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
14 using namespace clang::ast_matchers;
15 using namespace clang::ast_matchers::internal;
16
17 namespace clang::tidy::hicpp {
18
SignedBitwiseCheck(StringRef Name,ClangTidyContext * Context)19 SignedBitwiseCheck::SignedBitwiseCheck(StringRef Name,
20 ClangTidyContext *Context)
21 : ClangTidyCheck(Name, Context),
22 IgnorePositiveIntegerLiterals(
23 Options.get("IgnorePositiveIntegerLiterals", false)) {}
24
storeOptions(ClangTidyOptions::OptionMap & Opts)25 void SignedBitwiseCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
26 Options.store(Opts, "IgnorePositiveIntegerLiterals",
27 IgnorePositiveIntegerLiterals);
28 }
29
registerMatchers(MatchFinder * Finder)30 void SignedBitwiseCheck::registerMatchers(MatchFinder *Finder) {
31 const auto SignedIntegerOperand =
32 (IgnorePositiveIntegerLiterals
33 ? expr(ignoringImpCasts(
34 allOf(hasType(isSignedInteger()), unless(integerLiteral()))))
35 : expr(ignoringImpCasts(hasType(isSignedInteger()))))
36 .bind("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(declRefExpr(hasType(BitmaskType)));
47
48 // Match binary bitwise operations on signed integer arguments.
49 Finder->addMatcher(
50 binaryOperator(hasAnyOperatorName("^", "|", "&", "^=", "|=", "&="),
51
52 unless(allOf(hasLHS(IsStdBitmask), hasRHS(IsStdBitmask))),
53
54 hasEitherOperand(SignedIntegerOperand),
55 hasLHS(hasType(isInteger())), hasRHS(hasType(isInteger())))
56 .bind("binary-no-sign-interference"),
57 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 binaryOperator(hasAnyOperatorName("<<", ">>", "<<=", ">>="),
63 hasEitherOperand(SignedIntegerOperand),
64 hasLHS(hasType(isInteger())), hasRHS(hasType(isInteger())))
65 .bind("binary-sign-interference"),
66 this);
67
68 // Match unary operations on signed integer types.
69 Finder->addMatcher(
70 unaryOperator(hasOperatorName("~"), hasUnaryOperand(SignedIntegerOperand))
71 .bind("unary-signed"),
72 this);
73 }
74
check(const MatchFinder::MatchResult & Result)75 void SignedBitwiseCheck::check(const MatchFinder::MatchResult &Result) {
76 const ast_matchers::BoundNodes &N = Result.Nodes;
77 const auto *SignedOperand = N.getNodeAs<Expr>("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>("unary-signed")) {
85 IsUnary = true;
86 OperatorLoc = UnaryOp->getOperatorLoc();
87 } else {
88 if (const auto *BinaryOp =
89 N.getNodeAs<BinaryOperator>("binary-no-sign-interference"))
90 OperatorLoc = BinaryOp->getOperatorLoc();
91 else if (const auto *BinaryOp =
92 N.getNodeAs<BinaryOperator>("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