clang-tools-extra/clang-tidy/modernize/MakeSmartPtrCheck.cpp

   1 //===--- MakeSmartPtrCheck.cpp - clang-tidy--------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "../utils/TypeTraits.h"
  10 #include "MakeSharedCheck.h"
  11 #include "clang/Frontend/CompilerInstance.h"
  12 #include "clang/Lex/Lexer.h"
  13 #include "clang/Lex/Preprocessor.h"
  14
  15 using namespace clang::ast_matchers;
  16
  17 namespace clang::tidy::modernize {
  18
  19 namespace {
  20
  21 constexpr char ConstructorCall[] = "constructorCall";
  22 constexpr char ResetCall[] = "resetCall";
  23 constexpr char NewExpression[] = "newExpression";
  24
  25 std::string getNewExprName(const CXXNewExpr *NewExpr, const SourceManager &SM,
  26                            const LangOptions &Lang) {
  27   StringRef WrittenName = Lexer::getSourceText(
  28       CharSourceRange::getTokenRange(
  29           NewExpr->getAllocatedTypeSourceInfo()->getTypeLoc().getSourceRange()),
  30       SM, Lang);
  31   if (NewExpr->isArray()) {
  32     return (WrittenName + "[]").str();
  33   }
  34   return WrittenName.str();
  35 }
  36
  37 } // namespace
  38
  39 const char MakeSmartPtrCheck::PointerType[] = "pointerType";
  40
  41 MakeSmartPtrCheck::MakeSmartPtrCheck(StringRef Name, ClangTidyContext *Context,
  42                                      StringRef MakeSmartPtrFunctionName)
  43     : ClangTidyCheck(Name, Context),
  44       Inserter(Options.getLocalOrGlobal("IncludeStyle",
  45                                         utils::IncludeSorter::IS_LLVM),
  46                areDiagsSelfContained()),
  47       MakeSmartPtrFunctionHeader(
  48           Options.get("MakeSmartPtrFunctionHeader", "<memory>")),
  49       MakeSmartPtrFunctionName(
  50           Options.get("MakeSmartPtrFunction", MakeSmartPtrFunctionName)),
  51       IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)),
  52       IgnoreDefaultInitialization(
  53           Options.get("IgnoreDefaultInitialization", true)) {}
  54
  55 void MakeSmartPtrCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  56   Options.store(Opts, "IncludeStyle", Inserter.getStyle());
  57   Options.store(Opts, "MakeSmartPtrFunctionHeader", MakeSmartPtrFunctionHeader);
  58   Options.store(Opts, "MakeSmartPtrFunction", MakeSmartPtrFunctionName);
  59   Options.store(Opts, "IgnoreMacros", IgnoreMacros);
  60   Options.store(Opts, "IgnoreDefaultInitialization",
  61                 IgnoreDefaultInitialization);
  62 }
  63
  64 bool MakeSmartPtrCheck::isLanguageVersionSupported(
  65     const LangOptions &LangOpts) const {
  66   return LangOpts.CPlusPlus11;
  67 }
  68
  69 void MakeSmartPtrCheck::registerPPCallbacks(const SourceManager &SM,
  70                                             Preprocessor *PP,
  71                                             Preprocessor *ModuleExpanderPP) {
  72   Inserter.registerPreprocessor(PP);
  73 }
  74
  75 void MakeSmartPtrCheck::registerMatchers(ast_matchers::MatchFinder *Finder) {
  76   // Calling make_smart_ptr from within a member function of a type with a
  77   // private or protected constructor would be ill-formed.
  78   auto CanCallCtor = unless(has(ignoringImpCasts(
  79       cxxConstructExpr(hasDeclaration(decl(unless(isPublic())))))));
  80
  81   auto IsPlacement = hasAnyPlacementArg(anything());
  82
  83   Finder->addMatcher(
  84       traverse(
  85           TK_AsIs,
  86           cxxBindTemporaryExpr(has(ignoringParenImpCasts(
  87               cxxConstructExpr(
  88                   hasType(getSmartPointerTypeMatcher()), argumentCountIs(1),
  89                   hasArgument(
  90                       0, cxxNewExpr(hasType(pointsTo(qualType(hasCanonicalType(
  91                                         equalsBoundNode(PointerType))))),
  92                                     CanCallCtor, unless(IsPlacement))
  93                              .bind(NewExpression)),
  94                   unless(isInTemplateInstantiation()))
  95                   .bind(ConstructorCall))))),
  96       this);
  97
  98   Finder->addMatcher(
  99       traverse(TK_AsIs,
 100                cxxMemberCallExpr(
 101                    thisPointerType(getSmartPointerTypeMatcher()),
 102                    callee(cxxMethodDecl(hasName("reset"))),
 103                    hasArgument(0, cxxNewExpr(CanCallCtor, unless(IsPlacement))
 104                                       .bind(NewExpression)),
 105                    unless(isInTemplateInstantiation()))
 106                    .bind(ResetCall)),
 107       this);
 108 }
 109
 110 void MakeSmartPtrCheck::check(const MatchFinder::MatchResult &Result) {
 111   // 'smart_ptr' refers to 'std::shared_ptr' or 'std::unique_ptr' or other
 112   // pointer, 'make_smart_ptr' refers to 'std::make_shared' or
 113   // 'std::make_unique' or other function that creates smart_ptr.
 114
 115   SourceManager &SM = *Result.SourceManager;
 116   const auto *Construct =
 117       Result.Nodes.getNodeAs<CXXConstructExpr>(ConstructorCall);
 118   const auto *Reset = Result.Nodes.getNodeAs<CXXMemberCallExpr>(ResetCall);
 119   const auto *Type = Result.Nodes.getNodeAs<QualType>(PointerType);
 120   const auto *New = Result.Nodes.getNodeAs<CXXNewExpr>(NewExpression);
 121
 122   // Skip when this is a new-expression with `auto`, e.g. new auto(1)
 123   if (New->getType()->getPointeeType()->getContainedAutoType())
 124     return;
 125
 126   // Be conservative for cases where we construct and default initialize.
 127   //
 128   // For example,
 129   //    P.reset(new int)    // check fix: P = std::make_unique<int>()
 130   //    P.reset(new int[5]) // check fix: P = std::make_unique<int []>(5)
 131   //
 132   // The fix of the check has side effect, it introduces value initialization
 133   // which maybe unexpected and cause performance regression.
 134   bool Initializes = New->hasInitializer() ||
 135                      !utils::type_traits::isTriviallyDefaultConstructible(
 136                          New->getAllocatedType(), *Result.Context);
 137   if (!Initializes && IgnoreDefaultInitialization)
 138     return;
 139   if (Construct)
 140     checkConstruct(SM, Result.Context, Construct, Type, New);
 141   else if (Reset)
 142     checkReset(SM, Result.Context, Reset, New);
 143 }
 144
 145 void MakeSmartPtrCheck::checkConstruct(SourceManager &SM, ASTContext *Ctx,
 146                                        const CXXConstructExpr *Construct,
 147                                        const QualType *Type,
 148                                        const CXXNewExpr *New) {
 149   SourceLocation ConstructCallStart = Construct->getExprLoc();
 150   bool InMacro = ConstructCallStart.isMacroID();
 151
 152   if (InMacro && IgnoreMacros) {
 153     return;
 154   }
 155
 156   bool Invalid = false;
 157   StringRef ExprStr = Lexer::getSourceText(
 158       CharSourceRange::getCharRange(
 159           ConstructCallStart, Construct->getParenOrBraceRange().getBegin()),
 160       SM, getLangOpts(), &Invalid);
 161   if (Invalid)
 162     return;
 163
 164   auto Diag = diag(ConstructCallStart, "use %0 instead")
 165               << MakeSmartPtrFunctionName;
 166
 167   // Disable the fix in macros.
 168   if (InMacro) {
 169     return;
 170   }
 171
 172   if (!replaceNew(Diag, New, SM, Ctx)) {
 173     return;
 174   }
 175
 176   // Find the location of the template's left angle.
 177   size_t LAngle = ExprStr.find('<');
 178   SourceLocation ConstructCallEnd;
 179   if (LAngle == StringRef::npos) {
 180     // If the template argument is missing (because it is part of the alias)
 181     // we have to add it back.
