clang-tools  5.0.0
BracesAroundStatementsCheck.cpp
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1 //===--- BracesAroundStatementsCheck.cpp - clang-tidy ---------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 #include "clang/Lex/Lexer.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20 namespace {
21 
22 tok::TokenKind getTokenKind(SourceLocation Loc, const SourceManager &SM,
23  const ASTContext *Context) {
24  Token Tok;
25  SourceLocation Beginning =
26  Lexer::GetBeginningOfToken(Loc, SM, Context->getLangOpts());
27  const bool Invalid =
28  Lexer::getRawToken(Beginning, Tok, SM, Context->getLangOpts());
29  assert(!Invalid && "Expected a valid token.");
30 
31  if (Invalid)
32  return tok::NUM_TOKENS;
33 
34  return Tok.getKind();
35 }
36 
37 SourceLocation forwardSkipWhitespaceAndComments(SourceLocation Loc,
38  const SourceManager &SM,
39  const ASTContext *Context) {
40  assert(Loc.isValid());
41  for (;;) {
42  while (isWhitespace(*SM.getCharacterData(Loc)))
43  Loc = Loc.getLocWithOffset(1);
44 
45  tok::TokenKind TokKind = getTokenKind(Loc, SM, Context);
46  if (TokKind == tok::NUM_TOKENS || TokKind != tok::comment)
47  return Loc;
48 
49  // Fast-forward current token.
50  Loc = Lexer::getLocForEndOfToken(Loc, 0, SM, Context->getLangOpts());
51  }
52 }
53 
54 SourceLocation findEndLocation(SourceLocation LastTokenLoc,
55  const SourceManager &SM,
56  const ASTContext *Context) {
57  SourceLocation Loc =
58  Lexer::GetBeginningOfToken(LastTokenLoc, SM, Context->getLangOpts());
59  // Loc points to the beginning of the last (non-comment non-ws) token
60  // before end or ';'.
61  assert(Loc.isValid());
62  bool SkipEndWhitespaceAndComments = true;
63  tok::TokenKind TokKind = getTokenKind(Loc, SM, Context);
64  if (TokKind == tok::NUM_TOKENS || TokKind == tok::semi ||
65  TokKind == tok::r_brace) {
66  // If we are at ";" or "}", we found the last token. We could use as well
67  // `if (isa<NullStmt>(S))`, but it wouldn't work for nested statements.
68  SkipEndWhitespaceAndComments = false;
69  }
70 
71  Loc = Lexer::getLocForEndOfToken(Loc, 0, SM, Context->getLangOpts());
72  // Loc points past the last token before end or after ';'.
73  if (SkipEndWhitespaceAndComments) {
74  Loc = forwardSkipWhitespaceAndComments(Loc, SM, Context);
75  tok::TokenKind TokKind = getTokenKind(Loc, SM, Context);
76  if (TokKind == tok::semi)
77  Loc = Lexer::getLocForEndOfToken(Loc, 0, SM, Context->getLangOpts());
78  }
79 
80  for (;;) {
81  assert(Loc.isValid());
82  while (isHorizontalWhitespace(*SM.getCharacterData(Loc))) {
83  Loc = Loc.getLocWithOffset(1);
84  }
85 
86  if (isVerticalWhitespace(*SM.getCharacterData(Loc))) {
87  // EOL, insert brace before.
88  break;
89  }
90  tok::TokenKind TokKind = getTokenKind(Loc, SM, Context);
91  if (TokKind != tok::comment) {
92  // Non-comment token, insert brace before.
93  break;
94  }
95 
96  SourceLocation TokEndLoc =
97  Lexer::getLocForEndOfToken(Loc, 0, SM, Context->getLangOpts());
98  SourceRange TokRange(Loc, TokEndLoc);
99  StringRef Comment = Lexer::getSourceText(
100  CharSourceRange::getTokenRange(TokRange), SM, Context->getLangOpts());
101  if (Comment.startswith("/*") && Comment.find('\n') != StringRef::npos) {
102  // Multi-line block comment, insert brace before.
