1e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek//==- ObjCUnusedIVarsChecker.cpp - Check for unused ivars --------*- C++ -*-==// 2395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// 3395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// The LLVM Compiler Infrastructure 4395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// 5395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// This file is distributed under the University of Illinois Open Source 6395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// License. See LICENSE.TXT for details. 7395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// 8395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek//===----------------------------------------------------------------------===// 9395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// 10395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// This file defines a CheckObjCUnusedIvars, a checker that 11395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// analyzes an Objective-C class's interface/implementation to determine if it 12395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// has any ivars that are never accessed. 13395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek// 14395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek//===----------------------------------------------------------------------===// 15395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 167dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis#include "ClangSACheckers.h" 172fa67efeaf66a9332c30a026dc1c21bef6c33a6cBenjamin Kramer#include "clang/AST/Attr.h" 18395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek#include "clang/AST/DeclObjC.h" 192fa67efeaf66a9332c30a026dc1c21bef6c33a6cBenjamin Kramer#include "clang/AST/Expr.h" 202fa67efeaf66a9332c30a026dc1c21bef6c33a6cBenjamin Kramer#include "clang/AST/ExprObjC.h" 21395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek#include "clang/Basic/LangOptions.h" 2258652887b08da3207226ec6d8bdb59ec0e96edfeBenjamin Kramer#include "clang/Basic/SourceManager.h" 2355fc873017f10f6f566b182b70f6fc22aefa3464Chandler Carruth#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h" 2455fc873017f10f6f566b182b70f6fc22aefa3464Chandler Carruth#include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h" 2555fc873017f10f6f566b182b70f6fc22aefa3464Chandler Carruth#include "clang/StaticAnalyzer/Core/Checker.h" 26395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 27395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenekusing namespace clang; 289ef6537a894c33003359b1f9b9676e9178e028b7Ted Kremenekusing namespace ento; 29395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 30395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenekenum IVarState { Unused, Used }; 310b2dd776318e612c682d32e1f4ca70f7b223c05eTed Kremenektypedef llvm::DenseMap<const ObjCIvarDecl*,IVarState> IvarUsageMap; 32395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 339c378f705405d37f49795d5e915989de774fe11fTed Kremenekstatic void Scan(IvarUsageMap& M, const Stmt *S) { 34395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek if (!S) 35395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek return; 361eb4433ac451dc16f4133a88af2d002ac26c58efMike Stump 3735ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek if (const ObjCIvarRefExpr *Ex = dyn_cast<ObjCIvarRefExpr>(S)) { 3835ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek const ObjCIvarDecl *D = Ex->getDecl(); 39395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek IvarUsageMap::iterator I = M.find(D); 400b2dd776318e612c682d32e1f4ca70f7b223c05eTed Kremenek if (I != M.end()) 410b2dd776318e612c682d32e1f4ca70f7b223c05eTed Kremenek I->second = Used; 42694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek return; 43395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek } 441eb4433ac451dc16f4133a88af2d002ac26c58efMike Stump 4535ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek // Blocks can reference an instance variable of a class. 4635ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek if (const BlockExpr *BE = dyn_cast<BlockExpr>(S)) { 4735ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek Scan(M, BE->getBody()); 4835ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek return; 4935ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek } 5035ffcf3c2a054ee124fe8d47152c5d1bcdf86261Ted Kremenek 515ec351c9507f12d5bede569c51d5257fad167134Anna Zaks if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(S)) 525ec351c9507f12d5bede569c51d5257fad167134Anna Zaks for (PseudoObjectExpr::const_semantics_iterator 535ec351c9507f12d5bede569c51d5257fad167134Anna Zaks i = POE->semantics_begin(), e = POE->semantics_end(); i != e; ++i) { 545ec351c9507f12d5bede569c51d5257fad167134Anna Zaks const Expr *sub = *i; 555ec351c9507f12d5bede569c51d5257fad167134Anna Zaks if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(sub)) 565ec351c9507f12d5bede569c51d5257fad167134Anna Zaks sub = OVE->getSourceExpr(); 575ec351c9507f12d5bede569c51d5257fad167134Anna Zaks Scan(M, sub); 585ec351c9507f12d5bede569c51d5257fad167134Anna Zaks } 595ec351c9507f12d5bede569c51d5257fad167134Anna Zaks 600b2dd776318e612c682d32e1f4ca70f7b223c05eTed Kremenek for (Stmt::const_child_iterator I=S->child_begin(),E=S->child_end(); I!