1 //===--- UnconventionalAssignOperatorCheck.cpp - clang-tidy -----*- C++ -*-===//
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 "UnconventionalAssignOperatorCheck.h"
10 #include "clang/ASTMatchers/ASTMatchFinder.h"
11 #include "clang/ASTMatchers/ASTMatchers.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang {
16 namespace tidy {
17 namespace misc {
18
registerMatchers(ast_matchers::MatchFinder * Finder)19 void UnconventionalAssignOperatorCheck::registerMatchers(
20 ast_matchers::MatchFinder *Finder) {
21 const auto HasGoodReturnType =
22 cxxMethodDecl(returns(hasCanonicalType(lValueReferenceType(pointee(
23 unless(isConstQualified()),
24 anyOf(autoType(), hasDeclaration(equalsBoundNode("class"))))))));
25
26 const auto IsSelf = qualType(hasCanonicalType(
27 anyOf(hasDeclaration(equalsBoundNode("class")),
28 referenceType(pointee(hasDeclaration(equalsBoundNode("class")))))));
29 const auto IsAssign =
30 cxxMethodDecl(unless(anyOf(isDeleted(), isPrivate(), isImplicit())),
31 hasName("operator="), ofClass(recordDecl().bind("class")))
32 .bind("method");
33 const auto IsSelfAssign =
34 cxxMethodDecl(IsAssign, hasParameter(0, parmVarDecl(hasType(IsSelf))))
35 .bind("method");
36
37 Finder->addMatcher(
38 cxxMethodDecl(IsAssign, unless(HasGoodReturnType)).bind("ReturnType"),
39 this);
40
41 const auto BadSelf = qualType(hasCanonicalType(referenceType(
42 anyOf(lValueReferenceType(pointee(unless(isConstQualified()))),
43 rValueReferenceType(pointee(isConstQualified()))))));
44
45 Finder->addMatcher(
46 cxxMethodDecl(IsSelfAssign,
47 hasParameter(0, parmVarDecl(hasType(BadSelf))))
48 .bind("ArgumentType"),
49 this);
50
51 Finder->addMatcher(
52 cxxMethodDecl(IsSelfAssign, anyOf(isConst(), isVirtual())).bind("cv"),
53 this);
54
55 const auto IsBadReturnStatement = returnStmt(unless(has(ignoringParenImpCasts(
56 anyOf(unaryOperator(hasOperatorName("*"), hasUnaryOperand(cxxThisExpr())),
57 cxxOperatorCallExpr(argumentCountIs(1),
58 callee(unresolvedLookupExpr()),
59 hasArgument(0, cxxThisExpr())),
60 cxxOperatorCallExpr(
61 hasOverloadedOperatorName("="),
62 hasArgument(
63 0, unaryOperator(hasOperatorName("*"),
64 hasUnaryOperand(cxxThisExpr())))))))));
65 const auto IsGoodAssign = cxxMethodDecl(IsAssign, HasGoodReturnType);
66
67 Finder->addMatcher(returnStmt(IsBadReturnStatement, forFunction(IsGoodAssign))
68 .bind("returnStmt"),
69 this);
70 }
71
check(const MatchFinder::MatchResult & Result)72 void UnconventionalAssignOperatorCheck::check(
73 const MatchFinder::MatchResult &Result) {
74 if (const auto *RetStmt = Result.Nodes.getNodeAs<ReturnStmt>("returnStmt")) {
75 diag(RetStmt->getBeginLoc(), "operator=() should always return '*this'");
76 } else {
77 const auto *Method = Result.Nodes.getNodeAs<CXXMethodDecl>("method");
78 if (Result.Nodes.getNodeAs<CXXMethodDecl>("ReturnType"))
79 diag(Method->getBeginLoc(), "operator=() should return '%0&'")
80 << Method->getParent()->getName();
81 if (Result.Nodes.getNodeAs<CXXMethodDecl>("ArgumentType"))
82 diag(Method->getBeginLoc(),
83 "operator=() should take '%0 const&'%select{|, '%0&&'}1 or '%0'")
84 << Method->getParent()->getName() << getLangOpts().CPlusPlus11;
85 if (Result.Nodes.getNodeAs<CXXMethodDecl>("cv"))
86 diag(Method->getBeginLoc(),
87 "operator=() should not be marked '%select{const|virtual}0'")
88 << !Method->isConst();
89 }
90 }
91
92 } // namespace misc
93 } // namespace tidy
94 } // namespace clang
95