clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp

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