1 //===--- TransUnbridgedCasts.cpp - Tranformations to ARC mode -------------===//
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 // rewriteUnbridgedCasts:
12 // A cast of non-objc pointer to an objc one is checked. If the non-objc pointer
13 // is from a file-level variable, __bridge cast is used to convert it.
14 // For the result of a function call that we know is +1/+0,
15 // __bridge/__bridge_transfer is used.
17 // NSString *str = (NSString *)kUTTypePlainText;
18 // str = b ? kUTTypeRTF : kUTTypePlainText;
19 // NSString *_uuidString = (NSString *)CFUUIDCreateString(kCFAllocatorDefault,
22 // NSString *str = (__bridge NSString *)kUTTypePlainText;
23 // str = (__bridge NSString *)(b ? kUTTypeRTF : kUTTypePlainText);
24 // NSString *_uuidString = (__bridge_transfer NSString *)
25 // CFUUIDCreateString(kCFAllocatorDefault, _uuid);
27 // For a C pointer to ObjC, for casting 'self', __bridge is used.
29 // CFStringRef str = (CFStringRef)self;
31 // CFStringRef str = (__bridge CFStringRef)self;
33 //===----------------------------------------------------------------------===//
35 #include "Transforms.h"
36 #include "Internals.h"
37 #include "clang/Analysis/DomainSpecific/CocoaConventions.h"
38 #include "clang/Sema/SemaDiagnostic.h"
39 #include "clang/AST/ParentMap.h"
40 #include "clang/Basic/SourceManager.h"
41 #include "llvm/ADT/SmallString.h"
43 using namespace clang;
44 using namespace arcmt;
45 using namespace trans;
49 class UnbridgedCastRewriter : public RecursiveASTVisitor<UnbridgedCastRewriter>{
51 IdentifierInfo *SelfII;
52 OwningPtr<ParentMap> StmtMap;
55 UnbridgedCastRewriter(MigrationPass &pass) : Pass(pass) {
56 SelfII = &Pass.Ctx.Idents.get("self");
59 void transformBody(Stmt *body) {
60 StmtMap.reset(new ParentMap(body));
64 bool VisitCastExpr(CastExpr *E) {
65 if (E->getCastKind() != CK_CPointerToObjCPointerCast
66 && E->getCastKind() != CK_BitCast)
69 QualType castType = E->getType();
70 Expr *castExpr = E->getSubExpr();
71 QualType castExprType = castExpr->getType();
73 if (castType->isObjCObjectPointerType() &&
74 castExprType->isObjCObjectPointerType())
76 if (!castType->isObjCObjectPointerType() &&
77 !castExprType->isObjCObjectPointerType())
80 bool exprRetainable = castExprType->isObjCIndirectLifetimeType();
81 bool castRetainable = castType->isObjCIndirectLifetimeType();
82 if (exprRetainable == castRetainable) return true;
84 if (castExpr->isNullPointerConstant(Pass.Ctx,
85 Expr::NPC_ValueDependentIsNull))
88 SourceLocation loc = castExpr->getExprLoc();
89 if (loc.isValid() && Pass.Ctx.getSourceManager().isInSystemHeader(loc))
92 if (castType->isObjCObjectPointerType())
93 transformNonObjCToObjCCast(E);
95 transformObjCToNonObjCCast(E);
101 void transformNonObjCToObjCCast(CastExpr *E) {
104 // Global vars are assumed that are cast as unretained.
106 if (E->getSubExpr()->getType()->isPointerType()) {
107 castToObjCObject(E, /*retained=*/false);
111 // If the cast is directly over the result of a Core Foundation function
112 // try to figure out whether it should be cast as retained or unretained.
