1 //===--- SimplifyBooleanExpr.cpp clang-tidy ---------------------*- C++ -*-===//
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 
10 #include "SimplifyBooleanExprCheck.h"
11 #include "clang/Lex/Lexer.h"
12 
13 #include <cassert>
14 #include <string>
15 #include <utility>
16 
17 using namespace clang::ast_matchers;
18 
19 namespace clang {
20 namespace tidy {
21 namespace readability {
22 
23 namespace {
24 
25 StringRef getText(const MatchFinder::MatchResult &Result, SourceRange Range) {
26   return Lexer::getSourceText(CharSourceRange::getTokenRange(Range),
27                               *Result.SourceManager,
28                               Result.Context->getLangOpts());
29 }
30 
31 template <typename T>
32 StringRef getText(const MatchFinder::MatchResult &Result, T &Node) {
33   return getText(Result, Node.getSourceRange());
34 }
35 
36 const char RightExpressionId[] = "bool-op-expr-yields-expr";
37 const char LeftExpressionId[] = "expr-op-bool-yields-expr";
38 const char NegatedRightExpressionId[] = "bool-op-expr-yields-not-expr";
39 const char NegatedLeftExpressionId[] = "expr-op-bool-yields-not-expr";
40 const char ConditionThenStmtId[] = "if-bool-yields-then";
41 const char ConditionElseStmtId[] = "if-bool-yields-else";
42 const char TernaryId[] = "ternary-bool-yields-condition";
43 const char TernaryNegatedId[] = "ternary-bool-yields-not-condition";
44 const char IfReturnsBoolId[] = "if-return";
45 const char IfReturnsNotBoolId[] = "if-not-return";
46 const char ThenLiteralId[] = "then-literal";
47 const char IfAssignVariableId[] = "if-assign-lvalue";
48 const char IfAssignLocId[] = "if-assign-loc";
49 const char IfAssignBoolId[] = "if-assign";
50 const char IfAssignNotBoolId[] = "if-assign-not";
51 const char IfAssignObjId[] = "if-assign-obj";
52 const char CompoundReturnId[] = "compound-return";
53 const char CompoundBoolId[] = "compound-bool";
54 const char CompoundNotBoolId[] = "compound-bool-not";
55 
56 const char IfStmtId[] = "if";
57 const char LHSId[] = "lhs-expr";
58 const char RHSId[] = "rhs-expr";
59 
60 const char SimplifyOperatorDiagnostic[] =
61     "redundant boolean literal supplied to boolean operator";
62 const char SimplifyConditionDiagnostic[] =
63     "redundant boolean literal in if statement condition";
64 const char SimplifyConditionalReturnDiagnostic[] =
65     "redundant boolean literal in conditional return statement";
66 
67 const CXXBoolLiteralExpr *getBoolLiteral(const MatchFinder::MatchResult &Result,
68                                          StringRef Id) {
69   const auto *Literal = Result.Nodes.getNodeAs<CXXBoolLiteralExpr>(Id);
70   return (Literal &&
71           Result.SourceManager->isMacroBodyExpansion(Literal->getLocStart()))
72              ? nullptr
73              : Literal;
74 }
75 
76 internal::Matcher<Stmt> returnsBool(bool Value, StringRef Id = "ignored") {
77   auto SimpleReturnsBool =
78       returnStmt(has(cxxBoolLiteral(equals(Value)).bind(Id)))
79           .bind("returns-bool");
80   return anyOf(SimpleReturnsBool,
81                compoundStmt(statementCountIs(1), has(SimpleReturnsBool)));
82 }
83 
84 bool needsParensAfterUnaryNegation(const Expr *E) {
85   E = E->IgnoreImpCasts();
86   if (isa<BinaryOperator>(E) || isa<ConditionalOperator>(E))
87     return true;
88   if (const auto *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
89     return Op->getNumArgs() == 2 && Op->getOperator() != OO_Call &&
90            Op->getOperator() != OO_Subscript;
91   }
92   return false;
93 }
94 
95 std::pair<BinaryOperatorKind, BinaryOperatorKind> Opposites[] = {
96     {BO_LT, BO_GE}, {BO_GT, BO_LE}, {BO_EQ, BO_NE}};
97 
98 StringRef negatedOperator(const BinaryOperator *BinOp) {
99   const BinaryOperatorKind Opcode = BinOp->getOpcode();
100   for (auto NegatableOp : Opposites) {
101     if (Opcode == NegatableOp.first)
102       return BinOp->getOpcodeStr(NegatableOp.second);
103     if (Opcode == NegatableOp.second)
104       return BinOp->getOpcodeStr(NegatableOp.first);
