2), |
| hasArgument(0, IteratorComparisonMatcher), |
| hasArgument(1, IteratorBoundMatcher))); |
| |
| // 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(allOf( |
| 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( |
| anyOf(binaryOperator(hasOperatorName("!="), |
| hasLHS(IteratorComparisonMatcher), |
| hasRHS(IteratorBoundMatcher)), |
| binaryOperator(hasOperatorName("!="), |
| hasLHS(IteratorBoundMatcher), |
| hasRHS(IteratorComparisonMatcher)), |
| OverloadedNEQMatcher)), |
| hasIncrement(anyOf( |
| unaryOperator(hasOperatorName("++"), |
| hasUnaryOperand(declRefExpr( |
| to(varDecl(hasType(pointsTo(AnyType))) |
| .bind(IncrementVarName))))), |
| cxxOperatorCallExpr( |
| hasOverloadedOperatorName("++"), |
| hasArgument( |
| 0, declRefExpr(to(varDecl(TestDerefReturnsByValue) |
| .bind(IncrementVarName)))))))) |
| .bind(LoopNameIterator); |
| } |
| |
| /// \brief 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): |
| /// |
| /// Assuming f, g, and h are of type containerType::iterator, |
| /// \code |
| /// for (int i = 0, j = container.size(); f < g; ++h) { ... } |
| /// for (int i = 0; f < container.size(); ++h) { ... } |
| /// \endcode |
| /// The following string identifiers are bound to the parts of the AST: |
| /// InitVarName: 'i' (as a VarDecl) |
| /// ConditionVarName: 'f' (as a VarDecl) |
| /// LoopName: The entire for loop (as a ForStmt) |
| /// In the first example only: |
| /// EndVarName: 'j' (as a VarDecl) |
| /// ConditionEndVarName: 'g' (as a VarDecl) |
| /// In the second example only: |
| /// EndCallName: 'container.size()' (as a CXXMemberCallExpr) |
| /// |
| /// Client code will need to make sure that: |
| /// - The index variables 'i', 'f', and 'h' are the same. |
| /// - The containers on which 'size()' is called is the container indexed. |
| /// - The index variable is only used in overloaded operator[] or |
| /// container.at(). |
| /// - If the end iterator variable 'g' is defined, it is the same as 'j'. |
| /// - 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( |
| hasMethod(cxxMethodDecl(hasName("begin"), isConst())), |
| hasMethod(cxxMethodDecl(hasName("end"), |
| isConst())))) // hasDeclaration |
| ))), // qualType |
| qualType(unless(isConstQualified()), |
| hasUnqualifiedDesugaredType(recordType(hasDeclaration( |
| cxxRecordDecl(hasMethod(hasName("begin")), |
| hasMethod(hasName("end"))))))) // qualType |
| )); |
| |
| StatementMatcher SizeCallMatcher = cxxMemberCallExpr( |
| argumentCountIs(0), |
| callee(cxxMethodDecl(anyOf(hasName("size"), hasName("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(hasType(isInteger())).bind(ConditionEndVarName)))), |
| EndInitMatcher)); |
| |
| return forStmt( |
| unless(isInTemplateInstantiation()), |
| hasLoopInit( |
| anyOf(declStmt(declCountIs(2), |
| containsDeclaration(0, InitToZeroMatcher), |
| containsDeclaration(1, EndDeclMatcher)), |
| declStmt(hasSingleDecl(InitToZeroMatcher)))), |
| hasCondition(anyOf( |
| binaryOperator(hasOperatorName("<"), |
| hasLHS(IntegerComparisonMatcher), |
| hasRHS(IndexBoundMatcher)), |
| binaryOperator(hasOperatorName(">"), hasLHS(IndexBoundMatcher), |
| hasRHS(IntegerComparisonMatcher)))), |
| hasIncrement(unaryOperator(hasOperatorName("++"), |
| hasUnaryOperand(IncrementVarMatcher)))) |
| .bind(LoopNamePseudoArray); |
| } |
| |
| /// \brief 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) { |
| // FIXME: Maybe allow declaration/initialization outside of the for loop. |
| const auto *TheCall = |
| dyn_cast_or_null<CXXMemberCallExpr>(digThroughConstructors(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(); |
| StringRef TargetName = IsBegin ? "begin" : "end"; |
