1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
|
//===--- SignedCharMisuseCheck.cpp - clang-tidy ---------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "SignedCharMisuseCheck.h"
#include "../utils/OptionsUtils.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
using namespace clang::ast_matchers::internal;
namespace clang::tidy::bugprone {
static constexpr int UnsignedASCIIUpperBound = 127;
SignedCharMisuseCheck::SignedCharMisuseCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
CharTypdefsToIgnoreList(Options.get("CharTypdefsToIgnore", "")),
DiagnoseSignedUnsignedCharComparisons(
Options.get("DiagnoseSignedUnsignedCharComparisons", true)) {}
void SignedCharMisuseCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "CharTypdefsToIgnore", CharTypdefsToIgnoreList);
Options.store(Opts, "DiagnoseSignedUnsignedCharComparisons",
DiagnoseSignedUnsignedCharComparisons);
}
// Create a matcher for char -> integer cast.
BindableMatcher<clang::Stmt> SignedCharMisuseCheck::charCastExpression(
bool IsSigned, const Matcher<clang::QualType> &IntegerType,
const std::string &CastBindName) const {
// We can ignore typedefs which are some kind of integer types
// (e.g. typedef char sal_Int8). In this case, we don't need to
// worry about the misinterpretation of char values.
const auto IntTypedef = qualType(hasDeclaration(typedefDecl(
hasAnyName(utils::options::parseStringList(CharTypdefsToIgnoreList)))));
auto CharTypeExpr = expr();
if (IsSigned) {
CharTypeExpr = expr(hasType(
qualType(isAnyCharacter(), isSignedInteger(), unless(IntTypedef))));
} else {
CharTypeExpr = expr(hasType(qualType(
isAnyCharacter(), unless(isSignedInteger()), unless(IntTypedef))));
}
const auto ImplicitCastExpr =
implicitCastExpr(hasSourceExpression(CharTypeExpr),
hasImplicitDestinationType(IntegerType))
.bind(CastBindName);
const auto CStyleCastExpr = cStyleCastExpr(has(ImplicitCastExpr));
const auto StaticCastExpr = cxxStaticCastExpr(has(ImplicitCastExpr));
const auto FunctionalCastExpr = cxxFunctionalCastExpr(has(ImplicitCastExpr));
// We catch any type of casts to an integer. We need to have these cast
// expressions explicitly to catch only those casts which are direct children
// of the checked expressions. (e.g. assignment, declaration).
return traverse(TK_AsIs, expr(anyOf(ImplicitCastExpr, CStyleCastExpr,
StaticCastExpr, FunctionalCastExpr)));
}
void SignedCharMisuseCheck::registerMatchers(MatchFinder *Finder) {
const auto IntegerType =
qualType(isInteger(), unless(isAnyCharacter()), unless(booleanType()))
.bind("integerType");
const auto SignedCharCastExpr =
charCastExpression(true, IntegerType, "signedCastExpression");
const auto UnSignedCharCastExpr =
charCastExpression(false, IntegerType, "unsignedCastExpression");
// Catch assignments with signed char -> integer conversion.
const auto AssignmentOperatorExpr =
expr(binaryOperator(hasOperatorName("="), hasLHS(hasType(IntegerType)),
hasRHS(SignedCharCastExpr)));
Finder->addMatcher(AssignmentOperatorExpr, this);
// Catch declarations with signed char -> integer conversion.
const auto Declaration = varDecl(isDefinition(), hasType(IntegerType),
hasInitializer(SignedCharCastExpr));
Finder->addMatcher(Declaration, this);
if (DiagnoseSignedUnsignedCharComparisons) {
// Catch signed char/unsigned char comparison.
const auto CompareOperator =
expr(binaryOperator(hasAnyOperatorName("==", "!="),
anyOf(allOf(hasLHS(SignedCharCastExpr),
hasRHS(UnSignedCharCastExpr)),
allOf(hasLHS(UnSignedCharCastExpr),
hasRHS(SignedCharCastExpr)))))
.bind("comparison");
Finder->addMatcher(CompareOperator, this);
}
// Catch array subscripts with signed char -> integer conversion.
// Matcher for C arrays.
const auto CArraySubscript =
arraySubscriptExpr(hasIndex(SignedCharCastExpr)).bind("arraySubscript");
Finder->addMatcher(CArraySubscript, this);
// Matcher for std arrays.
const auto STDArraySubscript =
cxxOperatorCallExpr(
hasOverloadedOperatorName("[]"),
hasArgument(0, hasType(cxxRecordDecl(hasName("::std::array")))),
hasArgument(1, SignedCharCastExpr))
.bind("arraySubscript");
Finder->addMatcher(STDArraySubscript, this);
}
void SignedCharMisuseCheck::check(const MatchFinder::MatchResult &Result) {
const auto *SignedCastExpression =
Result.Nodes.getNodeAs<ImplicitCastExpr>("signedCastExpression");
const auto *IntegerType = Result.Nodes.getNodeAs<QualType>("integerType");
assert(SignedCastExpression);
assert(IntegerType);
// Ignore the match if we know that the signed char's value is not negative.
// The potential misinterpretation happens for negative values only.
Expr::EvalResult EVResult;
if (!SignedCastExpression->isValueDependent() &&
SignedCastExpression->getSubExpr()->EvaluateAsInt(EVResult,
*Result.Context)) {
llvm::APSInt Value = EVResult.Val.getInt();
if (Value.isNonNegative())
return;
}
if (const auto *Comparison = Result.Nodes.getNodeAs<Expr>("comparison")) {
const auto *UnSignedCastExpression =
Result.Nodes.getNodeAs<ImplicitCastExpr>("unsignedCastExpression");
// We can ignore the ASCII value range also for unsigned char.
Expr::EvalResult EVResult;
if (!UnSignedCastExpression->isValueDependent() &&
UnSignedCastExpression->getSubExpr()->EvaluateAsInt(EVResult,
*Result.Context)) {
llvm::APSInt Value = EVResult.Val.getInt();
if (Value <= UnsignedASCIIUpperBound)
return;
}
diag(Comparison->getBeginLoc(),
"comparison between 'signed char' and 'unsigned char'");
} else if (Result.Nodes.getNodeAs<Expr>("arraySubscript")) {
diag(SignedCastExpression->getBeginLoc(),
"'signed char' to %0 conversion in array subscript; "
"consider casting to 'unsigned char' first.")
<< *IntegerType;
} else {
diag(SignedCastExpression->getBeginLoc(),
"'signed char' to %0 conversion; "
"consider casting to 'unsigned char' first.")
<< *IntegerType;
}
}
} // namespace clang::tidy::bugprone
|
