clang-tools 10.0.0

VirtualNearMissCheck.cpp
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1 //===--- VirtualNearMissCheck.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 "VirtualNearMissCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/AST/CXXInheritance.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Lex/Lexer.h"
14
15 using namespace clang::ast_matchers;
16
17 namespace clang {
18 namespace tidy {
19 namespace bugprone {
20
21 namespace {
22 AST_MATCHER(CXXMethodDecl, isStatic) { return Node.isStatic(); }
23
24 AST_MATCHER(CXXMethodDecl, isOverloadedOperator) {
25 return Node.isOverloadedOperator();
26 }
27 } // namespace
28
29 /// Finds out if the given method overrides some method.
30 static bool isOverrideMethod(const CXXMethodDecl *MD) {
31 return MD->size_overridden_methods() > 0 || MD->hasAttr<OverrideAttr>();
32 }
33
34 /// Checks whether the return types are covariant, according to
35 /// C++[class.virtual]p7.
36 ///
37 /// Similar with clang::Sema::CheckOverridingFunctionReturnType.
38 /// \returns true if the return types of BaseMD and DerivedMD are covariant.
39 static bool checkOverridingFunctionReturnType(const ASTContext *Context,
40 const CXXMethodDecl *BaseMD,
41 const CXXMethodDecl *DerivedMD) {
42 QualType BaseReturnTy = BaseMD->getType()
43 ->getAs<FunctionType>()
44 ->getReturnType()
45 .getCanonicalType();
46 QualType DerivedReturnTy = DerivedMD->getType()
47 ->getAs<FunctionType>()
48 ->getReturnType()
49 .getCanonicalType();
50
51 if (DerivedReturnTy->isDependentType() || BaseReturnTy->isDependentType())
52 return false;
53
54 // Check if return types are identical.
55 if (Context->hasSameType(DerivedReturnTy, BaseReturnTy))
56 return true;
57
58 /// Check if the return types are covariant.
59
60 // Both types must be pointers or references to classes.
61 if (!(BaseReturnTy->isPointerType() && DerivedReturnTy->isPointerType()) &&
62 !(BaseReturnTy->isReferenceType() && DerivedReturnTy->isReferenceType()))
63 return false;
64
65 /// BTy is the class type in return type of BaseMD. For example,
66 /// B* Base::md()
67 /// While BRD is the declaration of B.
68 QualType DTy = DerivedReturnTy->getPointeeType().getCanonicalType();
69 QualType BTy = BaseReturnTy->getPointeeType().getCanonicalType();
70
71 const CXXRecordDecl *DRD = DTy->getAsCXXRecordDecl();
72 const CXXRecordDecl *BRD = BTy->getAsCXXRecordDecl();
73 if (DRD == nullptr || BRD == nullptr)
74 return false;
75
76 if (!DRD->hasDefinition() || !BRD->hasDefinition())
77 return false;
78
79 if (DRD == BRD)
80 return true;
81
82 if (!Context->hasSameUnqualifiedType(DTy, BTy)) {
83 // Begin checking whether the conversion from D to B is valid.
84 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
85 /*DetectVirtual=*/false);
86
87 // Check whether D is derived from B, and fill in a CXXBasePaths object.
88 if (!DRD->isDerivedFrom(BRD, Paths))
89 return false;
90
91 // Check ambiguity.
92 if (Paths.isAmbiguous(Context->getCanonicalType(BTy).getUnqualifiedType()))
93 return false;
94
95 // Check accessibility.
96 // FIXME: We currently only support checking if B is accessible base class
97 // of D, or D is the same class which DerivedMD is in.
98 bool IsItself =
99 DRD->getCanonicalDecl() == DerivedMD->getParent()->getCanonicalDecl();
100 bool HasPublicAccess = false;
101 for (const auto &Path : Paths) {
102 if (Path.Access == AS_public)
103 HasPublicAccess = true;
104 }
105 if (!HasPublicAccess && !IsItself)
106 return false;
107 // End checking conversion from D to B.
108 }
109
110 // Both pointers or references should have the same cv-qualification.
111 if (DerivedReturnTy.getLocalCVRQualifiers() !=
112 BaseReturnTy.getLocalCVRQualifiers())
113 return false;
114
115 // The class type D should have the same cv-qualification as or less
116 // cv-qualification than the class type B.
117 if (DTy.isMoreQualifiedThan(BTy))
118 return false;
119
120 return true;
121 }
122
123 /// \returns decayed type for arrays and functions.
