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/AST/RecursiveASTVisitor.h"
12 #include "clang/Lex/Lexer.h"
13 
14 #include <cassert>
15 #include <string>
16 #include <utility>
17 
18 using namespace clang::ast_matchers;
19 
20 namespace clang {
21 namespace tidy {
22 namespace readability {
23 
24 namespace {
25 
26 StringRef getText(const MatchFinder::MatchResult &Result, SourceRange Range) {
27   return Lexer::getSourceText(CharSourceRange::getTokenRange(Range),
28                               *Result.SourceManager,
29                               Result.Context->getLangOpts());
30 }
31 
32 template <typename T>
33 StringRef getText(const MatchFinder::MatchResult &Result, T &Node) {
34   return getText(Result, Node.getSourceRange());
35 }
36 
37 const char ConditionThenStmtId[] = "if-bool-yields-then";
38 const char ConditionElseStmtId[] = "if-bool-yields-else";
39 const char TernaryId[] = "ternary-bool-yields-condition";
40 const char TernaryNegatedId[] = "ternary-bool-yields-not-condition";
41 const char IfReturnsBoolId[] = "if-return";
42 const char IfReturnsNotBoolId[] = "if-not-return";
43 const char ThenLiteralId[] = "then-literal";
44 const char IfAssignVariableId[] = "if-assign-lvalue";
45 const char IfAssignLocId[] = "if-assign-loc";
46 const char IfAssignBoolId[] = "if-assign";
47 const char IfAssignNotBoolId[] = "if-assign-not";
48 const char IfAssignObjId[] = "if-assign-obj";
49 const char CompoundReturnId[] = "compound-return";
50 const char CompoundBoolId[] = "compound-bool";
51 const char CompoundNotBoolId[] = "compound-bool-not";
52 
53 const char IfStmtId[] = "if";
54 
55 const char SimplifyOperatorDiagnostic[] =
56     "redundant boolean literal supplied to boolean operator";
57 const char SimplifyConditionDiagnostic[] =
58     "redundant boolean literal in if statement condition";
59 const char SimplifyConditionalReturnDiagnostic[] =
60     "redundant boolean literal in conditional return statement";
61 
62 const CXXBoolLiteralExpr *getBoolLiteral(const MatchFinder::MatchResult &Result,
63                                          StringRef Id) {
64   const auto *Literal = Result.Nodes.getNodeAs<CXXBoolLiteralExpr>(Id);
65   return (Literal && Literal->getLocStart().isMacroID()) ? nullptr : Literal;
66 }
67 
68 internal::Matcher<Stmt> returnsBool(bool Value, StringRef Id = "ignored") {
69   auto SimpleReturnsBool =
70       returnStmt(has(cxxBoolLiteral(equals(Value)).bind(Id)))
71           .bind("returns-bool");
72   return anyOf(SimpleReturnsBool,
73                compoundStmt(statementCountIs(1), has(SimpleReturnsBool)));
74 }
75 
76 bool needsParensAfterUnaryNegation(const Expr *E) {
77   E = E->IgnoreImpCasts();
78   if (isa<BinaryOperator>(E) || isa<ConditionalOperator>(E))
79     return true;
80 
81   if (const auto *Op = dyn_cast<CXXOperatorCallExpr>(E))
82     return Op->getNumArgs() == 2 && Op->getOperator() != OO_Call &&
83            Op->getOperator() != OO_Subscript;
84 
85   return false;
86 }
87 
88 std::pair<BinaryOperatorKind, BinaryOperatorKind> Opposites[] = {
89     {BO_LT, BO_GE}, {BO_GT, BO_LE}, {BO_EQ, BO_NE}};
90 
91 StringRef negatedOperator(const BinaryOperator *BinOp) {
92   const BinaryOperatorKind Opcode = BinOp->getOpcode();
93   for (auto NegatableOp : Opposites) {
94     if (Opcode == NegatableOp.first)
95       return BinOp->getOpcodeStr(NegatableOp.second);
96     if (Opcode == NegatableOp.second)
97       return BinOp->getOpcodeStr(NegatableOp.first);
98   }
99   return StringRef();
100 }
101 
102 std::pair<OverloadedOperatorKind, StringRef> OperatorNames[] = {
103     {OO_EqualEqual, "=="},   {OO_ExclaimEqual, "!="}, {OO_Less, "<"},
104     {OO_GreaterEqual, ">="}, {OO_Greater, ">"},       {OO_LessEqual, "<="}};
105 
106 StringRef getOperatorName(OverloadedOperatorKind OpKind) {
107   for (auto Name : OperatorNames) {
108     if (Name.first == OpKind)
109       return Name.second;