105   }
106   return StringRef();
107 }
108 
109 std::pair<OverloadedOperatorKind, StringRef> OperatorNames[] = {
110     {OO_EqualEqual, "=="},
111     {OO_ExclaimEqual, "!="},
112     {OO_Less, "<"},
113     {OO_GreaterEqual, ">="},
114     {OO_Greater, ">"},
115     {OO_LessEqual, "<="}};
116 
117 StringRef getOperatorName(OverloadedOperatorKind OpKind) {
118   for (auto Name : OperatorNames) {
119     if (Name.first == OpKind)
120       return Name.second;
121   }
122 
123   return StringRef();
124 }
125 
126 std::pair<OverloadedOperatorKind, OverloadedOperatorKind> OppositeOverloads[] =
127     {{OO_EqualEqual, OO_ExclaimEqual},
128      {OO_Less, OO_GreaterEqual},
129      {OO_Greater, OO_LessEqual}};
130 
131 StringRef negatedOperator(const CXXOperatorCallExpr *OpCall) {
132   const OverloadedOperatorKind Opcode = OpCall->getOperator();
133   for (auto NegatableOp : OppositeOverloads) {
134     if (Opcode == NegatableOp.first)
135       return getOperatorName(NegatableOp.second);
136     if (Opcode == NegatableOp.second)
137       return getOperatorName(NegatableOp.first);
138   }
139   return StringRef();
140 }
141 
142 std::string asBool(StringRef text, bool NeedsStaticCast) {
143   if (NeedsStaticCast)
144     return ("static_cast<bool>(" + text + ")").str();
145 
146   return text;
147 }
148 
149 bool needsNullPtrComparison(const Expr *E) {
150   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E))
151     return ImpCast->getCastKind() == CK_PointerToBoolean;
152 
153   return false;
154 }
155 
156 bool needsStaticCast(const Expr *E) {
157   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
158     if (ImpCast->getCastKind() == CK_UserDefinedConversion &&
159         ImpCast->getSubExpr()->getType()->isBooleanType()) {
160       if (const auto *MemCall =
161               dyn_cast<CXXMemberCallExpr>(ImpCast->getSubExpr())) {
162         if (const auto *MemDecl =
163                 dyn_cast<CXXConversionDecl>(MemCall->getMethodDecl())) {
164           if (MemDecl->isExplicit())
165             return true;
166         }
167       }
168     }
169   }
170 
171   E = E->IgnoreImpCasts();
172   return !E->getType()->isBooleanType();
173 }
174 
175 std::string replacementExpression(const MatchFinder::MatchResult &Result,
176                                   bool Negated, const Expr *E) {
177   E = E->ignoreParenBaseCasts();
178   const bool NeedsStaticCast = needsStaticCast(E);
179   if (Negated) {
180     if (const auto *UnOp = dyn_cast<UnaryOperator>(E)) {
181       if (UnOp->getOpcode() == UO_LNot) {
182         if (needsNullPtrComparison(UnOp->getSubExpr()))
183           return (getText(Result, *UnOp->getSubExpr()) + " != nullptr").str();
184 
185         return replacementExpression(Result, false, UnOp->getSubExpr());
186       }
187     }
188 
189     if (needsNullPtrComparison(E))
190       return (getText(Result, *E) + " == nullptr").str();
191 
192     StringRef NegatedOperator;
193     const Expr *LHS = nullptr;
194     const Expr *RHS = nullptr;
195     if (const auto *BinOp = dyn_cast<BinaryOperator>(E)) {
196       NegatedOperator = negatedOperator(BinOp);
197       LHS = BinOp->getLHS();
198       RHS = BinOp->getRHS();
199     } else if (const auto *OpExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
200       if (OpExpr->getNumArgs() == 2) {
201         NegatedOperator = negatedOperator(OpExpr);
202         LHS = OpExpr->getArg(0);
203         RHS = OpExpr->getArg(1);
204       }
205     }
206     if (!NegatedOperator.empty() && LHS && RHS) {
207       return (asBool((getText(Result, *LHS) + " " + NegatedOperator + " " +
208                       getText(Result, *RHS)).str(),
209                      NeedsStaticCast));
210     }
211 
212     StringRef Text = getText(Result, *E);
213     if (!NeedsStaticCast && needsParensAfterUnaryNegation(E))
214       return ("!(" + Text + ")").str();
215 
216     if (needsNullPtrComparison(E))
217       return (getText(Result, *E) + " == nullptr").str();
