clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp

   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
  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::tidy::cert {
  41
  42 void DontModifyStdNamespaceCheck::registerMatchers(MatchFinder *Finder) {
  43   auto HasStdParent =
  44       hasDeclContext(namespaceDecl(hasAnyName("std", "posix"),
  45                                    unless(hasParent(namespaceDecl())))
  46                          .bind("nmspc"));
  47   auto UserDefinedType = qualType(
  48       hasUnqualifiedDesugaredType(tagType(unless(hasDeclaration(tagDecl(
  49           hasAncestor(namespaceDecl(hasAnyName("std", "posix"),
  50                                     unless(hasParent(namespaceDecl()))))))))));
  51   auto HasNoProgramDefinedTemplateArgument = unless(
  52       hasAnyTemplateArgumentIncludingPack(refersToType(UserDefinedType)));
  53   auto InsideStdClassOrClassTemplateSpecialization = hasDeclContext(
  54       anyOf(cxxRecordDecl(HasStdParent),
  55             classTemplateSpecializationDecl(
  56                 HasStdParent, HasNoProgramDefinedTemplateArgument)));
  57
  58   // Try to follow exactly CERT rule DCL58-CPP (this text is taken from C++
  59   // standard into the CERT rule):
  60   // "
  61   // 1 The behavior of a C++ program is undefined if it adds declarations or
  62   // definitions to namespace std or to a namespace within namespace std unless
  63   // otherwise specified. A program may add a template specialization for any
  64   // standard library template to namespace std only if the declaration depends
  65   // on a user-defined type and the specialization meets the standard library
  66   // requirements for the original template and is not explicitly prohibited. 2
  67   // The behavior of a C++ program is undefined if it declares — an explicit
  68   // specialization of any member function of a standard library class template,
  69   // or — an explicit specialization of any member function template of a
  70   // standard library class or class template, or — an explicit or partial
  71   // specialization of any member class template of a standard library class or
  72   // class template.
  73   // "
  74   // The "standard library requirements" and explicit prohibition are not
  75   // checked.
  76
  77   auto BadNonTemplateSpecializationDecl =
  78       decl(unless(anyOf(functionDecl(isExplicitTemplateSpecialization()),
  79                         varDecl(isExplicitTemplateSpecialization()),
  80                         cxxRecordDecl(isExplicitTemplateSpecialization()))),
  81            HasStdParent);
  82   auto BadClassTemplateSpec = classTemplateSpecializationDecl(
  83       HasNoProgramDefinedTemplateArgument, HasStdParent);
  84   auto BadInnerClassTemplateSpec = classTemplateSpecializationDecl(
  85       InsideStdClassOrClassTemplateSpecialization);
  86   auto BadFunctionTemplateSpec =
  87       functionDecl(unless(cxxMethodDecl()), isExplicitTemplateSpecialization(),
  88                    HasNoProgramDefinedTemplateArgument, HasStdParent);
  89   auto BadMemberFunctionSpec =
  90       cxxMethodDecl(isExplicitTemplateSpecialization(),
  91                     InsideStdClassOrClassTemplateSpecialization);
  92
  93   Finder->addMatcher(decl(anyOf(BadNonTemplateSpecializationDecl,
  94                                 BadClassTemplateSpec, BadInnerClassTemplateSpec,
  95                                 BadFunctionTemplateSpec, BadMemberFunctionSpec),
  96                           unless(isExpansionInSystemHeader()))
  97                          .bind("decl"),
  98                      this);
  99 }
 100 } // namespace clang::tidy::cert
 101
 102 static const NamespaceDecl *getTopLevelLexicalNamespaceDecl(const Decl *D) {
 103   const NamespaceDecl *LastNS = nullptr;
 104   while (D) {
 105     if (const auto *NS = dyn_cast<NamespaceDecl>(D))
 106       LastNS = NS;
 107     D = dyn_cast_or_null<Decl>(D->getLexicalDeclContext());
 108   }
 109   return LastNS;
 110 }
 111
 112 void clang::tidy::cert::DontModifyStdNamespaceCheck::check(
 113     const MatchFinder::MatchResult &Result) {
 114   const auto *D = Result.Nodes.getNodeAs<Decl>("decl");
 115   const auto *NS = Result.Nodes.getNodeAs<NamespaceDecl>("nmspc");
 116   if (!D || !NS)
 117     return;
 118
 119   diag(D->getLocation(),
 120        "modification of %0 namespace can result in undefined behavior")
 121       << NS;
 122   // 'NS' is not always the namespace declaration that lexically contains 'D',
 123   // try to find such a namespace.
 124   if (const NamespaceDecl *LexNS = getTopLevelLexicalNamespaceDecl(D)) {
 125     assert(NS->getCanonicalDecl() == LexNS->getCanonicalDecl() &&
 126            "Mismatch in found namespace");
 127     diag(LexNS->getLocation(), "%0 namespace opened here", DiagnosticIDs::Note)
 128         << LexNS;
 129   }
 130 }