//===----------------------------------------------------------------------===//
//
// 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 "clang-tidy/ClangTidyCheck.h"
#include "clang-tidy/ClangTidyModuleRegistry.h"
#include "llvm/ADT/ArrayRef.h"
#include "header_exportable_declarations.hpp"
#include <iostream>
#include <iterator>
#include <ranges>
#include <algorithm>
template <>
struct clang::tidy::OptionEnumMapping<libcpp::header_exportable_declarations::FileType> {
static llvm::ArrayRef<std::pair<libcpp::header_exportable_declarations::FileType, llvm::StringRef>> getEnumMapping() {
static constexpr std::pair<libcpp::header_exportable_declarations::FileType, llvm::StringRef> Mapping[] = {
{libcpp::header_exportable_declarations::FileType::Header, "Header"},
{libcpp::header_exportable_declarations::FileType::ModulePartition, "ModulePartition"},
{libcpp::header_exportable_declarations::FileType::Module, "Module"},
{libcpp::header_exportable_declarations::FileType::CHeader, "CHeader"},
{libcpp::header_exportable_declarations::FileType::CompatModulePartition, "CompatModulePartition"},
{libcpp::header_exportable_declarations::FileType::CompatModule, "CompatModule"}};
return ArrayRef(Mapping);
}
};
namespace libcpp {
header_exportable_declarations::header_exportable_declarations(
llvm::StringRef name, clang::tidy::ClangTidyContext* context)
: clang::tidy::ClangTidyCheck(name, context),
filename_(Options.get("Filename", "")),
file_type_(Options.get("FileType", header_exportable_declarations::FileType::Unknown)),
extra_header_(Options.get("ExtraHeader", "")) {
switch (file_type_) {
case header_exportable_declarations::FileType::CHeader:
case header_exportable_declarations::FileType::Header:
if (filename_.empty())
llvm::errs() << "No filename is provided.\n";
if (extra_header_.empty())
extra_header_ = "$^"; // Use a never matching regex to silence an error message.
break;
case header_exportable_declarations::FileType::ModulePartition:
case header_exportable_declarations::FileType::CompatModulePartition:
if (filename_.empty())
llvm::errs() << "No filename is provided.\n";
[[fallthrough]];
case header_exportable_declarations::FileType::Module:
case header_exportable_declarations::FileType::CompatModule:
if (!extra_header_.empty())
llvm::errs() << "Extra headers are not allowed for modules.\n";
if (Options.get("SkipDeclarations"))
llvm::errs() << "Modules may not skip declarations.\n";
if (Options.get("ExtraDeclarations"))
llvm::errs() << "Modules may not have extra declarations.\n";
break;
case header_exportable_declarations::FileType::Unknown:
llvm::errs() << "No file type is provided.\n";
break;
}
std::optional<llvm::StringRef> list = Options.get("SkipDeclarations");
if (list)
for (auto decl : std::views::split(*list, ' ')) {
std::string s;
std::ranges::copy(decl, std::back_inserter(s)); // use range based constructor
skip_decls_.emplace(std::move(s));
}
decls_ = skip_decls_;
list = Options.get("ExtraDeclarations");
if (list)
for (auto decl : std::views::split(*list, ' ')) {
auto common = decl | std::views::common;
std::cout << "using ::" << std::string{common.begin(), common.end()} << ";\n";
}
}
header_exportable_declarations::~header_exportable_declarations() {
for (const auto& name : global_decls_)
if (!skip_decls_.contains("std::" + name) && decls_.contains("std::" + name))
std::cout << "using ::" << name << ";\n";
}
void header_exportable_declarations::registerMatchers(clang::ast_matchers::MatchFinder* finder) {
// there are no public names in the Standard starting with an underscore, so
// no need to check the strict rules.
using namespace clang::ast_matchers;
switch (file_type_) {
case FileType::Header:
finder->addMatcher(
namedDecl(
// Looks at the common locations where headers store their data
// * header
// * __header/*.h
// * __fwd/header.h
anyOf(isExpansionInFileMatching(("v1/__" + filename_ + "/").str()),
isExpansionInFileMatching(extra_header_),
isExpansionInFileMatching(("v1/__fwd/" + filename_ + "\\.h$").str()),
isExpansionInFileMatching(("v1/" + filename_ + "$").str())),
unless(hasAncestor(friendDecl())))
.bind("header_exportable_declarations"),
this);
break;
case FileType::CHeader:
// For C headers of the std.compat two matchers are used
// - The cheader matcher; in libc++ these are never split in multiple
// headers so limiting the declarations to that header works.
// - The header.h; where the declarations of this header are provided
// is not specified and depends on the libc used. Therefore it is not
// possible to restrict the location in a portable way.
finder->addMatcher(namedDecl().bind("cheader_exportable_declarations"), this);
[[fallthrough]];
case FileType::ModulePartition:
case FileType::CompatModulePartition:
finder->addMatcher(namedDecl(isExpansionInFileMatching(filename_)).bind("header_exportable_declarations"), this);
break;
case FileType::Module:
case FileType::CompatModule:
finder->addMatcher(namedDecl().bind("header_exportable_declarations"), this);
break;
case header_exportable_declarations::FileType::Unknown:
llvm::errs() << "This should be unreachable.\n";
break;
}
}
/// Returns the qualified name of a public declaration.
///
/// There is a small issue with qualified names. Typically the name returned is
/// in the namespace \c std instead of the namespace \c std::__1. Except when a
/// name is declared both in the namespace \c std and in the namespace
/// \c std::__1. In that case the returned value will adjust the name to use
/// the namespace \c std.