 182     ConstructCallEnd = ConstructCallStart.getLocWithOffset(ExprStr.size());
 183     Diag << FixItHint::CreateInsertion(
 184         ConstructCallEnd, "<" + getNewExprName(New, SM, getLangOpts()) + ">");
 185   } else {
 186     ConstructCallEnd = ConstructCallStart.getLocWithOffset(LAngle);
 187   }
 188
 189   Diag << FixItHint::CreateReplacement(
 190       CharSourceRange::getCharRange(ConstructCallStart, ConstructCallEnd),
 191       MakeSmartPtrFunctionName);
 192
 193   // If the smart_ptr is built with brace enclosed direct initialization, use
 194   // parenthesis instead.
 195   if (Construct->isListInitialization()) {
 196     SourceRange BraceRange = Construct->getParenOrBraceRange();
 197     Diag << FixItHint::CreateReplacement(
 198         CharSourceRange::getCharRange(
 199             BraceRange.getBegin(), BraceRange.getBegin().getLocWithOffset(1)),
 200         "(");
 201     Diag << FixItHint::CreateReplacement(
 202         CharSourceRange::getCharRange(BraceRange.getEnd(),
 203                                       BraceRange.getEnd().getLocWithOffset(1)),
 204         ")");
 205   }
 206
 207   insertHeader(Diag, SM.getFileID(ConstructCallStart));
 208 }
 209
 210 void MakeSmartPtrCheck::checkReset(SourceManager &SM, ASTContext *Ctx,
 211                                    const CXXMemberCallExpr *Reset,
 212                                    const CXXNewExpr *New) {
 213   const auto *Expr = cast<MemberExpr>(Reset->getCallee());
 214   SourceLocation OperatorLoc = Expr->getOperatorLoc();
 215   SourceLocation ResetCallStart = Reset->getExprLoc();
 216   SourceLocation ExprStart = Expr->getBeginLoc();
 217   SourceLocation ExprEnd =
 218       Lexer::getLocForEndOfToken(Expr->getEndLoc(), 0, SM, getLangOpts());
 219
 220   bool InMacro = ExprStart.isMacroID();
 221
 222   if (InMacro && IgnoreMacros) {
 223     return;
 224   }
 225
 226   // There are some cases where we don't have operator ("." or "->") of the
 227   // "reset" expression, e.g. call "reset()" method directly in the subclass of
 228   // "std::unique_ptr<>". We skip these cases.
 229   if (OperatorLoc.isInvalid()) {
 230     return;
 231   }
 232
 233   auto Diag = diag(ResetCallStart, "use %0 instead")
 234               << MakeSmartPtrFunctionName;
 235
 236   // Disable the fix in macros.
 237   if (InMacro) {
 238     return;
 239   }
 240
 241   if (!replaceNew(Diag, New, SM, Ctx)) {
 242     return;
 243   }
 244
 245   Diag << FixItHint::CreateReplacement(
 246       CharSourceRange::getCharRange(OperatorLoc, ExprEnd),
 247       (llvm::Twine(" = ") + MakeSmartPtrFunctionName + "<" +
 248        getNewExprName(New, SM, getLangOpts()) + ">")
 249           .str());
 250
 251   if (Expr->isArrow())
 252     Diag << FixItHint::CreateInsertion(ExprStart, "*");
 253
 254   insertHeader(Diag, SM.getFileID(OperatorLoc));
 255 }
 256
 257 bool MakeSmartPtrCheck::replaceNew(DiagnosticBuilder &Diag,
 258                                    const CXXNewExpr *New, SourceManager &SM,
 259                                    ASTContext *Ctx) {
 260   auto SkipParensParents = [&](const Expr *E) {
 261     TraversalKindScope RAII(*Ctx, TK_AsIs);
 262
 263     for (const Expr *OldE = nullptr; E != OldE;) {
 264       OldE = E;
 265       for (const auto &Node : Ctx->getParents(*E)) {
 266         if (const Expr *Parent = Node.get<ParenExpr>()) {
 267           E = Parent;
 268           break;
 269         }
 270       }
 271     }
 272     return E;
 273   };
 274
 275   SourceRange NewRange = SkipParensParents(New)->getSourceRange();
 276   SourceLocation NewStart = NewRange.getBegin();
 277   SourceLocation NewEnd = NewRange.getEnd();
 278
 279   // Skip when the source location of the new expression is invalid.
 280   if (NewStart.isInvalid() || NewEnd.isInvalid())
 281     return false;
 282
 283   std::string ArraySizeExpr;
 284   if (const auto *ArraySize = New->getArraySize().value_or(nullptr)) {
 285     ArraySizeExpr = Lexer::getSourceText(CharSourceRange::getTokenRange(
 286                                              ArraySize->getSourceRange()),
 287                                          SM, getLangOpts())
 288                         .str();
 289   }
 290   // Returns true if the given constructor expression has any braced-init-list
 291   // argument, e.g.
 292   //   Foo({1, 2}, 1) => true
 293   //   Foo(Bar{1, 2}) => true
 294   //   Foo(1) => false
 295   //   Foo{1} => false
 296   auto HasListIntializedArgument = [](const CXXConstructExpr *CE) {
 297     for (const auto *Arg : CE->arguments()) {
 298       Arg = Arg->IgnoreImplicit();
 299
 300       if (isa<CXXStdInitializerListExpr>(Arg) || isa<InitListExpr>(Arg))
 301         return true;
 302       // Check whether we implicitly construct a class from a
 303       // std::initializer_list.
 304       if (const auto *CEArg = dyn_cast<CXXConstructExpr>(Arg)) {
 305         // Strip the elidable move constructor, it is present in the AST for
 306         // C++11/14, e.g. Foo(Bar{1, 2}), the move constructor is around the
 307         // init-list constructor.
 308         if (CEArg->isElidable()) {
 309           if (const auto *TempExp = CEArg->getArg(0)) {
 310             if (const auto *UnwrappedCE =
 311                     dyn_cast<CXXConstructExpr>(TempExp->IgnoreImplicit()))
 312               CEArg = UnwrappedCE;
 313           }
 314         }
 315         if (CEArg->isStdInitListInitialization())
 316           return true;
 317       }
 318     }
 319     return false;
 320   };
 321   switch (New->getInitializationStyle()) {
 322   case CXXNewExpr::NoInit: {
 323     if (ArraySizeExpr.empty()) {
 324       Diag << FixItHint::CreateRemoval(SourceRange(NewStart, NewEnd));
 325     } else {
 326       // New array expression without written initializer:
 327       //   smart_ptr<Foo[]>(new Foo[5]);
 328       Diag << FixItHint::CreateReplacement(SourceRange(NewStart, NewEnd),
 329                                            ArraySizeExpr);
 330     }
 331     break;
 332   }
 333   case CXXNewExpr::CallInit: {
 334     // FIXME: Add fixes for constructors with parameters that can be created
 335     // with a C++11 braced-init-list (e.g. std::vector, std::map).
 336     // Unlike ordinal cases, braced list can not be deduced in
 337     // std::make_smart_ptr, we need to specify the type explicitly in the fixes:
 338     //   struct S { S(std::initializer_list<int>, int); };
 339     //   struct S2 { S2(std::vector<int>); };
 340     //   struct S3 { S3(S2, int); };
 341     //   smart_ptr<S>(new S({1, 2, 3}, 1));  // C++98 call-style initialization
 342     //   smart_ptr<S>(new S({}, 1));
 343     //   smart_ptr<S2>(new S2({1})); // implicit conversion:
 344     //                               //   std::initializer_list => std::vector
 345     //   smart_ptr<S3>(new S3({1, 2}, 3));
 346     // The above samples have to be replaced with:
 347     //   std::make_smart_ptr<S>(std::initializer_list<int>({1, 2, 3}), 1);
 348     //   std::make_smart_ptr<S>(std::initializer_list<int>({}), 1);
 349     //   std::make_smart_ptr<S2>(std::vector<int>({1}));
 350     //   std::make_smart_ptr<S3>(S2{1, 2}, 3);
 351     if (const auto *CE = New->getConstructExpr()) {
 352       if (HasListIntializedArgument(CE))
 353         return false;
 354     }
 355     if (ArraySizeExpr.empty()) {
 356       SourceRange InitRange = New->getDirectInitRange();
 357       Diag << FixItHint::CreateRemoval(
 358           SourceRange(NewStart, InitRange.getBegin()));
 359       Diag << FixItHint::CreateRemoval(SourceRange(InitRange.getEnd(), NewEnd));
 360     }
 361     else {
 362       // New array expression with default/value initialization:
 363       //   smart_ptr<Foo[]>(new int[5]());
 364       //   smart_ptr<Foo[]>(new Foo[5]());
 365       Diag << FixItHint::CreateReplacement(SourceRange(NewStart, NewEnd),
 366                                            ArraySizeExpr);
 367     }
 368     break;
 369   }
 370   case CXXNewExpr::ListInit: {
 371     // Range of the substring that we do not want to remove.