218 
219     return ("!" + asBool(Text, NeedsStaticCast));
220   }
221 
222   if (const auto *UnOp = dyn_cast<UnaryOperator>(E)) {
223     if (UnOp->getOpcode() == UO_LNot) {
224       if (needsNullPtrComparison(UnOp->getSubExpr()))
225         return (getText(Result, *UnOp->getSubExpr()) + " == nullptr").str();
226     }
227   }
228 
229   if (needsNullPtrComparison(E))
230     return (getText(Result, *E) + " != nullptr").str();
231 
232   return asBool(getText(Result, *E), NeedsStaticCast);
233 }
234 
235 const CXXBoolLiteralExpr *stmtReturnsBool(const ReturnStmt *Ret, bool Negated) {
236   if (const auto *Bool = dyn_cast<CXXBoolLiteralExpr>(Ret->getRetValue())) {
237     if (Bool->getValue() == !Negated)
238       return Bool;
239   }
240 
241   return nullptr;
242 }
243 
244 const CXXBoolLiteralExpr *stmtReturnsBool(const IfStmt *IfRet, bool Negated) {
245   if (IfRet->getElse() != nullptr)
246     return nullptr;
247 
248   if (const auto *Ret = dyn_cast<ReturnStmt>(IfRet->getThen()))
249     return stmtReturnsBool(Ret, Negated);
250 
251   if (const auto *Compound = dyn_cast<CompoundStmt>(IfRet->getThen())) {
252     if (Compound->size() == 1) {
253       if (const auto *CompoundRet = dyn_cast<ReturnStmt>(Compound->body_back()))
254         return stmtReturnsBool(CompoundRet, Negated);
255     }
256   }
257 
258   return nullptr;
259 }
260 
261 } // namespace
262 
263 SimplifyBooleanExprCheck::SimplifyBooleanExprCheck(StringRef Name,
264                                                    ClangTidyContext *Context)
265     : ClangTidyCheck(Name, Context),
266       ChainedConditionalReturn(Options.get("ChainedConditionalReturn", 0U)),
267       ChainedConditionalAssignment(
268           Options.get("ChainedConditionalAssignment", 0U)) {}
269 
270 void SimplifyBooleanExprCheck::matchBoolBinOpExpr(MatchFinder *Finder,
271                                                   bool Value,
272                                                   StringRef OperatorName,
273                                                   StringRef BooleanId) {
274   Finder->addMatcher(
275       binaryOperator(
276           isExpansionInMainFile(), hasOperatorName(OperatorName),
277           hasLHS(allOf(expr().bind(LHSId),
278                        cxxBoolLiteral(equals(Value)).bind(BooleanId))),
279           hasRHS(expr().bind(RHSId)),
280           unless(hasRHS(hasDescendant(cxxBoolLiteral())))),
281       this);
282 }
283 
284 void SimplifyBooleanExprCheck::matchExprBinOpBool(MatchFinder *Finder,
285                                                   bool Value,
286                                                   StringRef OperatorName,
287                                                   StringRef BooleanId) {
288   Finder->addMatcher(
289       binaryOperator(
290           isExpansionInMainFile(), hasOperatorName(OperatorName),
291           hasLHS(expr().bind(LHSId)),
292           unless(
293               hasLHS(anyOf(cxxBoolLiteral(), hasDescendant(cxxBoolLiteral())))),
294           hasRHS(allOf(expr().bind(RHSId),
295                        cxxBoolLiteral(equals(Value)).bind(BooleanId)))),
296       this);
297 }
298 
299 void SimplifyBooleanExprCheck::matchBoolCompOpExpr(MatchFinder *Finder,
300                                                    bool Value,
301                                                    StringRef OperatorName,
302                                                    StringRef BooleanId) {
303   Finder->addMatcher(
304       binaryOperator(isExpansionInMainFile(), hasOperatorName(OperatorName),
305                      hasLHS(allOf(expr().bind(LHSId),
306                                   ignoringImpCasts(cxxBoolLiteral(equals(Value))
307                                                        .bind(BooleanId)))),
308                      hasRHS(expr().bind(RHSId)),
309                      unless(hasRHS(hasDescendant(cxxBoolLiteral())))),
310       this);
311 }
312 
313 void SimplifyBooleanExprCheck::matchExprCompOpBool(MatchFinder *Finder,
