1 //===--- TransARCAssign.cpp - Transformations to ARC mode -----------------===//
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 // makeAssignARCSafe:
10 //
11 // Add '__strong' where appropriate.
12 //
13 //  for (id x in collection) {
14 //    x = 0;
15 //  }
16 // ---->
17 //  for (__strong id x in collection) {
18 //    x = 0;
19 //  }
20 //
21 //===----------------------------------------------------------------------===//
22 
23 #include "Transforms.h"
24 #include "Internals.h"
25 #include "clang/AST/ASTContext.h"
26 #include "clang/Sema/SemaDiagnostic.h"
27 
28 using namespace clang;
29 using namespace arcmt;
30 using namespace trans;
31 
32 namespace {
33 
34 class ARCAssignChecker : public RecursiveASTVisitor<ARCAssignChecker> {
35   MigrationPass &Pass;
36   llvm::DenseSet<VarDecl *> ModifiedVars;
37 
38 public:
39   ARCAssignChecker(MigrationPass &pass) : Pass(pass) { }
40 
41   bool VisitBinaryOperator(BinaryOperator *Exp) {
42     if (Exp->getType()->isDependentType())
43       return true;
44 
45     Expr *E = Exp->getLHS();
46     SourceLocation OrigLoc = E->getExprLoc();
47     SourceLocation Loc = OrigLoc;
48     DeclRefExpr *declRef = dyn_cast<DeclRefExpr>(E->IgnoreParenCasts());
49     if (declRef && isa<VarDecl>(declRef->getDecl())) {
50       ASTContext &Ctx = Pass.Ctx;
51       Expr::isModifiableLvalueResult IsLV = E->isModifiableLvalue(Ctx, &Loc);
52       if (IsLV != Expr::MLV_ConstQualified)
53         return true;
54       VarDecl *var = cast<VarDecl>(declRef->getDecl());
55       if (var->isARCPseudoStrong()) {
56         Transaction Trans(Pass.TA);
57         if (Pass.TA.clearDiagnostic(diag::err_typecheck_arr_assign_enumeration,
58                                     Exp->getOperatorLoc())) {
59           if (!ModifiedVars.count(var)) {
60             TypeLoc TLoc = var->getTypeSourceInfo()->getTypeLoc();
61             Pass.TA.insert(TLoc.getBeginLoc(), "__strong ");
62             ModifiedVars.insert(var);
63           }
64         }
65       }
66     }
67 
68     return true;
69   }
70 };
71 
72 } // anonymous namespace
73 
74 void trans::makeAssignARCSafe(MigrationPass &pass) {
75   ARCAssignChecker assignCheck(pass);
76   assignCheck.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
77 }
78