Add test to ref loop printing.

src/types/dynamic.rs

@@ -488,10 +488,23 @@ impl fmt::Display for Dynamic {
                 f.write_str((***v).type_name())
             }
 
+            #[cfg(not(feature = "no_closure"))]
+            Union::Shared(ref cell, ..) if cfg!(feature = "unchecked") => {
+                #[cfg(not(feature = "sync"))]
+                match cell.try_borrow() {
+                    Ok(v) => {
+                        fmt::Display::fmt(&*v, f)?;
+                        f.write_str(" (shared)")
+                    }
+                    Err(_) => f.write_str("<shared>"),
+                }
+                #[cfg(feature = "sync")]
+                fmt::Display::fmt(&*cell.read().unwrap(), f)
+            }
             #[cfg(not(feature = "no_closure"))]
             Union::Shared(..) => {
                 // Avoid infinite recursion for shared values in a reference loop.
-                pub fn display_fmt(
+                fn display_fmt(
                     value: &Dynamic,
                     f: &mut fmt::Formatter<'_>,
                     dict: &mut std::collections::HashSet<*const Dynamic>,
@@ -646,10 +659,23 @@ impl fmt::Debug for Dynamic {
                 f.write_str((***v).type_name())
             }
 
+            #[cfg(not(feature = "no_closure"))]
+            Union::Shared(ref cell, ..) if cfg!(feature = "unchecked") => {
+                #[cfg(not(feature = "sync"))]
+                match cell.try_borrow() {
+                    Ok(v) => {
+                        fmt::Debug::fmt(&*v, f)?;
+                        f.write_str(" (shared)")
+                    }
+                    Err(_) => f.write_str("<shared>"),
+                }
+                #[cfg(feature = "sync")]
+                fmt::Debug::fmt(&*cell.read().unwrap(), f)
+            }
             #[cfg(not(feature = "no_closure"))]
             Union::Shared(..) => {
                 // Avoid infinite recursion for shared values in a reference loop.
-                pub fn debug_fmt(
+                fn debug_fmt(
                     value: &Dynamic,
                     f: &mut fmt::Formatter<'_>,
                     dict: &mut std::collections::HashSet<*const Dynamic>,

src/types/scope.rs

@@ -77,19 +77,13 @@ pub struct Scope<'a> {
 impl fmt::Display for Scope<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         for (i, (name, constant, value)) in self.iter_inner().enumerate() {
-            #[cfg(not(feature = "no_closure"))]
-            let value_is_shared = if value.is_shared() { " (shared)" } else { "" };
-            #[cfg(feature = "no_closure")]
-            let value_is_shared = "";
-
             writeln!(
                 f,
-                "[{}] {}{}{} = {:?}",
+                "[{}] {}{} = {:?}",
                 i + 1,
                 if constant { "const " } else { "" },
                 name,
-                value_is_shared,
-                *value.read_lock::<Dynamic>().unwrap(),
+                value,
             )?;
         }
 

tests/stack.rs

@@ -1,5 +1,5 @@
 #![cfg(not(feature = "unchecked"))]
-use rhai::{Engine, EvalAltResult, ParseErrorType, INT};
+use rhai::{Dynamic, Engine, EvalAltResult, ParseErrorType, INT};
 
 #[test]
 #[cfg(not(feature = "no_function"))]
@@ -20,7 +20,6 @@ fn test_stack_overflow_fn_calls() {
 
     let max = engine.max_call_levels();
 
-    #[cfg(not(feature = "unchecked"))]
     assert!(matches!(
         *engine
             .run(&format!(
@@ -132,3 +131,24 @@ fn test_stack_overflow_parsing() {
     #[cfg(not(feature = "no_function"))]
     engine.compile("fn abc(x) { x + 1 }").unwrap();
 }
+
+#[test]
+#[cfg(not(feature = "no_closure"))]
+#[cfg(not(feature = "no_function"))]
+#[cfg(not(feature = "no_object"))]
+fn test_stack_overflow_ref_loop() {
+    let engine = Engine::new();
+
+    let x = engine
+        .eval::<Dynamic>(
+            "
+                let x;
+                let data = #{ foo: || x = this };
+                data.foo();
+                x
+            ",
+        )
+        .unwrap();
+
+    println!("{x:?}");
+}