1 //===-- SimplifyBooleanExprCheck.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 "SimplifyBooleanExprCheck.h"
10 #include "clang/AST/RecursiveASTVisitor.h"
11 #include "clang/Lex/Lexer.h"
12 
13 #include <string>
14 #include <utility>
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace readability {
21 
22 namespace {
23 
24 StringRef getText(const ASTContext &Context, SourceRange Range) {
25   return Lexer::getSourceText(CharSourceRange::getTokenRange(Range),
26                               Context.getSourceManager(),
27                               Context.getLangOpts());
28 }
29 
30 template <typename T> StringRef getText(const ASTContext &Context, T &Node) {
31   return getText(Context, Node.getSourceRange());
32 }
33 
34 } // namespace
35 
36 static constexpr char SimplifyOperatorDiagnostic[] =
37     "redundant boolean literal supplied to boolean operator";
38 static constexpr char SimplifyConditionDiagnostic[] =
39     "redundant boolean literal in if statement condition";
40 static constexpr char SimplifyConditionalReturnDiagnostic[] =
41     "redundant boolean literal in conditional return statement";
42 
43 static bool needsParensAfterUnaryNegation(const Expr *E) {
44   E = E->IgnoreImpCasts();
45   if (isa<BinaryOperator>(E) || isa<ConditionalOperator>(E))
46     return true;
47 
48   if (const auto *Op = dyn_cast<CXXOperatorCallExpr>(E))
49     return Op->getNumArgs() == 2 && Op->getOperator() != OO_Call &&
50            Op->getOperator() != OO_Subscript;
51 
52   return false;
53 }
54 
55 static std::pair<BinaryOperatorKind, BinaryOperatorKind> Opposites[] = {
56     {BO_LT, BO_GE}, {BO_GT, BO_LE}, {BO_EQ, BO_NE}};
57 
58 static StringRef negatedOperator(const BinaryOperator *BinOp) {
59   const BinaryOperatorKind Opcode = BinOp->getOpcode();
60   for (auto NegatableOp : Opposites) {
61     if (Opcode == NegatableOp.first)
62       return BinOp->getOpcodeStr(NegatableOp.second);
63     if (Opcode == NegatableOp.second)
64       return BinOp->getOpcodeStr(NegatableOp.first);
65   }
66   return {};
67 }
68 
69 static std::pair<OverloadedOperatorKind, StringRef> OperatorNames[] = {
70     {OO_EqualEqual, "=="},   {OO_ExclaimEqual, "!="}, {OO_Less, "<"},
71     {OO_GreaterEqual, ">="}, {OO_Greater, ">"},       {OO_LessEqual, "<="}};
72 
73 static StringRef getOperatorName(OverloadedOperatorKind OpKind) {
74   for (auto Name : OperatorNames) {
75     if (Name.first == OpKind)
76       return Name.second;
77   }
78 
79   return {};
80 }
81 
82 static std::pair<OverloadedOperatorKind, OverloadedOperatorKind>
83     OppositeOverloads[] = {{OO_EqualEqual, OO_ExclaimEqual},
84                            {OO_Less, OO_GreaterEqual},
85                            {OO_Greater, OO_LessEqual}};
86 
87 static StringRef negatedOperator(const CXXOperatorCallExpr *OpCall) {
88   const OverloadedOperatorKind Opcode = OpCall->getOperator();
89   for (auto NegatableOp : OppositeOverloads) {
90     if (Opcode == NegatableOp.first)
91       return getOperatorName(NegatableOp.second);
92     if (Opcode == NegatableOp.second)
93       return getOperatorName(NegatableOp.first);
94   }
95   return {};
96 }
97 
98 static std::string asBool(StringRef Text, bool NeedsStaticCast) {
99   if (NeedsStaticCast)
100     return ("static_cast<bool>(" + Text + ")").str();
101 
102   return std::string(Text);
103 }
104 
105 static bool needsNullPtrComparison(const Expr *E) {
106   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E))
107     return ImpCast->getCastKind() == CK_PointerToBoolean ||
108            ImpCast->getCastKind() == CK_MemberPointerToBoolean;
109 
110   return false;
111 }
112 
113 static bool needsZeroComparison(const Expr *E) {
114   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E))
115     return ImpCast->getCastKind() == CK_IntegralToBoolean;
116 
117   return false;
118 }
119 
120 static bool needsStaticCast(const Expr *E) {
121   if (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
122     if (ImpCast->getCastKind() == CK_UserDefinedConversion &&