103  break;
104  }
105  // else: Trailing comment, insert brace after the newline.
106 
107  // Fast-forward current token.
108  Loc = TokEndLoc;
109  }
110  return Loc;
111 }
112 
113 } // namespace
114 
115 BracesAroundStatementsCheck::BracesAroundStatementsCheck(
116  StringRef Name, ClangTidyContext *Context)
117  : ClangTidyCheck(Name, Context),
118  // Always add braces by default.
119  ShortStatementLines(Options.get("ShortStatementLines", 0U)) {}
120 
123  Options.store(Opts, "ShortStatementLines", ShortStatementLines);
124 }
125 
127  Finder->addMatcher(ifStmt().bind("if"), this);
128  Finder->addMatcher(whileStmt().bind("while"), this);
129  Finder->addMatcher(doStmt().bind("do"), this);
130  Finder->addMatcher(forStmt().bind("for"), this);
131  Finder->addMatcher(cxxForRangeStmt().bind("for-range"), this);
132 }
133 
135  const MatchFinder::MatchResult &Result) {
136  const SourceManager &SM = *Result.SourceManager;
137  const ASTContext *Context = Result.Context;
138 
139  // Get location of closing parenthesis or 'do' to insert opening brace.
140  if (auto S = Result.Nodes.getNodeAs<ForStmt>("for")) {
141  checkStmt(Result, S->getBody(), S->getRParenLoc());
142  } else if (auto S = Result.Nodes.getNodeAs<CXXForRangeStmt>("for-range")) {
143  checkStmt(Result, S->getBody(), S->getRParenLoc());
144  } else if (auto S = Result.Nodes.getNodeAs<DoStmt>("do")) {
145  checkStmt(Result, S->getBody(), S->getDoLoc(), S->getWhileLoc());
146  } else if (auto S = Result.Nodes.getNodeAs<WhileStmt>("while")) {
147  SourceLocation StartLoc = findRParenLoc(S, SM, Context);
148  if (StartLoc.isInvalid())
149  return;
150  checkStmt(Result, S->getBody(), StartLoc);
151  } else if (auto S = Result.Nodes.getNodeAs<IfStmt>("if")) {
152  SourceLocation StartLoc = findRParenLoc(S, SM, Context);
153  if (StartLoc.isInvalid())
154  return;
155  if (ForceBracesStmts.erase(S))
156  ForceBracesStmts.insert(S->getThen());
157  bool BracedIf = checkStmt(Result, S->getThen(), StartLoc, S->getElseLoc());
158  const Stmt *Else = S->getElse();
159  if (Else && BracedIf)
160  ForceBracesStmts.insert(Else);
161  if (Else && !isa<IfStmt>(Else)) {
162  // Omit 'else if' statements here, they will be handled directly.
163  checkStmt(Result, Else, S->getElseLoc());
164  }
165  } else {
166  llvm_unreachable("Invalid match");
167  }
168 }
169 
170 /// Find location of right parenthesis closing condition.
171 template <typename IfOrWhileStmt>
172 SourceLocation
173 BracesAroundStatementsCheck::findRParenLoc(const IfOrWhileStmt *S,
174  const SourceManager &SM,
175  const ASTContext *Context) {
176  // Skip macros.
177  if (S->getLocStart().isMacroID())
178  return SourceLocation();
179 
180  SourceLocation CondEndLoc = S->getCond()->getLocEnd();
181  if (const DeclStmt *CondVar = S->getConditionVariableDeclStmt())
182  CondEndLoc = CondVar->getLocEnd();
183 
184  if (!CondEndLoc.isValid()) {
185  return SourceLocation();
186  }
187 
188  SourceLocation PastCondEndLoc =
189  Lexer::getLocForEndOfToken(CondEndLoc, 0, SM, Context->getLangOpts());
190  if (PastCondEndLoc.isInvalid())
191  return SourceLocation();
192  SourceLocation RParenLoc =
193  forwardSkipWhitespaceAndComments(PastCondEndLoc, SM, Context);
194  if (RParenLoc.isInvalid())
195  return SourceLocation();
196  tok::TokenKind TokKind = getTokenKind(RParenLoc, SM, Context);
197  if (TokKind != tok::r_paren)
198  return SourceLocation();
199  return RParenLoc;
200 }
201 
202 /// Determine if the statement needs braces around it, and add them if it does.
