clang-tools-extra/clang-tidy/modernize/UseOverrideCheck.cpp

   1 //===--- UseOverrideCheck.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 "UseOverrideCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/ASTMatchers/ASTMatchFinder.h"
  12 #include "clang/Lex/Lexer.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::modernize {
  17
  18 UseOverrideCheck::UseOverrideCheck(StringRef Name, ClangTidyContext *Context)
  19     : ClangTidyCheck(Name, Context),
  20       IgnoreDestructors(Options.get("IgnoreDestructors", false)),
  21       IgnoreTemplateInstantiations(
  22           Options.get("IgnoreTemplateInstantiations", false)),
  23       AllowOverrideAndFinal(Options.get("AllowOverrideAndFinal", false)),
  24       OverrideSpelling(Options.get("OverrideSpelling", "override")),
  25       FinalSpelling(Options.get("FinalSpelling", "final")) {}
  26
  27 void UseOverrideCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  28   Options.store(Opts, "IgnoreDestructors", IgnoreDestructors);
  29   Options.store(Opts, "IgnoreTemplateInstantiations",
  30                 IgnoreTemplateInstantiations);
  31   Options.store(Opts, "AllowOverrideAndFinal", AllowOverrideAndFinal);
  32   Options.store(Opts, "OverrideSpelling", OverrideSpelling);
  33   Options.store(Opts, "FinalSpelling", FinalSpelling);
  34 }
  35
  36 void UseOverrideCheck::registerMatchers(MatchFinder *Finder) {
  37
  38   auto IgnoreDestructorMatcher =
  39       IgnoreDestructors ? cxxMethodDecl(unless(cxxDestructorDecl()))
  40                         : cxxMethodDecl();
  41   auto IgnoreTemplateInstantiationsMatcher =
  42       IgnoreTemplateInstantiations
  43           ? cxxMethodDecl(unless(ast_matchers::isTemplateInstantiation()))
  44           : cxxMethodDecl();
  45   Finder->addMatcher(cxxMethodDecl(isOverride(),
  46                                    IgnoreTemplateInstantiationsMatcher,
  47                                    IgnoreDestructorMatcher)
  48                          .bind("method"),
  49                      this);
  50 }
  51
  52 // Re-lex the tokens to get precise locations to insert 'override' and remove
  53 // 'virtual'.
  54 static SmallVector<Token, 16>
  55 parseTokens(CharSourceRange Range, const MatchFinder::MatchResult &Result) {
  56   const SourceManager &Sources = *Result.SourceManager;
  57   std::pair<FileID, unsigned> LocInfo =
  58       Sources.getDecomposedLoc(Range.getBegin());
  59   StringRef File = Sources.getBufferData(LocInfo.first);
  60   const char *TokenBegin = File.data() + LocInfo.second;
  61   Lexer RawLexer(Sources.getLocForStartOfFile(LocInfo.first),
  62                  Result.Context->getLangOpts(), File.begin(), TokenBegin,
  63                  File.end());
  64   SmallVector<Token, 16> Tokens;
  65   Token Tok;
  66   int NestedParens = 0;
  67   while (!RawLexer.LexFromRawLexer(Tok)) {
  68     if ((Tok.is(tok::semi) || Tok.is(tok::l_brace)) && NestedParens == 0)
  69       break;
  70     if (Sources.isBeforeInTranslationUnit(Range.getEnd(), Tok.getLocation()))
  71       break;
  72     if (Tok.is(tok::l_paren))
  73       ++NestedParens;
  74     else if (Tok.is(tok::r_paren))
  75       --NestedParens;
  76     if (Tok.is(tok::raw_identifier)) {
  77       IdentifierInfo &Info = Result.Context->Idents.get(StringRef(
  78           Sources.getCharacterData(Tok.getLocation()), Tok.getLength()));
  79       Tok.setIdentifierInfo(&Info);
  80       Tok.setKind(Info.getTokenID());
  81     }
  82     Tokens.push_back(Tok);
  83   }
  84   return Tokens;
  85 }
  86
  87 static StringRef getText(const Token &Tok, const SourceManager &Sources) {
  88   return {Sources.getCharacterData(Tok.getLocation()), Tok.getLength()};
  89 }
  90
  91 void UseOverrideCheck::check(const MatchFinder::MatchResult &Result) {
  92   const auto *Method = Result.Nodes.getNodeAs<FunctionDecl>("method");
  93   const SourceManager &Sources = *Result.SourceManager;
  94
  95   ASTContext &Context = *Result.Context;
  96
  97   assert(Method != nullptr);
  98   if (Method->getInstantiatedFromMemberFunction() != nullptr)
  99     Method = Method->getInstantiatedFromMemberFunction();
 100
 101   if (Method->isImplicit() || Method->getLocation().isMacroID() ||
 102       Method->isOutOfLine())
 103     return;
 104
 105   bool HasVirtual = Method->isVirtualAsWritten();
 106   bool HasOverride = Method->getAttr<OverrideAttr>();
 107   bool HasFinal = Method->getAttr<FinalAttr>();
 108
 109   bool OnlyVirtualSpecified = HasVirtual && !HasOverride && !HasFinal;
 110   unsigned KeywordCount = HasVirtual + HasOverride + HasFinal;
 111
 112   if ((!OnlyVirtualSpecified && KeywordCount == 1) ||
 113       (!HasVirtual && HasOverride && HasFinal && AllowOverrideAndFinal))
 114     return; // Nothing to do.
