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
15using namespace clang::ast_matchers;
16
17namespace clang::tidy::readability {
18
19static const StringRef CompareMessage = "do not use 'compare' to test equality "
20 "of strings; use the string equality "
21 "operator instead";
22
23void StringCompareCheck::registerMatchers(MatchFinder *Finder) {
24 const auto StrCompare = cxxMemberCallExpr(
25 callee(InnerMatcher: cxxMethodDecl(hasName(Name: "compare"),
26 ofClass(InnerMatcher: classTemplateSpecializationDecl(
27 hasName(Name: "::std::basic_string"))))),
28 hasArgument(N: 0, InnerMatcher: expr().bind(ID: "str2")), argumentCountIs(N: 1),
29 callee(InnerMatcher: memberExpr().bind(ID: "str1")));
30
31 // First and second case: cast str.compare(str) to boolean.
32 Finder->addMatcher(
33 NodeMatch: traverse(TK: TK_AsIs,
34 InnerMatcher: implicitCastExpr(hasImplicitDestinationType(InnerMatcher: booleanType()),
35 has(StrCompare))
36 .bind(ID: "match1")),
37 Action: this);
38
39 // Third and fourth case: str.compare(str) == 0 and str.compare(str) != 0.
40 Finder->addMatcher(
41 NodeMatch: binaryOperator(hasAnyOperatorName("==", "!="),
42 hasOperands(Matcher1: StrCompare.bind(ID: "compare"),
43 Matcher2: integerLiteral(equals(Value: 0)).bind(ID: "zero")))
44 .bind(ID: "match2"),
45 Action: this);
46}
47
48void StringCompareCheck::check(const MatchFinder::MatchResult &Result) {
49 if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>(ID: "match1")) {
50 diag(Loc: Matched->getBeginLoc(), Description: CompareMessage);
51 return;
52 }
53
54 if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>(ID: "match2")) {
55 const ASTContext &Ctx = *Result.Context;
56
57 if (const auto *Zero = Result.Nodes.getNodeAs<Stmt>(ID: "zero")) {
58 const auto *Str1 = Result.Nodes.getNodeAs<MemberExpr>(ID: "str1");
59 const auto *Str2 = Result.Nodes.getNodeAs<Stmt>(ID: "str2");
60 const auto *Compare = Result.Nodes.getNodeAs<Stmt>(ID: "compare");
61
62 auto Diag = diag(Loc: Matched->getBeginLoc(), Description: CompareMessage);
63
64 if (Str1->isArrow())
65 Diag << FixItHint::CreateInsertion(InsertionLoc: Str1->getBeginLoc(), Code: "*");
66
67 Diag << tooling::fixit::createReplacement(Destination: *Zero, Source: *Str2, Context: Ctx)
68 << tooling::fixit::createReplacement(Destination: *Compare, Source: *Str1->getBase(),
69 Context: Ctx);
70 }
71 }
72
73 // FIXME: Add fixit to fix the code for case one and two (match1).
74}
75
76} // namespace clang::tidy::readability
77

source code of clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp