one more DFS fix (#53)

Author: matth2k

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "safety-net"
-version = "0.2.8"
+version = "0.2.9"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 

src/netlist.rs

@@ -1908,6 +1908,8 @@ pub mod iter {
                         self.stack
                             .push(NetRef::wrap(self.netlist.index_weak(&operand.root())));
                     }
+                } else {
+                    self.cycles = true;
                 }
 
                 return if self.stack.contains(&item) {

tests/analysis.rs

@@ -13,6 +13,10 @@ fn and_gate() -> Gate {
     Gate::new_logical("AND".into(), vec!["A".into(), "B".into()], "Y".into())
 }
 
+fn reg() -> Gate {
+    Gate::new_logical("REG".into(), vec!["D".into()], "Q".into())
+}
+
 fn get_simple_example() -> Rc<GateNetlist> {
     let netlist = Netlist::new("example".to_string());
 
@@ -28,6 +32,28 @@ fn get_simple_example() -> Rc<GateNetlist> {
     netlist
 }
 
+fn divider_netlist() -> Rc<GateNetlist> {
+    let netlist = Netlist::new("example".to_string());
+
+    // Add the the input
+    let a = netlist.insert_input("a".into());
+
+    // Instantiate a reg
+    let reg = netlist.insert_gate_disconnected(reg(), "inst_0".into());
+
+    // And last val and input
+    let and = netlist
+        .insert_gate(and_gate(), "inst_1".into(), &[a, reg.get_output(0)])
+        .unwrap();
+
+    reg.find_input(&"D".into()).unwrap().connect(and.into());
+
+    // Make this Reg an output
+    reg.expose_with_name("y".into());
+
+    netlist
+}
+
 #[test]
 fn test_detect_cycles() {
     let netlist = get_simple_example();
@@ -54,6 +80,14 @@ fn test_detect_cycles() {
     assert!(dfs_iter.detect_cycles());
 }
 
+#[test]
+fn test_detect_cycles2() {
+    let netlist = divider_netlist();
+
+    let dfs_iter = DFSIterator::new(&netlist, netlist.last().unwrap());
+    assert!(dfs_iter.detect_cycles());
+}
+
 #[test]
 fn test_attr_filter() {
     let netlist = GateNetlist::new("example".to_string());