clang-tools-extra/clang-tidy/cert/PostfixOperatorCheck.cpp

   1 //===--- PostfixOperatorCheck.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 "PostfixOperatorCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/ASTMatchers/ASTMatchFinder.h"
  12 #include "clang/Lex/Lexer.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::cert {
  17
  18 void PostfixOperatorCheck::registerMatchers(MatchFinder *Finder) {
  19   Finder->addMatcher(functionDecl(hasAnyOverloadedOperatorName("++", "--"),
  20                                   unless(isInstantiated()))
  21                          .bind("decl"),
  22                      this);
  23 }
  24
  25 void PostfixOperatorCheck::check(const MatchFinder::MatchResult &Result) {
  26   const auto *FuncDecl = Result.Nodes.getNodeAs<FunctionDecl>("decl");
  27
  28   bool HasThis = false;
  29   if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
  30     HasThis = MethodDecl->isInstance();
  31
  32   // Check if the operator is a postfix one.
  33   if (FuncDecl->getNumParams() != (HasThis ? 1 : 2))
  34     return;
  35
  36   SourceRange ReturnRange = FuncDecl->getReturnTypeSourceRange();
  37   SourceLocation Location = ReturnRange.getBegin();
  38   if (!Location.isValid())
  39     return;
  40
  41   QualType ReturnType = FuncDecl->getReturnType();
  42
  43   // Warn when the operators return a reference.
  44   if (const auto *RefType = ReturnType->getAs<ReferenceType>()) {
  45     auto Diag = diag(Location, "overloaded %0 returns a reference instead of a "
  46                                "constant object type")
  47                 << FuncDecl;
  48
  49     if (Location.isMacroID() || ReturnType->getAs<TypedefType>() ||
  50         RefType->getPointeeTypeAsWritten()->getAs<TypedefType>())
  51       return;
  52
  53     QualType ReplaceType =
  54         ReturnType.getNonReferenceType().getLocalUnqualifiedType();
  55     // The getReturnTypeSourceRange omits the qualifiers. We do not want to
  56     // duplicate the const.
  57     if (!ReturnType->getPointeeType().isConstQualified())
  58       ReplaceType.addConst();
  59
  60     Diag << FixItHint::CreateReplacement(
  61         ReturnRange,
  62         ReplaceType.getAsString(Result.Context->getPrintingPolicy()) + " ");
  63
  64     return;
  65   }
  66
  67   if (ReturnType.isConstQualified() || ReturnType->isBuiltinType() ||
  68       ReturnType->isPointerType())
  69     return;
  70
  71   auto Diag =
  72       diag(Location, "overloaded %0 returns a non-constant object instead of a "
  73                      "constant object type")
  74       << FuncDecl;
  75
  76   if (!Location.isMacroID() && !ReturnType->getAs<TypedefType>())
  77     Diag << FixItHint::CreateInsertion(Location, "const ");
  78 }
  79
  80 } // namespace clang::tidy::cert