124 static QualType getDecayedType(QualType Type) {
125 if (const auto *Decayed = Type->getAs<DecayedType>())
126 return Decayed->getDecayedType();
127 return Type;
128 }
129
130 /// \returns true if the param types are the same.
131 static bool checkParamTypes(const CXXMethodDecl *BaseMD,
132 const CXXMethodDecl *DerivedMD) {
133 unsigned NumParamA = BaseMD->getNumParams();
134 unsigned NumParamB = DerivedMD->getNumParams();
135 if (NumParamA != NumParamB)
136 return false;
137
138 for (unsigned I = 0; I < NumParamA; I++) {
139 if (getDecayedType(BaseMD->getParamDecl(I)->getType().getCanonicalType()) !=
140 getDecayedType(
141 DerivedMD->getParamDecl(I)->getType().getCanonicalType()))
142 return false;
143 }
144 return true;
145 }
146
147 /// \returns true if derived method can override base method except for the
148 /// name.
149 static bool checkOverrideWithoutName(const ASTContext *Context,
150 const CXXMethodDecl *BaseMD,
151 const CXXMethodDecl *DerivedMD) {
152 if (BaseMD->isStatic() != DerivedMD->isStatic())
153 return false;
154
155 if (BaseMD->getType() == DerivedMD->getType())
156 return true;
157
158 // Now the function types are not identical. Then check if the return types
159 // are covariant and if the param types are the same.
160 if (!checkOverridingFunctionReturnType(Context, BaseMD, DerivedMD))
161 return false;
162 return checkParamTypes(BaseMD, DerivedMD);
163 }
164
165 /// Check whether BaseMD overrides DerivedMD.
166 ///
167 /// Prerequisite: the class which BaseMD is in should be a base class of that
168 /// DerivedMD is in.
169 static bool checkOverrideByDerivedMethod(const CXXMethodDecl *BaseMD,
170 const CXXMethodDecl *DerivedMD) {
171 for (CXXMethodDecl::method_iterator I = DerivedMD->begin_overridden_methods(),
172 E = DerivedMD->end_overridden_methods();
173 I != E; ++I) {
174 const CXXMethodDecl *OverriddenMD = *I;
175 if (BaseMD->getCanonicalDecl() == OverriddenMD->getCanonicalDecl())
176 return true;
177 }
178
179 return false;
180 }
181
182 bool VirtualNearMissCheck::isPossibleToBeOverridden(
183 const CXXMethodDecl *BaseMD) {
184 auto Iter = PossibleMap.find(BaseMD);
185 if (Iter != PossibleMap.end())
186 return Iter->second;
187
188 bool IsPossible = !BaseMD->isImplicit() && !isa<CXXConstructorDecl>(BaseMD) &&
189 !isa<CXXDestructorDecl>(BaseMD) && BaseMD->isVirtual() &&
190 !BaseMD->isOverloadedOperator() &&
191 !isa<CXXConversionDecl>(BaseMD);
192 PossibleMap[BaseMD] = IsPossible;
193 return IsPossible;
194 }
195
196 bool VirtualNearMissCheck::isOverriddenByDerivedClass(
197 const CXXMethodDecl *BaseMD, const CXXRecordDecl *DerivedRD) {
198 auto Key = std::make_pair(BaseMD, DerivedRD);
199 auto Iter = OverriddenMap.find(Key);
200 if (Iter != OverriddenMap.end())
201 return Iter->second;
202
203 bool IsOverridden = false;
204 for (const CXXMethodDecl *DerivedMD : DerivedRD->methods()) {
205 if (!isOverrideMethod(DerivedMD))
206 continue;
207
208 if (checkOverrideByDerivedMethod(BaseMD, DerivedMD)) {
209 IsOverridden = true;
210 break;
211 }
212 }
213 OverriddenMap[Key] = IsOverridden;
214 return IsOverridden;
215 }
216
217 void VirtualNearMissCheck::registerMatchers(MatchFinder *Finder) {
218 if (!getLangOpts().CPlusPlus)
219 return;
220
221 Finder->addMatcher(
222 cxxMethodDecl(
223 unless(anyOf(isOverride(), isImplicit(), cxxConstructorDecl(),
224 cxxDestructorDecl(), cxxConversionDecl(), isStatic(),
225 isOverloadedOperator())))
226 .bind("method"),
227 this);
228 }
229
230 void VirtualNearMissCheck::check(const MatchFinder::MatchResult &Result) {
231 const auto *DerivedMD = Result.Nodes.getNodeAs<CXXMethodDecl>("method");
232 assert(DerivedMD);
233
234 const ASTContext *Context = Result.Context;
235
236 const auto *DerivedRD = DerivedMD->getParent()->getDefinition();
237 assert(DerivedRD);
238
239 for (const auto &BaseSpec : DerivedRD->bases()) {
240 if (const auto *BaseRD = BaseSpec.getType()->getAsCXXRecordDecl()) {
241 for (const auto *BaseMD : BaseRD->methods()) {
242 if (!isPossibleToBeOverridden(BaseMD))
243 continue;
244
245 if (isOverriddenByDerivedClass(BaseMD, DerivedRD))
246 continue;
247
248 unsigned EditDistance = BaseMD->getName().edit_distance(
249 DerivedMD->getName(), EditDistanceThreshold);
250 if (EditDistance > 0 && EditDistance <= EditDistanceThreshold) {
251 if (checkOverrideWithoutName(Context, BaseMD, DerivedMD)) {
252 // A "virtual near miss" is found.
