1 //===-- StringCompareCheck.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 "StringCompareCheck.h"
10 #include "../utils/FixItHintUtils.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.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 static const StringRef CompareMessage = "do not use 'compare' to test equality "
22 "of strings; use the string equality "
23 "operator instead";
24
registerMatchers(MatchFinder * Finder)25 void StringCompareCheck::registerMatchers(MatchFinder *Finder) {
26 const auto StrCompare = cxxMemberCallExpr(
27 callee(cxxMethodDecl(hasName("compare"),
28 ofClass(classTemplateSpecializationDecl(
29 hasName("::std::basic_string"))))),
30 hasArgument(0, expr().bind("str2")), argumentCountIs(1),
31 callee(memberExpr().bind("str1")));
32
33 // First and second case: cast str.compare(str) to boolean.
34 Finder->addMatcher(
35 traverse(ast_type_traits::TK_AsIs,
36 implicitCastExpr(hasImplicitDestinationType(booleanType()),
37 has(StrCompare))
38 .bind("match1")),
39 this);
40
41 // Third and fourth case: str.compare(str) == 0 and str.compare(str) != 0.
42 Finder->addMatcher(
43 binaryOperator(hasAnyOperatorName("==", "!="),
44 hasOperands(StrCompare.bind("compare"),
45 integerLiteral(equals(0)).bind("zero")))
46 .bind("match2"),
47 this);
48 }
49
check(const MatchFinder::MatchResult & Result)50 void StringCompareCheck::check(const MatchFinder::MatchResult &Result) {
51 if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>("match1")) {
52 diag(Matched->getBeginLoc(), CompareMessage);
53 return;
54 }
55
56 if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>("match2")) {
57 const ASTContext &Ctx = *Result.Context;
58
59 if (const auto *Zero = Result.Nodes.getNodeAs<Stmt>("zero")) {
60 const auto *Str1 = Result.Nodes.getNodeAs<MemberExpr>("str1");
61 const auto *Str2 = Result.Nodes.getNodeAs<Stmt>("str2");
62 const auto *Compare = Result.Nodes.getNodeAs<Stmt>("compare");
63
64 auto Diag = diag(Matched->getBeginLoc(), CompareMessage);
65
66 if (Str1->isArrow())
67 Diag << FixItHint::CreateInsertion(Str1->getBeginLoc(), "*");
68
69 Diag << tooling::fixit::createReplacement(*Zero, *Str2, Ctx)
70 << tooling::fixit::createReplacement(*Compare, *Str1->getBase(),
71 Ctx);
72 }
73 }
74
75 // FIXME: Add fixit to fix the code for case one and two (match1).
76 }
77
78 } // namespace readability
79 } // namespace tidy
80 } // namespace clang
81