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 = cxxMethodDecl(returns(lValueReferenceType(
22 pointee(unless(isConstQualified()),
23 anyOf(autoType(), hasDeclaration(equalsBoundNode("class")))))));
24
25 const auto IsSelf = qualType(
26 anyOf(hasDeclaration(equalsBoundNode("class")),
27 referenceType(pointee(hasDeclaration(equalsBoundNode("class"))))));
28 const auto IsAssign =
29 cxxMethodDecl(unless(anyOf(isDeleted(), isPrivate(), isImplicit())),
30 hasName("operator="), ofClass(recordDecl().bind("class")))
31 .bind("method");
32 const auto IsSelfAssign =
33 cxxMethodDecl(IsAssign, hasParameter(0, parmVarDecl(hasType(IsSelf))))
34 .bind("method");
35
36 Finder->addMatcher(
37 cxxMethodDecl(IsAssign, unless(HasGoodReturnType)).bind("ReturnType"),
38 this);
39
40 const auto BadSelf = referenceType(
41 anyOf(lValueReferenceType(pointee(unless(isConstQualified()))),
42 rValueReferenceType(pointee(isConstQualified()))));
43
44 Finder->addMatcher(
45 cxxMethodDecl(IsSelfAssign,
46 hasParameter(0, parmVarDecl(hasType(BadSelf))))
47 .bind("ArgumentType"),
48 this);
49
50 Finder->addMatcher(
51 cxxMethodDecl(IsSelfAssign, anyOf(isConst(), isVirtual())).bind("cv"),
52 this);
53
54 const auto IsBadReturnStatement = returnStmt(unless(has(ignoringParenImpCasts(
55 anyOf(unaryOperator(hasOperatorName("*"), hasUnaryOperand(cxxThisExpr())),
56 cxxOperatorCallExpr(argumentCountIs(1),
57 callee(unresolvedLookupExpr()),
58 hasArgument(0, cxxThisExpr())),
59 cxxOperatorCallExpr(
60 hasOverloadedOperatorName("="),
61 hasArgument(
62 0, unaryOperator(hasOperatorName("*"),
63 hasUnaryOperand(cxxThisExpr())))))))));
64 const auto IsGoodAssign = cxxMethodDecl(IsAssign, HasGoodReturnType);
65
66 Finder->addMatcher(returnStmt(IsBadReturnStatement, forFunction(IsGoodAssign))
67 .bind("returnStmt"),
68 this);
69 }
70
check(const MatchFinder::MatchResult & Result)71 void UnconventionalAssignOperatorCheck::check(
72 const MatchFinder::MatchResult &Result) {
73 if (const auto *RetStmt = Result.Nodes.getNodeAs<ReturnStmt>("returnStmt")) {
74 diag(RetStmt->getBeginLoc(), "operator=() should always return '*this'");
75 } else {
76 static const char *const Messages[][2] = {
77 {"ReturnType", "operator=() should return '%0&'"},
78 {"ArgumentType",
79 getLangOpts().CPlusPlus11
80 ? "operator=() should take '%0 const&', '%0&&' or '%0'"
81 : "operator=() should take '%0 const&' or '%0'"},
82 {"cv", "operator=() should not be marked '%1'"}};
83
84 const auto *Method = Result.Nodes.getNodeAs<CXXMethodDecl>("method");
85 for (const auto &Message : Messages) {
86 if (Result.Nodes.getNodeAs<Decl>(Message[0]))
87 diag(Method->getBeginLoc(), Message[1])
88 << Method->getParent()->getName()
89 << (Method->isConst() ? "const" : "virtual");
90 }
91 }
92 }
93
94 } // namespace misc
95 } // namespace tidy
96 } // namespace clang
97