Objective-C: Provide fixit suggestions when class object

is accessed via accessing 'isa' ivar to use
object_getClass/object_setClass apis.
// rdar://13503456

llvm-svn: 178282

clang/include/clang/AST/ExprObjC.h

@@ -1381,15 +1381,19 @@ class ObjCIsaExpr : public Expr {
   /// IsaMemberLoc - This is the location of the 'isa'.
   SourceLocation IsaMemberLoc;
   
+  /// OpLoc - This is the location of '.' or '->'
+  SourceLocation OpLoc;
+
   /// IsArrow - True if this is "X->F", false if this is "X.F".
   bool IsArrow;
 public:
-  ObjCIsaExpr(Expr *base, bool isarrow, SourceLocation l, QualType ty)
+  ObjCIsaExpr(Expr *base, bool isarrow, SourceLocation l, SourceLocation oploc,
+              QualType ty)
     : Expr(ObjCIsaExprClass, ty, VK_LValue, OK_Ordinary,
            /*TypeDependent=*/false, base->isValueDependent(),
            base->isInstantiationDependent(),
            /*ContainsUnexpandedParameterPack=*/false),
-      Base(base), IsaMemberLoc(l), IsArrow(isarrow) {}
+      Base(base), IsaMemberLoc(l), OpLoc(oploc), IsArrow(isarrow) {}
 
   /// \brief Build an empty expression.
   explicit ObjCIsaExpr(EmptyShell Empty) : Expr(ObjCIsaExprClass, Empty) { }
@@ -1405,9 +1409,17 @@ public:
   SourceLocation getIsaMemberLoc() const { return IsaMemberLoc; }
   void setIsaMemberLoc(SourceLocation L) { IsaMemberLoc = L; }
   
+  SourceLocation getOpLoc() const { return OpLoc; }
+  void setOpLoc(SourceLocation L) { OpLoc = L; }
+
   SourceLocation getLocStart() const LLVM_READONLY {
     return getBase()->getLocStart();
   }
+  
+  SourceLocation getBaseLocEnd() const LLVM_READONLY {
+    return getBase()->getLocEnd();
+  }
+  
   SourceLocation getLocEnd() const LLVM_READONLY { return IsaMemberLoc; }
 
   SourceLocation getExprLoc() const LLVM_READONLY { return IsaMemberLoc; }

clang/lib/Sema/SemaExpr.cpp

@@ -491,8 +491,18 @@ ExprResult Sema::DefaultLvalueConversion(Expr *E) {
   }
 
   CheckForNullPointerDereference(*this, E);
-  if (isa<ObjCIsaExpr>(E->IgnoreParens()))
-    Diag(E->getExprLoc(), diag::warn_objc_isa_use);
+  if (const ObjCIsaExpr *OISA = dyn_cast<ObjCIsaExpr>(E->IgnoreParenCasts())) {
+    NamedDecl *ObjectGetClass = LookupSingleName(TUScope,
+                                     &Context.Idents.get("object_getClass"),
+                                     SourceLocation(), LookupOrdinaryName);
+    if (ObjectGetClass)
+      Diag(E->getExprLoc(), diag::warn_objc_isa_use) <<
+        FixItHint::CreateInsertion(OISA->getLocStart(), "object_getClass(") <<
+        FixItHint::CreateReplacement(
+                    SourceRange(OISA->getOpLoc(), OISA->getIsaMemberLoc()), ")");
+    else
+      Diag(E->getExprLoc(), diag::warn_objc_isa_use);
+  }
 
   // C++ [conv.lval]p1:
   //   [...] If T is a non-class type, the type of the prvalue is the
@@ -8537,8 +8547,20 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
   CheckArrayAccess(LHS.get());
   CheckArrayAccess(RHS.get());
 
-  if (isa<ObjCIsaExpr>(LHS.get()->IgnoreParens()))
-    Diag(LHS.get()->getExprLoc(), diag::warn_objc_isa_assign);
+  if (const ObjCIsaExpr *OISA = dyn_cast<ObjCIsaExpr>(LHS.get()->IgnoreParenCasts())) {
+    NamedDecl *ObjectSetClass = LookupSingleName(TUScope,
+                                                 &Context.Idents.get("object_setClass"),
+                                                 SourceLocation(), LookupOrdinaryName);
+    if (ObjectSetClass && isa<ObjCIsaExpr>(LHS.get())) {
+      SourceLocation RHSLocEnd = PP.getLocForEndOfToken(RHS.get()->getLocEnd());
+      Diag(LHS.get()->getExprLoc(), diag::warn_objc_isa_assign) <<
+      FixItHint::CreateInsertion(LHS.get()->getLocStart(), "object_setClass(") <<
+      FixItHint::CreateReplacement(SourceRange(OISA->getOpLoc(), OpLoc), ",") <<
+      FixItHint::CreateInsertion(RHSLocEnd, ")");
+    }
+    else
+      Diag(LHS.get()->getExprLoc(), diag::warn_objc_isa_assign);
+  }
 
