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 {
25
isUsedToInitializeAConstant(const MatchFinder::MatchResult & Result,const DynTypedNode & Node)26 bool isUsedToInitializeAConstant(const MatchFinder::MatchResult &Result,
27 const DynTypedNode &Node) {
28
29 const auto *AsDecl = Node.get<clang::DeclaratorDecl>();
30 if (AsDecl) {
31 if (AsDecl->getType().isConstQualified())
32 return true;
33
34 return AsDecl->isImplicit();
35 }
36
37 if (Node.get<clang::EnumConstantDecl>() != nullptr)
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 } // namespace
47
48 namespace clang {
49 namespace tidy {
50 namespace readability {
51
52 const char DefaultIgnoredIntegerValues[] = "1;2;3;4;";
53 const char DefaultIgnoredFloatingPointValues[] = "1.0;100.0;";
54
MagicNumbersCheck(StringRef Name,ClangTidyContext * Context)55 MagicNumbersCheck::MagicNumbersCheck(StringRef Name, ClangTidyContext *Context)
56 : ClangTidyCheck(Name, Context),
57 IgnoreAllFloatingPointValues(
58 Options.get("IgnoreAllFloatingPointValues", false)),
59 IgnorePowersOf2IntegerValues(
60 Options.get("IgnorePowersOf2IntegerValues", false)) {
61 // Process the set of ignored integer values.
62 const std::vector<std::string> IgnoredIntegerValuesInput =
63 utils::options::parseStringList(
64 Options.get("IgnoredIntegerValues", DefaultIgnoredIntegerValues));
65 IgnoredIntegerValues.resize(IgnoredIntegerValuesInput.size());
66 llvm::transform(IgnoredIntegerValuesInput, IgnoredIntegerValues.begin(),
67 [](const std::string &Value) { return std::stoll(Value); });
68 llvm::sort(IgnoredIntegerValues);
69
70 if (!IgnoreAllFloatingPointValues) {
71 // Process the set of ignored floating point values.
72 const std::vector<std::string> IgnoredFloatingPointValuesInput =
73 utils::options::parseStringList(Options.get(
74 "IgnoredFloatingPointValues", DefaultIgnoredFloatingPointValues));
75 IgnoredFloatingPointValues.reserve(IgnoredFloatingPointValuesInput.size());
76 IgnoredDoublePointValues.reserve(IgnoredFloatingPointValuesInput.size());
77 for (const auto &InputValue : IgnoredFloatingPointValuesInput) {
78 llvm::APFloat FloatValue(llvm::APFloat::IEEEsingle());
79 FloatValue.convertFromString(InputValue, DefaultRoundingMode);
80 IgnoredFloatingPointValues.push_back(FloatValue.convertToFloat());
81
82 llvm::APFloat DoubleValue(llvm::APFloat::IEEEdouble());
83 DoubleValue.convertFromString(InputValue, DefaultRoundingMode);
84 IgnoredDoublePointValues.push_back(DoubleValue.convertToDouble());
85 }
86 llvm::sort(IgnoredFloatingPointValues.begin(),
87 IgnoredFloatingPointValues.end());
88 llvm::sort(IgnoredDoublePointValues.begin(),
89 IgnoredDoublePointValues.end());
90 }
91 }
92
storeOptions(ClangTidyOptions::OptionMap & Opts)93 void MagicNumbersCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
94 Options.store(Opts, "IgnoredIntegerValues", DefaultIgnoredIntegerValues);
95 Options.store(Opts, "IgnoredFloatingPointValues",
96 DefaultIgnoredFloatingPointValues);
97 }
98
registerMatchers(MatchFinder * Finder)99 void MagicNumbersCheck::registerMatchers(MatchFinder *Finder) {
100 Finder->addMatcher(integerLiteral().bind("integer"), this);
101 if (!IgnoreAllFloatingPointValues)
102 Finder->addMatcher(floatLiteral().bind("float"), this);
103 }
104
check(const MatchFinder::MatchResult & Result)105 void MagicNumbersCheck::check(const MatchFinder::MatchResult &Result) {
106 checkBoundMatch<IntegerLiteral>(Result, "integer");
107 checkBoundMatch<FloatingLiteral>(Result, "float");
108 }
109
isConstant(const MatchFinder::MatchResult & Result,const Expr & ExprResult) const110 bool MagicNumbersCheck::isConstant(const MatchFinder::MatchResult &Result,
111 const Expr &ExprResult) const {
112 return llvm::any_of(
113 Result.Context->getParents(ExprResult),
114 [&Result](const DynTypedNode &Parent) {
115 return isUsedToInitializeAConstant(Result, Parent) ||
116 // Ignore this instance, because this match reports the location
117 // where the template is defined, not where it is instantiated.
118 Parent.get<SubstNonTypeTemplateParmExpr>();
119 });
120 }
121
isIgnoredValue(const IntegerLiteral * Literal) const122 bool MagicNumbersCheck::isIgnoredValue(const IntegerLiteral *Literal) const {
123 const llvm::APInt IntValue = Literal->getValue();
124 const int64_t Value = IntValue.getZExtValue();
125 if (Value == 0)
126 return true;
127
128 if (IgnorePowersOf2IntegerValues && IntValue.isPowerOf2())
129 return true;
130
131 return std::binary_search(IgnoredIntegerValues.begin(),
132 IgnoredIntegerValues.end(), Value);
133 }
134
isIgnoredValue(const FloatingLiteral * Literal) const135 bool MagicNumbersCheck::isIgnoredValue(const FloatingLiteral *Literal) const {
136 const llvm::APFloat FloatValue = Literal->getValue();
137 if (FloatValue.isZero())
138 return true;
139
140 if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEsingle()) {
141 const float Value = FloatValue.convertToFloat();
142 return std::binary_search(IgnoredFloatingPointValues.begin(),
143 IgnoredFloatingPointValues.end(), Value);
144 }
145
146 if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEdouble()) {
147 const double Value = FloatValue.convertToDouble();
148 return std::binary_search(IgnoredDoublePointValues.begin(),
149 IgnoredDoublePointValues.end(), Value);
150 }
151
152 return false;
153 }
154
isSyntheticValue(const SourceManager * SourceManager,const IntegerLiteral * Literal) const155 bool MagicNumbersCheck::isSyntheticValue(const SourceManager *SourceManager,
156 const IntegerLiteral *Literal) const {
157 const std::pair<FileID, unsigned> FileOffset =
158 SourceManager->getDecomposedLoc(Literal->getLocation());
159 if (FileOffset.first.isInvalid())
160 return false;
161
162 const StringRef BufferIdentifier =
163 SourceManager->getBuffer(FileOffset.first)->getBufferIdentifier();
164
165 return BufferIdentifier.empty();
166 }
167
168 } // namespace readability
169 } // namespace tidy
170 } // namespace clang
171