RedundantParenthesesCheck.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 "RedundantParenthesesCheck.h"
#include "../utils/Matchers.h"
#include "../utils/OptionsUtils.h"
#include "clang/AST/Expr.h"
#include "clang/AST/TypeLoc.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/ASTMatchers/ASTMatchersMacros.h"
#include "clang/Lex/Lexer.h"
#include <cassert>
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::readability {
 
namespace {
 
AST_MATCHER_P(ParenExpr, subExpr, ast_matchers::internal::Matcher<Expr>,
              InnerMatcher) {
  return InnerMatcher.matches(*Node.getSubExpr(), Finder, Builder);
}
 
AST_MATCHER(ParenExpr, isInMacro) {
  const Expr *E = Node.getSubExpr();
  return Node.getLParen().isMacroID() || Node.getRParen().isMacroID() ||
         E->getBeginLoc().isMacroID() || E->getEndLoc().isMacroID();
}
 
AST_MATCHER(ParenExpr, isWritten) {
  return Node.getLParen() != Node.getRParen();
}
 
AST_MATCHER(TypeLoc, isTypeOfExprTypeLoc) {
  return !Node.getUnqualifiedLoc().getAs<TypeOfExprTypeLoc>().isNull();
}
 
AST_MATCHER(AutoType, isDecltypeAuto) { return Node.isDecltypeAuto(); }
 
} // namespace
 
static FixItHint createSpacedRemoval(SourceLocation Loc,
                                     const SourceManager &SM,
                                     const LangOptions &LangOpts) {
  if (Loc.isValid() && !Loc.isMacroID()) {
    const auto LocInfo = SM.getDecomposedLoc(Loc);
    bool Invalid = false;
    StringRef Buffer = SM.getBufferData(LocInfo.first, &Invalid);
    if (!Invalid && LocInfo.second > 0 && LocInfo.second + 1 < Buffer.size() &&
        Lexer::isAsciiIdentifierContinueChar(Buffer[LocInfo.second - 1],
                                             LangOpts) &&
        Lexer::isAsciiIdentifierContinueChar(Buffer[LocInfo.second + 1],
                                             LangOpts))
      return FixItHint::CreateReplacement(SourceRange(Loc, Loc), " ");
  }
  return FixItHint::CreateRemoval(Loc);
}
 
RedundantParenthesesCheck::RedundantParenthesesCheck(StringRef Name,
                                                     ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      AllowedDecls(utils::options::parseStringList(
          Options.get("AllowedDecls", "std::max;std::min"))) {}
 
void RedundantParenthesesCheck::storeOptions(
    ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "AllowedDecls",
                utils::options::serializeStringList(AllowedDecls));
}
 
void RedundantParenthesesCheck::registerMatchers(MatchFinder *Finder) {
  const auto ConstantExpr =
      expr(anyOf(integerLiteral(), floatLiteral(), characterLiteral(),
                 cxxBoolLiteral(), stringLiteral(), cxxNullPtrLiteralExpr()));
  // Include dependent and substituted operands so templates and their
  // instantiations protect the same outer pair of parentheses.
  const auto DecltypeOperand =
      expr(anyOf(declRefExpr(), memberExpr(), dependentScopeDeclRefExpr(),
                 cxxDependentScopeMemberExpr(), unresolvedLookupExpr(),
                 substNonTypeTemplateParmExpr()));
  const auto DecltypeAutoType = ignoringParens(autoType(isDecltypeAuto()));
  const auto DecltypeAutoVar = varDecl(hasType(DecltypeAutoType));
  // Operands that create temporaries are wrapped in ExprWithCleanups.
  const auto InDecltypeAutoContext = anyOf(
      hasParent(DecltypeAutoVar),
      hasParent(
          expr(anyOf(initListExpr(), parenListExpr()),
               anyOf(hasParent(DecltypeAutoVar),
                     hasParent(exprWithCleanups(hasParent(DecltypeAutoVar)))))),
      hasParent(
          returnStmt(forCallable(functionDecl(returns(DecltypeAutoType))))));
  const auto IsDecltypeOperand = allOf(
      subExpr(ignoringParens(DecltypeOperand)),
      anyOf(hasParent(typeLoc(loc(decltypeType()))), InDecltypeAutoContext,
            hasParent(exprWithCleanups(InDecltypeAutoContext))));
  Finder->addMatcher(
      parenExpr(subExpr(anyOf(
                    parenExpr(), ConstantExpr,
                    declRefExpr(to(namedDecl(unless(
                        matchers::matchesAnyListedRegexName(AllowedDecls))))),
                    memberExpr(),
                    callExpr(unless(cxxOperatorCallExpr(
                        unless(hasAnyOperatorName("()", "[]"))))),
                    arraySubscriptExpr())),
                isWritten(),
                unless(anyOf(isInMacro(),
                             // sizeof(...) is common used.
                             hasParent(unaryExprOrTypeTraitExpr()),
                             // typeof(...) parentheses are required syntax.
                             hasParent(typeLoc(isTypeOfExprTypeLoc())),
                             // decltype((x)) differs from decltype(x).
                             IsDecltypeOperand)))
          .bind("dup"),
      this);
}
 
void RedundantParenthesesCheck::check(const MatchFinder::MatchResult &Result) {
  const auto *PE = Result.Nodes.getNodeAs<ParenExpr>("dup");
  diag(PE->getBeginLoc(), "redundant parentheses around expression")
      << createSpacedRemoval(PE->getLParen(), *Result.SourceManager,
                             getLangOpts())
      << FixItHint::CreateRemoval(PE->getRParen());
}
 
} // namespace clang::tidy::readability