clang-tools 10.0.0

ImplicitBoolConversionCheck.cpp
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1 //===--- ImplicitBoolConversionCheck.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 "ImplicitBoolConversionCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13 #include "clang/Tooling/FixIt.h"
14 #include <queue>
15
16 using namespace clang::ast_matchers;
17
18 namespace clang {
19 namespace tidy {
20 namespace readability {
21
22 namespace {
23
24 AST_MATCHER(Stmt, isMacroExpansion) {
25 SourceManager &SM = Finder->getASTContext().getSourceManager();
26 SourceLocation Loc = Node.getBeginLoc();
27 return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
28 }
29
30 bool isNULLMacroExpansion(const Stmt *Statement, ASTContext &Context) {
31 SourceManager &SM = Context.getSourceManager();
32 const LangOptions &LO = Context.getLangOpts();
33 SourceLocation Loc = Statement->getBeginLoc();
34 return SM.isMacroBodyExpansion(Loc) &&
35 Lexer::getImmediateMacroName(Loc, SM, LO) == "NULL";
36 }
37
38 AST_MATCHER(Stmt, isNULLMacroExpansion) {
39 return isNULLMacroExpansion(&Node, Finder->getASTContext());
40 }
41
42 StringRef getZeroLiteralToCompareWithForType(CastKind CastExprKind,
43 QualType Type,
44 ASTContext &Context) {
45 switch (CastExprKind) {
46 case CK_IntegralToBoolean:
47 return Type->isUnsignedIntegerType() ? "0u" : "0";
48
49 case CK_FloatingToBoolean:
50 return Context.hasSameType(Type, Context.FloatTy) ? "0.0f" : "0.0";
51
52 case CK_PointerToBoolean:
53 case CK_MemberPointerToBoolean: // Fall-through on purpose.
54 return Context.getLangOpts().CPlusPlus11 ? "nullptr" : "0";
55
56 default:
57 llvm_unreachable("Unexpected cast kind");
58 }
59 }
60
61 bool isUnaryLogicalNotOperator(const Stmt *Statement) {
62 const auto *UnaryOperatorExpr = dyn_cast<UnaryOperator>(Statement);
63 return UnaryOperatorExpr && UnaryOperatorExpr->getOpcode() == UO_LNot;
64 }
65
66 bool areParensNeededForOverloadedOperator(OverloadedOperatorKind OperatorKind) {
67 switch (OperatorKind) {
68 case OO_New:
69 case OO_Delete: // Fall-through on purpose.
70 case OO_Array_New:
71 case OO_Array_Delete:
72 case OO_ArrowStar:
73 case OO_Arrow:
74 case OO_Call:
75 case OO_Subscript:
76 return false;
77
78 default:
79 return true;
80 }
81 }
82
83 bool areParensNeededForStatement(const Stmt *Statement) {
84 if (const auto *OperatorCall = dyn_cast<CXXOperatorCallExpr>(Statement)) {
85 return areParensNeededForOverloadedOperator(OperatorCall->getOperator());
86 }
87
88 return isa<BinaryOperator>(Statement) || isa<UnaryOperator>(Statement);
89 }
90
91 void fixGenericExprCastToBool(DiagnosticBuilder &Diag,
92 const ImplicitCastExpr *Cast, const Stmt *Parent,
93 ASTContext &Context) {
94 // In case of expressions like (! integer), we should remove the redundant not
95 // operator and use inverted comparison (integer == 0).
