clang-tools  9.0.0
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 {
25 
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 
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 =
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 =
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 
94  Options.store(Opts, "IgnoredIntegerValues", DefaultIgnoredIntegerValues);
95  Options.store(Opts, "IgnoredFloatingPointValues",
96  DefaultIgnoredFloatingPointValues);
97 }
98 
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 
105 void MagicNumbersCheck::check(const MatchFinder::MatchResult &Result) {
106  checkBoundMatch<IntegerLiteral>(Result, "integer");
107  checkBoundMatch<FloatingLiteral>(Result, "float");
108 }
109 
110 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 
122 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 
135 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 
155 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
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Base class for all clang-tidy checks.
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.
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.
static constexpr llvm::StringLiteral Name
std::map< std::string, std::string > OptionMap
const char DefaultIgnoredFloatingPointValues[]
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
llvm::Optional< llvm::Expected< tooling::AtomicChanges > > Result
Definition: Rename.cpp:36
std::string get(StringRef LocalName, StringRef Default) const
Read a named option from the Context.
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...