1 //===--- MagicNumbersCheck.h - clang-tidy-----------------------*- C++ -*-===//
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 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MAGICNUMBERSCHECK_H
10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MAGICNUMBERSCHECK_H
11 
12 #include "../ClangTidyCheck.h"
13 #include "clang/Lex/Lexer.h"
14 #include <llvm/ADT/APFloat.h>
15 #include <llvm/ADT/SmallVector.h>
16 
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20 
21 /// Detects magic numbers, integer and floating point literals embedded in code.
22 ///
23 /// For the user-facing documentation see:
24 /// http://clang.llvm.org/extra/clang-tidy/checks/readability-magic-numbers.html
25 class MagicNumbersCheck : public ClangTidyCheck {
26 public:
27   MagicNumbersCheck(StringRef Name, ClangTidyContext *Context);
28   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
29   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
30   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
31 
32 private:
33   bool isConstant(const clang::ast_matchers::MatchFinder::MatchResult &Result,
34                   const clang::Expr &ExprResult) const;
35 
36   bool isIgnoredValue(const IntegerLiteral *Literal) const;
37   bool isIgnoredValue(const FloatingLiteral *Literal) const;
38 
39   bool isSyntheticValue(const clang::SourceManager *,
40                         const FloatingLiteral *) const {
41     return false;
42   }
43   bool isSyntheticValue(const clang::SourceManager *SourceManager,
44                         const IntegerLiteral *Literal) const;
45 
46   bool isBitFieldWidth(const clang::ast_matchers::MatchFinder::MatchResult &,
47                        const FloatingLiteral &) const {
48      return false;
49   }
50 
51   bool isBitFieldWidth(const clang::ast_matchers::MatchFinder::MatchResult &Result,
52                        const IntegerLiteral &Literal) const;
53 
54   template <typename L>
55   void checkBoundMatch(const ast_matchers::MatchFinder::MatchResult &Result,
56                        const char *BoundName) {
57     const L *MatchedLiteral = Result.Nodes.getNodeAs<L>(BoundName);
58     if (!MatchedLiteral)
59       return;
60 
61     if (Result.SourceManager->isMacroBodyExpansion(
62             MatchedLiteral->getLocation()))
63       return;
64 
65     if (isIgnoredValue(MatchedLiteral))
66       return;
67 
68     if (isConstant(Result, *MatchedLiteral))
69       return;
70 
71     if (isSyntheticValue(Result.SourceManager, MatchedLiteral))
72       return;
73 
74     if (isBitFieldWidth(Result, *MatchedLiteral))
75       return;
76 
77     const StringRef LiteralSourceText = Lexer::getSourceText(
78         CharSourceRange::getTokenRange(MatchedLiteral->getSourceRange()),
79         *Result.SourceManager, getLangOpts());
80 
81     diag(MatchedLiteral->getLocation(),
82          "%0 is a magic number; consider replacing it with a named constant")
83         << LiteralSourceText;
84   }
85 
86   const bool IgnoreAllFloatingPointValues;
87   const bool IgnoreBitFieldsWidths;
88   const bool IgnorePowersOf2IntegerValues;
89   const std::string RawIgnoredIntegerValues;
90   const std::string RawIgnoredFloatingPointValues;
91 
92   constexpr static unsigned SensibleNumberOfMagicValueExceptions = 16;
93 
94   constexpr static llvm::APFloat::roundingMode DefaultRoundingMode =
95       llvm::APFloat::rmNearestTiesToEven;
96 
97   llvm::SmallVector<int64_t, SensibleNumberOfMagicValueExceptions>
98       IgnoredIntegerValues;
99   llvm::SmallVector<float, SensibleNumberOfMagicValueExceptions>
100       IgnoredFloatingPointValues;
101   llvm::SmallVector<double, SensibleNumberOfMagicValueExceptions>
102       IgnoredDoublePointValues;
103 };
104 
105 } // namespace readability
106 } // namespace tidy
107 } // namespace clang
108 
109 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MAGICNUMBERSCHECK_H
110