314                                                    bool Value,
315                                                    StringRef OperatorName,
316                                                    StringRef BooleanId) {
317   Finder->addMatcher(
318       binaryOperator(isExpansionInMainFile(), hasOperatorName(OperatorName),
319                      unless(hasLHS(hasDescendant(cxxBoolLiteral()))),
320                      hasLHS(expr().bind(LHSId)),
321                      hasRHS(allOf(expr().bind(RHSId),
322                                   ignoringImpCasts(cxxBoolLiteral(equals(Value))
323                                                        .bind(BooleanId))))),
324       this);
325 }
326 
327 void SimplifyBooleanExprCheck::matchBoolCondition(MatchFinder *Finder,
328                                                   bool Value,
329                                                   StringRef BooleanId) {
330   Finder->addMatcher(ifStmt(isExpansionInMainFile(),
331                             hasCondition(cxxBoolLiteral(equals(Value))
332                                              .bind(BooleanId))).bind(IfStmtId),
333                      this);
334 }
335 
336 void SimplifyBooleanExprCheck::matchTernaryResult(MatchFinder *Finder,
337                                                   bool Value,
338                                                   StringRef TernaryId) {
339   Finder->addMatcher(
340       conditionalOperator(isExpansionInMainFile(),
341                           hasTrueExpression(cxxBoolLiteral(equals(Value))),
342                           hasFalseExpression(cxxBoolLiteral(equals(!Value))))
343           .bind(TernaryId),
344       this);
345 }
346 
347 void SimplifyBooleanExprCheck::matchIfReturnsBool(MatchFinder *Finder,
348                                                   bool Value, StringRef Id) {
349   if (ChainedConditionalReturn) {
350     Finder->addMatcher(ifStmt(isExpansionInMainFile(),
351                               hasThen(returnsBool(Value, ThenLiteralId)),
352                               hasElse(returnsBool(!Value))).bind(Id),
353                        this);
354   } else {
355     Finder->addMatcher(ifStmt(isExpansionInMainFile(),
356                               unless(hasParent(ifStmt())),
357                               hasThen(returnsBool(Value, ThenLiteralId)),
358                               hasElse(returnsBool(!Value))).bind(Id),
359                        this);
360   }
361 }
362 
363 void SimplifyBooleanExprCheck::matchIfAssignsBool(MatchFinder *Finder,
364                                                   bool Value, StringRef Id) {
365   auto SimpleThen = binaryOperator(
366       hasOperatorName("="),
367       hasLHS(declRefExpr(hasDeclaration(decl().bind(IfAssignObjId)))),
368       hasLHS(expr().bind(IfAssignVariableId)),
369       hasRHS(cxxBoolLiteral(equals(Value)).bind(IfAssignLocId)));
370   auto Then = anyOf(SimpleThen, compoundStmt(statementCountIs(1),
371                                              hasAnySubstatement(SimpleThen)));
372   auto SimpleElse = binaryOperator(
373       hasOperatorName("="),
374       hasLHS(declRefExpr(hasDeclaration(equalsBoundNode(IfAssignObjId)))),
375       hasRHS(cxxBoolLiteral(equals(!Value))));
376   auto Else = anyOf(SimpleElse, compoundStmt(statementCountIs(1),
377                                              hasAnySubstatement(SimpleElse)));
378   if (ChainedConditionalAssignment) {
379     Finder->addMatcher(
380         ifStmt(isExpansionInMainFile(), hasThen(Then), hasElse(Else)).bind(Id),
381         this);
382   } else {
383     Finder->addMatcher(ifStmt(isExpansionInMainFile(),
384                               unless(hasParent(ifStmt())), hasThen(Then),
385                               hasElse(Else)).bind(Id),
386                        this);
387   }
388 }
389 
390 void SimplifyBooleanExprCheck::matchCompoundIfReturnsBool(MatchFinder *Finder,
