fix: GetEnums now resolves by looking through the chain of DeclContext

Author: Vipul-Cariappa

lib/Interpreter/CppInterOp.cpp

@@ -3082,23 +3082,26 @@ namespace Cpp {
     clang::DeclContext *DC;
     clang::DeclContext::decl_iterator decl;
 
+    llvm::SmallVector<clang::DeclContext*, 4> DCs;
+
     if (auto *TD = dyn_cast_or_null<TagDecl>(D)) {
       DC = clang::TagDecl::castToDeclContext(TD);
-      decl = DC->decls_begin();
-      decl++;
+      DCs.push_back(DC);
     } else if (auto *ND = dyn_cast_or_null<NamespaceDecl>(D)) {
       DC = clang::NamespaceDecl::castToDeclContext(ND);
-      decl = DC->decls_begin();
+      DC->collectAllContexts(DCs);
     } else if (auto *TUD = dyn_cast_or_null<TranslationUnitDecl>(D)) {
       DC = clang::TranslationUnitDecl::castToDeclContext(TUD);
-      decl = DC->decls_begin();
+      DC->collectAllContexts(DCs);
     } else {
       return;
     }
 
-    for (/* decl set above */; decl != DC->decls_end(); decl++) {
-      if (auto *ND = llvm::dyn_cast_or_null<EnumDecl>(*decl)) {
-        Result.push_back(ND->getNameAsString());
+    for (auto* DC : DCs) {
+      for (decl = DC->decls_begin(); decl != DC->decls_end(); decl++) {
+        if (auto* ND = llvm::dyn_cast_or_null<EnumDecl>(*decl)) {
+          Result.push_back(ND->getNameAsString());
+        }
       }
     }
   }