 115
 116   std::string Message;
 117   if (OnlyVirtualSpecified) {
 118     Message = "prefer using '%0' or (rarely) '%1' instead of 'virtual'";
 119   } else if (KeywordCount == 0) {
 120     Message = "annotate this function with '%0' or (rarely) '%1'";
 121   } else {
 122     StringRef Redundant =
 123         HasVirtual ? (HasOverride && HasFinal && !AllowOverrideAndFinal
 124                           ? "'virtual' and '%0' are"
 125                           : "'virtual' is")
 126                    : "'%0' is";
 127     StringRef Correct = HasFinal ? "'%1'" : "'%0'";
 128
 129     Message = (llvm::Twine(Redundant) +
 130                " redundant since the function is already declared " + Correct)
 131                   .str();
 132   }
 133
 134   auto Diag = diag(Method->getLocation(), Message)
 135               << OverrideSpelling << FinalSpelling;
 136
 137   CharSourceRange FileRange = Lexer::makeFileCharRange(
 138       CharSourceRange::getTokenRange(Method->getSourceRange()), Sources,
 139       getLangOpts());
 140
 141   if (!FileRange.isValid())
 142     return;
 143
 144   // FIXME: Instead of re-lexing and looking for specific macros such as
 145   // 'ABSTRACT', properly store the location of 'virtual' and '= 0' in each
 146   // FunctionDecl.
 147   SmallVector<Token, 16> Tokens = parseTokens(FileRange, Result);
 148
 149   // Add 'override' on inline declarations that don't already have it.
 150   if (!HasFinal && !HasOverride) {
 151     SourceLocation InsertLoc;
 152     std::string ReplacementText = (OverrideSpelling + " ").str();
 153     SourceLocation MethodLoc = Method->getLocation();
 154
 155     for (Token T : Tokens) {
 156       if (T.is(tok::kw___attribute) &&
 157           !Sources.isBeforeInTranslationUnit(T.getLocation(), MethodLoc)) {
 158         InsertLoc = T.getLocation();
 159         break;
 160       }
 161     }
 162
 163     if (Method->hasAttrs()) {
 164       for (const clang::Attr *A : Method->getAttrs()) {
 165         if (!A->isImplicit() && !A->isInherited()) {
 166           SourceLocation Loc =
 167               Sources.getExpansionLoc(A->getRange().getBegin());
 168           if ((!InsertLoc.isValid() ||
 169                Sources.isBeforeInTranslationUnit(Loc, InsertLoc)) &&
 170               !Sources.isBeforeInTranslationUnit(Loc, MethodLoc))
 171             InsertLoc = Loc;
 172         }
 173       }
 174     }
 175
 176     if (InsertLoc.isInvalid() && Method->doesThisDeclarationHaveABody() &&
 177         Method->getBody() && !Method->isDefaulted()) {
 178       // For methods with inline definition, add the override keyword at the
 179       // end of the declaration of the function, but prefer to put it on the
 180       // same line as the declaration if the beginning brace for the start of
 181       // the body falls on the next line.
 182       ReplacementText = (" " + OverrideSpelling).str();
 183       auto *LastTokenIter = std::prev(Tokens.end());
 184       // When try statement is used instead of compound statement as
 185       // method body - insert override keyword before it.
 186       if (LastTokenIter->is(tok::kw_try))
 187         LastTokenIter = std::prev(LastTokenIter);
 188       InsertLoc = LastTokenIter->getEndLoc();
 189     }
 190
 191     if (!InsertLoc.isValid()) {
 192       // For declarations marked with "= 0" or "= [default|delete]", the end
 193       // location will point until after those markings. Therefore, the override
 194       // keyword shouldn't be inserted at the end, but before the '='.
 195       if (Tokens.size() > 2 &&
 196           (getText(Tokens.back(), Sources) == "0" ||
 197            Tokens.back().is(tok::kw_default) ||
 198            Tokens.back().is(tok::kw_delete)) &&
 199           getText(Tokens[Tokens.size() - 2], Sources) == "=") {
 200         InsertLoc = Tokens[Tokens.size() - 2].getLocation();
 201         // Check if we need to insert a space.
 202         if ((Tokens[Tokens.size() - 2].getFlags() & Token::LeadingSpace) == 0)
 203           ReplacementText = (" " + OverrideSpelling + " ").str();
 204       } else if (getText(Tokens.back(), Sources) == "ABSTRACT")
 205         InsertLoc = Tokens.back().getLocation();
 206     }
 207
 208     if (!InsertLoc.isValid()) {
 209       InsertLoc = FileRange.getEnd();
 210       ReplacementText = (" " + OverrideSpelling).str();
 211     }
 212
 213     // If the override macro has been specified just ensure it exists,
 214     // if not don't apply a fixit but keep the warning.
 215     if (OverrideSpelling != "override" &&
 216         !Context.Idents.get(OverrideSpelling).hasMacroDefinition())
 217       return;
 218
 219     Diag << FixItHint::CreateInsertion(InsertLoc, ReplacementText);
 220   }
 221
 222   if (HasFinal && HasOverride && !AllowOverrideAndFinal) {
 223     SourceLocation OverrideLoc = Method->getAttr<OverrideAttr>()->getLocation();
 224     Diag << FixItHint::CreateRemoval(
 225         CharSourceRange::getTokenRange(OverrideLoc, OverrideLoc));
 226   }
 227
 228   if (HasVirtual) {
 229     for (Token Tok : Tokens) {
 230       if (Tok.is(tok::kw_virtual)) {
 231         Diag << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(
 232             Tok.getLocation(), Tok.getLocation()));
 233         break;
 234       }
 235     }
 236   }
 237 }
 238
 239 } // namespace clang::tidy::modernize