exn: preserve backtraces

ahrefs · Jul 31, 2024 · c5b26bd · c5b26bd
1 parent 8451877
commit c5b26bd
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/exn.ml b/exn.ml
@@ -33,7 +33,13 @@ let to_string exn =
 let str = to_string
 
 let fail ?exn fmt =
-  let fails s = match exn with None -> failwith s | Some exn -> failwith (s ^ " : " ^ to_string exn) in
+  let fails s =
+    match exn with
+    | None -> failwith s
+    | Some original_exn ->
+      let exn = Failure (s ^ " : " ^ to_string original_exn) in
+      Printexc.raise_with_backtrace exn (Printexc.get_raw_backtrace ())
+  in
   ksprintf fails fmt
 
 let invalid_arg fmt = ksprintf invalid_arg fmt