clang-tools 10.0.0

MagicNumbersCheck.cpp
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1 //===--- MagicNumbersCheck.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 // A checker for magic numbers: integer or floating point literals embedded
10 // in the code, outside the definition of a constant or an enumeration.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "MagicNumbersCheck.h"
15 #include "../utils/OptionsUtils.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/ASTMatchers/ASTMatchFinder.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include <algorithm>
20
21 using namespace clang::ast_matchers;
22 using namespace clang::ast_type_traits;
23
24 namespace clang {
25
26 static bool isUsedToInitializeAConstant(const MatchFinder::MatchResult &Result,
27 const DynTypedNode &Node) {
28
29 const auto *AsDecl = Node.get<DeclaratorDecl>();
30 if (AsDecl) {
31 if (AsDecl->getType().isConstQualified())
32 return true;
33
34 return AsDecl->isImplicit();
35 }
36
37 if (Node.get<EnumConstantDecl>())
38 return true;
39
40 return llvm::any_of(Result.Context->getParents(Node),
41 [&Result](const DynTypedNode &Parent) {
42 return isUsedToInitializeAConstant(Result, Parent);
43 });
44 }
45
46 static bool isUsedToDefineABitField(const MatchFinder::MatchResult &Result,
47 const DynTypedNode &Node) {
48 const auto *AsFieldDecl = Node.get<FieldDecl>();
49 if (AsFieldDecl && AsFieldDecl->isBitField())
50 return true;
51
52 return llvm::any_of(Result.Context->getParents(Node),
53 [&Result](const DynTypedNode &Parent) {
54 return isUsedToDefineABitField(Result, Parent);
55 });
56 }
57
58 namespace tidy {
59 namespace readability {
60
61 const char DefaultIgnoredIntegerValues[] = "1;2;3;4;";
62 const char DefaultIgnoredFloatingPointValues[] = "1.0;100.0;";
63
64 MagicNumbersCheck::MagicNumbersCheck(StringRef Name, ClangTidyContext *Context)
65 : ClangTidyCheck(Name, Context),
66 IgnoreAllFloatingPointValues(
67 Options.get("IgnoreAllFloatingPointValues", false)),
68 IgnoreBitFieldsWidths(Options.get("IgnoreBitFieldsWidths", true)),
69 IgnorePowersOf2IntegerValues(
70 Options.get("IgnorePowersOf2IntegerValues", false)) {
71 // Process the set of ignored integer values.
72 const std::vector<std::string> IgnoredIntegerValuesInput =
73 utils::options::parseStringList(
74 Options.get("IgnoredIntegerValues", DefaultIgnoredIntegerValues));
75 IgnoredIntegerValues.resize(IgnoredIntegerValuesInput.size());
76 llvm::transform(IgnoredIntegerValuesInput, IgnoredIntegerValues.begin(),
77 [](const std::string &Value) { return std::stoll(Value); });
78 llvm::sort(IgnoredIntegerValues);
79
80 if (!IgnoreAllFloatingPointValues) {
81 // Process the set of ignored floating point values.
82 const std::vector<std::string> IgnoredFloatingPointValuesInput =
83 utils::options::parseStringList(Options.get(
84 "IgnoredFloatingPointValues", DefaultIgnoredFloatingPointValues));
85 IgnoredFloatingPointValues.reserve(IgnoredFloatingPointValuesInput.size());
86 IgnoredDoublePointValues.reserve(IgnoredFloatingPointValuesInput.size());
87 for (const auto &InputValue : IgnoredFloatingPointValuesInput) {
88 llvm::APFloat FloatValue(llvm::APFloat::IEEEsingle());
89 auto StatusOrErr =
90 FloatValue.convertFromString(InputValue, DefaultRoundingMode);
91 assert(StatusOrErr && "Invalid floating point representation");
92 consumeError(StatusOrErr.takeError());
93 IgnoredFloatingPointValues.push_back(FloatValue.convertToFloat());
94
95 llvm::APFloat DoubleValue(llvm::APFloat::IEEEdouble());
96 StatusOrErr =
97 DoubleValue.convertFromString(InputValue, DefaultRoundingMode);
98 assert(StatusOrErr && "Invalid floating point representation");
99 consumeError(StatusOrErr.takeError());
100 IgnoredDoublePointValues.push_back(DoubleValue.convertToDouble());
101 }
102 llvm::sort(IgnoredFloatingPointValues.begin(),
103 IgnoredFloatingPointValues.end());
104 llvm::sort(IgnoredDoublePointValues.begin(),
105 IgnoredDoublePointValues.end());
106 }
107 }
108
109 void MagicNumbersCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
110 Options.store(Opts, "IgnoredIntegerValues", DefaultIgnoredIntegerValues);
111 Options.store(Opts, "IgnoredFloatingPointValues",
112 DefaultIgnoredFloatingPointValues);
113 }
114
115 void MagicNumbersCheck::registerMatchers(MatchFinder *Finder) {
116 Finder->addMatcher(integerLiteral().bind("integer"), this);
117 if (!IgnoreAllFloatingPointValues)
118 Finder->addMatcher(floatLiteral().bind("float"), this);
119 }
120
121 void MagicNumbersCheck::check(const MatchFinder::MatchResult &Result) {
122 checkBoundMatch<IntegerLiteral>(Result, "integer");
123 checkBoundMatch<FloatingLiteral>(Result, "float");
124 }
125
126 bool MagicNumbersCheck::isConstant(const MatchFinder::MatchResult &Result,
127 const Expr &ExprResult) const {
128 return llvm::any_of(
129 Result.Context->getParents(ExprResult),
130 [&Result](const DynTypedNode &Parent) {
131 if (isUsedToInitializeAConstant(Result, Parent))
132 return true;
133
134 // Ignore this instance, because this matches an
135 // expanded class enumeration value.