   if (CompResultTy.isNull())
     return Owned(new (Context) BinaryOperator(LHS.take(), RHS.take(), Opc,

clang/lib/Sema/SemaExprMember.cpp

@@ -1132,6 +1132,7 @@ Sema::LookupMemberExpr(LookupResult &R, ExprResult &BaseExpr,
       // apparently.
       if (OTy->isObjCId() && Member->isStr("isa"))
         return Owned(new (Context) ObjCIsaExpr(BaseExpr.take(), IsArrow, MemberLoc,
+                                               OpLoc,
                                                Context.getObjCClassType()));
       if (ShouldTryAgainWithRedefinitionType(*this, BaseExpr))
         return LookupMemberExpr(R, BaseExpr, IsArrow, OpLoc, SS,

clang/lib/Sema/TreeTransform.h

@@ -2389,13 +2389,14 @@ public:
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCIsaExpr(Expr *BaseArg, SourceLocation IsaLoc,
+                                SourceLocation OpLoc,
                                       bool IsArrow) {
     CXXScopeSpec SS;
     ExprResult Base = getSema().Owned(BaseArg);
     LookupResult R(getSema(), &getSema().Context.Idents.get("isa"), IsaLoc,
                    Sema::LookupMemberName);
     ExprResult Result = getSema().LookupMemberExpr(R, Base, IsArrow,
-                                                         /*FIME:*/IsaLoc,
+                                                         OpLoc,
                                                          SS, 0, false);
     if (Result.isInvalid() || Base.isInvalid())
       return ExprError();
@@ -2404,7 +2405,7 @@ public:
       return Result;
 
     return getSema().BuildMemberReferenceExpr(Base.get(), Base.get()->getType(),
-                                              /*FIXME:*/IsaLoc, IsArrow,
+                                              OpLoc, IsArrow,
                                               SS, SourceLocation(),
                                               /*FirstQualifierInScope=*/0,
                                               R,
@@ -8788,6 +8789,7 @@ TreeTransform<Derived>::TransformObjCIsaExpr(ObjCIsaExpr *E) {
     return SemaRef.Owned(E);
 
   return getDerived().RebuildObjCIsaExpr(Base.get(), E->getIsaMemberLoc(),
+                                         E->getOpLoc(),
                                          E->isArrow());
 }
 

clang/lib/Serialization/ASTReaderStmt.cpp

@@ -528,6 +528,7 @@ void ASTStmtReader::VisitObjCIsaExpr(ObjCIsaExpr *E) {
   VisitExpr(E);
   E->setBase(Reader.ReadSubExpr());
   E->setIsaMemberLoc(ReadSourceLocation(Record, Idx));
+  E->setOpLoc(ReadSourceLocation(Record, Idx));
   E->setArrow(Record[Idx++]);
 }
 

clang/lib/Serialization/ASTWriterStmt.cpp

@@ -498,6 +498,7 @@ void ASTStmtWriter::VisitObjCIsaExpr(ObjCIsaExpr *E) {
   VisitExpr(E);
   Writer.AddStmt(E->getBase());
   Writer.AddSourceLocation(E->getIsaMemberLoc(), Record);
+  Writer.AddSourceLocation(E->getOpLoc(), Record);
   Record.push_back(E->isArrow());
   Code = serialization::EXPR_OBJC_ISA;
 }

clang/test/FixIt/auto-isa-fixit.m

@@ -0,0 +1,19 @@
+// RUN: cp %s %t
+// RUN: %clang_cc1 -x objective-c -fixit %t
+// RUN: %clang_cc1 -x objective-c -Werror %t
+// rdar://13503456
+
+void object_setClass(id, id);
+Class object_getClass(id);
+
+id rhs();
+
+Class pr6302(id x123) {
+  x123->isa  = 0;
+  x123->isa = rhs();
+  x123->isa = (id)(x123->isa);
+  x123->isa = (id)x123->isa;
+  x123->isa = (x123->isa);
+  x123->isa = (id)(x123->isa);
+  return x123->isa;
+}