1//===--- ConfusableIdentifierCheck.cpp -
2// clang-tidy--------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#include "ConfusableIdentifierCheck.h"
11
12#include "clang/Frontend/CompilerInstance.h"
13#include "clang/Lex/Preprocessor.h"
14#include "llvm/ADT/SmallString.h"
15#include "llvm/Support/ConvertUTF.h"
16
17namespace {
18// Preprocessed version of
19// https://www.unicode.org/Public/security/latest/confusables.txt
20//
21// This contains a sorted array of { UTF32 codepoint; UTF32 values[N];}
22#include "Confusables.inc"
23} // namespace
24
25namespace clang::tidy::misc {
26
27ConfusableIdentifierCheck::ConfusableIdentifierCheck(StringRef Name,
28 ClangTidyContext *Context)
29 : ClangTidyCheck(Name, Context) {}
30
31ConfusableIdentifierCheck::~ConfusableIdentifierCheck() = default;
32
33// Build a skeleton out of the Original identifier, inspired by the algorithm
34// described in http://www.unicode.org/reports/tr39/#def-skeleton
35//
36// FIXME: TR39 mandates:
37//
38// For an input string X, define skeleton(X) to be the following transformation
39// on the string:
40//
41// 1. Convert X to NFD format, as described in [UAX15].
42// 2. Concatenate the prototypes for each character in X according to the
43// specified data, producing a string of exemplar characters.
44// 3. Reapply NFD.
45//
46// We're skipping 1. and 3. for the sake of simplicity, but this can lead to
47// false positive.
48
49static llvm::SmallString<64U> skeleton(StringRef Name) {
50 using namespace llvm;
51 SmallString<64U> Skeleton;
52 Skeleton.reserve(1U + Name.size());
53
54 const char *Curr = Name.data();
55 const char *End = Curr + Name.size();
56 while (Curr < End) {
57
58 const char *Prev = Curr;
59 UTF32 CodePoint = 0;
60 ConversionResult Result = convertUTF8Sequence(
61 source: reinterpret_cast<const UTF8 **>(&Curr),
62 sourceEnd: reinterpret_cast<const UTF8 *>(End), target: &CodePoint, flags: strictConversion);
63 if (Result != conversionOK) {
64 errs() << "Unicode conversion issue\n";
65 break;
66 }
67
68 StringRef Key(Prev, Curr - Prev);
69 auto Where = llvm::lower_bound(ConfusableEntries, CodePoint,
70 [](decltype(ConfusableEntries[0]) x,
71 UTF32 y) { return x.codepoint < y; });
72 if (Where == std::end(ConfusableEntries) || CodePoint != Where->codepoint) {
73 Skeleton.append(Prev, Curr);
74 } else {
75 UTF8 Buffer[32];
76 UTF8 *BufferStart = std::begin(Buffer);
77 UTF8 *IBuffer = BufferStart;
78 const UTF32 *ValuesStart = std::begin(Where->values);
79 const UTF32 *ValuesEnd = llvm::find(Where->values, '\0');
80 if (ConvertUTF32toUTF8(&ValuesStart, ValuesEnd, &IBuffer,
81 std::end(Buffer),
82 strictConversion) != conversionOK) {
83 errs() << "Unicode conversion issue\n";
84 break;
85 }
86 Skeleton.append((char *)BufferStart, (char *)IBuffer);
87 }
88 }
89 return Skeleton;
90}
91
92static bool mayShadowImpl(const DeclContext *DC0, const DeclContext *DC1) {
93 return DC0 && DC0 == DC1;
94}
95
96static bool mayShadowImpl(const NamedDecl *ND0, const NamedDecl *ND1) {
97 return isa<TemplateTypeParmDecl>(ND0) || isa<TemplateTypeParmDecl>(ND1);
98}
99
100static bool isMemberOf(const ConfusableIdentifierCheck::ContextInfo *DC0,
101 const ConfusableIdentifierCheck::ContextInfo *DC1) {
102 return llvm::is_contained(DC1->Bases, DC0->PrimaryContext);
103}
104
105static bool enclosesContext(const ConfusableIdentifierCheck::ContextInfo *DC0,
106 const ConfusableIdentifierCheck::ContextInfo *DC1) {
107 if (DC0->PrimaryContext == DC1->PrimaryContext)
108 return true;
109
