Fix utop detection by using correct version flag (#1939)

* Initial plan

* Fix utop detection by changing --version to -version

Co-authored-by: smorimoto <38746192+smorimoto@users.noreply.github.com>

* Add changelog entry for utop detection fix

Co-authored-by: smorimoto <38746192+smorimoto@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: smorimoto <38746192+smorimoto@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+- Fix utop detection by using `-version` flag instead of `--version` to align
+  with OCaml toolchain conventions. This ensures the extension properly detects
+  and uses utop when running code selections. (#1938)
+
 ## 1.32.2
 
 - Reword DPM notification to inform users DPM is available and not selected. (#1930)

src/repl.ml

@@ -54,7 +54,7 @@ let name = "REPL"
 
 let has_utop (sandbox : Sandbox.t) =
   let open Promise.Syntax in
-  let cmd = Sandbox.get_command sandbox "utop" [ "--version" ] `Tool in
+  let cmd = Sandbox.get_command sandbox "utop" [ "-version" ] `Tool in
   let cwd = Sandbox.workspace_root () in
   let+ result = Cmd.output ?cwd cmd in
   match result with