From 94aa5c91b295183133f75df0268c07bf711a2dce Mon Sep 17 00:00:00 2001
From: Cam Pedersen <cam@campedersen.com>
Date: Tue, 14 Jul 2026 09:54:15 -0400
Subject: [PATCH] EIR VM: assert-eq uses structural equality, not handle
 identity

[assert-eq {:a 1} {:a 1}] failed on the EIR VM because Built::AssertEq
compared raw Val handles; two separately-allocated but structurally
equal heap values (maps, vecs, non-interned strings) never matched.
Route it through the same val_eq that = already uses, and add a
backend-parity regression test.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 crates/loon-lang/src/eir/vm.rs           | 2 +-
 crates/loon-lang/tests/backend_parity.rs | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/crates/loon-lang/src/eir/vm.rs b/crates/loon-lang/src/eir/vm.rs
index 02ee237..ee32bdd 100644
--- a/crates/loon-lang/src/eir/vm.rs
+++ b/crates/loon-lang/src/eir/vm.rs
@@ -2608,7 +2608,7 @@ impl Vm {
                 // [assert-eq actual expected] → Unit or panic
                 let actual = args.first().copied().unwrap_or(Val::UNIT);
                 let expected = args.get(1).copied().unwrap_or(Val::UNIT);
-                if actual == expected {
+                if self.val_eq(actual, expected) {
                     Ok(Val::UNIT)
                 } else {
                     let actual_s = self.val_to_string(actual);
diff --git a/crates/loon-lang/tests/backend_parity.rs b/crates/loon-lang/tests/backend_parity.rs
index 8def2e5..1cd2322 100644
--- a/crates/loon-lang/tests/backend_parity.rs
+++ b/crates/loon-lang/tests/backend_parity.rs
@@ -216,6 +216,13 @@ const CORPUS: &[(&str, &str)] = &[
         "map-eq-order-independent",
         "[fn main [] [println [= {:a 1 :b 2} {:b 2 :a 1}]]]",
     ),
+    (
+        // assert-eq must use the same structural equality as `=` — the EIR VM
+        // used to compare raw heap handles, so two separately-allocated but
+        // equal maps failed the assertion.
+        "assert-eq-structural",
+        "[fn main [] [assert-eq {:a 1 :b \"x\"} {:b \"x\" :a 1}] [println \"ok\"]]",
+    ),
     // map destructuring in let: `{name name}` shorthand binds a key to its
     // value; both backends must bind the names (the EIR VM used to drop the
     // pattern silently and bind nothing). Present keys read through.