1 //==- CheckObjCDealloc.cpp - Check ObjC -dealloc implementation --*- C++ -*-==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines a CheckObjCDealloc, a checker that
11 // analyzes an Objective-C class's implementation to determine if it
12 // correctly implements -dealloc.
14 //===----------------------------------------------------------------------===//
16 #include "ClangSACheckers.h"
17 #include "clang/AST/Attr.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/Expr.h"
20 #include "clang/AST/ExprObjC.h"
21 #include "clang/Basic/LangOptions.h"
22 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
23 #include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
24 #include "clang/StaticAnalyzer/Core/Checker.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
26 #include "llvm/Support/raw_ostream.h"
28 using namespace clang;
31 static bool scan_dealloc(Stmt *S, Selector Dealloc) {
33 if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S))
34 if (ME->getSelector() == Dealloc) {
35 switch (ME->getReceiverKind()) {
36 case ObjCMessageExpr::Instance: return false;
37 case ObjCMessageExpr::SuperInstance: return true;
38 case ObjCMessageExpr::Class: break;
39 case ObjCMessageExpr::SuperClass: break;
43 // Recurse to children.
45 for (Stmt::child_iterator I = S->child_begin(), E= S->child_end(); I!=E; ++I)
46 if (*I && scan_dealloc(*I, Dealloc))
52 static bool scan_ivar_release(Stmt *S, ObjCIvarDecl *ID,
53 const ObjCPropertyDecl *PD,
55 IdentifierInfo* SelfII,
59 if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S))
60 if (ME->getSelector() == Release)
61 if (ME->getInstanceReceiver())
62 if (Expr *Receiver = ME->getInstanceReceiver()->IgnoreParenCasts())
63 if (ObjCIvarRefExpr *E = dyn_cast<ObjCIvarRefExpr>(Receiver))
64 if (E->getDecl() == ID)
67 // [self setMyIvar:nil];
68 if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S))
69 if (ME->getInstanceReceiver())
70 if (Expr *Receiver = ME->getInstanceReceiver()->IgnoreParenCasts())
71 if (DeclRefExpr *E = dyn_cast<DeclRefExpr>(Receiver))
72 if (E->getDecl()->getIdentifier() == SelfII)
73 if (ME->getMethodDecl() == PD->getSetterMethodDecl() &&
74 ME->getNumArgs() == 1 &&
75 ME->getArg(0)->isNullPointerConstant(Ctx,
76 Expr::NPC_ValueDependentIsNull))
80 if (BinaryOperator* BO = dyn_cast<BinaryOperator>(S))
81 if (BO->isAssignmentOp())
82 if (ObjCPropertyRefExpr *PRE =
83 dyn_cast<ObjCPropertyRefExpr>(BO->getLHS()->IgnoreParenCasts()))
84 if (PRE->isExplicitProperty() && PRE->getExplicitProperty() == PD)
85 if (BO->getRHS()->isNullPointerConstant(Ctx,
86 Expr::NPC_ValueDependentIsNull)) {
87 // This is only a 'release' if the property kind is not
89 return PD->getSetterKind() != ObjCPropertyDecl::Assign;
92 // Recurse to children.
93 for (Stmt::child_iterator I = S->child_begin(), E= S->child_end(); I!=E; ++I)
94 if (*I && scan_ivar_release(*I, ID, PD, Release, SelfII, Ctx))
100 static void checkObjCDealloc(const ObjCImplementationDecl *D,
101 const LangOptions& LOpts, BugReporter& BR) {
103 assert (LOpts.getGC() != LangOptions::GCOnly);
105 ASTContext &Ctx = BR.getContext();
106 const ObjCInterfaceDecl *ID = D->getClassInterface();
108 // Does the class contain any ivars that are pointers (or id<...>)?
109 // If not, skip the check entirely.
110 // NOTE: This is motivated by PR 2517:
111 // http://llvm.org/bugs/show_bug.cgi?id=2517
113 bool containsPointerIvar = false;
115 for (ObjCInterfaceDecl::ivar_iterator I=ID->ivar_begin(), E=ID->ivar_end();
118 ObjCIvarDecl *ID = *I;
119 QualType T = ID->getType();
121 if (!T->isObjCObjectPointerType() ||
122 ID->getAttr<IBOutletAttr>() || // Skip IBOutlets.
123 ID->getAttr<IBOutletCollectionAttr>()) // Skip IBOutletCollections.
126 containsPointerIvar = true;
130 if (!containsPointerIvar)
133 // Determine if the class subclasses NSObject.
134 IdentifierInfo* NSObjectII = &Ctx.Idents.get("NSObject");
135 IdentifierInfo* SenTestCaseII = &Ctx.Idents.get("SenTestCase");
138 for ( ; ID ; ID = ID->getSuperClass()) {
139 IdentifierInfo *II = ID->getIdentifier();
141 if (II == NSObjectII)
144 // FIXME: For now, ignore classes that subclass SenTestCase, as these don't
145 // need to implement -dealloc. They implement tear down in another way,
146 // which we should try and catch later.
