From 2efa5cd07564a5d4c04474022a568a457eed0438 Mon Sep 17 00:00:00 2001
From: Vern Paxson <vern@corelight.com>
Date: Sat, 27 Sep 2025 16:47:11 -0700
Subject: [PATCH] importing fix for redeclaring variables

---
 src/Var.cc | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/Var.cc b/src/Var.cc
index f719a4f2ec..14e108c31b 100644
--- a/src/Var.cc
+++ b/src/Var.cc
@@ -348,6 +348,28 @@ extern ExprPtr add_and_assign_local(IDPtr id, ExprPtr init, ValPtr val) {
 }
 
 void add_type(ID* id, TypePtr t, std::unique_ptr<std::vector<AttrPtr>> attr) {
+    if ( const auto& old_t = id->GetType() ) {
+        // The identifier already has a type associated with it. This can
+        // be okay if (1) it's already been marked as a Type identifier,
+        // (2) the previous type is a stub.
+        if ( ! id->IsType() ) {
+            reporter->Error("Identifier %s has already been declared and is not a type", id->Name());
+            return;
+        }
+
+        if ( old_t->Tag() == t->Tag() &&
+             ((old_t->Tag() == TYPE_RECORD && old_t->AsRecordType()->NumFields() == 0) || t->Tag() == TYPE_ENUM) )
+            // It has a consistent tag and is either redeclaring a stub
+            // record (used in init-bare.zeek) or an enum (which can
+            // appear due to specifiers in BiFs, for example).
+            ;
+
+        else {
+            reporter->Error("Type %s has already been declared", id->Name());
+            return;
+        }
+    }
+
     std::string new_type_name = id->Name();
     std::string old_type_name = t->GetName();