391                                                           bool Value,
392                                                           StringRef Id) {
393   Finder->addMatcher(
394       compoundStmt(allOf(hasAnySubstatement(ifStmt(hasThen(returnsBool(Value)),
395                                                    unless(hasElse(stmt())))),
396                          hasAnySubstatement(
397                              returnStmt(has(cxxBoolLiteral(equals(!Value))))
398                                  .bind(CompoundReturnId)))).bind(Id),
399       this);
400 }
401 
402 void SimplifyBooleanExprCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
403   Options.store(Opts, "ChainedConditionalReturn", ChainedConditionalReturn);
404   Options.store(Opts, "ChainedConditionalAssignment",
405                 ChainedConditionalAssignment);
406 }
407 
408 void SimplifyBooleanExprCheck::registerMatchers(MatchFinder *Finder) {
409   matchBoolBinOpExpr(Finder, true, "&&", RightExpressionId);
410   matchBoolBinOpExpr(Finder, false, "||", RightExpressionId);
411   matchExprBinOpBool(Finder, false, "&&", RightExpressionId);
412   matchExprBinOpBool(Finder, true, "||", RightExpressionId);
413   matchBoolCompOpExpr(Finder, true, "==", RightExpressionId);
414   matchBoolCompOpExpr(Finder, false, "!=", RightExpressionId);
415 
416   matchExprBinOpBool(Finder, true, "&&", LeftExpressionId);
417   matchExprBinOpBool(Finder, false, "||", LeftExpressionId);
418   matchBoolBinOpExpr(Finder, false, "&&", LeftExpressionId);
419   matchBoolBinOpExpr(Finder, true, "||", LeftExpressionId);
420   matchExprCompOpBool(Finder, true, "==", LeftExpressionId);
421   matchExprCompOpBool(Finder, false, "!=", LeftExpressionId);
422 
423   matchBoolCompOpExpr(Finder, false, "==", NegatedRightExpressionId);
424   matchBoolCompOpExpr(Finder, true, "!=", NegatedRightExpressionId);
425 
426   matchExprCompOpBool(Finder, false, "==", NegatedLeftExpressionId);
427   matchExprCompOpBool(Finder, true, "!=", NegatedLeftExpressionId);
428 
429   matchBoolCondition(Finder, true, ConditionThenStmtId);
430   matchBoolCondition(Finder, false, ConditionElseStmtId);
431 
432   matchTernaryResult(Finder, true, TernaryId);
433   matchTernaryResult(Finder, false, TernaryNegatedId);
434 
435   matchIfReturnsBool(Finder, true, IfReturnsBoolId);
436   matchIfReturnsBool(Finder, false, IfReturnsNotBoolId);
437 
438   matchIfAssignsBool(Finder, true, IfAssignBoolId);
439   matchIfAssignsBool(Finder, false, IfAssignNotBoolId);
440 
441   matchCompoundIfReturnsBool(Finder, true, CompoundBoolId);
442   matchCompoundIfReturnsBool(Finder, false, CompoundNotBoolId);
443 }
444 
445 void SimplifyBooleanExprCheck::check(const MatchFinder::MatchResult &Result) {
446   if (const CXXBoolLiteralExpr *LeftRemoved =
447           getBoolLiteral(Result, RightExpressionId)) {
448     replaceWithExpression(Result, LeftRemoved, false);
449   } else if (const CXXBoolLiteralExpr *RightRemoved =
450                  getBoolLiteral(Result, LeftExpressionId)) {
451     replaceWithExpression(Result, RightRemoved, true);
452   } else if (const CXXBoolLiteralExpr *NegatedLeftRemoved =
453                  getBoolLiteral(Result, NegatedRightExpressionId)) {
454     replaceWithExpression(Result, NegatedLeftRemoved, false, true);
455   } else if (const CXXBoolLiteralExpr *NegatedRightRemoved =
456                  getBoolLiteral(Result, NegatedLeftExpressionId)) {
457     replaceWithExpression(Result, NegatedRightRemoved, true, true);
458   } else if (const CXXBoolLiteralExpr *TrueConditionRemoved =
459                  getBoolLiteral(Result, ConditionThenStmtId)) {
460     replaceWithThenStatement(Result, TrueConditionRemoved);
461   } else if (const CXXBoolLiteralExpr *FalseConditionRemoved =
462                  getBoolLiteral(Result, ConditionElseStmtId)) {
463     replaceWithElseStatement(Result, FalseConditionRemoved);
464   } else if (const auto *Ternary =
465                  Result.Nodes.getNodeAs<ConditionalOperator>(TernaryId)) {