96 bool InvertComparison =
97 Parent != nullptr && isUnaryLogicalNotOperator(Parent);
98 if (InvertComparison) {
99 SourceLocation ParentStartLoc = Parent->getBeginLoc();
100 SourceLocation ParentEndLoc =
101 cast<UnaryOperator>(Parent)->getSubExpr()->getBeginLoc();
102 Diag << FixItHint::CreateRemoval(
103 CharSourceRange::getCharRange(ParentStartLoc, ParentEndLoc));
104
105 Parent = Context.getParents(*Parent)[0].get<Stmt>();
106 }
107
108 const Expr *SubExpr = Cast->getSubExpr();
109
110 bool NeedInnerParens = areParensNeededForStatement(SubExpr);
111 bool NeedOuterParens =
112 Parent != nullptr && areParensNeededForStatement(Parent);
113
114 std::string StartLocInsertion;
115
116 if (NeedOuterParens) {
117 StartLocInsertion += "(";
118 }
119 if (NeedInnerParens) {
120 StartLocInsertion += "(";
121 }
122
123 if (!StartLocInsertion.empty()) {
124 Diag << FixItHint::CreateInsertion(Cast->getBeginLoc(), StartLocInsertion);
125 }
126
127 std::string EndLocInsertion;
128
129 if (NeedInnerParens) {
130 EndLocInsertion += ")";
131 }
132
133 if (InvertComparison) {
134 EndLocInsertion += " == ";
135 } else {
136 EndLocInsertion += " != ";
137 }
138
139 EndLocInsertion += getZeroLiteralToCompareWithForType(
140 Cast->getCastKind(), SubExpr->getType(), Context);
141
142 if (NeedOuterParens) {
143 EndLocInsertion += ")";
144 }
145
146 SourceLocation EndLoc = Lexer::getLocForEndOfToken(
147 Cast->getEndLoc(), 0, Context.getSourceManager(), Context.getLangOpts());
148 Diag << FixItHint::CreateInsertion(EndLoc, EndLocInsertion);
149 }
150
151 StringRef getEquivalentBoolLiteralForExpr(const Expr *Expression,
152 ASTContext &Context) {
153 if (isNULLMacroExpansion(Expression, Context)) {
154 return "false";
155 }
156
157 if (const auto *IntLit = dyn_cast<IntegerLiteral>(Expression)) {
158 return (IntLit->getValue() == 0) ? "false" : "true";
159 }
160
161 if (const auto *FloatLit = dyn_cast<FloatingLiteral>(Expression)) {
162 llvm::APFloat FloatLitAbsValue = FloatLit->getValue();
163 FloatLitAbsValue.clearSign();
164 return (FloatLitAbsValue.bitcastToAPInt() == 0) ? "false" : "true";
165 }
166
167 if (const auto *CharLit = dyn_cast<CharacterLiteral>(Expression)) {
168 return (CharLit->getValue() == 0) ? "false" : "true";
169 }
170
171 if (isa<StringLiteral>(Expression->IgnoreCasts())) {
172 return "true";
173 }
174
175 return StringRef();
176 }
177
178 void fixGenericExprCastFromBool(DiagnosticBuilder &Diag,
179 const ImplicitCastExpr *Cast,
180 ASTContext &Context, StringRef OtherType) {
181 const Expr *SubExpr = Cast->getSubExpr();
182 bool NeedParens = !isa<ParenExpr>(SubExpr);
183
184 Diag << FixItHint::CreateInsertion(
185 Cast->getBeginLoc(),
186 (Twine("static_cast<") + OtherType + ">" + (NeedParens ? "(" : ""))
187 .str());
188
189 if (NeedParens) {
190 SourceLocation EndLoc = Lexer::getLocForEndOfToken(
191 Cast->getEndLoc(), 0, Context.getSourceManager(),
192 Context.getLangOpts());
193
194 Diag << FixItHint::CreateInsertion(EndLoc, ")");
195 }
196 }
197
198 StringRef getEquivalentForBoolLiteral(const CXXBoolLiteralExpr *BoolLiteral,
199 QualType DestType, ASTContext &Context) {
200 // Prior to C++11, false literal could be implicitly converted to pointer.
201 if (!Context.getLangOpts().CPlusPlus11 &&
202 (DestType->isPointerType() || DestType->isMemberPointerType()) &&
203 BoolLiteral->getValue() == false) {
204 return "0";
205 }
206
207 if (DestType->isFloatingType()) {
208 if (Context.hasSameType(DestType, Context.FloatTy)) {
209 return BoolLiteral->getValue() ? "1.0f" : "0.0f";
210 }
211 return BoolLiteral->getValue() ? "1.0" : "0.0";
212 }
213
214 if (DestType->isUnsignedIntegerType()) {
215 return BoolLiteral->getValue() ? "1u" : "0u";
216 }
217 return BoolLiteral->getValue() ? "1" : "0";
218 }
219
220 bool isCastAllowedInCondition(const ImplicitCastExpr *Cast,
221 ASTContext &Context) {
222 std::queue<const Stmt *> Q;
223 Q.push(Cast);
224 while (!Q.empty()) {
225 for (const auto &N : Context.getParents(*Q.front())) {
226 const Stmt *S = N.get<Stmt>();
227 if (!S)
228 return false;
229 if (isa<IfStmt>(S) || isa<ConditionalOperator>(S) || isa<ForStmt>(S) ||
230 isa<WhileStmt>(S) || isa<BinaryConditionalOperator>(S))
231 return true;
232 if (isa<ParenExpr>(S) || isa<ImplicitCastExpr>(S) ||
233 isUnaryLogicalNotOperator(S) ||
234 (isa<BinaryOperator>(S) && cast<BinaryOperator>(S)->isLogicalOp())) {
235 Q.push(S);
236 } else {
237 return false;
238 }
239 }
240 Q.pop();
241 }
242 return false;
243 }
244
245 } // anonymous namespace
246
247 ImplicitBoolConversionCheck::ImplicitBoolConversionCheck(
248 StringRef Name, ClangTidyContext *Context)
249 : ClangTidyCheck(Name, Context),
250 AllowIntegerConditions(Options.get("AllowIntegerConditions", false)),
251 AllowPointerConditions(Options.get("AllowPointerConditions", false)) {}
252
253 void ImplicitBoolConversionCheck::storeOptions(
254 ClangTidyOptions::OptionMap &Opts) {
255 Options.store(Opts, "AllowIntegerConditions", AllowIntegerConditions);
256 Options.store(Opts, "AllowPointerConditions", AllowPointerConditions);
257 }
258
259 void ImplicitBoolConversionCheck::registerMatchers(MatchFinder *Finder) {
260 // This check doesn't make much sense if we run it on language without
261 // built-in bool support.
