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
|
//===--- ConstCorrectnessCheck.cpp - clang-tidy -----------------*- C++ -*-===//
//
// 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 "ConstCorrectnessCheck.h"
#include "../utils/FixItHintUtils.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace misc {
namespace {
// FIXME: This matcher exists in some other code-review as well.
// It should probably move to ASTMatchers.
AST_MATCHER(VarDecl, isLocal) { return Node.isLocalVarDecl(); }
AST_MATCHER_P(DeclStmt, containsAnyDeclaration,
ast_matchers::internal::Matcher<Decl>, InnerMatcher) {
return ast_matchers::internal::matchesFirstInPointerRange(
InnerMatcher, Node.decl_begin(), Node.decl_end(), Finder,
Builder) != Node.decl_end();
}
AST_MATCHER(ReferenceType, isSpelledAsLValue) {
return Node.isSpelledAsLValue();
}
AST_MATCHER(Type, isDependentType) { return Node.isDependentType(); }
} // namespace
ConstCorrectnessCheck::ConstCorrectnessCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
AnalyzeValues(Options.get("AnalyzeValues", true)),
AnalyzeReferences(Options.get("AnalyzeReferences", true)),
WarnPointersAsValues(Options.get("WarnPointersAsValues", false)),
TransformValues(Options.get("TransformValues", true)),
TransformReferences(Options.get("TransformReferences", true)),
TransformPointersAsValues(
Options.get("TransformPointersAsValues", false)) {
if (AnalyzeValues == false && AnalyzeReferences == false)
this->configurationDiag(
"The check 'misc-const-correctness' will not "
"perform any analysis because both 'AnalyzeValues' and "
"'AnalyzeReferences' are false.");
}
void ConstCorrectnessCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "AnalyzeValues", AnalyzeValues);
Options.store(Opts, "AnalyzeReferences", AnalyzeReferences);
Options.store(Opts, "WarnPointersAsValues", WarnPointersAsValues);
Options.store(Opts, "TransformValues", TransformValues);
Options.store(Opts, "TransformReferences", TransformReferences);
Options.store(Opts, "TransformPointersAsValues", TransformPointersAsValues);
}
void ConstCorrectnessCheck::registerMatchers(MatchFinder *Finder) {
const auto ConstType = hasType(isConstQualified());
const auto ConstReference = hasType(references(isConstQualified()));
const auto RValueReference = hasType(
referenceType(anyOf(rValueReferenceType(), unless(isSpelledAsLValue()))));
const auto TemplateType = anyOf(
hasType(hasCanonicalType(templateTypeParmType())),
hasType(substTemplateTypeParmType()), hasType(isDependentType()),
// References to template types, their substitutions or typedefs to
// template types need to be considered as well.
hasType(referenceType(pointee(hasCanonicalType(templateTypeParmType())))),
hasType(referenceType(pointee(substTemplateTypeParmType()))));
const auto AutoTemplateType = varDecl(
anyOf(hasType(autoType()), hasType(referenceType(pointee(autoType()))),
hasType(pointerType(pointee(autoType())))));
const auto FunctionPointerRef =
hasType(hasCanonicalType(referenceType(pointee(functionType()))));
// Match local variables which could be 'const' if not modified later.
// Example: `int i = 10` would match `int i`.
const auto LocalValDecl = varDecl(
allOf(isLocal(), hasInitializer(anything()),
unless(anyOf(ConstType, ConstReference, TemplateType,
hasInitializer(isInstantiationDependent()),
AutoTemplateType, RValueReference, FunctionPointerRef,
hasType(cxxRecordDecl(isLambda())), isImplicit()))));
// Match the function scope for which the analysis of all local variables
// shall be run.
const auto FunctionScope =
functionDecl(
hasBody(
compoundStmt(forEachDescendant(
declStmt(containsAnyDeclaration(
LocalValDecl.bind("local-value")),
unless(has(decompositionDecl())))
.bind("decl-stmt")))
.bind("scope")))
.bind("function-decl");
Finder->addMatcher(FunctionScope, this);
}
/// Classify for a variable in what the Const-Check is interested.
