MathMissingParenthesesCheck.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 "MathMissingParenthesesCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::readability {
 
void MathMissingParenthesesCheck::registerMatchers(MatchFinder *Finder) {
  Finder->addMatcher(
      binaryOperator(
          unless(hasParent(binaryOperator(unless(isAssignmentOperator()),
                                          unless(isComparisonOperator())))),
          unless(isAssignmentOperator()), unless(isComparisonOperator()),
          unless(hasAnyOperatorName("&&", "||")),
          hasDescendant(binaryOperator()))
          .bind("binOp"),
      this);
}
 
static int getPrecedence(const BinaryOperator *BinOp) {
  if (!BinOp)
    return 0;
  switch (BinOp->getOpcode()) {
  case BO_Mul:
  case BO_Div:
  case BO_Rem:
    return 5;
  case BO_Add:
  case BO_Sub:
    return 4;
  case BO_And:
    return 3;
  case BO_Xor:
    return 2;
  case BO_Or:
    return 1;
  default:
    return 0;
  }
}
static void addParentheses(const Expr *E, const BinaryOperator *ParentBinOp,
                           ClangTidyCheck *Check, const SourceManager &SM,
                           const LangOptions &LangOpts) {
  if (const auto *Paren = dyn_cast<ParenExpr>(E)) {
    addParentheses(Paren->getSubExpr()->IgnoreImpCasts(), nullptr, Check, SM,
                   LangOpts);
    return;
  }
 
  const auto *BinOp = dyn_cast<BinaryOperator>(E);
  if (!BinOp)
    return;
 
  const int Precedence1 = getPrecedence(BinOp);
  const int Precedence2 = getPrecedence(ParentBinOp);
 
  if (ParentBinOp != nullptr && Precedence1 != Precedence2 && Precedence1 > 0 &&
      Precedence2 > 0) {
    const SourceLocation StartLoc = BinOp->getBeginLoc();
    const SourceLocation EndLoc =
        Lexer::getLocForEndOfToken(BinOp->getEndLoc(), 0, SM, LangOpts);
 
    auto Diag =
        Check->diag(StartLoc,
                    "'%0' has higher precedence than '%1'; add parentheses to "
                    "explicitly specify the order of operations")
        << (Precedence1 > Precedence2 ? BinOp->getOpcodeStr()
                                      : ParentBinOp->getOpcodeStr())
        << (Precedence1 > Precedence2 ? ParentBinOp->getOpcodeStr()
                                      : BinOp->getOpcodeStr())
        << SourceRange(StartLoc, EndLoc);
 
    if (EndLoc.isValid()) {
      Diag << FixItHint::CreateInsertion(StartLoc, "(")
           << FixItHint::CreateInsertion(EndLoc, ")");
    }
  }
 
  addParentheses(BinOp->getLHS()->IgnoreImpCasts(), BinOp, Check, SM, LangOpts);
  addParentheses(BinOp->getRHS()->IgnoreImpCasts(), BinOp, Check, SM, LangOpts);
}
 
void MathMissingParenthesesCheck::check(
    const MatchFinder::MatchResult &Result) {
  const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binOp");
  const SourceManager &SM = *Result.SourceManager;
  const LangOptions &LO = Result.Context->getLangOpts();
  addParentheses(BinOp, nullptr, this, SM, LO);
}
 
} // namespace clang::tidy::readability