262 if (!getLangOpts().Bool) {
263 return;
264 }
265
266 auto exceptionCases =
267 expr(anyOf(allOf(isMacroExpansion(), unless(isNULLMacroExpansion())),
268 has(ignoringImplicit(memberExpr(hasDeclaration(fieldDecl(hasBitWidth(1)))))),
269 hasParent(explicitCastExpr())));
270 auto implicitCastFromBool = implicitCastExpr(
271 anyOf(hasCastKind(CK_IntegralCast), hasCastKind(CK_IntegralToFloating),
272 // Prior to C++11 cast from bool literal to pointer was allowed.
273 allOf(anyOf(hasCastKind(CK_NullToPointer),
274 hasCastKind(CK_NullToMemberPointer)),
275 hasSourceExpression(cxxBoolLiteral()))),
276 hasSourceExpression(expr(hasType(booleanType()))),
277 unless(exceptionCases));
278 auto boolXor =
279 binaryOperator(hasOperatorName("^"), hasLHS(implicitCastFromBool),
280 hasRHS(implicitCastFromBool));
281 Finder->addMatcher(
282 implicitCastExpr(
283 anyOf(hasCastKind(CK_IntegralToBoolean),
284 hasCastKind(CK_FloatingToBoolean),
285 hasCastKind(CK_PointerToBoolean),
286 hasCastKind(CK_MemberPointerToBoolean)),
287 // Exclude case of using if or while statements with variable
288 // declaration, e.g.:
289 // if (int var = functionCall()) {}
290 unless(
291 hasParent(stmt(anyOf(ifStmt(), whileStmt()), has(declStmt())))),
292 // Exclude cases common to implicit cast to and from bool.
293 unless(exceptionCases), unless(has(boolXor)),
294 // Retrive also parent statement, to check if we need additional
295 // parens in replacement.
296 anyOf(hasParent(stmt().bind("parentStmt")), anything()),
297 unless(isInTemplateInstantiation()),
298 unless(hasAncestor(functionTemplateDecl())))
299 .bind("implicitCastToBool"),
300 this);
301
302 auto boolComparison = binaryOperator(
303 anyOf(hasOperatorName("=="), hasOperatorName("!=")),
304 hasLHS(implicitCastFromBool), hasRHS(implicitCastFromBool));
305 auto boolOpAssignment =
306 binaryOperator(anyOf(hasOperatorName("|="), hasOperatorName("&=")),
307 hasLHS(expr(hasType(booleanType()))));
308 auto bitfieldAssignment = binaryOperator(
309 hasLHS(memberExpr(hasDeclaration(fieldDecl(hasBitWidth(1))))));
310 auto bitfieldConstruct = cxxConstructorDecl(hasDescendant(cxxCtorInitializer(
311 withInitializer(equalsBoundNode("implicitCastFromBool")),
312 forField(hasBitWidth(1)))));
313 Finder->addMatcher(
314 implicitCastExpr(
315 implicitCastFromBool,
316 // Exclude comparisons of bools, as they are always cast to integers
317 // in such context:
318 // bool_expr_a == bool_expr_b
319 // bool_expr_a != bool_expr_b
320 unless(hasParent(binaryOperator(anyOf(
321 boolComparison, boolXor, boolOpAssignment, bitfieldAssignment)))),
322 implicitCastExpr().bind("implicitCastFromBool"),
323 unless(hasParent(bitfieldConstruct)),
324 // Check also for nested casts, for example: bool -> int -> float.