enum class VariableCategory { Value, Reference, Pointer };
void ConstCorrectnessCheck::check(const MatchFinder::MatchResult &Result) {
const auto *LocalScope = Result.Nodes.getNodeAs<CompoundStmt>("scope");
const auto *Variable = Result.Nodes.getNodeAs<VarDecl>("local-value");
const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("function-decl");
/// If the variable was declared in a template it might be analyzed multiple
/// times. Only one of those instantiations shall emit a warning. NOTE: This
/// shall only deduplicate warnings for variables that are not instantiation
/// dependent. Variables like 'int x = 42;' in a template that can become
/// const emit multiple warnings otherwise.
bool IsNormalVariableInTemplate = Function->isTemplateInstantiation();
if (IsNormalVariableInTemplate &&
TemplateDiagnosticsCache.contains(Variable->getBeginLoc()))
return;
VariableCategory VC = VariableCategory::Value;
if (Variable->getType()->isReferenceType())
VC = VariableCategory::Reference;
if (Variable->getType()->isPointerType())
VC = VariableCategory::Pointer;
if (Variable->getType()->isArrayType()) {
if (const auto *ArrayT = dyn_cast<ArrayType>(Variable->getType())) {
if (ArrayT->getElementType()->isPointerType())
VC = VariableCategory::Pointer;
}
}
// Each variable can only be in one category: Value, Pointer, Reference.
// Analysis can be controlled for every category.
if (VC == VariableCategory::Reference && !AnalyzeReferences)
return;
if (VC == VariableCategory::Reference &&
Variable->getType()->getPointeeType()->isPointerType() &&
!WarnPointersAsValues)
return;
if (VC == VariableCategory::Pointer && !WarnPointersAsValues)
return;
if (VC == VariableCategory::Value && !AnalyzeValues)
return;
// The scope is only registered if the analysis shall be run.
registerScope(LocalScope, Result.Context);
// Offload const-analysis to utility function.
if (ScopesCache[LocalScope]->isMutated(Variable))
return;
auto Diag = diag(Variable->getBeginLoc(),
"variable %0 of type %1 can be declared 'const'")
<< Variable << Variable->getType();
if (IsNormalVariableInTemplate)
TemplateDiagnosticsCache.insert(Variable->getBeginLoc());
const auto *VarDeclStmt = Result.Nodes.getNodeAs<DeclStmt>("decl-stmt");
// It can not be guaranteed that the variable is declared isolated, therefore
// a transformation might effect the other variables as well and be incorrect.
if (VarDeclStmt == nullptr || !VarDeclStmt->isSingleDecl())
return;
using namespace utils::fixit;
if (VC == VariableCategory::Value && TransformValues) {
Diag << addQualifierToVarDecl(*Variable, *Result.Context,
DeclSpec::TQ_const, QualifierTarget::Value,
QualifierPolicy::Right);
// FIXME: Add '{}' for default initialization if no user-defined default
// constructor exists and there is no initializer.
return;
}
if (VC == VariableCategory::Reference && TransformReferences) {
Diag << addQualifierToVarDecl(*Variable, *Result.Context,
DeclSpec::TQ_const, QualifierTarget::Value,
QualifierPolicy::Right);
return;
}
if (VC == VariableCategory::Pointer) {
if (WarnPointersAsValues && TransformPointersAsValues) {
Diag << addQualifierToVarDecl(*Variable, *Result.Context,
DeclSpec::TQ_const, QualifierTarget::Value,
QualifierPolicy::Right);
}
return;
}
}
void ConstCorrectnessCheck::registerScope(const CompoundStmt *LocalScope,
ASTContext *Context) {
auto &Analyzer = ScopesCache[LocalScope];
if (!Analyzer)
Analyzer = std::make_unique<ExprMutationAnalyzer>(*LocalScope, *Context);
}
} // namespace misc
} // namespace tidy
} // namespace clang
|