110   }
111 
112   return StringRef();
113 }
114 
115 std::pair<OverloadedOperatorKind, OverloadedOperatorKind> OppositeOverloads[] =
116     {{OO_EqualEqual, OO_ExclaimEqual},
117      {OO_Less, OO_GreaterEqual},
118      {OO_Greater, OO_LessEqual}};
119 
120 StringRef negatedOperator(const CXXOperatorCallExpr *OpCall) {
121   const OverloadedOperatorKind Opcode = OpCall->getOperator();
122   for (auto NegatableOp : OppositeOverloads) {
123     if (Opcode == NegatableOp.first)
124       return getOperatorName(NegatableOp.second);
125     if (Opcode == NegatableOp.second)
126       return getOperatorName(NegatableOp.first);
127   }
128   return StringRef();
129 }
130 
131 std::string asBool(StringRef text, bool NeedsStaticCast) {
132   if (NeedsStaticCast)
133     return ("static_cast<bool>(" + text + ")").str();
134 
135   return text;
136 }
137 
138 bool needsNullPtrComparison(const Expr *E) {
139   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E))
140     return ImpCast->getCastKind() == CK_PointerToBoolean ||
141            ImpCast->getCastKind() == CK_MemberPointerToBoolean;
142 
143   return false;
144 }
145 
146 bool needsZeroComparison(const Expr *E) {
147   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E))
148     return ImpCast->getCastKind() == CK_IntegralToBoolean;
149 
150   return false;
151 }
152 
153 bool needsStaticCast(const Expr *E) {
154   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
155     if (ImpCast->getCastKind() == CK_UserDefinedConversion &&
156         ImpCast->getSubExpr()->getType()->isBooleanType()) {
157       if (const auto *MemCall =
158               dyn_cast<CXXMemberCallExpr>(ImpCast->getSubExpr())) {
159         if (const auto *MemDecl =
160                 dyn_cast<CXXConversionDecl>(MemCall->getMethodDecl())) {
161           if (MemDecl->isExplicit())
162             return true;
163         }
164       }
165     }
166   }
167 
168   E = E->IgnoreImpCasts();
169   return !E->getType()->isBooleanType();
170 }
171 
172 std::string compareExpressionToConstant(const MatchFinder::MatchResult &Result,
173                                         const Expr *E, bool Negated,
174                                         const char *Constant) {
175   E = E->IgnoreImpCasts();
176   const std::string ExprText =
177       (isa<BinaryOperator>(E) ? ("(" + getText(Result, *E) + ")")
178                               : getText(Result, *E))
179           .str();
180   return ExprText + " " + (Negated ? "!=" : "==") + " " + Constant;
181 }
182 
183 std::string compareExpressionToNullPtr(const MatchFinder::MatchResult &Result,
184                                        const Expr *E, bool Negated) {
185   const char *NullPtr =
186       Result.Context->getLangOpts().CPlusPlus11 ? "nullptr" : "NULL";
187   return compareExpressionToConstant(Result, E, Negated, NullPtr);
188 }
189 
190 std::string compareExpressionToZero(const MatchFinder::MatchResult &Result,
191                                     const Expr *E, bool Negated) {
192   return compareExpressionToConstant(Result, E, Negated, "0");
193 }
194 
195 std::string replacementExpression(const MatchFinder::MatchResult &Result,
196                                   bool Negated, const Expr *E) {
197   E = E->ignoreParenBaseCasts();
198   const bool NeedsStaticCast = needsStaticCast(E);
199   if (Negated) {
200     if (const auto *UnOp = dyn_cast<UnaryOperator>(E)) {
201       if (UnOp->getOpcode() == UO_LNot) {
202         if (needsNullPtrComparison(UnOp->getSubExpr()))
203           return compareExpressionToNullPtr(Result, UnOp->getSubExpr(), true);
204 
205         if (needsZeroComparison(UnOp->getSubExpr()))
206           return compareExpressionToZero(Result, UnOp->getSubExpr(), true);
207 
208         return replacementExpression(Result, false, UnOp->getSubExpr());
209       }
210     }
211 
212     if (needsNullPtrComparison(E))
