[lldb][TypeSystemClang] Create EnumExtensibilityAttr from DW_AT_APPLE_enum_kind (#126221)

This patch consumes the `DW_AT_APPLE_enum_kind` attribute added in
https://github.com/llvm/llvm-project/pull/124752 and turns it into a
Clang attribute in the AST. This will currently be used by the Swift
language plugin when it creates `EnumDecl`s from debug-info and passes
it to Swift compiler, which expects these attributes

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -492,6 +492,10 @@ ParsedDWARFTypeAttributes::ParsedDWARFTypeAttributes(const DWARFDIE &die) {
     case DW_AT_reference:
       ref_qual = clang::RQ_LValue;
       break;
+    case DW_AT_APPLE_enum_kind:
+      enum_kind = static_cast<clang::EnumExtensibilityAttr::Kind>(
+          form_value.Unsigned());
+      break;
     }
   }
 }
@@ -1001,9 +1005,10 @@ TypeSP DWARFASTParserClang::ParseEnum(const SymbolContext &sc,
   }
 
   CompilerType clang_type = m_ast.CreateEnumerationType(
-      attrs.name.GetStringRef(), GetClangDeclContextContainingDIE(def_die, nullptr),
+      attrs.name.GetStringRef(),
+      GetClangDeclContextContainingDIE(def_die, nullptr),
       GetOwningClangModule(def_die), attrs.decl, enumerator_clang_type,
-      attrs.is_scoped_enum);
+      attrs.is_scoped_enum, attrs.enum_kind);
   TypeSP type_sp =
       dwarf->MakeType(def_die.GetID(), attrs.name, attrs.byte_size, nullptr,
                       attrs.type.Reference().GetID(), Type::eEncodingIsUID,

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h

@@ -568,6 +568,10 @@ struct ParsedDWARFTypeAttributes {
   ///< Indicates ref-qualifier of C++ member function if present.
   ///< Is RQ_None otherwise.
   clang::RefQualifierKind ref_qual = clang::RQ_None;
+
+  ///< Has a value if this DIE represents an enum that was declared
+  ///< with enum_extensibility.
+  std::optional<clang::EnumExtensibilityAttr::Kind> enum_kind;
 };
 
 #endif // LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DWARFASTPARSERCLANG_H

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -2303,7 +2303,8 @@ CompilerType TypeSystemClang::GetOrCreateStructForIdentifier(
 CompilerType TypeSystemClang::CreateEnumerationType(
     llvm::StringRef name, clang::DeclContext *decl_ctx,
     OptionalClangModuleID owning_module, const Declaration &decl,
-    const CompilerType &integer_clang_type, bool is_scoped) {
+    const CompilerType &integer_clang_type, bool is_scoped,
+    std::optional<clang::EnumExtensibilityAttr::Kind> enum_kind) {
   // TODO: Do something intelligent with the Declaration object passed in
   // like maybe filling in the SourceLocation with it...
   ASTContext &ast = getASTContext();
@@ -2321,6 +2322,10 @@ CompilerType TypeSystemClang::CreateEnumerationType(
   if (decl_ctx)
     decl_ctx->addDecl(enum_decl);
 
+  if (enum_kind)
+    enum_decl->addAttr(
+        clang::EnumExtensibilityAttr::CreateImplicit(ast, *enum_kind));
+
   // TODO: check if we should be setting the promotion type too?
   enum_decl->setIntegerType(ClangUtil::GetQualType(integer_clang_type));
 

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h

@@ -22,6 +22,7 @@
 
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTFwd.h"
+#include "clang/AST/Attr.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/TemplateBase.h"
 #include "clang/AST/Type.h"
@@ -498,12 +499,12 @@ public:
                                bool is_vector);
 
   // Enumeration Types
-  CompilerType CreateEnumerationType(llvm::StringRef name,
-                                     clang::DeclContext *decl_ctx,
-                                     OptionalClangModuleID owning_module,
-                                     const Declaration &decl,
-                                     const CompilerType &integer_qual_type,
-                                     bool is_scoped);
+  CompilerType CreateEnumerationType(
+      llvm::StringRef name, clang::DeclContext *decl_ctx,
+      OptionalClangModuleID owning_module, const Declaration &decl,
+      const CompilerType &integer_qual_type, bool is_scoped,
+      std::optional<clang::EnumExtensibilityAttr::Kind> enum_kind =
+          std::nullopt);
 
   // Integer type functions
 

lldb/test/Shell/Expr/TestEnumExtensibility.m

@@ -0,0 +1,33 @@
+// UNSUPPORTED: system-linux, system-windows
+
+// RUN: %clangxx_host %s -c -g -o %t
+// RUN: %lldb %t \
+// RUN:   -o "target var gClosed gOpen gNS gNSOpts" \
+// RUN:   -o "image dump ast" \
+// RUN:   2>&1 | FileCheck %s
+
+#import <Foundation/Foundation.h>
+
+enum __attribute__((enum_extensibility(closed))) Closed { C1 } gClosed;
+
+enum __attribute__((enum_extensibility(open))) Open { O1 } gOpen;
+
+typedef NS_ENUM(int, NS) { N1 } gNS;
+
+typedef NS_OPTIONS(int, NSO) { OPT1 } gNSOpts;
+
+// CHECK:      EnumDecl {{.*}} Closed
+// CHECK-NEXT: |-EnumExtensibilityAttr {{.*}} Closed
+// CHECK-NEXT: `-EnumConstantDecl {{.*}} C1 'Closed'
+
+// CHECK:      EnumDecl {{.*}} Open
+// CHECK-NEXT: |-EnumExtensibilityAttr {{.*}} Open
+// CHECK-NEXT: `-EnumConstantDecl {{.*}} O1 'Open'
+
+// CHECK:      EnumDecl {{.*}} NS
+// CHECK-NEXT: |-EnumExtensibilityAttr {{.*}} Open
+// CHECK-NEXT: `-EnumConstantDecl {{.*}} N1 'NS'
+
+// CHECK:      EnumDecl {{.*}} NSO
+// CHECK-NEXT: |-EnumExtensibilityAttr {{.*}} Open
+// CHECK-NEXT: `-EnumConstantDecl {{.*}} OPT1 'NSO'