123         ImpCast->getSubExpr()->getType()->isBooleanType()) {
124       if (const auto *MemCall =
125               dyn_cast<CXXMemberCallExpr>(ImpCast->getSubExpr())) {
126         if (const auto *MemDecl =
127                 dyn_cast<CXXConversionDecl>(MemCall->getMethodDecl())) {
128           if (MemDecl->isExplicit())
129             return true;
130         }
131       }
132     }
133   }
134 
135   E = E->IgnoreImpCasts();
136   return !E->getType()->isBooleanType();
137 }
138 
139 static std::string compareExpressionToConstant(const ASTContext &Context,
140                                                const Expr *E, bool Negated,
141                                                const char *Constant) {
142   E = E->IgnoreImpCasts();
143   const std::string ExprText =
144       (isa<BinaryOperator>(E) ? ("(" + getText(Context, *E) + ")")
145                               : getText(Context, *E))
146           .str();
147   return ExprText + " " + (Negated ? "!=" : "==") + " " + Constant;
148 }
149 
150 static std::string compareExpressionToNullPtr(const ASTContext &Context,
151                                               const Expr *E, bool Negated) {
152   const char *NullPtr = Context.getLangOpts().CPlusPlus11 ? "nullptr" : "NULL";
153   return compareExpressionToConstant(Context, E, Negated, NullPtr);
154 }
155 
156 static std::string compareExpressionToZero(const ASTContext &Context,
157                                            const Expr *E, bool Negated) {
158   return compareExpressionToConstant(Context, E, Negated, "0");
159 }
160 
161 static std::string replacementExpression(const ASTContext &Context,
162                                          bool Negated, const Expr *E) {
163   E = E->IgnoreParenBaseCasts();
164   if (const auto *EC = dyn_cast<ExprWithCleanups>(E))
165     E = EC->getSubExpr();
166 
167   const bool NeedsStaticCast = needsStaticCast(E);
168   if (Negated) {
169     if (const auto *UnOp = dyn_cast<UnaryOperator>(E)) {
170       if (UnOp->getOpcode() == UO_LNot) {
171         if (needsNullPtrComparison(UnOp->getSubExpr()))
172           return compareExpressionToNullPtr(Context, UnOp->getSubExpr(), true);
173 
174         if (needsZeroComparison(UnOp->getSubExpr()))
175           return compareExpressionToZero(Context, UnOp->getSubExpr(), true);
176 
177         return replacementExpression(Context, false, UnOp->getSubExpr());
178       }
179     }
180 
181     if (needsNullPtrComparison(E))
182       return compareExpressionToNullPtr(Context, E, false);
183 
184     if (needsZeroComparison(E))
185       return compareExpressionToZero(Context, E, false);
186 
187     StringRef NegatedOperator;
188     const Expr *LHS = nullptr;
189     const Expr *RHS = nullptr;
190     if (const auto *BinOp = dyn_cast<BinaryOperator>(E)) {
191       NegatedOperator = negatedOperator(BinOp);
192       LHS = BinOp->getLHS();
193       RHS = BinOp->getRHS();
194     } else if (const auto *OpExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
195       if (OpExpr->getNumArgs() == 2) {
196         NegatedOperator = negatedOperator(OpExpr);
197         LHS = OpExpr->getArg(0);
198         RHS = OpExpr->getArg(1);
199       }
200     }
201     if (!NegatedOperator.empty() && LHS && RHS)
202       return (asBool((getText(Context, *LHS) + " " + NegatedOperator + " " +
203                       getText(Context, *RHS))
204                          .str(),
205                      NeedsStaticCast));
206 
207     StringRef Text = getText(Context, *E);
208     if (!NeedsStaticCast && needsParensAfterUnaryNegation(E))
209       return ("!(" + Text + ")").str();
210 
211     if (needsNullPtrComparison(E))
212       return compareExpressionToNullPtr(Context, E, false);
213 
214     if (needsZeroComparison(E))
215       return compareExpressionToZero(Context, E, false);
216 
217     return ("!" + asBool(Text, NeedsStaticCast));
218   }
219 
220   if (const auto *UnOp = dyn_cast<UnaryOperator>(E)) {
221     if (UnOp->getOpcode() == UO_LNot) {