213       return compareExpressionToNullPtr(Result, E, false);
214 
215     if (needsZeroComparison(E))
216       return compareExpressionToZero(Result, E, false);
217 
218     StringRef NegatedOperator;
219     const Expr *LHS = nullptr;
220     const Expr *RHS = nullptr;
221     if (const auto *BinOp = dyn_cast<BinaryOperator>(E)) {
222       NegatedOperator = negatedOperator(BinOp);
223       LHS = BinOp->getLHS();
224       RHS = BinOp->getRHS();
225     } else if (const auto *OpExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
226       if (OpExpr->getNumArgs() == 2) {
227         NegatedOperator = negatedOperator(OpExpr);
228         LHS = OpExpr->getArg(0);
229         RHS = OpExpr->getArg(1);
230       }
231     }
232     if (!NegatedOperator.empty() && LHS && RHS)
233       return (asBool((getText(Result, *LHS) + " " + NegatedOperator + " " +
234                       getText(Result, *RHS))
235                          .str(),
236                      NeedsStaticCast));
237 
238     StringRef Text = getText(Result, *E);
239     if (!NeedsStaticCast && needsParensAfterUnaryNegation(E))
240       return ("!(" + Text + ")").str();
241 
242     if (needsNullPtrComparison(E))
243       return compareExpressionToNullPtr(Result, E, false);
244 
245     if (needsZeroComparison(E))
246       return compareExpressionToZero(Result, E, false);
247 
248     return ("!" + asBool(Text, NeedsStaticCast));
249   }
250 
251   if (const auto *UnOp = dyn_cast<UnaryOperator>(E)) {
252     if (UnOp->getOpcode() == UO_LNot) {
253       if (needsNullPtrComparison(UnOp->getSubExpr()))
254         return compareExpressionToNullPtr(Result, UnOp->getSubExpr(), false);
255 
256       if (needsZeroComparison(UnOp->getSubExpr()))
257         return compareExpressionToZero(Result, UnOp->getSubExpr(), false);
258     }
259   }
260 
261   if (needsNullPtrComparison(E))
262     return compareExpressionToNullPtr(Result, E, true);
263 
264   if (needsZeroComparison(E))
265     return compareExpressionToZero(Result, E, true);
266 
267   return asBool(getText(Result, *E), NeedsStaticCast);
268 }
269 
270 const CXXBoolLiteralExpr *stmtReturnsBool(const ReturnStmt *Ret, bool Negated) {
271   if (const auto *Bool = dyn_cast<CXXBoolLiteralExpr>(Ret->getRetValue())) {
272     if (Bool->getValue() == !Negated)
273       return Bool;
274   }
275 
276   return nullptr;
277 }
278 
279 const CXXBoolLiteralExpr *stmtReturnsBool(const IfStmt *IfRet, bool Negated) {
280   if (IfRet->getElse() != nullptr)
281     return nullptr;
282 
283   if (const auto *Ret = dyn_cast<ReturnStmt>(IfRet->getThen()))
284     return stmtReturnsBool(Ret, Negated);
285 
286   if (const auto *Compound = dyn_cast<CompoundStmt>(IfRet->getThen())) {
287     if (Compound->size() == 1) {
288       if (const auto *CompoundRet = dyn_cast<ReturnStmt>(Compound->body_back()))
289         return stmtReturnsBool(CompoundRet, Negated);
290     }
291   }
292 
293   return nullptr;
294 }
295 
296 bool containsDiscardedTokens(const MatchFinder::MatchResult &Result,
297                              CharSourceRange CharRange) {
298   std::string ReplacementText =
299       Lexer::getSourceText(CharRange, *Result.SourceManager,
300                            Result.Context->getLangOpts())
301           .str();
302   Lexer Lex(CharRange.getBegin(), Result.Context->getLangOpts(),
303             ReplacementText.data(), ReplacementText.data(),
304             ReplacementText.data() + ReplacementText.size());
305   Lex.SetCommentRetentionState(true);
306 
307   Token Tok;
308   while (!Lex.LexFromRawLexer(Tok)) {
309     if (Tok.is(tok::TokenKind::comment) || Tok.is(tok::TokenKind::hash))
310       return true;
311   }
312 
313   return false;
314 }
315 
316 } // namespace
317 
318 class SimplifyBooleanExprCheck::Visitor : public RecursiveASTVisitor<Visitor> {
319   using Base = RecursiveASTVisitor<Visitor>;
320 
321  public:
322   Visitor(SimplifyBooleanExprCheck *Check,
323           const MatchFinder::MatchResult &Result)
324       : Check(Check), Result(Result) {}
325 
326   bool VisitBinaryOperator(BinaryOperator *Op) {
327     Check->reportBinOp(Result, Op);
328     return true;
329   }
330 
331  private:
332   SimplifyBooleanExprCheck *Check;
333   const MatchFinder::MatchResult &Result;
334 };
335 
336 
337 SimplifyBooleanExprCheck::SimplifyBooleanExprCheck(StringRef Name,
338                                                    ClangTidyContext *Context)
339     : ClangTidyCheck(Name, Context),
340       ChainedConditionalReturn(Options.get("ChainedConditionalReturn", 0U)),
341       ChainedConditionalAssignment(
342           Options.get("ChainedConditionalAssignment", 0U)) {}
343 
344 bool containsBoolLiteral(const Expr *E) {
345   if (!E)
346     return false;
347   E = E->IgnoreParenImpCasts();
348   if (isa<CXXBoolLiteralExpr>(E))
349     return true;
350   if (const auto *BinOp = dyn_cast<BinaryOperator>(E))
351     return containsBoolLiteral(BinOp->getLHS()) ||
352            containsBoolLiteral(BinOp->getRHS());
353   if (const auto *UnaryOp = dyn_cast<UnaryOperator>(E))
354     return containsBoolLiteral(UnaryOp->getSubExpr());
355   return false;
356 }
357 
358 void SimplifyBooleanExprCheck::reportBinOp(
359     const MatchFinder::MatchResult &Result, const BinaryOperator *Op) {
360   const auto *LHS = Op->getLHS()->IgnoreParenImpCasts();
361   const auto *RHS = Op->getRHS()->IgnoreParenImpCasts();
362 
363   const CXXBoolLiteralExpr *Bool = nullptr;
364   const Expr *Other = nullptr;
365   if ((Bool = dyn_cast<CXXBoolLiteralExpr>(LHS)))
366     Other = RHS;
367   else if ((Bool = dyn_cast<CXXBoolLiteralExpr>(RHS)))
368     Other = LHS;
369   else
370     return;
371 
372   if (Bool->getLocStart().isMacroID())
373     return;
374 
375   // FIXME: why do we need this?
376   if (!isa<CXXBoolLiteralExpr>(Other) && containsBoolLiteral(Other))
377     return;
378 
379   bool BoolValue = Bool->getValue();
380 
381   auto replaceWithExpression = [this, &Result, LHS, RHS, Bool](
382                                    const Expr *ReplaceWith, bool Negated) {
383     std::string Replacement =
384         replacementExpression(Result, Negated, ReplaceWith);
385     SourceRange Range(LHS->getLocStart(), RHS->getLocEnd());
386     issueDiag(Result, Bool->getLocStart(), SimplifyOperatorDiagnostic, Range,
387               Replacement);
388   };
389 
390   switch (Op->getOpcode()) {
391     case BO_LAnd:
392       if (BoolValue) {
393         // expr && true -> expr
394         replaceWithExpression(Other, /*Negated=*/false);
395       } else {
396         // expr && false -> false
397         replaceWithExpression(Bool, /*Negated=*/false);
398       }
399       break;
400     case BO_LOr:
401       if (BoolValue) {
402         // expr || true -> true
403         replaceWithExpression(Bool, /*Negated=*/false);
404       } else {
405         // expr || false -> expr
406         replaceWithExpression(Other, /*Negated=*/false);
407       }
408       break;
409     case BO_EQ:
410       // expr == true -> expr, expr == false -> !expr
411       replaceWithExpression(Other, /*Negated=*/!BoolValue);
412       break;
413     case BO_NE:
414       // expr != true -> !expr, expr != false -> expr
415       replaceWithExpression(Other, /*Negated=*/BoolValue);
416       break;
417     default:
418       break;
419   }
420 }
421 
422 void SimplifyBooleanExprCheck::matchBoolCondition(MatchFinder *Finder,
423                                                   bool Value,
424                                                   StringRef BooleanId) {
425   Finder->addMatcher(
426       ifStmt(isExpansionInMainFile(),
427              hasCondition(cxxBoolLiteral(equals(Value)).bind(BooleanId)))
428           .bind(IfStmtId),
429       this);
430 }
431 
432 void SimplifyBooleanExprCheck::matchTernaryResult(MatchFinder *Finder,