325 anyOf(hasParent(implicitCastExpr().bind("furtherImplicitCast")),
326 anything()),
327 unless(isInTemplateInstantiation()),
328 unless(hasAncestor(functionTemplateDecl()))),
329 this);
330 }
331
332 void ImplicitBoolConversionCheck::check(
333 const MatchFinder::MatchResult &Result) {
334 if (const auto *CastToBool =
335 Result.Nodes.getNodeAs<ImplicitCastExpr>("implicitCastToBool")) {
336 const auto *Parent = Result.Nodes.getNodeAs<Stmt>("parentStmt");
337 return handleCastToBool(CastToBool, Parent, *Result.Context);
338 }
339
340 if (const auto *CastFromBool =
341 Result.Nodes.getNodeAs<ImplicitCastExpr>("implicitCastFromBool")) {
342 const auto *NextImplicitCast =
343 Result.Nodes.getNodeAs<ImplicitCastExpr>("furtherImplicitCast");
344 return handleCastFromBool(CastFromBool, NextImplicitCast, *Result.Context);
345 }
346 }
347
348 void ImplicitBoolConversionCheck::handleCastToBool(const ImplicitCastExpr *Cast,
349 const Stmt *Parent,
350 ASTContext &Context) {
351 if (AllowPointerConditions &&
352 (Cast->getCastKind() == CK_PointerToBoolean ||
353 Cast->getCastKind() == CK_MemberPointerToBoolean) &&
354 isCastAllowedInCondition(Cast, Context)) {
355 return;
356 }
357
358 if (AllowIntegerConditions && Cast->getCastKind() == CK_IntegralToBoolean &&
359 isCastAllowedInCondition(Cast, Context)) {
360 return;
361 }
362
363 auto Diag = diag(Cast->getBeginLoc(), "implicit conversion %0 -> bool")
364 << Cast->getSubExpr()->getType();
365
366 StringRef EquivalentLiteral =
367 getEquivalentBoolLiteralForExpr(Cast->getSubExpr(), Context);
368 if (!EquivalentLiteral.empty()) {
369 Diag << tooling::fixit::createReplacement(*Cast, EquivalentLiteral);
370 } else {
371 fixGenericExprCastToBool(Diag, Cast, Parent, Context);
372 }
373 }
374
375 void ImplicitBoolConversionCheck::handleCastFromBool(
376 const ImplicitCastExpr *Cast, const ImplicitCastExpr *NextImplicitCast,
377 ASTContext &Context) {
378 QualType DestType =
379 NextImplicitCast ? NextImplicitCast->getType() : Cast->getType();
380 auto Diag = diag(Cast->getBeginLoc(), "implicit conversion bool -> %0")
381 << DestType;
382
383 if (const auto *BoolLiteral =
384 dyn_cast<CXXBoolLiteralExpr>(Cast->getSubExpr())) {
385 Diag << tooling::fixit::createReplacement(
386 *Cast, getEquivalentForBoolLiteral(BoolLiteral, DestType, Context));
387 } else {
388 fixGenericExprCastFromBool(Diag, Cast, Context, DestType.getAsString());
389 }
390 }
391
392 } // namespace readability
393 } // namespace tidy
394 } // namespace clang
Loc
SourceLocation Loc
&#39;#&#39; location in the include directive
Definition: IncludeOrderCheck.cpp:37
clang::ast_matchers
Definition: AbseilMatcher.h:14
Parent
const Node * Parent
Definition: ExtractFunction.cpp:148
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:18
clang::tidy::readability::ImplicitBoolConversionCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Definition: ImplicitBoolConversionCheck.cpp:259
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidyCheck.h:47
clang::tidy::ClangTidyCheck::getLangOpts
const LangOptions & getLangOpts() const
Returns the language options from the context.
Definition: ClangTidyCheck.h:188
clang::tidy::readability::ImplicitBoolConversionCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: ImplicitBoolConversionCheck.cpp:332
clang::tidy::ClangTidyCheck::Options
OptionsView Options
Definition: ClangTidyCheck.h:184
clang::tidy::ClangTidyCheck::OptionsView::store
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: ClangTidyCheck.cpp:58
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:27
clang::tidy::ClangTidyOptions::OptionMap
std::map< std::string, std::string > OptionMap
Definition: ClangTidyOptions.h:97
ImplicitBoolConversionCheck.h
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:77
clang::tidy::readability::ImplicitBoolConversionCheck::storeOptions
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
Definition: ImplicitBoolConversionCheck.cpp:253
Type
NodeType Type
Definition: HTMLGenerator.cpp:73
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.
Definition: ClangTidyCheck.cpp:21