[lldb][NFC] Move LLVM RTTI implementation from enum to static ID variable

Summary:
swift-lldb currently has to patch the ExpressionKind enum to add support for Swift expressions. If we implement LLVM's RTTI
with a static ID variable instead of a centralised enum we can drop that patch.

Reviewers: labath, davide

Reviewed By: labath

Subscribers: JDevlieghere, lldb-commits

Tags: #upstreaming_lldb_s_downstream_patches, #lldb

Differential Revision: https://reviews.llvm.org/D70070

1 files changed, 6 insertions, 3 deletions

diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangUtilityFunction.h b/lldb/source/Plugins/ExpressionParser/Clang/ClangUtilityFunction.h
index 70ebb2f3ad8..9efaa0254c3 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangUtilityFunction.h
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangUtilityFunction.h
@@ -33,11 +33,14 @@ namespace lldb_private {
 /// simply provide a way to push a function into the target for the debugger
 /// to call later on.
 class ClangUtilityFunction : public UtilityFunction {
+  // LLVM RTTI support
+  static char ID;
+
 public:
-  /// LLVM-style RTTI support.
-  static bool classof(const Expression *E) {
-    return E->getKind() == eKindClangUtilityFunction;
+  bool isA(const void *ClassID) const override {
+    return ClassID == &ID || UtilityFunction::isA(ClassID);
   }
+  static bool classof(const Expression *obj) { return obj->isA(&ID); }
 
   class ClangUtilityFunctionHelper : public ClangExpressionHelper {
   public: