1 //===--- BracesAroundStatementsCheck.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 "BracesAroundStatementsCheck.h"
10 #include "../utils/BracesAroundStatement.h"
11 #include "../utils/LexerUtils.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchers.h"
14 #include "clang/Lex/Lexer.h"
15
16 using namespace clang::ast_matchers;
17
18 namespace clang::tidy::readability {
19
getTokenKind(SourceLocation Loc,const SourceManager & SM,const LangOptions & LangOpts)20 static tok::TokenKind getTokenKind(SourceLocation Loc, const SourceManager &SM,
21 const LangOptions &LangOpts) {
22 Token Tok;
23 SourceLocation Beginning = Lexer::GetBeginningOfToken(Loc, SM, LangOpts);
24 const bool Invalid = Lexer::getRawToken(Beginning, Tok, SM, LangOpts);
25 assert(!Invalid && "Expected a valid token.");
26
27 if (Invalid)
28 return tok::NUM_TOKENS;
29
30 return Tok.getKind();
31 }
32
33 static SourceLocation
forwardSkipWhitespaceAndComments(SourceLocation Loc,const SourceManager & SM,const LangOptions & LangOpts)34 forwardSkipWhitespaceAndComments(SourceLocation Loc, const SourceManager &SM,
35 const LangOptions &LangOpts) {
36 assert(Loc.isValid());
37 for (;;) {
38 while (isWhitespace(*SM.getCharacterData(Loc)))
39 Loc = Loc.getLocWithOffset(1);
40
41 tok::TokenKind TokKind = getTokenKind(Loc, SM, LangOpts);
42 if (TokKind != tok::comment)
43 return Loc;
44
45 // Fast-forward current token.
46 Loc = Lexer::getLocForEndOfToken(Loc, 0, SM, LangOpts);
47 }
48 }
49
BracesAroundStatementsCheck(StringRef Name,ClangTidyContext * Context)50 BracesAroundStatementsCheck::BracesAroundStatementsCheck(
51 StringRef Name, ClangTidyContext *Context)
52 : ClangTidyCheck(Name, Context),
53 // Always add braces by default.
54 ShortStatementLines(Options.get("ShortStatementLines", 0U)) {}
55
storeOptions(ClangTidyOptions::OptionMap & Opts)56 void BracesAroundStatementsCheck::storeOptions(
57 ClangTidyOptions::OptionMap &Opts) {
58 Options.store(Opts, "ShortStatementLines", ShortStatementLines);
59 }
60
registerMatchers(MatchFinder * Finder)61 void BracesAroundStatementsCheck::registerMatchers(MatchFinder *Finder) {
62 Finder->addMatcher(ifStmt().bind("if"), this);
63 Finder->addMatcher(whileStmt().bind("while"), this);
64 Finder->addMatcher(doStmt().bind("do"), this);
65 Finder->addMatcher(forStmt().bind("for"), this);
66 Finder->addMatcher(cxxForRangeStmt().bind("for-range"), this);
67 }
68
check(const MatchFinder::MatchResult & Result)69 void BracesAroundStatementsCheck::check(
70 const MatchFinder::MatchResult &Result) {
71 const SourceManager &SM = *Result.SourceManager;
72 const ASTContext *Context = Result.Context;
73
74 // Get location of closing parenthesis or 'do' to insert opening brace.
75 if (const auto *S = Result.Nodes.getNodeAs<ForStmt>("for")) {
76 checkStmt(Result, S->getBody(), S->getRParenLoc());
77 } else if (const auto *S =
78 Result.Nodes.getNodeAs<CXXForRangeStmt>("for-range")) {
79 checkStmt(Result, S->getBody(), S->getRParenLoc());
80 } else if (const auto *S = Result.Nodes.getNodeAs<DoStmt>("do")) {
81 checkStmt(Result, S->getBody(), S->getDoLoc(), S->getWhileLoc());
82 } else if (const auto *S = Result.Nodes.getNodeAs<WhileStmt>("while")) {
83 SourceLocation StartLoc = findRParenLoc(S, SM, Context->getLangOpts());
84 if (StartLoc.isInvalid())
85 return;
86 checkStmt(Result, S->getBody(), StartLoc);
87 } else if (const auto *S = Result.Nodes.getNodeAs<IfStmt>("if")) {
88 // "if consteval" always has braces.
89 if (S->isConsteval())
90 return;
91
92 SourceLocation StartLoc = findRParenLoc(S, SM, Context->getLangOpts());
93 if (StartLoc.isInvalid())
94 return;
95 if (ForceBracesStmts.erase(S))
96 ForceBracesStmts.insert(S->getThen());
97 bool BracedIf = checkStmt(Result, S->getThen(), StartLoc, S->getElseLoc());
98 const Stmt *Else = S->getElse();
99 if (Else && BracedIf)
100 ForceBracesStmts.insert(Else);
101 if (Else && !isa<IfStmt>(Else)) {
102 // Omit 'else if' statements here, they will be handled directly.
103 checkStmt(Result, Else, S->getElseLoc());
104 }
105 } else {
106 llvm_unreachable("Invalid match");
107 }
108 }
109
110 /// Find location of right parenthesis closing condition.
111 template <typename IfOrWhileStmt>
112 SourceLocation
findRParenLoc(const IfOrWhileStmt * S,const SourceManager & SM,const LangOptions & LangOpts)113 BracesAroundStatementsCheck::findRParenLoc(const IfOrWhileStmt *S,
114 const SourceManager &SM,
115 const LangOptions &LangOpts) {
116 // Skip macros.
117 if (S->getBeginLoc().isMacroID())
118 return {};
119
120 SourceLocation CondEndLoc = S->getCond()->getEndLoc();
121 if (const DeclStmt *CondVar = S->getConditionVariableDeclStmt())
122 CondEndLoc = CondVar->getEndLoc();
123
124 if (!CondEndLoc.isValid()) {
125 return {};
126 }
127
128 SourceLocation PastCondEndLoc =
129 Lexer::getLocForEndOfToken(CondEndLoc, 0, SM, LangOpts);
130 if (PastCondEndLoc.isInvalid())
131 return {};
132 SourceLocation RParenLoc =
133 forwardSkipWhitespaceAndComments(PastCondEndLoc, SM, LangOpts);
134 if (RParenLoc.isInvalid())
135 return {};
136 tok::TokenKind TokKind = getTokenKind(RParenLoc, SM, LangOpts);
137 if (TokKind != tok::r_paren)
138 return {};
139 return RParenLoc;
140 }
141
142 /// Determine if the statement needs braces around it, and add them if it does.
143 /// Returns true if braces where added.
checkStmt(const MatchFinder::MatchResult & Result,const Stmt * S,SourceLocation StartLoc,SourceLocation EndLocHint)144 bool BracesAroundStatementsCheck::checkStmt(
145 const MatchFinder::MatchResult &Result, const Stmt *S,
146 SourceLocation StartLoc, SourceLocation EndLocHint) {
147 while (const auto *AS = dyn_cast<AttributedStmt>(S))
148 S = AS->getSubStmt();
149
150 const auto BraceInsertionHints = utils::getBraceInsertionsHints(
151 S, Result.Context->getLangOpts(), *Result.SourceManager, StartLoc,
152 EndLocHint);
153 if (BraceInsertionHints) {
154 if (ShortStatementLines && !ForceBracesStmts.erase(S) &&
155 BraceInsertionHints.resultingCompoundLineExtent(*Result.SourceManager) <
156 ShortStatementLines)
157 return false;
158 auto Diag = diag(BraceInsertionHints.DiagnosticPos,
159 "statement should be inside braces");
160 if (BraceInsertionHints.offersFixIts())
161 Diag << BraceInsertionHints.openingBraceFixIt()
162 << BraceInsertionHints.closingBraceFixIt();
163 }
164 return true;
165 }
166
onEndOfTranslationUnit()167 void BracesAroundStatementsCheck::onEndOfTranslationUnit() {
168 ForceBracesStmts.clear();
169 }
170
171 } // namespace clang::tidy::readability
172