TrivialSwitchCheck.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 "TrivialSwitchCheck.h"
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::readability {
 
TrivialSwitchCheck::TrivialSwitchCheck(StringRef Name,
                                       ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      IgnoreMacros(Options.get("IgnoreMacros", true)) {}
 
void TrivialSwitchCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "IgnoreMacros", IgnoreMacros);
}
 
void TrivialSwitchCheck::registerMatchers(MatchFinder *Finder) {
  Finder->addMatcher(switchStmt().bind("switch"), this);
}
 
void TrivialSwitchCheck::check(const MatchFinder::MatchResult &Result) {
  const auto *Switch = Result.Nodes.getNodeAs<SwitchStmt>("switch");
  if (IgnoreMacros && Switch->getBeginLoc().isMacroID())
    return;
 
  std::size_t CaseCount = 0;
  bool HasDefault = false;
 
  for (const SwitchCase *CurrentCase = Switch->getSwitchCaseList(); CurrentCase;
       CurrentCase = CurrentCase->getNextSwitchCase()) {
    ++CaseCount;
    if (isa<DefaultStmt>(CurrentCase))
      HasDefault = true;
  }
 
  // FIXME: Try to add fix-it for each case.
  switch (const SourceLocation Loc = Switch->getBeginLoc(); CaseCount) {
  case 0:
    diag(Loc, "switch statement without labels has no effect");
    return;
  case 1:
    if (HasDefault)
      diag(Loc, "switch with default label only");
    else
      diag(Loc, "switch with only one case; use an if statement");
    return;
  case 2:
    if (HasDefault)
      diag(Loc, "switch could be better written as an if-else statement");
    [[fallthrough]];
  default:
    break;
  }
}
 
} // namespace clang::tidy::readability