222       if (needsNullPtrComparison(UnOp->getSubExpr()))
223         return compareExpressionToNullPtr(Context, UnOp->getSubExpr(), false);
224 
225       if (needsZeroComparison(UnOp->getSubExpr()))
226         return compareExpressionToZero(Context, UnOp->getSubExpr(), false);
227     }
228   }
229 
230   if (needsNullPtrComparison(E))
231     return compareExpressionToNullPtr(Context, E, true);
232 
233   if (needsZeroComparison(E))
234     return compareExpressionToZero(Context, E, true);
235 
236   return asBool(getText(Context, *E), NeedsStaticCast);
237 }
238 
239 static bool containsDiscardedTokens(const ASTContext &Context,
240                                     CharSourceRange CharRange) {
241   std::string ReplacementText =
242       Lexer::getSourceText(CharRange, Context.getSourceManager(),
243                            Context.getLangOpts())
244           .str();
245   Lexer Lex(CharRange.getBegin(), Context.getLangOpts(), ReplacementText.data(),
246             ReplacementText.data(),
247             ReplacementText.data() + ReplacementText.size());
248   Lex.SetCommentRetentionState(true);
249 
250   Token Tok;
251   while (!Lex.LexFromRawLexer(Tok)) {
252     if (Tok.is(tok::TokenKind::comment) || Tok.is(tok::TokenKind::hash))
253       return true;
254   }
255 
256   return false;
257 }
258 
259 class SimplifyBooleanExprCheck::Visitor : public RecursiveASTVisitor<Visitor> {
260 public:
261   Visitor(SimplifyBooleanExprCheck *Check, ASTContext &Context)
262       : Check(Check), Context(Context) {}
263 
264   bool traverse() { return TraverseAST(Context); }
265 
266   static bool shouldIgnore(Stmt *S) {
267     switch (S->getStmtClass()) {
268     case Stmt::ImplicitCastExprClass:
269     case Stmt::MaterializeTemporaryExprClass:
270     case Stmt::CXXBindTemporaryExprClass:
271       return true;
272     default:
273       return false;
274     }
275   }
276 
277   bool dataTraverseStmtPre(Stmt *S) {
278     if (S && !shouldIgnore(S))
279       StmtStack.push_back(S);
280     return true;
281   }
282 
283   bool dataTraverseStmtPost(Stmt *S) {
284     if (S && !shouldIgnore(S)) {
285       assert(StmtStack.back() == S);
286       StmtStack.pop_back();
287     }
288     return true;
289   }
290 
291   bool VisitBinaryOperator(const BinaryOperator *Op) const {
292     Check->reportBinOp(Context, Op);
293     return true;
294   }
295 
296   // Extracts a bool if an expression is (true|false|!true|!false);
297   static Optional<bool> getAsBoolLiteral(const Expr *E, bool FilterMacro) {
298     if (const auto *Bool = dyn_cast<CXXBoolLiteralExpr>(E)) {
299       if (FilterMacro && Bool->getBeginLoc().isMacroID())
300         return llvm::None;
301       return Bool->getValue();
302     }
303     if (const auto *UnaryOp = dyn_cast<UnaryOperator>(E)) {
304       if (FilterMacro && UnaryOp->getBeginLoc().isMacroID())
305         return None;
306       if (UnaryOp->getOpcode() == UO_LNot)
307         if (Optional<bool> Res = getAsBoolLiteral(
308                 UnaryOp->getSubExpr()->IgnoreImplicit(), FilterMacro))
309           return !*Res;
310     }
311     return llvm::None;
312   }
313 
314   template <typename Node> struct NodeAndBool {
315     const Node *Item = nullptr;
316     bool Bool = false;
317 
318     operator bool() const { return Item != nullptr; }
319   };
320 
321   using ExprAndBool = NodeAndBool<Expr>;
322   using DeclAndBool = NodeAndBool<Decl>;
323 
324   /// Detect's return (true|false|!true|!false);
325   static ExprAndBool parseReturnLiteralBool(const Stmt *S) {
326     const auto *RS = dyn_cast<ReturnStmt>(S);
327     if (!RS || !RS->getRetValue())
328       return {};
329     if (Optional<bool> Ret =
330             getAsBoolLiteral(RS->getRetValue()->IgnoreImplicit(), false)) {
331       return {RS->getRetValue(), *Ret};
332     }
333     return {};
334   }
335 
336   /// If \p S is not a \c CompoundStmt, applies F on \p S, otherwise if there is
337   /// only 1 statement in the \c CompoundStmt, applies F on that single
338   /// statement.
