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#include "clang/ASTMatchers/ASTMatchers.h"
13
14using namespace clang::ast_matchers;
15using namespace clang::ast_matchers::internal;
16
17namespace clang::tidy::hicpp {
18
19SignedBitwiseCheck::SignedBitwiseCheck(StringRef Name,
20 ClangTidyContext *Context)
21 : ClangTidyCheck(Name, Context),
22 IgnorePositiveIntegerLiterals(
23 Options.get(LocalName: "IgnorePositiveIntegerLiterals", Default: false)) {}
24
25void SignedBitwiseCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
26 Options.store(Options&: Opts, LocalName: "IgnorePositiveIntegerLiterals",
27 Value: IgnorePositiveIntegerLiterals);
28}
29
30void SignedBitwiseCheck::registerMatchers(MatchFinder *Finder) {
31 const auto SignedIntegerOperand =
32 (IgnorePositiveIntegerLiterals
33 ? expr(ignoringImpCasts(
34 InnerMatcher: allOf(hasType(InnerMatcher: isSignedInteger()), unless(integerLiteral()))))
35 : expr(ignoringImpCasts(InnerMatcher: hasType(InnerMatcher: isSignedInteger()))))
36 .bind(ID: "signed-operand");
37
38 // The standard [bitmask.types] allows some integral types to be implemented
39 // as signed types. Exclude these types from diagnosing for bitwise or(|) and
40 // bitwise and(&). Shifting and complementing such values is still not
41 // allowed.
42 const auto BitmaskType = namedDecl(
43 hasAnyName("::std::locale::category", "::std::ctype_base::mask",
44 "::std::ios_base::fmtflags", "::std::ios_base::iostate",
45 "::std::ios_base::openmode"));
46 const auto IsStdBitmask = ignoringImpCasts(InnerMatcher: declRefExpr(hasType(InnerMatcher: BitmaskType)));
47
48 // Match binary bitwise operations on signed integer arguments.
49 Finder->addMatcher(
50 NodeMatch: binaryOperator(hasAnyOperatorName("^", "|", "&", "^=", "|=", "&="),
51
52 unless(allOf(hasLHS(InnerMatcher: IsStdBitmask), hasRHS(InnerMatcher: IsStdBitmask))),
53
54 hasEitherOperand(InnerMatcher: SignedIntegerOperand),
55 hasLHS(InnerMatcher: hasType(InnerMatcher: isInteger())), hasRHS(InnerMatcher: hasType(InnerMatcher: isInteger())))
56 .bind(ID: "binary-no-sign-interference"),
57 Action: this);
58
59 // Shifting and complement is not allowed for any signed integer type because
60 // the sign bit may corrupt the result.
61 Finder->addMatcher(
62 NodeMatch: binaryOperator(hasAnyOperatorName("<<", ">>", "<<=", ">>="),
63 hasEitherOperand(InnerMatcher: SignedIntegerOperand),
64 hasLHS(InnerMatcher: hasType(InnerMatcher: isInteger())), hasRHS(InnerMatcher: hasType(InnerMatcher: isInteger())))
65 .bind(ID: "binary-sign-interference"),
66 Action: this);
67
68 // Match unary operations on signed integer types.
69 Finder->addMatcher(
70 NodeMatch: unaryOperator(hasOperatorName(Name: "~"), hasUnaryOperand(InnerMatcher: SignedIntegerOperand))
71 .bind(ID: "unary-signed"),
72 Action: this);
73}
74
75void SignedBitwiseCheck::check(const MatchFinder::MatchResult &Result) {
76 const ast_matchers::BoundNodes &N = Result.Nodes;
77 const auto *SignedOperand = N.getNodeAs<Expr>(ID: "signed-operand");
78 assert(SignedOperand &&
79 "No signed operand found in problematic bitwise operations");
80
81 bool IsUnary = false;
82 SourceLocation OperatorLoc;
83
84 if (const auto *UnaryOp = N.getNodeAs<UnaryOperator>(ID: "unary-signed")) {
85 IsUnary = true;
86 OperatorLoc = UnaryOp->getOperatorLoc();
87 } else {
88 if (const auto *BinaryOp =
89 N.getNodeAs<BinaryOperator>(ID: "binary-no-sign-interference"))
90 OperatorLoc = BinaryOp->getOperatorLoc();
91 else if (const auto *BinaryOp =
92 N.getNodeAs<BinaryOperator>(ID: "binary-sign-interference"))
93 OperatorLoc = BinaryOp->getOperatorLoc();
94 else
95 llvm_unreachable("unexpected matcher result");
96 }
97 diag(SignedOperand->getBeginLoc(), "use of a signed integer operand with a "
98 "%select{binary|unary}0 bitwise operator")
99 << IsUnary << SignedOperand->getSourceRange() << OperatorLoc;
100}
101
102} // namespace clang::tidy::hicpp
103

source code of clang-tools-extra/clang-tidy/hicpp/SignedBitwiseCheck.cpp