147 // http://llvm.org/bugs/show_bug.cgi?id=3187
148 if (II == SenTestCaseII)
155 // Get the "dealloc" selector.
156 IdentifierInfo* II = &Ctx.Idents.get("dealloc");
157 Selector S = Ctx.Selectors.getSelector(0, &II);
158 ObjCMethodDecl *MD = 0;
160 // Scan the instance methods for "dealloc".
161 for (ObjCImplementationDecl::instmeth_iterator I = D->instmeth_begin(),
162 E = D->instmeth_end(); I!=E; ++I) {
164 if ((*I)->getSelector() == S) {
170 PathDiagnosticLocation DLoc =
171 PathDiagnosticLocation::createBegin(D, BR.getSourceManager());
173 if (!MD) { // No dealloc found.
175 const char* name = LOpts.getGC() == LangOptions::NonGC
177 : "missing -dealloc (Hybrid MM, non-GC)";
180 llvm::raw_string_ostream os(buf);
181 os << "Objective-C class '" << *D << "' lacks a 'dealloc' instance method";
183 BR.EmitBasicReport(D, name, categories::CoreFoundationObjectiveC,
188 // dealloc found. Scan for missing [super dealloc].
189 if (MD->getBody() && !scan_dealloc(MD->getBody(), S)) {
191 const char* name = LOpts.getGC() == LangOptions::NonGC
192 ? "missing [super dealloc]"
193 : "missing [super dealloc] (Hybrid MM, non-GC)";
196 llvm::raw_string_ostream os(buf);
197 os << "The 'dealloc' instance method in Objective-C class '" << *D
198 << "' does not send a 'dealloc' message to its super class"
199 " (missing [super dealloc])";
201 BR.EmitBasicReport(MD, name, categories::CoreFoundationObjectiveC,
206 // Get the "release" selector.
207 IdentifierInfo* RII = &Ctx.Idents.get("release");
208 Selector RS = Ctx.Selectors.getSelector(0, &RII);
210 // Get the "self" identifier
211 IdentifierInfo* SelfII = &Ctx.Idents.get("self");
213 // Scan for missing and extra releases of ivars used by implementations
214 // of synthesized properties
215 for (ObjCImplementationDecl::propimpl_iterator I = D->propimpl_begin(),
216 E = D->propimpl_end(); I!=E; ++I) {
218 // We can only check the synthesized properties
219 if (I->getPropertyImplementation() != ObjCPropertyImplDecl::Synthesize)
222 ObjCIvarDecl *ID = I->getPropertyIvarDecl();
226 QualType T = ID->getType();
227 if (!T->isObjCObjectPointerType()) // Skip non-pointer ivars
230 const ObjCPropertyDecl *PD = I->getPropertyDecl();
234 // ivars cannot be set via read-only properties, so we'll skip them
235 if (PD->isReadOnly())
238 // ivar must be released if and only if the kind of setter was not 'assign'
239 bool requiresRelease = PD->getSetterKind() != ObjCPropertyDecl::Assign;
240 if (scan_ivar_release(MD->getBody(), ID, PD, RS, SelfII, Ctx)
241 != requiresRelease) {
242 const char *name = 0;
244 llvm::raw_string_ostream os(buf);
246 if (requiresRelease) {
247 name = LOpts.getGC() == LangOptions::NonGC
248 ? "missing ivar release (leak)"
249 : "missing ivar release (Hybrid MM, non-GC)";
252 << "' instance variable was retained by a synthesized property but "
253 "wasn't released in 'dealloc'";
255 name = LOpts.getGC() == LangOptions::NonGC
256 ? "extra ivar release (use-after-release)"
257 : "extra ivar release (Hybrid MM, non-GC)";
260 << "' instance variable was not retained by a synthesized property "
261 "but was released in 'dealloc'";
264 PathDiagnosticLocation SDLoc =
265 PathDiagnosticLocation::createBegin(*I, BR.getSourceManager());
267 BR.EmitBasicReport(MD, name, categories::CoreFoundationObjectiveC,
273 //===----------------------------------------------------------------------===//
274 // ObjCDeallocChecker
275 //===----------------------------------------------------------------------===//
278 class ObjCDeallocChecker : public Checker<
279 check::ASTDecl<ObjCImplementationDecl> > {
281 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
282 BugReporter &BR) const {
283 if (mgr.getLangOpts().getGC() == LangOptions::GCOnly)
285 checkObjCDealloc(cast<ObjCImplementationDecl>(D), mgr.getLangOpts(), BR);
290 void ento::registerObjCDeallocChecker(CheckerManager &mgr) {
291 mgr.registerChecker<ObjCDeallocChecker>();