339   template <typename Functor>
340   static auto checkSingleStatement(Stmt *S, Functor F) -> decltype(F(S)) {
341     if (auto *CS = dyn_cast<CompoundStmt>(S)) {
342       if (CS->size() == 1)
343         return F(CS->body_front());
344       return {};
345     }
346     return F(S);
347   }
348 
349   Stmt *parent() const {
350     return StmtStack.size() < 2 ? nullptr : StmtStack[StmtStack.size() - 2];
351   }
352 
353   bool VisitIfStmt(IfStmt *If) {
354     // Skip any if's that have a condition var or an init statement.
355     if (If->hasInitStorage() || If->hasVarStorage())
356       return true;
357     /*
358      * if (true) ThenStmt(); -> ThenStmt();
359      * if (false) ThenStmt(); -> <Empty>;
360      * if (false) ThenStmt(); else ElseStmt() -> ElseStmt();
361      */
362     Expr *Cond = If->getCond()->IgnoreImplicit();
363     if (Optional<bool> Bool = getAsBoolLiteral(Cond, true)) {
364       if (*Bool)
365         Check->replaceWithThenStatement(Context, If, Cond);
366       else
367         Check->replaceWithElseStatement(Context, If, Cond);
368     }
369 
370     if (If->getElse()) {
371       /*
372        * if (Cond) return true; else return false; -> return Cond;
373        * if (Cond) return false; else return true; -> return !Cond;
374        */
375       if (ExprAndBool ThenReturnBool =
376               checkSingleStatement(If->getThen(), parseReturnLiteralBool)) {
377         ExprAndBool ElseReturnBool =
378             checkSingleStatement(If->getElse(), parseReturnLiteralBool);
379         if (ElseReturnBool && ThenReturnBool.Bool != ElseReturnBool.Bool) {
380           if (Check->ChainedConditionalReturn ||
381               !isa_and_nonnull<IfStmt>(parent())) {
382             Check->replaceWithReturnCondition(Context, If, ThenReturnBool.Item,
383                                               ElseReturnBool.Bool);
384           }
385         }
386       } else {
387         /*
388          * if (Cond) A = true; else A = false; -> A = Cond;
389          * if (Cond) A = false; else A = true; -> A = !Cond;
390          */
391         Expr *Var = nullptr;
392         SourceLocation Loc;
393         auto VarBoolAssignmentMatcher = [&Var,
394                                          &Loc](const Stmt *S) -> DeclAndBool {
395           const auto *BO = dyn_cast<BinaryOperator>(S);
396           if (!BO || BO->getOpcode() != BO_Assign)
397             return {};
398           Optional<bool> RightasBool =
399               getAsBoolLiteral(BO->getRHS()->IgnoreImplicit(), false);
400           if (!RightasBool)
401             return {};
402           Expr *IgnImp = BO->getLHS()->IgnoreImplicit();
403           if (!Var) {
404             // We only need to track these for the Then branch.
405             Loc = BO->getRHS()->getBeginLoc();
406             Var = IgnImp;
407           }
408           if (auto *DRE = dyn_cast<DeclRefExpr>(IgnImp))
409             return {DRE->getDecl(), *RightasBool};
410           if (auto *ME = dyn_cast<MemberExpr>(IgnImp))
411             return {ME->getMemberDecl(), *RightasBool};
412           return {};
413         };
414         if (DeclAndBool ThenAssignment =
415                 checkSingleStatement(If->getThen(), VarBoolAssignmentMatcher)) {
416           DeclAndBool ElseAssignment =
417               checkSingleStatement(If->getElse(), VarBoolAssignmentMatcher);
418           if (ElseAssignment.Item == ThenAssignment.Item &&
419               ElseAssignment.Bool != ThenAssignment.Bool) {
420             if (Check->ChainedConditionalAssignment ||
421                 !isa_and_nonnull<IfStmt>(parent())) {
422               Check->replaceWithAssignment(Context, If, Var, Loc,
423                                            ElseAssignment.Bool);
424             }
425           }
426         }
427       }
428     }
429     return true;
430   }
431 
432   bool VisitConditionalOperator(ConditionalOperator *Cond) {
433     /*
434      * Condition ? true : false; -> Condition
435      * Condition ? false : true; -> !Condition;
436      */
437     if (Optional<bool> Then =
438             getAsBoolLiteral(Cond->getTrueExpr()->IgnoreImplicit(), false)) {
439       if (Optional<bool> Else =
440               getAsBoolLiteral(Cond->getFalseExpr()->IgnoreImplicit(), false)) {
441         if (*Then != *Else)
442           Check->replaceWithCondition(Context, Cond, *Else);
443       }
444     }
445     return true;
446   }
447 
448   bool VisitCompoundStmt(CompoundStmt *CS) {
449     if (CS->size() < 2)
450       return true;
451     bool CurIf = false, PrevIf = false;
452     for (auto First = CS->body_begin(), Second = std::next(First),
453               End = CS->body_end();
454          Second != End; ++Second, ++First) {
455       PrevIf = CurIf;
456       CurIf = isa<IfStmt>(*First);
457       ExprAndBool TrailingReturnBool = parseReturnLiteralBool(*Second);
458       if (!TrailingReturnBool)
459         continue;
460 
461       if (CurIf) {
462         /*
463          * if (Cond) return true; return false; -> return Cond;
464          * if (Cond) return false; return true; -> return !Cond;
465          */
466         auto *If = cast<IfStmt>(*First);
467         if (!If->hasInitStorage() && !If->hasVarStorage()) {
468           ExprAndBool ThenReturnBool =
469               checkSingleStatement(If->getThen(), parseReturnLiteralBool);
470           if (ThenReturnBool &&
471               ThenReturnBool.Bool != TrailingReturnBool.Bool) {
472             if (Check->ChainedConditionalReturn ||
473                 (!PrevIf && If->getElse() == nullptr)) {
474               Check->replaceCompoundReturnWithCondition(
475                   Context, cast<ReturnStmt>(*Second), TrailingReturnBool.Bool,
476                   If, ThenReturnBool.Item);
477             }
478           }
479         }
480       } else if (isa<LabelStmt, CaseStmt, DefaultStmt>(*First)) {
481         /*
482          * (case X|label_X|default): if (Cond) return BoolLiteral;
483          *                           return !BoolLiteral
484          */
485         Stmt *SubStmt =
486             isa<LabelStmt>(*First)  ? cast<LabelStmt>(*First)->getSubStmt()
487             : isa<CaseStmt>(*First) ? cast<CaseStmt>(*First)->getSubStmt()
488                                     : cast<DefaultStmt>(*First)->getSubStmt();
489         auto *SubIf = dyn_cast<IfStmt>(SubStmt);
490         if (SubIf && !SubIf->getElse() && !SubIf->hasInitStorage() &&
491             !SubIf->hasVarStorage()) {
492           ExprAndBool ThenReturnBool =
493               checkSingleStatement(SubIf->getThen(), parseReturnLiteralBool);
494           if (ThenReturnBool &&
495               ThenReturnBool.Bool != TrailingReturnBool.Bool) {
496             Check->replaceCompoundReturnWithCondition(