433                                                   bool Value,
434                                                   StringRef TernaryId) {
435   Finder->addMatcher(
436       conditionalOperator(isExpansionInMainFile(),
437                           hasTrueExpression(cxxBoolLiteral(equals(Value))),
438                           hasFalseExpression(cxxBoolLiteral(equals(!Value))))
439           .bind(TernaryId),
440       this);
441 }
442 
443 void SimplifyBooleanExprCheck::matchIfReturnsBool(MatchFinder *Finder,
444                                                   bool Value, StringRef Id) {
445   if (ChainedConditionalReturn)
446     Finder->addMatcher(ifStmt(isExpansionInMainFile(),
447                               hasThen(returnsBool(Value, ThenLiteralId)),
448                               hasElse(returnsBool(!Value)))
449                            .bind(Id),
450                        this);
451   else
452     Finder->addMatcher(ifStmt(isExpansionInMainFile(),
453                               unless(hasParent(ifStmt())),
454                               hasThen(returnsBool(Value, ThenLiteralId)),
455                               hasElse(returnsBool(!Value)))
456                            .bind(Id),
457                        this);
458 }
459 
460 void SimplifyBooleanExprCheck::matchIfAssignsBool(MatchFinder *Finder,
461                                                   bool Value, StringRef Id) {
462   auto SimpleThen = binaryOperator(
463       hasOperatorName("="),
464       hasLHS(declRefExpr(hasDeclaration(decl().bind(IfAssignObjId)))),
465       hasLHS(expr().bind(IfAssignVariableId)),
466       hasRHS(cxxBoolLiteral(equals(Value)).bind(IfAssignLocId)));
467   auto Then = anyOf(SimpleThen, compoundStmt(statementCountIs(1),
468                                              hasAnySubstatement(SimpleThen)));
469   auto SimpleElse = binaryOperator(
470       hasOperatorName("="),
471       hasLHS(declRefExpr(hasDeclaration(equalsBoundNode(IfAssignObjId)))),
472       hasRHS(cxxBoolLiteral(equals(!Value))));
473   auto Else = anyOf(SimpleElse, compoundStmt(statementCountIs(1),
474                                              hasAnySubstatement(SimpleElse)));
475   if (ChainedConditionalAssignment)
476     Finder->addMatcher(
477         ifStmt(isExpansionInMainFile(), hasThen(Then), hasElse(Else)).bind(Id),
478         this);
479   else
480     Finder->addMatcher(ifStmt(isExpansionInMainFile(),
481                               unless(hasParent(ifStmt())), hasThen(Then),
482                               hasElse(Else))
483                            .bind(Id),
484                        this);
485 }
486 
487 void SimplifyBooleanExprCheck::matchCompoundIfReturnsBool(MatchFinder *Finder,
488                                                           bool Value,
489                                                           StringRef Id) {
490   Finder->addMatcher(
491       compoundStmt(allOf(hasAnySubstatement(ifStmt(hasThen(returnsBool(Value)),
492                                                    unless(hasElse(stmt())))),
493                          hasAnySubstatement(
494                              returnStmt(has(ignoringParenImpCasts(
495                                             cxxBoolLiteral(equals(!Value)))))
496                                  .bind(CompoundReturnId))))
497           .bind(Id),
498       this);
499 }
500 
501 void SimplifyBooleanExprCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
502   Options.store(Opts, "ChainedConditionalReturn", ChainedConditionalReturn);
503   Options.store(Opts, "ChainedConditionalAssignment",
504                 ChainedConditionalAssignment);
505 }
506 
507 void SimplifyBooleanExprCheck::registerMatchers(MatchFinder *Finder) {
508   Finder->addMatcher(translationUnitDecl().bind("top"), this);
509 
510   matchBoolCondition(Finder, true, ConditionThenStmtId);