| StringRef ConstTargetName = IsBegin ? "cbegin" : "cend"; |
| if (Name != TargetName && Name != ConstTargetName) |
| return nullptr; |
| |
| const Expr *SourceExpr = Member->getBase(); |
| if (!SourceExpr) |
| return nullptr; |
| |
| *IsArrow = Member->isArrow(); |
| return SourceExpr; |
| } |
| |
| /// \brief 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) { |
| // 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); |
| if (!BeginContainerExpr) |
| return nullptr; |
| |
| const Expr *EndContainerExpr = |
| getContainerFromBeginEndCall(EndExpr, /*IsBegin=*/false, &EndIsArrow); |
| // 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; |
| } |
| |
| /// \brief 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); |
| } |
| |
| /// \brief 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; |
| } |
| |
| /// \brief 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; |
| } |
| |
| /// \brief 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 && |
| 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; |
| } |
| |
| /// \brief 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; |
| } |
| |
| /// \brief 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->isRValue()) |
| return false; |
| } |
| return true; |
| } |
| |
| /// \brief 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) {} |
| |
| LoopConvertCheck::LoopConvertCheck(StringRef Name, ClangTidyContext *Context) |
| : ClangTidyCheck(Name, Context), TUInfo(new TUTrackingInfo), |
| MaxCopySize(std::stoull(Options.get("MaxCopySize", "16"))), |
| MinConfidence(StringSwitch<Confidence::Level>( |
| Options.get("MinConfidence", "reasonable")) |
| .Case("safe", Confidence::CL_Safe) |
| .Case("risky", Confidence::CL_Risky) |
| .Default(Confidence::CL_Reasonable)), |
| NamingStyle(StringSwitch<VariableNamer::NamingStyle>( |
| Options.get("NamingStyle", "CamelCase")) |
| .Case("camelBack", VariableNamer::NS_CamelBack) |
| .Case("lower_case", VariableNamer::NS_LowerCase) |
| .Case("UPPER_CASE", VariableNamer::NS_UpperCase) |
| .Default(VariableNamer::NS_CamelCase)) {} |
| |
| void LoopConvertCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) { |
| Options.store(Opts, "MaxCopySize", std::to_string(MaxCopySize)); |
| SmallVector<std::string, 3> Confs{"risky", "reasonable", "safe"}; |
| Options.store(Opts, "MinConfidence", Confs[static_cast<int>(MinConfidence)]); |
| |
| SmallVector<std::string, 4> Styles{"camelBack", "CamelCase", "lower_case", |
| "UPPER_CASE"}; |
| Options.store(Opts, "NamingStyle", Styles[static_cast<int>(NamingStyle)]); |
| } |
| |
| void LoopConvertCheck::registerMatchers(MatchFinder *Finder) { |
| // Only register the matchers for C++. Because this checker is used for |
| // modernization, it is reasonable to run it on any C++ standard with the |
| // assumption the user is trying to modernize their codebase. |
| if (!getLangOpts().CPlusPlus) |
| return; |
| |
| Finder->addMatcher(makeArrayLoopMatcher(), this); |
| Finder->addMatcher(makeIteratorLoopMatcher(), this); |
| Finder->addMatcher(makePseudoArrayLoopMatcher(), this); |
| } |
| |
| /// \brief 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)); |
| } |
| |
| /// \brief 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) { |
| auto Diag = diag(Loop->getForLoc(), "use range-based for loop instead"); |
| |
| std::string VarName; |
| bool VarNameFromAlias = (Usages.size() == 1) && AliasDecl; |
| bool AliasVarIsRef = false; |
| bool CanCopy = true; |
| |
| 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); |
| } |
| |
| Diag << 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)); |
| Diag << 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(); |
