PointerArithmeticOnPolymorphicObjectCheck.cpp

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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "PointerArithmeticOnPolymorphicObjectCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::bugprone {
 
namespace {
AST_MATCHER(CXXRecordDecl, isAbstract) { return Node.isAbstract(); }
AST_MATCHER(CXXRecordDecl, isPolymorphic) { return Node.isPolymorphic(); }
} // namespace
 
PointerArithmeticOnPolymorphicObjectCheck::
    PointerArithmeticOnPolymorphicObjectCheck(StringRef Name,
                                              ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      IgnoreInheritedVirtualFunctions(
          Options.get("IgnoreInheritedVirtualFunctions", false)) {}
 
void PointerArithmeticOnPolymorphicObjectCheck::storeOptions(
    ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "IgnoreInheritedVirtualFunctions",
                IgnoreInheritedVirtualFunctions);
}
 
void PointerArithmeticOnPolymorphicObjectCheck::registerMatchers(
    MatchFinder *Finder) {
  const auto PolymorphicPointerExpr =
      expr(hasType(hasCanonicalType(pointerType(pointee(hasCanonicalType(
               hasDeclaration(cxxRecordDecl(unless(isFinal()), isPolymorphic())
                                  .bind("pointee"))))))))
          .bind("pointer");
 
  const auto PointerExprWithVirtualMethod =
      expr(hasType(hasCanonicalType(
               pointerType(pointee(hasCanonicalType(hasDeclaration(
                   cxxRecordDecl(
                       unless(isFinal()),
                       anyOf(hasMethod(isVirtualAsWritten()), isAbstract()))
                       .bind("pointee"))))))))
          .bind("pointer");
 
  const auto SelectedPointerExpr = IgnoreInheritedVirtualFunctions
                                       ? PointerExprWithVirtualMethod
                                       : PolymorphicPointerExpr;
 
  const auto ArraySubscript = arraySubscriptExpr(hasBase(SelectedPointerExpr));
 
  const auto BinaryOperators =
      binaryOperator(hasAnyOperatorName("+", "-", "+=", "-="),
                     hasEitherOperand(SelectedPointerExpr));
 
  const auto UnaryOperators = unaryOperator(
      hasAnyOperatorName("++", "--"), hasUnaryOperand(SelectedPointerExpr));
 
  Finder->addMatcher(ArraySubscript, this);
  Finder->addMatcher(BinaryOperators, this);
  Finder->addMatcher(UnaryOperators, this);
}
 
void PointerArithmeticOnPolymorphicObjectCheck::check(
    const MatchFinder::MatchResult &Result) {
  const auto *PointerExpr = Result.Nodes.getNodeAs<Expr>("pointer");
  const auto *PointeeDecl = Result.Nodes.getNodeAs<CXXRecordDecl>("pointee");
 
  diag(PointerExpr->getBeginLoc(),
       "pointer arithmetic on polymorphic object of type %0 can result in "
       "undefined behavior if the dynamic type differs from the pointer type")
      << PointeeDecl << PointerExpr->getSourceRange();
}
 
} // namespace clang::tidy::bugprone