511   matchBoolCondition(Finder, false, ConditionElseStmtId);
512 
513   matchTernaryResult(Finder, true, TernaryId);
514   matchTernaryResult(Finder, false, TernaryNegatedId);
515 
516   matchIfReturnsBool(Finder, true, IfReturnsBoolId);
517   matchIfReturnsBool(Finder, false, IfReturnsNotBoolId);
518 
519   matchIfAssignsBool(Finder, true, IfAssignBoolId);
520   matchIfAssignsBool(Finder, false, IfAssignNotBoolId);
521 
522   matchCompoundIfReturnsBool(Finder, true, CompoundBoolId);
523   matchCompoundIfReturnsBool(Finder, false, CompoundNotBoolId);
524 }
525 
526 void SimplifyBooleanExprCheck::check(const MatchFinder::MatchResult &Result) {
527   if (const CXXBoolLiteralExpr *TrueConditionRemoved =
528           getBoolLiteral(Result, ConditionThenStmtId))
529     replaceWithThenStatement(Result, TrueConditionRemoved);
530   else if (const CXXBoolLiteralExpr *FalseConditionRemoved =
531                getBoolLiteral(Result, ConditionElseStmtId))
532     replaceWithElseStatement(Result, FalseConditionRemoved);
533   else if (const auto *Ternary =
534                Result.Nodes.getNodeAs<ConditionalOperator>(TernaryId))
535     replaceWithCondition(Result, Ternary);
536   else if (const auto *TernaryNegated =
537                Result.Nodes.getNodeAs<ConditionalOperator>(TernaryNegatedId))
538     replaceWithCondition(Result, TernaryNegated, true);
539   else if (const auto *If = Result.Nodes.getNodeAs<IfStmt>(IfReturnsBoolId))
540     replaceWithReturnCondition(Result, If);
541   else if (const auto *IfNot =
542                Result.Nodes.getNodeAs<IfStmt>(IfReturnsNotBoolId))
543     replaceWithReturnCondition(Result, IfNot, true);
544   else if (const auto *IfAssign =
545                Result.Nodes.getNodeAs<IfStmt>(IfAssignBoolId))
546     replaceWithAssignment(Result, IfAssign);
547   else if (const auto *IfAssignNot =
548                Result.Nodes.getNodeAs<IfStmt>(IfAssignNotBoolId))
549     replaceWithAssignment(Result, IfAssignNot, true);
550   else if (const auto *Compound =
551                Result.Nodes.getNodeAs<CompoundStmt>(CompoundBoolId))
552     replaceCompoundReturnWithCondition(Result, Compound);
553   else if (const auto *Compound =
554                Result.Nodes.getNodeAs<CompoundStmt>(CompoundNotBoolId))
555     replaceCompoundReturnWithCondition(Result, Compound, true);
556   else if (const auto TU = Result.Nodes.getNodeAs<Decl>("top"))
557     Visitor(this, Result).TraverseDecl(const_cast<Decl*>(TU));
558 }
559 
560 void SimplifyBooleanExprCheck::issueDiag(
561     const ast_matchers::MatchFinder::MatchResult &Result, SourceLocation Loc,
562     StringRef Description, SourceRange ReplacementRange,
563     StringRef Replacement) {
564   CharSourceRange CharRange =
565       Lexer::makeFileCharRange(CharSourceRange::getTokenRange(ReplacementRange),
566                                *Result.SourceManager, getLangOpts());
567 
568   DiagnosticBuilder Diag = diag(Loc, Description);
569   if (!containsDiscardedTokens(Result, CharRange))
570     Diag << FixItHint::CreateReplacement(CharRange, Replacement);
571 }
572 
573 void SimplifyBooleanExprCheck::replaceWithThenStatement(
574     const MatchFinder::MatchResult &Result,
575     const CXXBoolLiteralExpr *TrueConditionRemoved) {
576   const auto *IfStatement = Result.Nodes.getNodeAs<IfStmt>(IfStmtId);
577   issueDiag(Result, TrueConditionRemoved->getLocStart(),
578             SimplifyConditionDiagnostic, IfStatement->getSourceRange(),
579             getText(Result, *IfStatement->getThen()));
580 }
581 
582 void SimplifyBooleanExprCheck::replaceWithElseStatement(
583     const MatchFinder::MatchResult &Result,
584     const CXXBoolLiteralExpr *FalseConditionRemoved) {
585   const auto *IfStatement = Result.Nodes.getNodeAs<IfStmt>(IfStmtId);
586   const Stmt *ElseStatement = IfStatement->getElse();
587   issueDiag(Result, FalseConditionRemoved->getLocStart(),
