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      1 //===--- TransUnusedInitDelegate.cpp - Transformations to ARC mode --------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 // Transformations:
     10 //===----------------------------------------------------------------------===//
     11 //
     12 // rewriteUnusedInitDelegate:
     13 //
     14 // Rewrites an unused result of calling a delegate initialization, to assigning
     15 // the result to self.
     16 // e.g
     17 //  [self init];
     18 // ---->
     19 //  self = [self init];
     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 UnusedInitRewriter : public RecursiveASTVisitor<UnusedInitRewriter> {
     35   Stmt *Body;
     36   MigrationPass &Pass;
     37 
     38   ExprSet Removables;
     39 
     40 public:
     41   UnusedInitRewriter(MigrationPass &pass)
     42     : Body(nullptr), Pass(pass) { }
     43 
     44   void transformBody(Stmt *body, Decl *ParentD) {
     45     Body = body;
     46     collectRemovables(body, Removables);
     47     TraverseStmt(body);
     48   }
     49 
     50   bool VisitObjCMessageExpr(ObjCMessageExpr *ME) {
     51     if (ME->isDelegateInitCall() &&
     52         isRemovable(ME) &&
     53         Pass.TA.hasDiagnostic(diag::err_arc_unused_init_message,
     54                               ME->getExprLoc())) {
     55       Transaction Trans(Pass.TA);
     56       Pass.TA.clearDiagnostic(diag::err_arc_unused_init_message,
     57                               ME->getExprLoc());
     58       SourceRange ExprRange = ME->getSourceRange();
     59       Pass.TA.insert(ExprRange.getBegin(), "if (!(self = ");
     60       std::string retStr = ")) return ";
     61       retStr += getNilString(Pass.Ctx);
     62       Pass.TA.insertAfterToken(ExprRange.getEnd(), retStr);
     63     }
     64     return true;
     65   }
     66 
     67 private:
     68   bool isRemovable(Expr *E) const {
     69     return Removables.count(E);
     70   }
     71 };
     72 
     73 } // anonymous namespace
     74 
     75 void trans::rewriteUnusedInitDelegate(MigrationPass &pass) {
     76   BodyTransform<UnusedInitRewriter> trans(pass);
     77   trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
     78 }
     79