1 //===--- MagicNumbersCheck.cpp - clang-tidy-------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // A checker for magic numbers: integer or floating point literals embedded
11 // in the code, outside the definition of a constant or an enumeration.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "MagicNumbersCheck.h"
16 #include "../utils/OptionsUtils.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/ASTMatchers/ASTMatchFinder.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include <algorithm>
21
22 using namespace clang::ast_matchers;
23 using namespace clang::ast_type_traits;
24
25 namespace {
26
isUsedToInitializeAConstant(const MatchFinder::MatchResult & Result,const DynTypedNode & Node)27 bool isUsedToInitializeAConstant(const MatchFinder::MatchResult &Result,
28 const DynTypedNode &Node) {
29
30 const auto *AsDecl = Node.get<clang::DeclaratorDecl>();
31 if (AsDecl) {
32 if (AsDecl->getType().isConstQualified())
33 return true;
34
35 return AsDecl->isImplicit();
36 }
37
38 if (Node.get<clang::EnumConstantDecl>() != nullptr)
39 return true;
40
41 return llvm::any_of(Result.Context->getParents(Node),
42 [&Result](const DynTypedNode &Parent) {
43 return isUsedToInitializeAConstant(Result, Parent);
44 });
45 }
46
47 } // namespace
48
49 namespace clang {
50 namespace tidy {
51 namespace readability {
52
53 const char DefaultIgnoredIntegerValues[] = "1;2;3;4;";
54 const char DefaultIgnoredFloatingPointValues[] = "1.0;100.0;";
55
MagicNumbersCheck(StringRef Name,ClangTidyContext * Context)56 MagicNumbersCheck::MagicNumbersCheck(StringRef Name, ClangTidyContext *Context)
57 : ClangTidyCheck(Name, Context),
58 IgnoreAllFloatingPointValues(
59 Options.get("IgnoreAllFloatingPointValues", false)),
60 IgnorePowersOf2IntegerValues(
61 Options.get("IgnorePowersOf2IntegerValues", false)) {
62 // Process the set of ignored integer values.
63 const std::vector<std::string> IgnoredIntegerValuesInput =
64 utils::options::parseStringList(
65 Options.get("IgnoredIntegerValues", DefaultIgnoredIntegerValues));
66 IgnoredIntegerValues.resize(IgnoredIntegerValuesInput.size());
67 llvm::transform(IgnoredIntegerValuesInput, IgnoredIntegerValues.begin(),
68 [](const std::string &Value) { return std::stoll(Value); });
69 llvm::sort(IgnoredIntegerValues);
70
71 if (!IgnoreAllFloatingPointValues) {
72 // Process the set of ignored floating point values.
73 const std::vector<std::string> IgnoredFloatingPointValuesInput =
74 utils::options::parseStringList(Options.get(
75 "IgnoredFloatingPointValues", DefaultIgnoredFloatingPointValues));
76 IgnoredFloatingPointValues.reserve(IgnoredFloatingPointValuesInput.size());
77 IgnoredDoublePointValues.reserve(IgnoredFloatingPointValuesInput.size());
78 for (const auto &InputValue : IgnoredFloatingPointValuesInput) {
79 llvm::APFloat FloatValue(llvm::APFloat::IEEEsingle());
80 FloatValue.convertFromString(InputValue, DefaultRoundingMode);
81 IgnoredFloatingPointValues.push_back(FloatValue.convertToFloat());
82
83 llvm::APFloat DoubleValue(llvm::APFloat::IEEEdouble());
84 DoubleValue.convertFromString(InputValue, DefaultRoundingMode);
85 IgnoredDoublePointValues.push_back(DoubleValue.convertToDouble());
86 }
87 llvm::sort(IgnoredFloatingPointValues.begin(),
88 IgnoredFloatingPointValues.end());
89 llvm::sort(IgnoredDoublePointValues.begin(),
90 IgnoredDoublePointValues.end());
91 }
92 }
93
storeOptions(ClangTidyOptions::OptionMap & Opts)94 void MagicNumbersCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
95 Options.store(Opts, "IgnoredIntegerValues", DefaultIgnoredIntegerValues);
96 Options.store(Opts, "IgnoredFloatingPointValues",
97 DefaultIgnoredFloatingPointValues);
98 }
99
registerMatchers(MatchFinder * Finder)100 void MagicNumbersCheck::registerMatchers(MatchFinder *Finder) {
101 Finder->addMatcher(integerLiteral().bind("integer"), this);
102 if (!IgnoreAllFloatingPointValues)
103 Finder->addMatcher(floatLiteral().bind("float"), this);
104 }
105
check(const MatchFinder::MatchResult & Result)106 void MagicNumbersCheck::check(const MatchFinder::MatchResult &Result) {
107 checkBoundMatch<IntegerLiteral>(Result, "integer");
108 checkBoundMatch<FloatingLiteral>(Result, "float");
109 }
110
isConstant(const MatchFinder::MatchResult & Result,const Expr & ExprResult) const111 bool MagicNumbersCheck::isConstant(const MatchFinder::MatchResult &Result,
112 const Expr &ExprResult) const {
113 return llvm::any_of(
114 Result.Context->getParents(ExprResult),
115 [&Result](const DynTypedNode &Parent) {
116 return isUsedToInitializeAConstant(Result, Parent) ||
117 // Ignore this instance, because this match reports the location
118 // where the template is defined, not where it is instantiated.
119 Parent.get<SubstNonTypeTemplateParmExpr>();
120 });
121 }
122
isIgnoredValue(const IntegerLiteral * Literal) const123 bool MagicNumbersCheck::isIgnoredValue(const IntegerLiteral *Literal) const {
124 const llvm::APInt IntValue = Literal->getValue();
125 const int64_t Value = IntValue.getZExtValue();
126 if (Value == 0)
127 return true;
128
129 if (IgnorePowersOf2IntegerValues && IntValue.isPowerOf2())
130 return true;
131
132 return std::binary_search(IgnoredIntegerValues.begin(),
133 IgnoredIntegerValues.end(), Value);
134 }
135
isIgnoredValue(const FloatingLiteral * Literal) const136 bool MagicNumbersCheck::isIgnoredValue(const FloatingLiteral *Literal) const {
137 const llvm::APFloat FloatValue = Literal->getValue();
138 if (FloatValue.isZero())
139 return true;
140
141 if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEsingle()) {
142 const float Value = FloatValue.convertToFloat();
143 return std::binary_search(IgnoredFloatingPointValues.begin(),
144 IgnoredFloatingPointValues.end(), Value);
145 }
146
147 if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEdouble()) {
148 const double Value = FloatValue.convertToDouble();
149 return std::binary_search(IgnoredDoublePointValues.begin(),
150 IgnoredDoublePointValues.end(), Value);
151 }
152
153 return false;
154 }
155
isSyntheticValue(const SourceManager * SourceManager,const IntegerLiteral * Literal) const156 bool MagicNumbersCheck::isSyntheticValue(const SourceManager *SourceManager,
157 const IntegerLiteral *Literal) const {
158 const std::pair<FileID, unsigned> FileOffset =
159 SourceManager->getDecomposedLoc(Literal->getLocation());
160 if (FileOffset.first.isInvalid())
161 return false;
162
163 const StringRef BufferIdentifier =
164 SourceManager->getBuffer(FileOffset.first)->getBufferIdentifier();
165
166 return BufferIdentifier.empty();
167 }
168
169 } // namespace readability
170 } // namespace tidy
171 } // namespace clang
172