in debug, include location information in error message on panic

godot-core/src/private.rs

@@ -387,27 +387,39 @@ where
             // Handle panic info only in Debug mode.
             #[cfg(debug_assertions)]
             {
-                let guard = info.lock().unwrap();
-                let info = guard.as_ref().expect("no panic info available");
+                let msg = extract_panic_message(err);
+                let mut msg = format_panic_message(msg);
+
+                // Try to add location information.
+                if let Ok(guard) = info.lock() {
+                    if let Some(info) = guard.as_ref() {
+                        msg = format!("{}\n  at {}:{}", msg, info.file, info.line);
+                    }
+                }
+
                 if print {
                     godot_error!(
-                        "Rust function panicked at {}:{}.\n  Context: {}",
-                        info.file,
-                        info.line,
+                        "Rust function panicked: {}\n  Context: {}",
+                        msg,
                         error_context()
                     );
                     //eprintln!("Backtrace:\n{}", info.backtrace);
                 }
+
+                Err(msg)
             }
 
-            let msg = extract_panic_message(err);
-            let msg = format_panic_message(msg);
+            #[cfg(not(debug_assertions))]
+            {
+                let msg = extract_panic_message(err);
+                let msg = format_panic_message(msg);
+
+                if print {
+                    godot_error!("{msg}");
+                }
 
-            if print {
-                godot_error!("{msg}");
+                Err(msg)
             }
-
-            Err(msg)
         }
     }
 }

itest/rust/src/object_tests/dynamic_call_test.rs

@@ -148,13 +148,30 @@ fn dynamic_call_with_panic() {
 
     assert_eq!(call_error.class_name(), Some("Object"));
     assert_eq!(call_error.method_name(), "call");
-    assert_eq!(
-        call_error.to_string(),
+
+    let appendix = if cfg!(debug_assertions) {
+        let mut path = "itest/rust/src/object_tests/object_test.rs".to_string();
+
+        if cfg!(target_os = "windows") {
+            path = path.replace('/', "\\")
+        }
+
+        // Obtain line number dynamically, avoids tedious maintenance on code reorganization.
+        let line = ObjPayload::get_panic_line();
+
+        format!("\n  at {path}:{line}")
+    } else {
+        String::new()
+    };
+
+    let expected_error_message = format!(
         "godot-rust function call failed: Object::call(&\"do_panic\")\
         \n  Source: ObjPayload::do_panic()\
-        \n    Reason: [panic]  do_panic exploded"
+        \n    Reason: [panic]  do_panic exploded{appendix}"
     );
 
+    assert_eq!(call_error.to_string(), expected_error_message);
+
     obj.free();
 }
 

itest/rust/src/object_tests/object_test.rs

@@ -887,6 +887,11 @@ impl ObjPayload {
     fn do_panic(&self) {
         panic!("do_panic exploded");
     }
+
+    // Obtain the line number of the panic!() call above; keep equidistant to do_panic() method.
+    pub fn get_panic_line() -> u32 {
+        line!() - 5
+    }
 }
 
 // ----------------------------------------------------------------------------------------------------------------------------------------------