113 Expr *inner = E->IgnoreParenCasts();
114 if (CallExpr *callE = dyn_cast<CallExpr>(inner)) {
115 if (FunctionDecl *FD = callE->getDirectCallee()) {
116 if (FD->getAttr<CFReturnsRetainedAttr>()) {
117 castToObjCObject(E, /*retained=*/true);
120 if (FD->getAttr<CFReturnsNotRetainedAttr>()) {
121 castToObjCObject(E, /*retained=*/false);
124 if (FD->isGlobal() &&
125 FD->getIdentifier() &&
126 ento::cocoa::isRefType(E->getSubExpr()->getType(), "CF",
127 FD->getIdentifier()->getName())) {
128 StringRef fname = FD->getIdentifier()->getName();
129 if (fname.endswith("Retain") ||
130 fname.find("Create") != StringRef::npos ||
131 fname.find("Copy") != StringRef::npos) {
132 // Do not migrate to couple of bridge transfer casts which
133 // cancel each other out. Leave it unchanged so error gets user
134 // attention instead.
135 if (FD->getName() == "CFRetain" &&
136 FD->getNumParams() == 1 &&
137 FD->getParent()->isTranslationUnit() &&
138 FD->getLinkage() == ExternalLinkage) {
139 Expr *Arg = callE->getArg(0);
140 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) {
141 const Expr *sub = ICE->getSubExpr();
142 QualType T = sub->getType();
143 if (T->isObjCObjectPointerType())
147 castToObjCObject(E, /*retained=*/true);
151 if (fname.find("Get") != StringRef::npos) {
152 castToObjCObject(E, /*retained=*/false);
160 void castToObjCObject(CastExpr *E, bool retained) {
161 rewriteToBridgedCast(E, retained ? OBC_BridgeTransfer : OBC_Bridge);
164 void rewriteToBridgedCast(CastExpr *E, ObjCBridgeCastKind Kind) {
165 Transaction Trans(Pass.TA);
166 rewriteToBridgedCast(E, Kind, Trans);
169 void rewriteToBridgedCast(CastExpr *E, ObjCBridgeCastKind Kind,
170 Transaction &Trans) {
171 TransformActions &TA = Pass.TA;
173 // We will remove the compiler diagnostic.
174 if (!TA.hasDiagnostic(diag::err_arc_mismatched_cast,
175 diag::err_arc_cast_requires_bridge,
184 bridge = "__bridge "; break;
185 case OBC_BridgeTransfer:
186 bridge = "__bridge_transfer "; break;
187 case OBC_BridgeRetained:
188 bridge = "__bridge_retained "; break;
191 TA.clearDiagnostic(diag::err_arc_mismatched_cast,
192 diag::err_arc_cast_requires_bridge,
194 if (CStyleCastExpr *CCE = dyn_cast<CStyleCastExpr>(E)) {
195 TA.insertAfterToken(CCE->getLParenLoc(), bridge);
197 SourceLocation insertLoc = E->getSubExpr()->getLocStart();
198 SmallString<128> newCast;
201 newCast += E->getType().getAsString(Pass.Ctx.getPrintingPolicy());
204 if (isa<ParenExpr>(E->getSubExpr())) {
205 TA.insert(insertLoc, newCast.str());
208 TA.insert(insertLoc, newCast.str());
209 TA.insertAfterToken(E->getLocEnd(), ")");
214 void rewriteCastForCFRetain(CastExpr *castE, CallExpr *callE) {
215 Transaction Trans(Pass.TA);
216 Pass.TA.replace(callE->getSourceRange(), callE->getArg(0)->getSourceRange());
217 rewriteToBridgedCast(castE, OBC_BridgeRetained, Trans);
220 void transformObjCToNonObjCCast(CastExpr *E) {
221 if (isSelf(E->getSubExpr()))
222 return rewriteToBridgedCast(E, OBC_Bridge);
225 if (isPassedToCFRetain(E, callE))
226 return rewriteCastForCFRetain(E, callE);
228 ObjCMethodFamily family = getFamilyOfMessage(E->getSubExpr());
229 if (family == OMF_retain)
230 return rewriteToBridgedCast(E, OBC_BridgeRetained);
