clang-tools  10.0.0git
SignedBitwiseCheck.cpp
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1 //===--- SignedBitwiseCheck.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 #include "SignedBitwiseCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 
13 using namespace clang::ast_matchers;
14 using namespace clang::ast_matchers::internal;
15 
16 namespace clang {
17 namespace tidy {
18 namespace hicpp {
19 
20 SignedBitwiseCheck::SignedBitwiseCheck(StringRef Name,
21  ClangTidyContext *Context)
22  : ClangTidyCheck(Name, Context),
23  IgnorePositiveIntegerLiterals(
24  Options.get("IgnorePositiveIntegerLiterals", false)) {}
25 
27  Options.store(Opts, "IgnorePositiveIntegerLiterals",
28  IgnorePositiveIntegerLiterals);
29 }
30 
31 void SignedBitwiseCheck::registerMatchers(MatchFinder *Finder) {
32  const auto SignedIntegerOperand =
33  (IgnorePositiveIntegerLiterals
34  ? expr(ignoringImpCasts(hasType(isSignedInteger())),
35  unless(integerLiteral()))
36  : expr(ignoringImpCasts(hasType(isSignedInteger()))))
37  .bind("signed-operand");
38 
39  // The standard [bitmask.types] allows some integral types to be implemented
40  // as signed types. Exclude these types from diagnosing for bitwise or(|) and
41  // bitwise and(&). Shifting and complementing such values is still not
42  // allowed.
43  const auto BitmaskType = namedDecl(
44  hasAnyName("::std::locale::category", "::std::ctype_base::mask",
45  "::std::ios_base::fmtflags", "::std::ios_base::iostate",
46  "::std::ios_base::openmode"));
47  const auto IsStdBitmask = ignoringImpCasts(declRefExpr(hasType(BitmaskType)));
48 
49  // Match binary bitwise operations on signed integer arguments.
50  Finder->addMatcher(
51  binaryOperator(anyOf(hasOperatorName("^"), hasOperatorName("|"),
52  hasOperatorName("&"), hasOperatorName("^="),
53  hasOperatorName("|="), hasOperatorName("&=")),
54 
55  unless(allOf(hasLHS(IsStdBitmask), hasRHS(IsStdBitmask))),
56 
57  hasEitherOperand(SignedIntegerOperand),
58  hasLHS(hasType(isInteger())), hasRHS(hasType(isInteger())))
59  .bind("binary-no-sign-interference"),
60  this);
61 
62  // Shifting and complement is not allowed for any signed integer type because
63  // the sign bit may corrupt the result.
64  Finder->addMatcher(
65  binaryOperator(anyOf(hasOperatorName("<<"), hasOperatorName(">>"),
66  hasOperatorName("<<="), hasOperatorName(">>=")),
67  hasEitherOperand(SignedIntegerOperand),
68  hasLHS(hasType(isInteger())), hasRHS(hasType(isInteger())))
69  .bind("binary-sign-interference"),
70  this);
71 
72  // Match unary operations on signed integer types.
73  Finder->addMatcher(
74  unaryOperator(hasOperatorName("~"), hasUnaryOperand(SignedIntegerOperand))
75  .bind("unary-signed"),
76  this);
77 }
78 
79 void SignedBitwiseCheck::check(const MatchFinder::MatchResult &Result) {
80  const ast_matchers::BoundNodes &N = Result.Nodes;
81  const auto *SignedOperand = N.getNodeAs<Expr>("signed-operand");
82  assert(SignedOperand &&
83  "No signed operand found in problematic bitwise operations");
84 
85  bool IsUnary = false;
86  SourceLocation Location;
87 
88  if (const auto *UnaryOp = N.getNodeAs<UnaryOperator>("unary-signed")) {
89  IsUnary = true;
90  Location = UnaryOp->getBeginLoc();
91  } else {
92  if (const auto *BinaryOp =
93  N.getNodeAs<BinaryOperator>("binary-no-sign-interference"))
94  Location = BinaryOp->getBeginLoc();
95  else if (const auto *BinaryOp =
96  N.getNodeAs<BinaryOperator>("binary-sign-interference"))
97  Location = BinaryOp->getBeginLoc();
98  else
99  llvm_unreachable("unexpected matcher result");
100  }
101  diag(Location, "use of a signed integer operand with a "
102  "%select{binary|unary}0 bitwise operator")
103  << IsUnary << SignedOperand->getSourceRange();
104 }
105 
106 } // namespace hicpp
107 } // namespace tidy
108 } // namespace clang
Base class for all clang-tidy checks.
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
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
void storeOptions(ClangTidyOptions::OptionMap &Options) override
Should store all options supported by this check with their current values or default values for opti...
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.