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      1 //===--- TransUnusedInitDelegate.cpp - Tranformations 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/Sema/SemaDiagnostic.h"
     26 
     27 using namespace clang;
     28 using namespace arcmt;
     29 using namespace trans;
     30 using llvm::StringRef;
     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(0), Pass(pass) { }
     43 
     44   void transformBody(Stmt *body) {
     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       Pass.TA.insert(ME->getExprLoc(), "self = ");
     59     }
     60     return true;
     61   }
     62 
     63 private:
     64   bool isRemovable(Expr *E) const {
     65     return Removables.count(E);
     66   }
     67 };
     68 
     69 } // anonymous namespace
     70 
     71 void trans::rewriteUnusedInitDelegate(MigrationPass &pass) {
     72   BodyTransform<UnusedInitRewriter> trans(pass);
     73   trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
     74 }
     75