1 //===--- DontModifyStdNamespaceCheck.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 "DontModifyStdNamespaceCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/ASTMatchers/ASTMatchersInternal.h"
13
14 using namespace clang;
15 using namespace clang::ast_matchers;
16
17 namespace {
18
AST_POLYMORPHIC_MATCHER_P(hasAnyTemplateArgumentIncludingPack,AST_POLYMORPHIC_SUPPORTED_TYPES (ClassTemplateSpecializationDecl,TemplateSpecializationType,FunctionDecl),clang::ast_matchers::internal::Matcher<TemplateArgument>,InnerMatcher)19 AST_POLYMORPHIC_MATCHER_P(
20 hasAnyTemplateArgumentIncludingPack,
21 AST_POLYMORPHIC_SUPPORTED_TYPES(ClassTemplateSpecializationDecl,
22 TemplateSpecializationType, FunctionDecl),
23 clang::ast_matchers::internal::Matcher<TemplateArgument>, InnerMatcher) {
24 ArrayRef<TemplateArgument> Args =
25 clang::ast_matchers::internal::getTemplateSpecializationArgs(Node);
26 for (const auto &Arg : Args) {
27 if (Arg.getKind() != TemplateArgument::Pack)
28 continue;
29 ArrayRef<TemplateArgument> PackArgs = Arg.getPackAsArray();
30 if (matchesFirstInRange(InnerMatcher, PackArgs.begin(), PackArgs.end(),
31 Finder, Builder) != PackArgs.end())
32 return true;
33 }
34 return matchesFirstInRange(InnerMatcher, Args.begin(), Args.end(), Finder,
35 Builder) != Args.end();
36 }
37
38 } // namespace
39
40 namespace clang {
41 namespace tidy {
42 namespace cert {
43
registerMatchers(MatchFinder * Finder)44 void DontModifyStdNamespaceCheck::registerMatchers(MatchFinder *Finder) {
45 auto HasStdParent =
46 hasDeclContext(namespaceDecl(hasAnyName("std", "posix"),
47 unless(hasParent(namespaceDecl())))
48 .bind("nmspc"));
49 auto UserDefinedType = qualType(
50 hasUnqualifiedDesugaredType(tagType(unless(hasDeclaration(tagDecl(
51 hasAncestor(namespaceDecl(hasAnyName("std", "posix"),
52 unless(hasParent(namespaceDecl()))))))))));
53 auto HasNoProgramDefinedTemplateArgument = unless(
54 hasAnyTemplateArgumentIncludingPack(refersToType(UserDefinedType)));
55 auto InsideStdClassOrClassTemplateSpecialization = hasDeclContext(
56 anyOf(cxxRecordDecl(HasStdParent),
57 classTemplateSpecializationDecl(
58 HasStdParent, HasNoProgramDefinedTemplateArgument)));
59
60 // Try to follow exactly CERT rule DCL58-CPP (this text is taken from C++
61 // standard into the CERT rule):
62 // "
63 // 1 The behavior of a C++ program is undefined if it adds declarations or
64 // definitions to namespace std or to a namespace within namespace std unless
65 // otherwise specified. A program may add a template specialization for any
66 // standard library template to namespace std only if the declaration depends
67 // on a user-defined type and the specialization meets the standard library
68 // requirements for the original template and is not explicitly prohibited. 2
69 // The behavior of a C++ program is undefined if it declares — an explicit
70 // specialization of any member function of a standard library class template,
71 // or — an explicit specialization of any member function template of a
72 // standard library class or class template, or — an explicit or partial
73 // specialization of any member class template of a standard library class or
74 // class template.
75 // "
76 // The "standard library requirements" and explicit prohibition are not
77 // checked.
78
79 auto BadNonTemplateSpecializationDecl =
80 decl(unless(anyOf(functionDecl(isExplicitTemplateSpecialization()),
81 varDecl(isExplicitTemplateSpecialization()),
82 cxxRecordDecl(isExplicitTemplateSpecialization()))),
83 HasStdParent);
84 auto BadClassTemplateSpec = classTemplateSpecializationDecl(
85 HasNoProgramDefinedTemplateArgument, HasStdParent);
86 auto BadInnerClassTemplateSpec = classTemplateSpecializationDecl(
87 InsideStdClassOrClassTemplateSpecialization);
88 auto BadFunctionTemplateSpec =
89 functionDecl(unless(cxxMethodDecl()), isExplicitTemplateSpecialization(),
90 HasNoProgramDefinedTemplateArgument, HasStdParent);
91 auto BadMemberFunctionSpec =
92 cxxMethodDecl(isExplicitTemplateSpecialization(),
93 InsideStdClassOrClassTemplateSpecialization);
94
95 Finder->addMatcher(decl(anyOf(BadNonTemplateSpecializationDecl,
96 BadClassTemplateSpec, BadInnerClassTemplateSpec,
97 BadFunctionTemplateSpec, BadMemberFunctionSpec),
98 unless(isExpansionInSystemHeader()))
99 .bind("decl"),
100 this);
101 }
102 } // namespace cert
103 } // namespace tidy
104 } // namespace clang
105
getTopLevelLexicalNamespaceDecl(const Decl * D)106 static const NamespaceDecl *getTopLevelLexicalNamespaceDecl(const Decl *D) {
107 const NamespaceDecl *LastNS = nullptr;
108 while (D) {
109 if (const auto *NS = dyn_cast<NamespaceDecl>(D))
110 LastNS = NS;
111 D = dyn_cast_or_null<Decl>(D->getLexicalDeclContext());
112 }
113 return LastNS;
114 }
115
check(const MatchFinder::MatchResult & Result)116 void clang::tidy::cert::DontModifyStdNamespaceCheck::check(
117 const MatchFinder::MatchResult &Result) {
118 const auto *D = Result.Nodes.getNodeAs<Decl>("decl");
119 const auto *NS = Result.Nodes.getNodeAs<NamespaceDecl>("nmspc");
120 if (!D || !NS)
121 return;
122
123 diag(D->getLocation(),
124 "modification of %0 namespace can result in undefined behavior")
125 << NS;
126 // 'NS' is not always the namespace declaration that lexically contains 'D',
127 // try to find such a namespace.
128 if (const NamespaceDecl *LexNS = getTopLevelLexicalNamespaceDecl(D)) {
129 assert(NS->getCanonicalDecl() == LexNS->getCanonicalDecl() &&
130 "Mismatch in found namespace");
131 diag(LexNS->getLocation(), "%0 namespace opened here", DiagnosticIDs::Note)
132 << LexNS;
133 }
134 }
135