497                 Context, cast<ReturnStmt>(*Second), TrailingReturnBool.Bool,
498                 SubIf, ThenReturnBool.Item);
499           }
500         }
501       }
502     }
503     return true;
504   }
505 
506 private:
507   SimplifyBooleanExprCheck *Check;
508   SmallVector<Stmt *, 32> StmtStack;
509   ASTContext &Context;
510 };
511 
512 SimplifyBooleanExprCheck::SimplifyBooleanExprCheck(StringRef Name,
513                                                    ClangTidyContext *Context)
514     : ClangTidyCheck(Name, Context),
515       ChainedConditionalReturn(Options.get("ChainedConditionalReturn", false)),
516       ChainedConditionalAssignment(
517           Options.get("ChainedConditionalAssignment", false)) {}
518 
519 static bool containsBoolLiteral(const Expr *E) {
520   if (!E)
521     return false;
522   E = E->IgnoreParenImpCasts();
523   if (isa<CXXBoolLiteralExpr>(E))
524     return true;
525   if (const auto *BinOp = dyn_cast<BinaryOperator>(E))
526     return containsBoolLiteral(BinOp->getLHS()) ||
527            containsBoolLiteral(BinOp->getRHS());
528   if (const auto *UnaryOp = dyn_cast<UnaryOperator>(E))
529     return containsBoolLiteral(UnaryOp->getSubExpr());
530   return false;
531 }
532 
533 void SimplifyBooleanExprCheck::reportBinOp(const ASTContext &Context,
534                                            const BinaryOperator *Op) {
535   const auto *LHS = Op->getLHS()->IgnoreParenImpCasts();
536   const auto *RHS = Op->getRHS()->IgnoreParenImpCasts();
537 
538   const CXXBoolLiteralExpr *Bool;
539   const Expr *Other;
540   if ((Bool = dyn_cast<CXXBoolLiteralExpr>(LHS)) != nullptr)
541     Other = RHS;
542   else if ((Bool = dyn_cast<CXXBoolLiteralExpr>(RHS)) != nullptr)
543     Other = LHS;
544   else
545     return;
546 
547   if (Bool->getBeginLoc().isMacroID())
548     return;
549 
550   // FIXME: why do we need this?
551   if (!isa<CXXBoolLiteralExpr>(Other) && containsBoolLiteral(Other))
552     return;
553 
554   bool BoolValue = Bool->getValue();
555 
556   auto ReplaceWithExpression = [this, &Context, LHS, RHS,
557                                 Bool](const Expr *ReplaceWith, bool Negated) {
558     std::string Replacement =
559         replacementExpression(Context, Negated, ReplaceWith);
560     SourceRange Range(LHS->getBeginLoc(), RHS->getEndLoc());
561     issueDiag(Context, Bool->getBeginLoc(), SimplifyOperatorDiagnostic, Range,
562               Replacement);
563   };
564 
565   switch (Op->getOpcode()) {
566   case BO_LAnd:
567     if (BoolValue)
568       // expr && true -> expr
569       ReplaceWithExpression(Other, /*Negated=*/false);
570     else
571       // expr && false -> false
572       ReplaceWithExpression(Bool, /*Negated=*/false);
573     break;
574   case BO_LOr:
575     if (BoolValue)
576       // expr || true -> true
577       ReplaceWithExpression(Bool, /*Negated=*/false);
578     else
579       // expr || false -> expr
580       ReplaceWithExpression(Other, /*Negated=*/false);
581     break;
582   case BO_EQ:
583     // expr == true -> expr, expr == false -> !expr
584     ReplaceWithExpression(Other, /*Negated=*/!BoolValue);
585     break;
586   case BO_NE:
587     // expr != true -> !expr, expr != false -> expr
588     ReplaceWithExpression(Other, /*Negated=*/BoolValue);
589     break;
590   default:
591     break;
592   }
593 }
594 
595 void SimplifyBooleanExprCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
596   Options.store(Opts, "ChainedConditionalReturn", ChainedConditionalReturn);
597   Options.store(Opts, "ChainedConditionalAssignment",
598                 ChainedConditionalAssignment);
599 }
600 
601 void SimplifyBooleanExprCheck::registerMatchers(MatchFinder *Finder) {
602   Finder->addMatcher(translationUnitDecl(), this);
603 }
604 
605 void SimplifyBooleanExprCheck::check(const MatchFinder::MatchResult &Result) {
606   Visitor(this, *Result.Context).traverse();
607 }
608 
609 void SimplifyBooleanExprCheck::issueDiag(const ASTContext &Context,
