[clang] p1099 using enum part 2

This implements the 'using enum maybe-qualified-enum-tag ;' part of
1099. It introduces a new 'UsingEnumDecl', subclassed from
'BaseUsingDecl'. Much of the diff is the boilerplate needed to get the
new class set up.

There is one case where we accept ill-formed, but I believe this is
merely an extended case of an existing bug, so consider it
orthogonal. AFAICT in class-scope the c++20 rule is that no 2 using
decls can bring in the same target decl ([namespace.udecl]/8). But we
already accept:

struct A { enum { a }; };
struct B : A { using A::a; };
struct C : B { using A::a;
using B::a; }; // same enumerator

this patch permits mixtures of 'using enum Bob;' and 'using Bob::member;' in the same way.

Differential Revision: https://reviews.llvm.org/D102241

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 0bde8ea..1ab9c50 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -3915,6 +3915,9 @@ CXCursorKind clang::getCursorKindForDecl(const Decl *D) {
   case Decl::UnresolvedUsingTypename:
     return CXCursor_UsingDeclaration;
 
+  case Decl::UsingEnum:
+    return CXCursor_EnumDecl;
+
   case Decl::ObjCPropertyImpl:
     switch (cast<ObjCPropertyImplDecl>(D)->getPropertyImplementation()) {
     case ObjCPropertyImplDecl::Dynamic: