clang-tools  8.0.0
MagicNumbersCheck.cpp
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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 
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 
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 =
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 =
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 
95  Options.store(Opts, "IgnoredIntegerValues", DefaultIgnoredIntegerValues);
96  Options.store(Opts, "IgnoredFloatingPointValues",
97  DefaultIgnoredFloatingPointValues);
98 }
99 
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 
106 void MagicNumbersCheck::check(const MatchFinder::MatchResult &Result) {
107  checkBoundMatch<IntegerLiteral>(Result, "integer");
108  checkBoundMatch<FloatingLiteral>(Result, "float");
109 }
110 
111 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 
123 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 
136 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 
156 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
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: ClangTidy.cpp:473
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
std::string get(StringRef LocalName, StringRef Default) const
Read a named option from the Context.
Definition: ClangTidy.cpp:454
Base class for all clang-tidy checks.
Definition: ClangTidy.h:127
std::vector< std::string > parseStringList(StringRef Option)
Parse a semicolon separated list of strings.
const char DefaultIgnoredIntegerValues[]
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
static constexpr llvm::StringLiteral Name
std::map< std::string, std::string > OptionMap
llvm::Optional< llvm::Expected< tooling::AtomicChanges > > Result
const char DefaultIgnoredFloatingPointValues[]
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...