From e491a76861679cc8974af8d2a7ba1fbb7632a327 Mon Sep 17 00:00:00 2001
From: Ryan Fleury <ryan.j.fleury@gmail.com>
Date: Fri, 9 May 2025 09:58:39 -0700
Subject: [PATCH] prevent mutating nil trees in irtree generation

---
 src/eval/eval_ir.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/eval/eval_ir.c b/src/eval/eval_ir.c
index 87bffbd8..4f3104c3 100644
--- a/src/eval/eval_ir.c
+++ b/src/eval/eval_ir.c
@@ -122,7 +122,10 @@ e_push_irnode(Arena *arena, RDI_EvalOp op)
 internal void
 e_irnode_push_child(E_IRNode *parent, E_IRNode *child)
 {
-  SLLQueuePush_NZ(&e_irnode_nil, parent->first, parent->last, child, next);
+  if(parent != &e_irnode_nil && child != &e_irnode_nil)
+  {
+    SLLQueuePush_NZ(&e_irnode_nil, parent->first, parent->last, child, next);
+  }
 }
 
 //- rjf: ir subtree building helpers