=E;++I) 61694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek Scan(M, *I); 62694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek} 63694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek 649c378f705405d37f49795d5e915989de774fe11fTed Kremenekstatic void Scan(IvarUsageMap& M, const ObjCPropertyImplDecl *D) { 65694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek if (!D) 66694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek return; 671eb4433ac451dc16f4133a88af2d002ac26c58efMike Stump 689c378f705405d37f49795d5e915989de774fe11fTed Kremenek const ObjCIvarDecl *ID = D->getPropertyIvarDecl(); 69694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek 70694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek if (!ID) 71694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek return; 721eb4433ac451dc16f4133a88af2d002ac26c58efMike Stump 73694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek IvarUsageMap::iterator I = M.find(ID); 740b2dd776318e612c682d32e1f4ca70f7b223c05eTed Kremenek if (I != M.end()) 750b2dd776318e612c682d32e1f4ca70f7b223c05eTed Kremenek I->second = Used; 76395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek} 77395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 789c378f705405d37f49795d5e915989de774fe11fTed Kremenekstatic void Scan(IvarUsageMap& M, const ObjCContainerDecl *D) { 798fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek // Scan the methods for accesses. 80651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines for (const auto *I : D->instance_methods()) 81651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines Scan(M, I->getBody()); 82e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek 83e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek if (const ObjCImplementationDecl *ID = dyn_cast<ObjCImplementationDecl>(D)) { 848fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek // Scan for @synthesized property methods that act as setters/getters 858fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek // to an ivar. 86651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines for (const auto *I : ID->property_impls()) 87651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines Scan(M, I); 88e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek 89e8ec699167a7c3a2872feefd03e0ea2fabb980e0Ted Kremenek // Scan the associated categories as well. 90651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines for (const auto *Cat : ID->getClassInterface()->visible_categories()) { 91d329724745b49f894b768d47275b7c2713106e89Douglas Gregor if (const ObjCCategoryImplDecl *CID = Cat->getImplementation()) 92e8ec699167a7c3a2872feefd03e0ea2fabb980e0Ted Kremenek Scan(M, CID); 93e8ec699167a7c3a2872feefd03e0ea2fabb980e0Ted Kremenek } 948fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek } 958fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek} 968fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek 97b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenekstatic void Scan(IvarUsageMap &M, const DeclContext *C, const FileID FID, 98b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek SourceManager &SM) { 99651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines for (const auto *I : C->decls()) 100651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines if (const auto *FD = dyn_cast<FunctionDecl>(I)) { 101b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek SourceLocation L = FD->getLocStart(); 102e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek if (SM.getFileID(L) == FID) 103b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek Scan(M, FD->getBody()); 104b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek } 105b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek} 106b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek 1077dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidisstatic void checkObjCUnusedIvar(const ObjCImplementationDecl *D, 108651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines BugReporter &BR, 109651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines const CheckerBase *Checker) { 110395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 1119c378f705405d37f49795d5e915989de774fe11fTed Kremenek const ObjCInterfaceDecl *ID = D->getClassInterface(); 112395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek IvarUsageMap M; 113395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 114395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek // Iterate over the ivars. 115651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines for (const auto *Ivar : ID->ivars()) { 116e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek // Ignore ivars that... 117e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek // (a) aren't private 118e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek // (b) explicitly marked unused 119e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek // (c) are iboutlets 120ed50a8a7a8b5fbb5d365b39c81ec389e19e4360eTed Kremenek // (d) are unnamed bitfields 121651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines if (Ivar->getAccessControl() != ObjCIvarDecl::Private || 122651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines Ivar->hasAttr<UnusedAttr>() || Ivar->hasAttr<IBOutletAttr>() || 123651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines Ivar->hasAttr<IBOutletCollectionAttr>() || 124651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines Ivar->isUnnamedBitfield()) 125395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek continue; 1261eb4433ac451dc16f4133a88af2d002ac26c58efMike Stump 127651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines M[Ivar] = Unused; 128395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek } 129395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek 130395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek if (M.empty()) 131395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek return; 132e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek 1338fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek // Now scan the implementation declaration. 