588             SimplifyConditionDiagnostic, IfStatement->getSourceRange(),
589             ElseStatement ? getText(Result, *ElseStatement) : "");
590 }
591 
592 void SimplifyBooleanExprCheck::replaceWithCondition(
593     const MatchFinder::MatchResult &Result, const ConditionalOperator *Ternary,
594     bool Negated) {
595   std::string Replacement =
596       replacementExpression(Result, Negated, Ternary->getCond());
597   issueDiag(Result, Ternary->getTrueExpr()->getLocStart(),
598             "redundant boolean literal in ternary expression result",
599             Ternary->getSourceRange(), Replacement);
600 }
601 
602 void SimplifyBooleanExprCheck::replaceWithReturnCondition(
603     const MatchFinder::MatchResult &Result, const IfStmt *If, bool Negated) {
604   StringRef Terminator = isa<CompoundStmt>(If->getElse()) ? ";" : "";
605   std::string Condition = replacementExpression(Result, Negated, If->getCond());
606   std::string Replacement = ("return " + Condition + Terminator).str();
607   SourceLocation Start =
608       Result.Nodes.getNodeAs<CXXBoolLiteralExpr>(ThenLiteralId)->getLocStart();
609   issueDiag(Result, Start, SimplifyConditionalReturnDiagnostic,
610             If->getSourceRange(), Replacement);
611 }
612 
613 void SimplifyBooleanExprCheck::replaceCompoundReturnWithCondition(
614     const MatchFinder::MatchResult &Result, const CompoundStmt *Compound,
615     bool Negated) {
616   const auto *Ret = Result.Nodes.getNodeAs<ReturnStmt>(CompoundReturnId);
617 
618   // The body shouldn't be empty because the matcher ensures that it must
619   // contain at least two statements:
620   // 1) A `return` statement returning a boolean literal `false` or `true`
621   // 2) An `if` statement with no `else` clause that consists of a single
622   //    `return` statement returning the opposite boolean literal `true` or
623   //    `false`.
624   assert(Compound->size() >= 2);
625   const IfStmt *BeforeIf = nullptr;
626   CompoundStmt::const_body_iterator Current = Compound->body_begin();
627   CompoundStmt::const_body_iterator After = Compound->body_begin();
628   for (++After; After != Compound->body_end() && *Current != Ret;
629        ++Current, ++After) {
630     if (const auto *If = dyn_cast<IfStmt>(*Current)) {
631       if (const CXXBoolLiteralExpr *Lit = stmtReturnsBool(If, Negated)) {
632         if (*After == Ret) {
633           if (!ChainedConditionalReturn && BeforeIf)
634             continue;
635 
636           const Expr *Condition = If->getCond();
637           std::string Replacement =
638               "return " + replacementExpression(Result, Negated, Condition);
639           issueDiag(
640               Result, Lit->getLocStart(), SimplifyConditionalReturnDiagnostic,
641               SourceRange(If->getLocStart(), Ret->getLocEnd()), Replacement);
642           return;
643         }
644 
645         BeforeIf = If;
646       }
647     } else {
648       BeforeIf = nullptr;
649     }
650   }
651 }
652 
653 void SimplifyBooleanExprCheck::replaceWithAssignment(
654     const MatchFinder::MatchResult &Result, const IfStmt *IfAssign,
655     bool Negated) {
656   SourceRange Range = IfAssign->getSourceRange();
657   StringRef VariableName =
658       getText(Result, *Result.Nodes.getNodeAs<Expr>(IfAssignVariableId));
659   StringRef Terminator = isa<CompoundStmt>(IfAssign->getElse()) ? ";" : "";
660   std::string Condition =
661       replacementExpression(Result, Negated, IfAssign->getCond());
662   std::string Replacement =
663       (VariableName + " = " + Condition + Terminator).str();
664   SourceLocation Location =
665       Result.Nodes.getNodeAs<CXXBoolLiteralExpr>(IfAssignLocId)->getLocStart();
666   issueDiag(Result, Location,
667             "redundant boolean literal in conditional assignment", Range,
668             Replacement);
669 }
670 
671 } // namespace readability
672 } // namespace tidy
673 } // namespace clang
674