203 /// Returns true if braces where added.
204 bool BracesAroundStatementsCheck::checkStmt(
205  const MatchFinder::MatchResult &Result, const Stmt *S,
206  SourceLocation InitialLoc, SourceLocation EndLocHint) {
207  // 1) If there's a corresponding "else" or "while", the check inserts "} "
208  // right before that token.
209  // 2) If there's a multi-line block comment starting on the same line after
210  // the location we're inserting the closing brace at, or there's a non-comment
211  // token, the check inserts "\n}" right before that token.
212  // 3) Otherwise the check finds the end of line (possibly after some block or
213  // line comments) and inserts "\n}" right before that EOL.
214  if (!S || isa<CompoundStmt>(S)) {
215  // Already inside braces.
216  return false;
217  }
218 
219  if (!InitialLoc.isValid())
220  return false;
221  const SourceManager &SM = *Result.SourceManager;
222  const ASTContext *Context = Result.Context;
223 
224  // Treat macros.
225  CharSourceRange FileRange = Lexer::makeFileCharRange(
226  CharSourceRange::getTokenRange(S->getSourceRange()), SM,
227  Context->getLangOpts());
228  if (FileRange.isInvalid())
229  return false;
230 
231  // Convert InitialLoc to file location, if it's on the same macro expansion
232  // level as the start of the statement. We also need file locations for
233  // Lexer::getLocForEndOfToken working properly.
234  InitialLoc = Lexer::makeFileCharRange(
235  CharSourceRange::getCharRange(InitialLoc, S->getLocStart()),
236  SM, Context->getLangOpts())
237  .getBegin();
238  if (InitialLoc.isInvalid())
239  return false;
240  SourceLocation StartLoc =
241  Lexer::getLocForEndOfToken(InitialLoc, 0, SM, Context->getLangOpts());
242 
243  // StartLoc points at the location of the opening brace to be inserted.
244  SourceLocation EndLoc;
245  std::string ClosingInsertion;
246  if (EndLocHint.isValid()) {
247  EndLoc = EndLocHint;
248  ClosingInsertion = "} ";
249  } else {
250  const auto FREnd = FileRange.getEnd().getLocWithOffset(-1);
251  EndLoc = findEndLocation(FREnd, SM, Context);
252  ClosingInsertion = "\n}";
253  }
254 
255  assert(StartLoc.isValid());
256  assert(EndLoc.isValid());
257  // Don't require braces for statements spanning less than certain number of
258  // lines.
259  if (ShortStatementLines && !ForceBracesStmts.erase(S)) {
260  unsigned StartLine = SM.getSpellingLineNumber(StartLoc);
261  unsigned EndLine = SM.getSpellingLineNumber(EndLoc);
262  if (EndLine - StartLine < ShortStatementLines)
263  return false;
264  }
265 
266  auto Diag = diag(StartLoc, "statement should be inside braces");
267  Diag << FixItHint::CreateInsertion(StartLoc, " {")
268  << FixItHint::CreateInsertion(EndLoc, ClosingInsertion);
269  return true;
270 }
271 
273  ForceBracesStmts.clear();
274 }
275 
276 } // namespace readability
277 } // namespace tidy
278 } // namespace clang
SourceLocation Loc
'#' location in the include directive
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
StringHandle Name
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275
Base class for all clang-tidy checks.
Definition: ClangTidy.h:127
SourceManager & SM
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
Definition: ClangTidy.cpp:449
std::map< std::string, std::string > OptionMap
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
ClangTidyContext & Context
Definition: ClangTidy.cpp:87
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidy.cpp:416
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.