232 if (family == OMF_autorelease || family == OMF_release) {
233 std::string err = "it is not safe to cast to '";
234 err += E->getType().getAsString(Pass.Ctx.getPrintingPolicy());
235 err += "' the result of '";
236 err += family == OMF_autorelease ? "autorelease" : "release";
237 err += "' message; a __bridge cast may result in a pointer to a "
238 "destroyed object and a __bridge_retained may leak the object";
239 Pass.TA.reportError(err, E->getLocStart(),
240 E->getSubExpr()->getSourceRange());
243 parent = StmtMap->getParentIgnoreParenImpCasts(parent);
244 } while (parent && isa<ExprWithCleanups>(parent));
246 if (ReturnStmt *retS = dyn_cast_or_null<ReturnStmt>(parent)) {
247 std::string note = "remove the cast and change return type of function "
249 note += E->getSubExpr()->getType().getAsString(Pass.Ctx.getPrintingPolicy());
250 note += "' to have the object automatically autoreleased";
251 Pass.TA.reportNote(note, retS->getLocStart());
255 Expr *subExpr = E->getSubExpr();
257 // Look through pseudo-object expressions.
258 if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(subExpr)) {
259 subExpr = pseudo->getResultExpr();
260 assert(subExpr && "no result for pseudo-object of non-void type?");
263 if (ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(subExpr)) {
264 if (implCE->getCastKind() == CK_ARCConsumeObject)
265 return rewriteToBridgedCast(E, OBC_BridgeRetained);
266 if (implCE->getCastKind() == CK_ARCReclaimReturnedObject)
267 return rewriteToBridgedCast(E, OBC_Bridge);
270 bool isConsumed = false;
271 if (isPassedToCParamWithKnownOwnership(E, isConsumed))
272 return rewriteToBridgedCast(E, isConsumed ? OBC_BridgeRetained
276 static ObjCMethodFamily getFamilyOfMessage(Expr *E) {
277 E = E->IgnoreParenCasts();
278 if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E))
279 return ME->getMethodFamily();
284 bool isPassedToCFRetain(Expr *E, CallExpr *&callE) const {
285 if ((callE = dyn_cast_or_null<CallExpr>(
286 StmtMap->getParentIgnoreParenImpCasts(E))))
288 FD = dyn_cast_or_null<FunctionDecl>(callE->getCalleeDecl()))
289 if (FD->getName() == "CFRetain" && FD->getNumParams() == 1 &&
290 FD->getParent()->isTranslationUnit() &&
291 FD->getLinkage() == ExternalLinkage)
297 bool isPassedToCParamWithKnownOwnership(Expr *E, bool &isConsumed) const {
298 if (CallExpr *callE = dyn_cast_or_null<CallExpr>(
299 StmtMap->getParentIgnoreParenImpCasts(E)))
301 FD = dyn_cast_or_null<FunctionDecl>(callE->getCalleeDecl())) {
303 for (unsigned e = callE->getNumArgs(); i != e; ++i) {
304 Expr *arg = callE->getArg(i);
305 if (arg == E || arg->IgnoreParenImpCasts() == E)
308 if (i < callE->getNumArgs()) {
309 ParmVarDecl *PD = FD->getParamDecl(i);
310 if (PD->getAttr<CFConsumedAttr>()) {
320 bool isSelf(Expr *E) const {
321 E = E->IgnoreParenLValueCasts();
322 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
323 if (ImplicitParamDecl *IPD = dyn_cast<ImplicitParamDecl>(DRE->getDecl()))
324 if (IPD->getIdentifier() == SelfII)
331 } // end anonymous namespace
333 void trans::rewriteUnbridgedCasts(MigrationPass &pass) {
334 BodyTransform<UnbridgedCastRewriter> trans(pass);
335 trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());