 372     SourceRange InitRange;
 373     if (const auto *NewConstruct = New->getConstructExpr()) {
 374       if (NewConstruct->isStdInitListInitialization() ||
 375           HasListIntializedArgument(NewConstruct)) {
 376         // FIXME: Add fixes for direct initialization with the initializer-list
 377         // constructor. Similar to the above CallInit case, the type has to be
 378         // specified explicitly in the fixes.
 379         //   struct S { S(std::initializer_list<int>); };
 380         //   struct S2 { S2(S, int); };
 381         //   smart_ptr<S>(new S{1, 2, 3});  // C++11 direct list-initialization
 382         //   smart_ptr<S>(new S{});  // use initializer-list constructor
 383         //   smart_ptr<S2>()new S2{ {1,2}, 3 }; // have a list-initialized arg
 384         // The above cases have to be replaced with:
 385         //   std::make_smart_ptr<S>(std::initializer_list<int>({1, 2, 3}));
 386         //   std::make_smart_ptr<S>(std::initializer_list<int>({}));
 387         //   std::make_smart_ptr<S2>(S{1, 2}, 3);
 388         return false;
 389       }
 390       // Direct initialization with ordinary constructors.
 391       //   struct S { S(int x); S(); };
 392       //   smart_ptr<S>(new S{5});
 393       //   smart_ptr<S>(new S{}); // use default constructor
 394       // The arguments in the initialization list are going to be forwarded to
 395       // the constructor, so this has to be replaced with:
 396       //   std::make_smart_ptr<S>(5);
 397       //   std::make_smart_ptr<S>();
 398       InitRange = SourceRange(
 399           NewConstruct->getParenOrBraceRange().getBegin().getLocWithOffset(1),
 400           NewConstruct->getParenOrBraceRange().getEnd().getLocWithOffset(-1));
 401     } else {
 402       // Aggregate initialization.
 403       //   smart_ptr<Pair>(new Pair{first, second});
 404       // Has to be replaced with:
 405       //   smart_ptr<Pair>(Pair{first, second});
 406       //
 407       // The fix (std::make_unique) needs to see copy/move constructor of
 408       // Pair. If we found any invisible or deleted copy/move constructor, we
 409       // stop generating fixes -- as the C++ rule is complicated and we are less
 410       // certain about the correct fixes.
 411       if (const CXXRecordDecl *RD = New->getType()->getPointeeCXXRecordDecl()) {
 412         if (llvm::any_of(RD->ctors(), [](const CXXConstructorDecl *Ctor) {
 413               return Ctor->isCopyOrMoveConstructor() &&
 414                      (Ctor->isDeleted() || Ctor->getAccess() == AS_private);
 415             })) {
 416           return false;
 417         }
 418       }
 419       InitRange = SourceRange(
 420           New->getAllocatedTypeSourceInfo()->getTypeLoc().getBeginLoc(),
 421           New->getInitializer()->getSourceRange().getEnd());
 422     }
 423     Diag << FixItHint::CreateRemoval(
 424         CharSourceRange::getCharRange(NewStart, InitRange.getBegin()));
 425     Diag << FixItHint::CreateRemoval(
 426         SourceRange(InitRange.getEnd().getLocWithOffset(1), NewEnd));
 427     break;
 428   }
 429   }
 430   return true;
 431 }
 432
 433 void MakeSmartPtrCheck::insertHeader(DiagnosticBuilder &Diag, FileID FD) {
 434   if (MakeSmartPtrFunctionHeader.empty()) {
 435     return;
 436   }
 437   Diag << Inserter.createIncludeInsertion(FD, MakeSmartPtrFunctionHeader);
 438 }
 439
 440 } // namespace clang::tidy::modernize