AntonBikineev created this revision.
AntonBikineev added a reviewer: rsmith.
AntonBikineev added a project: clang.
AntonBikineev requested review of this revision.
This change merely allows nested-name-specifiers for enums in using
declarations but doesn't add support for the "using-enum-declaration"
syntax proposed in P1099 <https://reviews.llvm.org/P1099>.
Repository:
rC Clang
https://reviews.llvm.org/D99396
Files:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/SemaCXX/cxx20-using-enum.cpp
clang/test/SemaCXX/enum-scoped.cpp
Index: clang/test/SemaCXX/enum-scoped.cpp
===================================================================
--- clang/test/SemaCXX/enum-scoped.cpp
+++ clang/test/SemaCXX/enum-scoped.cpp
@@ -301,7 +301,7 @@
int E::*p; // expected-error {{does not point into a class}}
using E::f; // expected-error {{no member named 'f'}}
- using E::a; // expected-error {{using declaration cannot refer to a scoped enumerator}}
+ using E::a; // expected-error {{using declaration cannot refer to a scoped enumerator before C++20}}
E b = a; // expected-error {{undeclared}}
}
Index: clang/test/SemaCXX/cxx20-using-enum.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/cxx20-using-enum.cpp
@@ -0,0 +1,38 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++20 -verify %s
+
+enum class E {
+ e1,
+ e2
+};
+
+void foo() {
+ using E::e1;
+ auto a = e1;
+}
+
+namespace N {
+using E::e2;
+constexpr auto a = e2;
+} // namespace N
+
+struct C {
+ using E::e1;
+ E e = e1;
+};
+
+namespace N1 {
+enum class E {
+ e1,
+};
+using E::e1;
+auto a = e1;
+} // namespace N1
+
+enum class E1 {
+ e1 // expected-note{{conflicting declaration}}
+};
+enum class E2 {
+ e1 // expected-note{{target of using declaration}}
+};
+using E1::e1;
+using E2::e1; // expected-error{{target of using declaration conflicts with declaration already in scope}}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -12231,7 +12231,8 @@
// C++14 [namespace.udecl]p7:
// A using-declaration shall not name a scoped enumerator.
if (auto *ED = R.getAsSingle<EnumConstantDecl>()) {
- if (cast<EnumDecl>(ED->getDeclContext())->isScoped()) {
+ if (!LangOpts.CPlusPlus20 &&
+ cast<EnumDecl>(ED->getDeclContext())->isScoped()) {
Diag(IdentLoc, diag::err_using_decl_can_not_refer_to_scoped_enum)
<< SS.getRange();
return BuildInvalid();
@@ -12392,10 +12393,13 @@
// C++03 [namespace.udecl]p3:
// C++0x [namespace.udecl]p8:
// A using-declaration for a class member shall be a member-declaration.
+ // C++20 [namespace.udecl]p7:
+ // A using-declaration that names a class member other than an enumerator
+ // shall be a member-declaration.
// If we weren't able to compute a valid scope, it might validly be a
- // dependent class scope or a dependent enumeration unscoped scope. If
- // we have a 'typename' keyword, the scope must resolve to a class type.
+ // dependent class scope or a dependent scoped/unscoped enumeration scope.
+ // If we have a 'typename' keyword, the scope must resolve to a class type.
if ((HasTypename && !NamedContext) ||
(NamedContext && NamedContext->getRedeclContext()->isRecord())) {
auto *RD = NamedContext
@@ -12484,7 +12488,11 @@
return false;
}
- if (!NamedContext->isRecord()) {
+ bool IsCXX20ScopedEnum = LangOpts.CPlusPlus20 &&
+ NamedContext->getDeclKind() == Decl::Enum &&
+ cast<EnumDecl>(NamedContext)->isScoped();
+
+ if (!NamedContext->isRecord() && !IsCXX20ScopedEnum) {
// Ideally this would point at the last name in the specifier,
// but we don't have that level of source info.
Diag(SS.getRange().getBegin(),
@@ -12503,6 +12511,13 @@
// nested-name-specifier shall name a base class of the class
// being defined.
+ // C++20 [namespace.udecl]p3:
+ // In a using-declaration used as a member-declaration, each
+ // using-declarator shall either name an enumerator or have a
+ // nested-name-specifier naming a base class of the class being defined.
+ if (IsCXX20ScopedEnum)
+ return false;
+
if (cast<CXXRecordDecl>(CurContext)->isProvablyNotDerivedFrom(
cast<CXXRecordDecl>(NamedContext))) {
if (CurContext == NamedContext) {
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -539,7 +539,7 @@
def err_using_decl_can_not_refer_to_namespace : Error<
"using declaration cannot refer to a namespace">;
def err_using_decl_can_not_refer_to_scoped_enum : Error<
- "using declaration cannot refer to a scoped enumerator">;
+ "using declaration cannot refer to a scoped enumerator before C++20">;
def err_using_decl_constructor : Error<
"using declaration cannot refer to a constructor">;
def warn_cxx98_compat_using_decl_constructor : Warning<
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