610                                          SourceLocation Loc,
611                                          StringRef Description,
612                                          SourceRange ReplacementRange,
613                                          StringRef Replacement) {
614   CharSourceRange CharRange =
615       Lexer::makeFileCharRange(CharSourceRange::getTokenRange(ReplacementRange),
616                                Context.getSourceManager(), getLangOpts());
617 
618   DiagnosticBuilder Diag = diag(Loc, Description);
619   if (!containsDiscardedTokens(Context, CharRange))
620     Diag << FixItHint::CreateReplacement(CharRange, Replacement);
621 }
622 
623 void SimplifyBooleanExprCheck::replaceWithThenStatement(
624     const ASTContext &Context, const IfStmt *IfStatement,
625     const Expr *BoolLiteral) {
626   issueDiag(Context, BoolLiteral->getBeginLoc(), SimplifyConditionDiagnostic,
627             IfStatement->getSourceRange(),
628             getText(Context, *IfStatement->getThen()));
629 }
630 
631 void SimplifyBooleanExprCheck::replaceWithElseStatement(
632     const ASTContext &Context, const IfStmt *IfStatement,
633     const Expr *BoolLiteral) {
634   const Stmt *ElseStatement = IfStatement->getElse();
635   issueDiag(Context, BoolLiteral->getBeginLoc(), SimplifyConditionDiagnostic,
636             IfStatement->getSourceRange(),
637             ElseStatement ? getText(Context, *ElseStatement) : "");
638 }
639 
640 void SimplifyBooleanExprCheck::replaceWithCondition(
641     const ASTContext &Context, const ConditionalOperator *Ternary,
642     bool Negated) {
643   std::string Replacement =
644       replacementExpression(Context, Negated, Ternary->getCond());
645   issueDiag(Context, Ternary->getTrueExpr()->getBeginLoc(),
646             "redundant boolean literal in ternary expression result",
647             Ternary->getSourceRange(), Replacement);
648 }
649 
650 void SimplifyBooleanExprCheck::replaceWithReturnCondition(
651     const ASTContext &Context, const IfStmt *If, const Expr *BoolLiteral,
652     bool Negated) {
653   StringRef Terminator = isa<CompoundStmt>(If->getElse()) ? ";" : "";
654   std::string Condition =
655       replacementExpression(Context, Negated, If->getCond());
656   std::string Replacement = ("return " + Condition + Terminator).str();
657   SourceLocation Start = BoolLiteral->getBeginLoc();
658   issueDiag(Context, Start, SimplifyConditionalReturnDiagnostic,
659             If->getSourceRange(), Replacement);
660 }
661 
662 void SimplifyBooleanExprCheck::replaceCompoundReturnWithCondition(
663     const ASTContext &Context, const ReturnStmt *Ret, bool Negated,
664     const IfStmt *If, const Expr *ThenReturn) {
665   const std::string Replacement =
666       "return " + replacementExpression(Context, Negated, If->getCond());
667   issueDiag(Context, ThenReturn->getBeginLoc(),
668             SimplifyConditionalReturnDiagnostic,
669             SourceRange(If->getBeginLoc(), Ret->getEndLoc()), Replacement);
670 }
671 
672 void SimplifyBooleanExprCheck::replaceWithAssignment(const ASTContext &Context,
673                                                      const IfStmt *IfAssign,
674                                                      const Expr *Var,
675                                                      SourceLocation Loc,
676                                                      bool Negated) {
677   SourceRange Range = IfAssign->getSourceRange();
678   StringRef VariableName = getText(Context, *Var);
679   StringRef Terminator = isa<CompoundStmt>(IfAssign->getElse()) ? ";" : "";
680   std::string Condition =
681       replacementExpression(Context, Negated, IfAssign->getCond());
682   std::string Replacement =
683       (VariableName + " = " + Condition + Terminator).str();
684   issueDiag(Context, Loc, "redundant boolean literal in conditional assignment",
685             Range, Replacement);
686 }
687 
688 } // namespace readability
689 } // namespace tidy
690 } // namespace clang
691