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
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
//===--- AvoidCStyleCastsCheck.cpp - clang-tidy -----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "AvoidCStyleCastsCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace google {
namespace readability {
void AvoidCStyleCastsCheck::registerMatchers(
ast_matchers::MatchFinder *Finder) {
Finder->addMatcher(
cStyleCastExpr(
// Filter out (EnumType)IntegerLiteral construct, which is generated
// for non-type template arguments of enum types.
// FIXME: Remove this once this is fixed in the AST.
unless(hasParent(substNonTypeTemplateParmExpr())),
// Avoid matches in template instantiations.
unless(isInTemplateInstantiation()))
.bind("cast"),
this);
}
static bool needsConstCast(QualType SourceType, QualType DestType) {
while ((SourceType->isPointerType() && DestType->isPointerType()) ||
(SourceType->isReferenceType() && DestType->isReferenceType())) {
SourceType = SourceType->getPointeeType();
DestType = DestType->getPointeeType();
if (SourceType.isConstQualified() && !DestType.isConstQualified()) {
return (SourceType->isPointerType() == DestType->isPointerType()) &&
(SourceType->isReferenceType() == DestType->isReferenceType());
}
}
return false;
}
static bool pointedUnqualifiedTypesAreEqual(QualType T1, QualType T2) {
while ((T1->isPointerType() && T2->isPointerType()) ||
(T1->isReferenceType() && T2->isReferenceType())) {
T1 = T1->getPointeeType();
T2 = T2->getPointeeType();
}
return T1.getUnqualifiedType() == T2.getUnqualifiedType();
}
void AvoidCStyleCastsCheck::check(const MatchFinder::MatchResult &Result) {
const auto *CastExpr = Result.Nodes.getNodeAs<CStyleCastExpr>("cast");
// Ignore casts in macros.
if (CastExpr->getExprLoc().isMacroID())
return;
// Casting to void is an idiomatic way to mute "unused variable" and similar
// warnings.
if (CastExpr->getCastKind() == CK_ToVoid)
return;
auto isFunction = [](QualType T) {
T = T.getCanonicalType().getNonReferenceType();
return T->isFunctionType() || T->isFunctionPointerType() ||
T->isMemberFunctionPointerType();
};
const QualType DestTypeAsWritten =
CastExpr->getTypeAsWritten().getUnqualifiedType();
const QualType SourceTypeAsWritten =
CastExpr->getSubExprAsWritten()->getType().getUnqualifiedType();
const QualType SourceType = SourceTypeAsWritten.getCanonicalType();
const QualType DestType = DestTypeAsWritten.getCanonicalType();
auto ReplaceRange = CharSourceRange::getCharRange(
CastExpr->getLParenLoc(), CastExpr->getSubExprAsWritten()->getLocStart());
bool FnToFnCast =
isFunction(SourceTypeAsWritten) && isFunction(DestTypeAsWritten);
if (CastExpr->getCastKind() == CK_NoOp && !FnToFnCast) {
// Function pointer/reference casts may be needed to resolve ambiguities in
// case of overloaded functions, so detection of redundant casts is trickier
// in this case. Don't emit "redundant cast" warnings for function
// pointer/reference types.
if (SourceTypeAsWritten == DestTypeAsWritten) {
diag(CastExpr->getLocStart(), "redundant cast to the same type")
<< FixItHint::CreateRemoval(ReplaceRange);
return;
}
}
// The rest of this check is only relevant to C++.
if (!getLangOpts().CPlusPlus)
return;
// Ignore code inside extern "C" {} blocks.
if (!match(expr(hasAncestor(linkageSpecDecl())), *CastExpr, *Result.Context)
.empty())
return;
// Ignore code in .c files and headers included from them, even if they are
// compiled as C++.
if (getCurrentMainFile().endswith(".c"))
return;
SourceManager &SM = *Result.SourceManager;
// Ignore code in .c files #included in other files (which shouldn't be done,
// but people still do this for test and other purposes).
if (SM.getFilename(SM.getSpellingLoc(CastExpr->getLocStart())).endswith(".c"))
return;
// Leave type spelling exactly as it was (unlike
// getTypeAsWritten().getAsString() which would spell enum types 'enum X').
StringRef DestTypeString =
Lexer::getSourceText(CharSourceRange::getTokenRange(
CastExpr->getLParenLoc().getLocWithOffset(1),
CastExpr->getRParenLoc().getLocWithOffset(-1)),
SM, getLangOpts());
auto Diag =
diag(CastExpr->getLocStart(), "C-style casts are discouraged; use %0");
auto ReplaceWithCast = [&](std::string CastText) {
const Expr *SubExpr = CastExpr->getSubExprAsWritten()->IgnoreImpCasts();
if (!isa<ParenExpr>(SubExpr)) {
CastText.push_back('(');
Diag << FixItHint::CreateInsertion(
Lexer::getLocForEndOfToken(SubExpr->getLocEnd(), 0, SM,
getLangOpts()),
")");
}
Diag << FixItHint::CreateReplacement(ReplaceRange, CastText);
};
auto ReplaceWithNamedCast = [&](StringRef CastType) {
Diag << CastType;
ReplaceWithCast((CastType + "<" + DestTypeString + ">").str());
};
// Suggest appropriate C++ cast. See [expr.cast] for cast notation semantics.
switch (CastExpr->getCastKind()) {
case CK_FunctionToPointerDecay:
ReplaceWithNamedCast("static_cast");
return;
case CK_ConstructorConversion:
if (!CastExpr->getTypeAsWritten().hasQualifiers() &&
DestTypeAsWritten->isRecordType() &&
!DestTypeAsWritten->isElaboratedTypeSpecifier()) {
Diag << "constructor call syntax";
// FIXME: Validate DestTypeString, maybe.
ReplaceWithCast(DestTypeString.str());
} else {
ReplaceWithNamedCast("static_cast");
}
return;
case CK_NoOp:
if (FnToFnCast) {
ReplaceWithNamedCast("static_cast");
return;
}
if (SourceType == DestType) {
Diag << "static_cast (if needed, the cast may be redundant)";
ReplaceWithCast(("static_cast<" + DestTypeString + ">").str());
return;
}
if (needsConstCast(SourceType, DestType) &&
pointedUnqualifiedTypesAreEqual(SourceType, DestType)) {
ReplaceWithNamedCast("const_cast");
return;
}
if (DestType->isReferenceType()) {
QualType Dest = DestType.getNonReferenceType();
QualType Source = SourceType.getNonReferenceType();
if (Source == Dest.withConst() ||
SourceType.getNonReferenceType() == DestType.getNonReferenceType()) {
ReplaceWithNamedCast("const_cast");
return;
}
break;
}
// FALLTHROUGH
case clang::CK_IntegralCast:
// Convert integral and no-op casts between builtin types and enums to
// static_cast. A cast from enum to integer may be unnecessary, but it's
// still retained.
if ((SourceType->isBuiltinType() || SourceType->isEnumeralType()) &&
(DestType->isBuiltinType() || DestType->isEnumeralType())) {
ReplaceWithNamedCast("static_cast");
return;
}
break;
case CK_BitCast:
// FIXME: Suggest const_cast<...>(reinterpret_cast<...>(...)) replacement.
if (!needsConstCast(SourceType, DestType)) {
if (SourceType->isVoidPointerType())
ReplaceWithNamedCast("static_cast");
else
ReplaceWithNamedCast("reinterpret_cast");
return;
}
break;
default:
break;
}
Diag << "static_cast/const_cast/reinterpret_cast";
}
} // namespace readability
} // namespace google
} // namespace tidy
} // namespace clang
|
