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:
UnusedInitRewriter(MigrationPass & pass)41   UnusedInitRewriter(MigrationPass &pass)
42     : Body(nullptr), Pass(pass) { }
43 
transformBody(Stmt * body,Decl * ParentD)44   void transformBody(Stmt *body, Decl *ParentD) {
45     Body = body;
46     collectRemovables(body, Removables);
47     TraverseStmt(body);
48   }
49 
VisitObjCMessageExpr(ObjCMessageExpr * ME)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);
62       Pass.TA.insertAfterToken(ExprRange.getEnd(), retStr);
63     }
64     return true;
65   }
66 
67 private:
isRemovable(Expr * E) const68   bool isRemovable(Expr *E) const {
69     return Removables.count(E);
70   }
71 };
72 
73 } // anonymous namespace
74 
rewriteUnusedInitDelegate(MigrationPass & pass)75 void trans::rewriteUnusedInitDelegate(MigrationPass &pass) {
76   BodyTransform<UnusedInitRewriter> trans(pass);
77   trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
78 }
79