///
/// The reason this happens is due to some parts of libc++ using
/// \code namespace std \endcode instead of
/// \code _LIBCPP_BEGIN_NAMESPACE_STD \endcode
/// Some examples
/// * cstddef has bitwise operators for the type \c byte
/// * exception has equality operators for the type \c exception_ptr
/// * initializer_list has the functions \c begin and \c end
///
/// When the named declaration uses a reserved name the result is an
/// empty string.
static std::string get_qualified_name(const clang::NamedDecl& decl) {
std::string result = decl.getNameAsString();
// Reject reserved names (ignoring _ in global namespace).
if (result.size() >= 2 && result[0] == '_')
if (result[1] == '_' || std::isupper(result[1]))
if (result != "_Exit")
return "";
for (auto* context = llvm::dyn_cast_or_null<clang::NamespaceDecl>(decl.getDeclContext()); //
context;
context = llvm::dyn_cast_or_null<clang::NamespaceDecl>(context->getDeclContext())) {
std::string ns = std::string(context->getName());
if (ns.starts_with("__")) {
// When the reserved name is an inline namespace the namespace is
// not added to the qualified name instead of removed. Libc++ uses
// several inline namespace with reserved names. For example,
// __1 for every declaration, __cpo in range-based algorithms.
//
// Note other inline namespaces are expanded. This resolves
// ambiguity when two named declarations have the same name but in
// different inline namespaces. These typically are the literal
// conversion operators like operator""s which can be a
// std::string or std::chrono::seconds.
if (!context->isInline())
return "";
} else
result = ns + "::" + result;
}
return result;
}
static bool is_viable_declaration(const clang::NamedDecl* decl) {
// Declarations that are a subobject of a friend Declaration are automatically exported with the record itself.
if (decl->getFriendObjectKind() != clang::Decl::FOK_None)
return false;
// *** Function declarations ***
if (clang::CXXMethodDecl::classof(decl))
return false;
if (clang::CXXDeductionGuideDecl::classof(decl))
return false;
if (clang::FunctionDecl::classof(decl))
return true;
if (clang::CXXConstructorDecl::classof(decl))
return false;
// implicit constructors disallowed
if (const auto* r = llvm::dyn_cast_or_null<clang::RecordDecl>(decl))
return !r->isLambda() && !r->isImplicit();
// *** Unconditionally accepted declarations ***
return llvm::isa<clang::EnumDecl, clang::VarDecl, clang::ConceptDecl, clang::TypedefNameDecl, clang::UsingDecl>(decl);
}
/// Some declarations in the global namespace are exported from the std module.
static bool is_global_name_exported_by_std_module(std::string_view name) {
static const std::set<std::string_view> valid{
"operator delete", "operator delete[]", "operator new", "operator new[]"};
return valid.contains(name);
}
static bool is_valid_declaration_context(
const clang::NamedDecl& decl, std::string_view name, header_exportable_declarations::FileType file_type) {
const clang::DeclContext& context = *decl.getDeclContext();
if (context.isNamespace())
return true;
if (context.isFunctionOrMethod() || context.isRecord())
return false;
if (is_global_name_exported_by_std_module(name))
return true;
return file_type != header_exportable_declarations::FileType::Header;
}
static bool is_module(header_exportable_declarations::FileType file_type) {
switch (file_type) {
case header_exportable_declarations::FileType::Module:
case header_exportable_declarations::FileType::ModulePartition:
case header_exportable_declarations::FileType::CompatModule:
case header_exportable_declarations::FileType::CompatModulePartition:
return true;
case header_exportable_declarations::FileType::Header:
case header_exportable_declarations::FileType::CHeader:
return false;
case header_exportable_declarations::FileType::Unknown:
llvm::errs() << "This should be unreachable.\n";
return false;
}
}
void header_exportable_declarations::check(const clang::ast_matchers::MatchFinder::MatchResult& result) {
if (const auto* decl = result.Nodes.getNodeAs<clang::NamedDecl>("header_exportable_declarations"); decl != nullptr) {
if (!is_viable_declaration(decl))
return;
std::string name = get_qualified_name(*decl);
if (name.empty())
return;
// For modules only take the declarations exported.
if (is_module(file_type_))
if (decl->getModuleOwnershipKind() != clang::Decl::ModuleOwnershipKind::VisibleWhenImported)
return;
if (!is_valid_declaration_context(*decl, name, file_type_))
return;
if (decls_.contains(name)) {
// For modules avoid exporting the same named declaration twice. For
// header files this is common and valid.
if (file_type_ == FileType::ModulePartition || file_type_ == FileType::CompatModulePartition)
// After the warning the script continues.
// The test will fail since modules have duplicated entries and headers not.
llvm::errs() << "Duplicated export of '" << name << "'.\n";
else
return;
}
// For named declarations in std this is valid
// using std::foo;
// for named declarations it is invalid to use
// using bar;
// Since fully qualifying named declarations in the std namespace is valid
// using fully qualified names unconditionally.
std::cout << "using ::" << std::string{name} << ";\n";
decls_.insert(name);
} else if (const auto* decl = result.Nodes.getNodeAs<clang::NamedDecl>("cheader_exportable_declarations");
decl != nullptr) {
if (decl->getDeclContext()->isNamespace())
return;
if (!is_viable_declaration(decl))
return;
std::string name = get_qualified_name(*decl);
if (name.empty())
return;
if (global_decls_.contains(name))
return;
global_decls_.insert(name);
}
}
} // namespace libcpp
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