1 //===--- MisplacedArrayIndexCheck.cpp - clang-tidy-------------------------===//
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 
9 #include "MisplacedArrayIndexCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13 #include "clang/Tooling/FixIt.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20 
21 void MisplacedArrayIndexCheck::registerMatchers(MatchFinder *Finder) {
22   Finder->addMatcher(
23       traverse(TK_AsIs, arraySubscriptExpr(hasLHS(hasType(isInteger())),
24                                            hasRHS(hasType(isAnyPointer())))
25                             .bind("expr")),
26       this);
27 }
28 
29 void MisplacedArrayIndexCheck::check(const MatchFinder::MatchResult &Result) {
30   const auto *ArraySubscriptE =
31       Result.Nodes.getNodeAs<ArraySubscriptExpr>("expr");
32 
33   auto Diag = diag(ArraySubscriptE->getBeginLoc(), "confusing array subscript "
34                                                    "expression, usually the "
35                                                    "index is inside the []");
36 
37   // Only try to fixit when LHS and RHS can be swapped directly without changing
38   // the logic.
39   const Expr *RHSE = ArraySubscriptE->getRHS()->IgnoreParenImpCasts();
40   if (!isa<StringLiteral>(RHSE) && !isa<DeclRefExpr>(RHSE) &&
41       !isa<MemberExpr>(RHSE))
42     return;
43 
44   const StringRef LText = tooling::fixit::getText(
45       ArraySubscriptE->getLHS()->getSourceRange(), *Result.Context);
46   const StringRef RText = tooling::fixit::getText(
47       ArraySubscriptE->getRHS()->getSourceRange(), *Result.Context);
48 
49   Diag << FixItHint::CreateReplacement(
50       ArraySubscriptE->getLHS()->getSourceRange(), RText);
51   Diag << FixItHint::CreateReplacement(
52       ArraySubscriptE->getRHS()->getSourceRange(), LText);
53 }
54 
55 } // namespace readability
56 } // namespace tidy
57 } // namespace clang
58