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
27using namespace clang;
28using namespace arcmt;
29using namespace trans;
30
31namespace {
32
33class UnusedInitRewriter : public RecursiveASTVisitor<UnusedInitRewriter> {
34  Stmt *Body;
35  MigrationPass &Pass;
36
37  ExprSet Removables;
38
39public:
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
66private:
67  bool isRemovable(Expr *E) const {
68    return Removables.count(E);
69  }
70};
71
72} // anonymous namespace
73
74void trans::rewriteUnusedInitDelegate(MigrationPass &pass) {
75  BodyTransform<UnusedInitRewriter> trans(pass);
76  trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
77}
78