1348fa3a1a6732dda5e4bd8815cc64ab516da5c19fcTed Kremenek Scan(M, D); 1351eb4433ac451dc16f4133a88af2d002ac26c58efMike Stump 136b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek // Any potentially unused ivars? 137b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek bool hasUnused = false; 138b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek for (IvarUsageMap::iterator I = M.begin(), E = M.end(); I!=E; ++I) 139b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek if (I->second == Unused) { 140b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek hasUnused = true; 141b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek break; 142b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek } 143e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek 144b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek if (!hasUnused) 145b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek return; 146e3972a902d4a6f61fb21df092da2cace2b16cb3eTed Kremenek 147b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek // We found some potentially unused ivars. Scan the entire translation unit 148b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek // for functions inside the @implementation that reference these ivars. 149b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek // FIXME: In the future hopefully we can just use the lexical DeclContext 150b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek // to go from the ObjCImplementationDecl to the lexically "nested" 151b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek // C functions. 152b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek SourceManager &SM = BR.getSourceManager(); 153b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek Scan(M, D->getDeclContext(), SM.getFileID(D->getLocation()), SM); 154b221e4fb46f6e35b0721399ed2734daadbcc1f00Ted Kremenek 155395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek // Find ivars that are unused. 156395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek for (IvarUsageMap::iterator I = M.begin(), E = M.end(); I!=E; ++I) 157395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek if (I->second == Unused) { 15853ba0b636194dbeaa65a6f85316c9397a0c5298bTed Kremenek std::string sbuf; 15953ba0b636194dbeaa65a6f85316c9397a0c5298bTed Kremenek llvm::raw_string_ostream os(sbuf); 160b8989f27f116ff2400e92a52c067a69846119eb5Benjamin Kramer os << "Instance variable '" << *I->first << "' in class '" << *ID 161694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek << "' is never used by the methods in its @implementation " 162694eefb7452dd650bae16e1026571ab5a43a74fcTed Kremenek "(although it may be used by category methods)."; 163cc87ba2b950cfef2ef43019627330975a7daf73aTed Kremenek 164590dd8e0959d8df5621827768987c4792b74fc06Anna Zaks PathDiagnosticLocation L = 165590dd8e0959d8df5621827768987c4792b74fc06Anna Zaks PathDiagnosticLocation::create(I->first, BR.getSourceManager()); 166651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines BR.EmitBasicReport(D, Checker, "Unused instance variable", "Optimization", 167590dd8e0959d8df5621827768987c4792b74fc06Anna Zaks os.str(), L); 168395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek } 169395aaf20d6e1ab04741562dc6b7d47164bcbd87eTed Kremenek} 1707dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis 1717dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis//===----------------------------------------------------------------------===// 1727dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis// ObjCUnusedIvarsChecker 1737dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis//===----------------------------------------------------------------------===// 1747dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis 1757dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidisnamespace { 176ec8605f1d7ec846dbf51047bfd5c56d32d1ff91cArgyrios Kyrtzidisclass ObjCUnusedIvarsChecker : public Checker< 1777dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis check::ASTDecl<ObjCImplementationDecl> > { 1787dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidispublic: 1797dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr, 1807dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis BugReporter &BR) const { 181651f13cea278ec967336033dd032faef0e9fc2ecStephen Hines checkObjCUnusedIvar(D, BR, this); 1827dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis } 1837dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis}; 1847dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis} 1857dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis 1867dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidisvoid ento::registerObjCUnusedIvarsChecker(CheckerManager &mgr) { 1877dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis mgr.registerChecker<ObjCUnusedIvarsChecker>(); 1887dd445ec20e704846cfbdb132e56539280d71311Argyrios Kyrtzidis} 189