OptionalValueConversionCheck.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 "OptionalValueConversionCheck.h"
#include "../utils/LexerUtils.h"
#include "../utils/Matchers.h"
#include "../utils/OptionsUtils.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include <array>
 
using namespace clang::ast_matchers;
using clang::ast_matchers::internal::Matcher;
 
namespace clang::tidy::bugprone {
 
namespace {
 
AST_MATCHER_P(QualType, hasCleanType, Matcher<QualType>, InnerMatcher) {
  return InnerMatcher.matches(
      Node.getNonReferenceType().getUnqualifiedType().getCanonicalType(),
      Finder, Builder);
}
 
constexpr std::array<StringRef, 2> MakeSmartPtrList{
    "::std::make_unique",
    "::std::make_shared",
};
constexpr StringRef MakeOptional = "::std::make_optional";
 
} // namespace
 
OptionalValueConversionCheck::OptionalValueConversionCheck(
    StringRef Name, ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      OptionalTypes(utils::options::parseStringList(
          Options.get("OptionalTypes",
                      "::std::optional;::absl::optional;::boost::optional"))),
      ValueMethods(utils::options::parseStringList(
          Options.get("ValueMethods", "::value$;::get$"))) {}
 
std::optional<TraversalKind>
OptionalValueConversionCheck::getCheckTraversalKind() const {
  return TK_AsIs;
}
 
void OptionalValueConversionCheck::registerMatchers(MatchFinder *Finder) {
  auto BindOptionalType = qualType(
      hasCleanType(qualType(hasDeclaration(namedDecl(
                                matchers::matchesAnyListedName(OptionalTypes))))
                       .bind("optional-type")));
 
  auto EqualsBoundOptionalType =
      qualType(hasCleanType(equalsBoundNode("optional-type")));
 
  auto OptionalDerefMatcherImpl = callExpr(
      anyOf(
          cxxOperatorCallExpr(hasOverloadedOperatorName("*"),
                              hasUnaryOperand(hasType(EqualsBoundOptionalType)))
              .bind("op-call"),
          cxxMemberCallExpr(thisPointerType(EqualsBoundOptionalType),
                            callee(cxxMethodDecl(anyOf(
                                hasOverloadedOperatorName("*"),
                                matchers::matchesAnyListedName(ValueMethods)))))
              .bind("member-call")),
      hasType(qualType().bind("value-type")));
 
  auto StdMoveCallMatcher =
      callExpr(argumentCountIs(1), callee(functionDecl(hasName("::std::move"))),
               hasArgument(0, ignoringImpCasts(OptionalDerefMatcherImpl)));
  auto OptionalDerefMatcher =
      ignoringImpCasts(anyOf(OptionalDerefMatcherImpl, StdMoveCallMatcher));
 
  Finder->addMatcher(
      expr(anyOf(
               // construct optional
               cxxConstructExpr(argumentCountIs(1), hasType(BindOptionalType),
                                hasArgument(0, OptionalDerefMatcher)),
               // known template methods in std
               callExpr(
                   argumentCountIs(1),
                   anyOf(
                       // match std::make_unique std::make_shared
                       callee(functionDecl(
                           matchers::matchesAnyListedName(MakeSmartPtrList),
                           hasTemplateArgument(
                               0, refersToType(BindOptionalType)))),
                       // match first std::make_optional by limit argument count
                       // (1) and template count (1).
                       // 1. template< class T > constexpr
                       //    std::optional<decay_t<T>> make_optional(T&& value);
                       // 2. template< class T, class... Args > constexpr
                       //    std::optional<T> make_optional(Args&&... args);
                       callee(functionDecl(templateArgumentCountIs(1),
                                           hasName(MakeOptional),
                                           returns(BindOptionalType)))),
                   hasArgument(0, OptionalDerefMatcher)),
               callExpr(
 
                   argumentCountIs(1),
 
                   hasArgument(0, OptionalDerefMatcher))),
           unless(anyOf(hasAncestor(typeLoc()),
                        hasAncestor(expr(matchers::hasUnevaluatedContext())))))
          .bind("expr"),
      this);
}
 
void OptionalValueConversionCheck::storeOptions(
    ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "OptionalTypes",
                utils::options::serializeStringList(OptionalTypes));
  Options.store(Opts, "ValueMethods",
                utils::options::serializeStringList(ValueMethods));
}
 
void OptionalValueConversionCheck::check(
    const MatchFinder::MatchResult &Result) {
  const auto *MatchedExpr = Result.Nodes.getNodeAs<Expr>("expr");
  const auto *OptionalType = Result.Nodes.getNodeAs<QualType>("optional-type");
  const auto *ValueType = Result.Nodes.getNodeAs<QualType>("value-type");
 
  diag(MatchedExpr->getExprLoc(),
       "conversion from %0 into %1 and back into %0, remove potentially "
       "error-prone optional dereference")
      << *OptionalType << ValueType->getUnqualifiedType();
 
  if (const auto *OperatorExpr =
          Result.Nodes.getNodeAs<CXXOperatorCallExpr>("op-call")) {
    diag(OperatorExpr->getExprLoc(), "remove '*' to silence this warning",
         DiagnosticIDs::Note)
        << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(
               OperatorExpr->getBeginLoc(), OperatorExpr->getExprLoc()));
    return;
  }
  if (const auto *CallExpr =
          Result.Nodes.getNodeAs<CXXMemberCallExpr>("member-call")) {
    const SourceLocation Begin =
        utils::lexer::getPreviousToken(CallExpr->getExprLoc(),
                                       *Result.SourceManager, getLangOpts())
            .getLocation();
    auto Diag =
        diag(CallExpr->getExprLoc(),
             "remove call to %0 to silence this warning", DiagnosticIDs::Note);
    Diag << CallExpr->getMethodDecl()
         << FixItHint::CreateRemoval(
                CharSourceRange::getTokenRange(Begin, CallExpr->getEndLoc()));
    if (const auto *Member =
            llvm::dyn_cast<MemberExpr>(CallExpr->getCallee()->IgnoreImplicit());
        Member && Member->isArrow())
      Diag << FixItHint::CreateInsertion(CallExpr->getBeginLoc(), "*");
    return;
  }
}
 
} // namespace clang::tidy::bugprone