253 auto Range = CharSourceRange::getTokenRange(
254 SourceRange(DerivedMD->getLocation()));
255
256 bool ApplyFix = !BaseMD->isTemplateInstantiation() &&
257 !DerivedMD->isTemplateInstantiation();
258 auto Diag =
259 diag(DerivedMD->getBeginLoc(),
260 "method '%0' has a similar name and the same signature as "
261 "virtual method '%1'; did you mean to override it?")
262 << DerivedMD->getQualifiedNameAsString()
263 << BaseMD->getQualifiedNameAsString();
264 if (ApplyFix)
265 Diag << FixItHint::CreateReplacement(Range, BaseMD->getName());
266 }
267 }
268 }
269 }
270 }
271 }
272
273 } // namespace bugprone
274 } // namespace tidy
275 } // namespace clang
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::tidy::bugprone::isOverrideMethod
static bool isOverrideMethod(const CXXMethodDecl *MD)
Finds out if the given method overrides some method.
Definition: VirtualNearMissCheck.cpp:30
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:18
clang::tidy::bugprone::checkOverrideWithoutName
static bool checkOverrideWithoutName(const ASTContext *Context, const CXXMethodDecl *BaseMD, const CXXMethodDecl *DerivedMD)
Definition: VirtualNearMissCheck.cpp:149
clang::tidy::bugprone::getDecayedType
static QualType getDecayedType(QualType Type)
Definition: VirtualNearMissCheck.cpp:124
Path
std::vector< HeaderHandle > Path
Definition: PreprocessorTracker.cpp:537
clang::clangd::getReturnType
std::string getReturnType(const CodeCompletionString &CCS)
Gets detail to be used as the detail field in an LSP completion item.
Definition: CodeCompletionStrings.cpp:238
VirtualNearMissCheck.h
clang::tidy::bugprone::checkParamTypes
static bool checkParamTypes(const CXXMethodDecl *BaseMD, const CXXMethodDecl *DerivedMD)
Definition: VirtualNearMissCheck.cpp:131
clang::tidy::bugprone::checkOverridingFunctionReturnType
static bool checkOverridingFunctionReturnType(const ASTContext *Context, const CXXMethodDecl *BaseMD, const CXXMethodDecl *DerivedMD)
Checks whether the return types are covariant, according to C++[class.virtual]p7. ...
Definition: VirtualNearMissCheck.cpp:39
clang::clangd::getTokenRange
llvm::Optional< Range > getTokenRange(const SourceManager &SM, const LangOptions &LangOpts, SourceLocation TokLoc)
Returns the taken range at TokLoc.
Definition: SourceCode.cpp:227
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::doc::MD
static GeneratorRegistry::Add< MDGenerator > MD(MDGenerator::Format, "Generator for MD output.")
Range
CharSourceRange Range
SourceRange for the file name.
Definition: IncludeOrderCheck.cpp:38
clang::tidy::bugprone::checkOverrideByDerivedMethod
static bool checkOverrideByDerivedMethod(const CXXMethodDecl *BaseMD, const CXXMethodDecl *DerivedMD)
Check whether BaseMD overrides DerivedMD.
Definition: VirtualNearMissCheck.cpp:169
E
const Expr * E
Definition: AvoidBindCheck.cpp:82
Type
NodeType Type
Definition: HTMLGenerator.cpp:73