110 return llvm::is_contained(DC0->PrimaryContexts, DC1->PrimaryContext) ||
111 llvm::is_contained(DC1->PrimaryContexts, DC0->PrimaryContext);
112}
113
114static bool mayShadow(const NamedDecl *ND0,
115 const ConfusableIdentifierCheck::ContextInfo *DC0,
116 const NamedDecl *ND1,
117 const ConfusableIdentifierCheck::ContextInfo *DC1) {
118
119 if (!DC0->Bases.empty() && !DC1->Bases.empty()) {
120 // if any of the declaration is a non-private member of the other
121 // declaration, it's shadowed by the former
122
123 if (ND1->getAccess() != AS_private && isMemberOf(DC0: DC1, DC1: DC0))
124 return true;
125
126 if (ND0->getAccess() != AS_private && isMemberOf(DC0, DC1))
127 return true;
128 }
129
130 if (!mayShadowImpl(DC0: DC0->NonTransparentContext, DC1: DC1->NonTransparentContext) &&
131 !mayShadowImpl(ND0, ND1))
132 return false;
133
134 return enclosesContext(DC0, DC1);
135}
136
137const ConfusableIdentifierCheck::ContextInfo *
138ConfusableIdentifierCheck::getContextInfo(const DeclContext *DC) {
139 const DeclContext *PrimaryContext = DC->getPrimaryContext();
140 auto It = ContextInfos.find(PrimaryContext);
141 if (It != ContextInfos.end())
142 return &It->second;
143
144 ContextInfo &Info = ContextInfos[PrimaryContext];
145 Info.PrimaryContext = PrimaryContext;
146 Info.NonTransparentContext = PrimaryContext;
147
148 while (Info.NonTransparentContext->isTransparentContext()) {
149 Info.NonTransparentContext = Info.NonTransparentContext->getParent();
150 if (!Info.NonTransparentContext)
151 break;
152 }
153
154 if (Info.NonTransparentContext)
155 Info.NonTransparentContext =
156 Info.NonTransparentContext->getPrimaryContext();
157
158 while (DC) {
159 if (!isa<LinkageSpecDecl>(DC) && !isa<ExportDecl>(DC))
160 Info.PrimaryContexts.push_back(Elt: DC->getPrimaryContext());
161 DC = DC->getParent();
162 }
163
164 if (const auto *RD = dyn_cast<CXXRecordDecl>(PrimaryContext)) {
165 RD = RD->getDefinition();
166 if (RD) {
167 Info.Bases.push_back(Elt: RD);
168 RD->forallBases([&](const CXXRecordDecl *Base) {
169 Info.Bases.push_back(Elt: Base);
170 return false;
171 });
172 }
173 }
174
175 return &Info;
176}
177
178void ConfusableIdentifierCheck::check(
179 const ast_matchers::MatchFinder::MatchResult &Result) {
180 const auto *ND = Result.Nodes.getNodeAs<NamedDecl>("nameddecl");
181 if (!ND)
182 return;
183
184 IdentifierInfo *NDII = ND->getIdentifier();
185 if (!NDII)
186 return;
187
188 StringRef NDName = NDII->getName();
189 if (NDName.empty())
190 return;
191
192 const ContextInfo *Info = getContextInfo(DC: ND->getDeclContext());
193
194 llvm::SmallVector<Entry> &Mapped = Mapper[skeleton(NDName)];
195 for (const Entry &E : Mapped) {
196 if (!mayShadow(ND, Info, E.Declaration, E.Info))
197 continue;
198
199 const IdentifierInfo *ONDII = E.Declaration->getIdentifier();
200 StringRef ONDName = ONDII->getName();
201 if (ONDName == NDName)
202 continue;
203
204 diag(ND->getLocation(), "%0 is confusable with %1") << ND << E.Declaration;
205 diag(E.Declaration->getLocation(), "other declaration found here",
206 DiagnosticIDs::Note);
207 }
208
209 Mapped.push_back({ND, Info});
210}
211
212void ConfusableIdentifierCheck::onEndOfTranslationUnit() {
213 Mapper.clear();
214 ContextInfos.clear();
215}
216
217void ConfusableIdentifierCheck::registerMatchers(
218 ast_matchers::MatchFinder *Finder) {
219 Finder->addMatcher(ast_matchers::namedDecl().bind("nameddecl"), this);
220}
221
222} // namespace clang::tidy::misc
223

source code of clang-tools-extra/clang-tidy/misc/ConfusableIdentifierCheck.cpp