clang/lib/ARCMigrate/TransUnusedInitDelegate.cpp

   1 //===--- TransUnusedInitDelegate.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 // Transformations:
   9 //===----------------------------------------------------------------------===//
  10 //
  11 // rewriteUnusedInitDelegate:
  12 //
  13 // Rewrites an unused result of calling a delegate initialization, to assigning
  14 // the result to self.
  15 // e.g
  16 //  [self init];
  17 // ---->
  18 //  self = [self init];
  19 //
  20 //===----------------------------------------------------------------------===//
  21
  22 #include "Transforms.h"
  23 #include "Internals.h"
  24 #include "clang/AST/ASTContext.h"
  25 #include "clang/Sema/SemaDiagnostic.h"
  26
  27 using namespace clang;
  28 using namespace arcmt;
  29 using namespace trans;
  30
  31 namespace {
  32
  33 class UnusedInitRewriter : public RecursiveASTVisitor<UnusedInitRewriter> {
  34   Stmt *Body;
  35   MigrationPass &Pass;
  36
  37   ExprSet Removables;
  38
  39 public:
  40   UnusedInitRewriter(MigrationPass &pass)
  41     : Body(nullptr), Pass(pass) { }
  42
  43   void transformBody(Stmt *body, Decl *ParentD) {
  44     Body = body;
  45     collectRemovables(body, Removables);
  46     TraverseStmt(body);
  47   }
  48
  49   bool VisitObjCMessageExpr(ObjCMessageExpr *ME) {
  50     if (ME->isDelegateInitCall() &&
  51         isRemovable(ME) &&
  52         Pass.TA.hasDiagnostic(diag::err_arc_unused_init_message,
  53                               ME->getExprLoc())) {
  54       Transaction Trans(Pass.TA);
  55       Pass.TA.clearDiagnostic(diag::err_arc_unused_init_message,
  56                               ME->getExprLoc());
  57       SourceRange ExprRange = ME->getSourceRange();
  58       Pass.TA.insert(ExprRange.getBegin(), "if (!(self = ");
  59       std::string retStr = ")) return ";
  60       retStr += getNilString(Pass);
  61       Pass.TA.insertAfterToken(ExprRange.getEnd(), retStr);
  62     }
  63     return true;
  64   }
  65
  66 private:
  67   bool isRemovable(Expr *E) const {
  68     return Removables.count(E);
  69   }
  70 };
  71
  72 } // anonymous namespace
  73
  74 void trans::rewriteUnusedInitDelegate(MigrationPass &pass) {
  75   BodyTransform<UnusedInitRewriter> trans(pass);
  76   trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
  77 }