| |
| // 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); |
| } |
| } |
| |
| StringRef MaybeDereference = Descriptor.ContainerNeedsDereference ? "*" : ""; |
| std::string TypeString = Type.getAsString(getLangOpts()); |
| std::string Range = ("(" + TypeString + " " + VarName + " : " + |
| MaybeDereference + Descriptor.ContainerString + ")") |
| .str(); |
| Diag << FixItHint::CreateReplacement( |
| CharSourceRange::getTokenRange(ParenRange), Range); |
| TUInfo->getGeneratedDecls().insert(make_pair(Loop, VarName)); |
| } |
| |
| /// \brief Returns a string which refers to the container iterated over. |
| StringRef LoopConvertCheck::getContainerString(ASTContext *Context, |
| const ForStmt *Loop, |
| const Expr *ContainerExpr) { |
| StringRef ContainerString; |
| if (isa<CXXThisExpr>(ContainerExpr->IgnoreParenImpCasts())) { |
| ContainerString = "this"; |
| } else { |
| ContainerString = |
| getStringFromRange(Context->getSourceManager(), Context->getLangOpts(), |
| ContainerExpr->getSourceRange()); |
| } |
| |
| return ContainerString; |
| } |
| |
| /// \brief 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; |
| } |
| } |
| |
| /// \brief 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(); |
| } |
| } |
| } |
| |
| /// \brief 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 = getContainerString(Context, Loop, ContainerExpr); |
| |
| if (FixerKind == LFK_Iterator) |
| getIteratorLoopQualifiers(Context, Nodes, Descriptor); |
| else |
| getArrayLoopQualifiers(Context, Nodes, ContainerExpr, Usages, Descriptor); |
| } |
| |
| /// \brief 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) { |
| // If we already modified the range of this for loop, don't do any further |
| // updates on this iteration. |
| if (TUInfo->getReplacedVars().count(Loop)) |
| return false; |
| |
| // Check that we have exactly one index variable and at most one end variable. |
| const auto *LoopVar = Nodes.getNodeAs<VarDecl>(IncrementVarName); |
| const auto *CondVar = Nodes.getNodeAs<VarDecl>(ConditionVarName); |
| const auto *InitVar = Nodes.getNodeAs<VarDecl>(InitVarName); |
| if (!areSameVariable(LoopVar, CondVar) || !areSameVariable(LoopVar, InitVar)) |
| return false; |
| const auto *EndVar = Nodes.getNodeAs<VarDecl>(EndVarName); |
| const auto *ConditionEndVar = Nodes.getNodeAs<VarDecl>(ConditionEndVarName); |
| if (EndVar && !areSameVariable(EndVar, ConditionEndVar)) |
| return false; |
| |
| // FIXME: Try to put most of this logic inside a matcher. |
| if (FixerKind == LFK_Iterator) { |
| 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 (!Context->hasSameType(CanonicalInitVarType, |
| CanonicalBeginType)) { |
| // Check for qualified types to avoid conversions from non-const to const |
| // iterator types. |
| return false; |
| } |
| } else if (FixerKind == LFK_PseudoArray) { |
| // This call is required to obtain the container. |
| const auto *EndCall = Nodes.getNodeAs<CXXMemberCallExpr>(EndCallName); |
| if (!EndCall || !dyn_cast<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 { |
| 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>(IncrementVarName); |
| 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) { |
| ContainerExpr = findContainer(Context, LoopVar->getInit(), |
| EndVar ? EndVar->getInit() : EndCall, |
| &Descriptor.ContainerNeedsDereference); |
| } 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. |
| 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->getTranslationUnitDecl()); |
| 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); |
| } |
| |
| } // namespace modernize |
| } // namespace tidy |
| } // namespace clang |