466     replaceWithCondition(Result, Ternary);
467   } else if (const auto *TernaryNegated =
468                  Result.Nodes.getNodeAs<ConditionalOperator>(
469                      TernaryNegatedId)) {
470     replaceWithCondition(Result, TernaryNegated, true);
471   } else if (const auto *If = Result.Nodes.getNodeAs<IfStmt>(IfReturnsBoolId)) {
472     replaceWithReturnCondition(Result, If);
473   } else if (const auto *IfNot =
474                  Result.Nodes.getNodeAs<IfStmt>(IfReturnsNotBoolId)) {
475     replaceWithReturnCondition(Result, IfNot, true);
476   } else if (const auto *IfAssign =
477                  Result.Nodes.getNodeAs<IfStmt>(IfAssignBoolId)) {
478     replaceWithAssignment(Result, IfAssign);
479   } else if (const auto *IfAssignNot =
480                  Result.Nodes.getNodeAs<IfStmt>(IfAssignNotBoolId)) {
481     replaceWithAssignment(Result, IfAssignNot, true);
482   } else if (const auto *Compound =
483                  Result.Nodes.getNodeAs<CompoundStmt>(CompoundBoolId)) {
484     replaceCompoundReturnWithCondition(Result, Compound);
485   } else if (const auto *Compound =
486                  Result.Nodes.getNodeAs<CompoundStmt>(CompoundNotBoolId)) {
487     replaceCompoundReturnWithCondition(Result, Compound, true);
488   }
489 }
490 
491 bool containsDiscardedTokens(
492     const ast_matchers::MatchFinder::MatchResult &Result,
493     CharSourceRange CharRange) {
494   std::string ReplacementText =
495       Lexer::getSourceText(CharRange, *Result.SourceManager,
496                            Result.Context->getLangOpts())
497           .str();
498   Lexer Lex(CharRange.getBegin(), Result.Context->getLangOpts(),
499             ReplacementText.data(), ReplacementText.data(),
500             ReplacementText.data() + ReplacementText.size());
501   Lex.SetCommentRetentionState(true);
502   Token Tok;
503 
504   while (!Lex.LexFromRawLexer(Tok)) {
505     if (Tok.is(tok::TokenKind::comment) || Tok.is(tok::TokenKind::hash))
506       return true;
507   }
508 
509   return false;
510 }
511 
512 void SimplifyBooleanExprCheck::issueDiag(
513     const ast_matchers::MatchFinder::MatchResult &Result, SourceLocation Loc,
514     StringRef Description, SourceRange ReplacementRange,
515     StringRef Replacement) {
516   CharSourceRange CharRange = Lexer::makeFileCharRange(
517       CharSourceRange::getTokenRange(ReplacementRange), *Result.SourceManager,
518       Result.Context->getLangOpts());
519 
520   DiagnosticBuilder Diag = diag(Loc, Description);
521   if (!containsDiscardedTokens(Result, CharRange))
522     Diag << FixItHint::CreateReplacement(CharRange, Replacement);
523 }
524 
525 void SimplifyBooleanExprCheck::replaceWithExpression(
526     const ast_matchers::MatchFinder::MatchResult &Result,
527     const CXXBoolLiteralExpr *BoolLiteral, bool UseLHS, bool Negated) {
528   const auto *LHS = Result.Nodes.getNodeAs<Expr>(LHSId);
529   const auto *RHS = Result.Nodes.getNodeAs<Expr>(RHSId);
530   std::string Replacement =
531       replacementExpression(Result, Negated, UseLHS ? LHS : RHS);
532   SourceRange Range(LHS->getLocStart(), RHS->getLocEnd());
533   issueDiag(Result, BoolLiteral->getLocStart(), SimplifyOperatorDiagnostic,
534             Range, Replacement);
535 }
536 
537 void SimplifyBooleanExprCheck::replaceWithThenStatement(
538     const MatchFinder::MatchResult &Result,
539     const CXXBoolLiteralExpr *TrueConditionRemoved) {
540   const auto *IfStatement = Result.Nodes.getNodeAs<IfStmt>(IfStmtId);
541   issueDiag(Result, TrueConditionRemoved->getLocStart(),
542             SimplifyConditionDiagnostic, IfStatement->getSourceRange(),
543             getText(Result, *IfStatement->getThen()));
544 }
545 
546 void SimplifyBooleanExprCheck::replaceWithElseStatement(
547     const MatchFinder::MatchResult &Result,
548     const CXXBoolLiteralExpr *FalseConditionRemoved) {
549   const auto *IfStatement = Result.Nodes.getNodeAs<IfStmt>(IfStmtId);
550   const Stmt *ElseStatement = IfStatement->getElse();
