update some logic and comments

crates/compiler/mono/src/inc_dec.rs

@@ -1094,7 +1094,7 @@ fn insert_refcount_operations_binding<'a>(
             }
         }
         Expr::Reset { .. } | Expr::ResetRef { .. } => {
-            unreachable!("Reset(ref) and reuse should not exist at this point")
+            unreachable!("Reset(ref) should not exist at this point")
         }
     }
 }

crates/compiler/mono/src/ir.rs

@@ -7583,7 +7583,7 @@ fn substitute_in_expr<'a>(
         NullPointer => None,
 
         Reset { .. } | ResetRef { .. } => {
-            unreachable!("reset/resetref/reuse have not been introduced yet")
+            unreachable!("reset(ref) has not been introduced yet")
         }
 
         Struct(args) => {

crates/compiler/mono/src/tail_recursion.rs

@@ -1089,7 +1089,12 @@ fn expr_contains_symbol(expr: &Expr, needle: Symbol) -> bool {
     match expr {
         Expr::Literal(_) => false,
         Expr::Call(call) => call.arguments.contains(&needle),
-        Expr::Tag { arguments, .. } => arguments.contains(&needle),
+        Expr::Tag {
+            arguments, reuse, ..
+        } => match reuse {
+            None => arguments.contains(&needle),
+            Some(ru) => ru.symbol == needle || arguments.contains(&needle),
+        },
         Expr::Struct(fields) => fields.contains(&needle),
         Expr::NullPointer => false,
         Expr::StructAtIndex { structure, .. }