clang-tools-extra/clang-tidy/bugprone/SuspiciousSemicolonCheck.cpp

   1 //===--- SuspiciousSemicolonCheck.cpp - clang-tidy-------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "SuspiciousSemicolonCheck.h"
  10 #include "../utils/LexerUtils.h"
  11 #include "clang/AST/ASTContext.h"
  12 #include "clang/ASTMatchers/ASTMatchFinder.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::bugprone {
  17
  18 void SuspiciousSemicolonCheck::registerMatchers(MatchFinder *Finder) {
  19   Finder->addMatcher(
  20       stmt(anyOf(ifStmt(hasThen(nullStmt().bind("semi")),
  21                         unless(hasElse(stmt())),
  22                         unless(isConstexpr())),
  23                  forStmt(hasBody(nullStmt().bind("semi"))),
  24                  cxxForRangeStmt(hasBody(nullStmt().bind("semi"))),
  25                  whileStmt(hasBody(nullStmt().bind("semi")))))
  26           .bind("stmt"),
  27       this);
  28 }
  29
  30 void SuspiciousSemicolonCheck::check(const MatchFinder::MatchResult &Result) {
  31   if (Result.Context->getDiagnostics().hasUncompilableErrorOccurred())
  32     return;
  33
  34   const auto *Semicolon = Result.Nodes.getNodeAs<NullStmt>("semi");
  35   SourceLocation LocStart = Semicolon->getBeginLoc();
  36
  37   if (LocStart.isMacroID())
  38     return;
  39
  40   ASTContext &Ctxt = *Result.Context;
  41   auto Token = utils::lexer::getPreviousToken(LocStart, Ctxt.getSourceManager(),
  42                                               Ctxt.getLangOpts());
  43   auto &SM = *Result.SourceManager;
  44   unsigned SemicolonLine = SM.getSpellingLineNumber(LocStart);
  45
  46   const auto *Statement = Result.Nodes.getNodeAs<Stmt>("stmt");
  47   const bool IsIfStmt = isa<IfStmt>(Statement);
  48
  49   if (!IsIfStmt &&
  50       SM.getSpellingLineNumber(Token.getLocation()) != SemicolonLine)
  51     return;
  52
  53   SourceLocation LocEnd = Semicolon->getEndLoc();
  54   FileID FID = SM.getFileID(LocEnd);
  55   llvm::MemoryBufferRef Buffer = SM.getBufferOrFake(FID, LocEnd);
  56   Lexer Lexer(SM.getLocForStartOfFile(FID), Ctxt.getLangOpts(),
  57               Buffer.getBufferStart(), SM.getCharacterData(LocEnd) + 1,
  58               Buffer.getBufferEnd());
  59   if (Lexer.LexFromRawLexer(Token))
  60     return;
  61
  62   unsigned BaseIndent = SM.getSpellingColumnNumber(Statement->getBeginLoc());
  63   unsigned NewTokenIndent = SM.getSpellingColumnNumber(Token.getLocation());
  64   unsigned NewTokenLine = SM.getSpellingLineNumber(Token.getLocation());
  65
  66   if (!IsIfStmt && NewTokenIndent <= BaseIndent &&
  67       Token.getKind() != tok::l_brace && NewTokenLine != SemicolonLine)
  68     return;
  69
  70   diag(LocStart, "potentially unintended semicolon")
  71       << FixItHint::CreateRemoval(SourceRange(LocStart, LocEnd));
  72 }
  73
  74 } // namespace clang::tidy::bugprone