551   issueDiag(Result, FalseConditionRemoved->getLocStart(),
552             SimplifyConditionDiagnostic, IfStatement->getSourceRange(),
553             ElseStatement ? getText(Result, *ElseStatement) : "");
554 }
555 
556 void SimplifyBooleanExprCheck::replaceWithCondition(
557     const MatchFinder::MatchResult &Result, const ConditionalOperator *Ternary,
558     bool Negated) {
559   std::string Replacement =
560       replacementExpression(Result, Negated, Ternary->getCond());
561   issueDiag(Result, Ternary->getTrueExpr()->getLocStart(),
562             "redundant boolean literal in ternary expression result",
563             Ternary->getSourceRange(), Replacement);
564 }
565 
566 void SimplifyBooleanExprCheck::replaceWithReturnCondition(
567     const MatchFinder::MatchResult &Result, const IfStmt *If, bool Negated) {
568   StringRef Terminator = isa<CompoundStmt>(If->getElse()) ? ";" : "";
569   std::string Condition = replacementExpression(Result, Negated, If->getCond());
570   std::string Replacement = ("return " + Condition + Terminator).str();
571   SourceLocation Start =
572       Result.Nodes.getNodeAs<CXXBoolLiteralExpr>(ThenLiteralId)->getLocStart();
573   issueDiag(Result, Start, SimplifyConditionalReturnDiagnostic,
574             If->getSourceRange(), Replacement);
575 }
576 
577 void SimplifyBooleanExprCheck::replaceCompoundReturnWithCondition(
578     const MatchFinder::MatchResult &Result, const CompoundStmt *Compound,
579     bool Negated) {
580   const auto *Ret = Result.Nodes.getNodeAs<ReturnStmt>(CompoundReturnId);
581 
582   // The body shouldn't be empty because the matcher ensures that it must
583   // contain at least two statements:
584   // 1) A `return` statement returning a boolean literal `false` or `true`
585   // 2) An `if` statement with no `else` clause that consists fo a single
586   //    `return` statement returning the opposite boolean literal `true` or
587   //    `false`.
588   assert(Compound->size() >= 2);
589   const IfStmt *BeforeIf = nullptr;
590   CompoundStmt::const_body_iterator Current = Compound->body_begin();
591   CompoundStmt::const_body_iterator After = Compound->body_begin();
592   for (++After; After != Compound->body_end() && *Current != Ret;
593        ++Current, ++After) {
594     if (const auto *If = dyn_cast<IfStmt>(*Current)) {
595       if (const CXXBoolLiteralExpr *Lit = stmtReturnsBool(If, Negated)) {
596         if (*After == Ret) {
597           if (!ChainedConditionalReturn && BeforeIf)
598             continue;
599 
600           const Expr *Condition = If->getCond();
601           std::string Replacement =
602               "return " + replacementExpression(Result, Negated, Condition);
603           issueDiag(
604               Result, Lit->getLocStart(), SimplifyConditionalReturnDiagnostic,
605               SourceRange(If->getLocStart(), Ret->getLocEnd()), Replacement);
606           return;
607         }
608 
609         BeforeIf = If;
610       }
611     } else {
612       BeforeIf = nullptr;
613     }
614   }
615 }
616 
617 void SimplifyBooleanExprCheck::replaceWithAssignment(
618     const MatchFinder::MatchResult &Result, const IfStmt *IfAssign,
619     bool Negated) {
620   SourceRange Range = IfAssign->getSourceRange();
621   StringRef VariableName =
622       getText(Result, *Result.Nodes.getNodeAs<Expr>(IfAssignVariableId));
623   StringRef Terminator = isa<CompoundStmt>(IfAssign->getElse()) ? ";" : "";
624   std::string Condition =
625       replacementExpression(Result, Negated, IfAssign->getCond());
626   std::string Replacement =
627       (VariableName + " = " + Condition + Terminator).str();
628   SourceLocation Location =
629       Result.Nodes.getNodeAs<CXXBoolLiteralExpr>(IfAssignLocId)->getLocStart();
630   issueDiag(Result, Location,
631             "redundant boolean literal in conditional assignment", Range,
632             Replacement);
633 }
634 
635 } // namespace readability
636 } // namespace tidy
637 } // namespace clang
638