136 if (Parent.get<CStyleCastExpr>() &&
137 llvm::any_of(
138 Result.Context->getParents(Parent),
139 [](const DynTypedNode &GrandParent) {
140 return GrandParent.get<SubstNonTypeTemplateParmExpr>() !=
141 nullptr;
142 }))
143 return true;
144
145 // Ignore this instance, because this match reports the
146 // location where the template is defined, not where it
147 // is instantiated.
148 if (Parent.get<SubstNonTypeTemplateParmExpr>())
149 return true;
150
151 // Don't warn on string user defined literals:
152 // std::string s = "Hello World"s;
153 if (const auto *UDL = Parent.get<UserDefinedLiteral>())
154 if (UDL->getLiteralOperatorKind() == UserDefinedLiteral::LOK_String)
155 return true;
156
157 return false;
158 });
159 }
160
161 bool MagicNumbersCheck::isIgnoredValue(const IntegerLiteral *Literal) const {
162 const llvm::APInt IntValue = Literal->getValue();
163 const int64_t Value = IntValue.getZExtValue();
164 if (Value == 0)
165 return true;
166
167 if (IgnorePowersOf2IntegerValues && IntValue.isPowerOf2())
168 return true;
169
170 return std::binary_search(IgnoredIntegerValues.begin(),
171 IgnoredIntegerValues.end(), Value);
172 }
173
174 bool MagicNumbersCheck::isIgnoredValue(const FloatingLiteral *Literal) const {
175 const llvm::APFloat FloatValue = Literal->getValue();
176 if (FloatValue.isZero())
177 return true;
178
179 if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEsingle()) {
180 const float Value = FloatValue.convertToFloat();
181 return std::binary_search(IgnoredFloatingPointValues.begin(),
182 IgnoredFloatingPointValues.end(), Value);
183 }
184
185 if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEdouble()) {
186 const double Value = FloatValue.convertToDouble();
187 return std::binary_search(IgnoredDoublePointValues.begin(),
188 IgnoredDoublePointValues.end(), Value);
189 }
190
191 return false;
192 }
193
194 bool MagicNumbersCheck::isSyntheticValue(const SourceManager *SourceManager,
195 const IntegerLiteral *Literal) const {
196 const std::pair<FileID, unsigned> FileOffset =
197 SourceManager->getDecomposedLoc(Literal->getLocation());
198 if (FileOffset.first.isInvalid())
199 return false;
200
201 const StringRef BufferIdentifier =
202 SourceManager->getBuffer(FileOffset.first)->getBufferIdentifier();
203
204 return BufferIdentifier.empty();
205 }
206
207 bool MagicNumbersCheck::isBitFieldWidth(
208 const clang::ast_matchers::MatchFinder::MatchResult &Result,
209 const IntegerLiteral &Literal) const {
210 return IgnoreBitFieldsWidths &&
211 llvm::any_of(Result.Context->getParents(Literal),
212 [&Result](const DynTypedNode &Parent) {
213 return isUsedToDefineABitField(Result, Parent);
214 });
215 }
216
217 } // namespace readability
218 } // namespace tidy
219 } // namespace clang
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::isUsedToDefineABitField
static bool isUsedToDefineABitField(const MatchFinder::MatchResult &Result, const DynTypedNode &Node)
Definition: MagicNumbersCheck.cpp:46
clang::tidy::readability::MagicNumbersCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: MagicNumbersCheck.cpp:121
Parent
const Node * Parent
Definition: ExtractFunction.cpp:148
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidyCheck.h:47
clang::tidy::utils::options::parseStringList
std::vector< std::string > parseStringList(StringRef Option)
Parse a semicolon separated list of strings.
Definition: OptionsUtils.cpp:18
clang::tidy::ClangTidyCheck::Options
OptionsView Options
Definition: ClangTidyCheck.h:184
clang::tidy::readability::DefaultIgnoredIntegerValues
const char DefaultIgnoredIntegerValues[]
Definition: MagicNumbersCheck.cpp:61
ast_type_traits
clang::tidy::readability::MagicNumbersCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Definition: MagicNumbersCheck.cpp:115
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
clang::isUsedToInitializeAConstant
static bool isUsedToInitializeAConstant(const MatchFinder::MatchResult &Result, const DynTypedNode &Node)
Definition: MagicNumbersCheck.cpp:26
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
clang::tidy::readability::DefaultIgnoredFloatingPointValues
const char DefaultIgnoredFloatingPointValues[]
Definition: MagicNumbersCheck.cpp:62
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
MagicNumbersCheck.h
clang::tidy::ClangTidyCheck::OptionsView::get
std::string get(StringRef LocalName, StringRef Default) const
Read a named option from the Context.
Definition: ClangTidyCheck.cpp:37
clang::tidy::readability::MagicNumbersCheck::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: MagicNumbersCheck.cpp:109