fix

src/action.ml

@@ -110,9 +110,15 @@ module Mini_shexp = struct
 
   module Unexpanded = struct
     type t = (String_with_vars.t, String_with_vars.t) Ast.t
-    let t = Ast.t String_with_vars.t String_with_vars.t
     let sexp_of_t = Ast.sexp_of_t String_with_vars.sexp_of_t String_with_vars.sexp_of_t
 
+    let t sexp =
+      match sexp with
+      | Atom _ ->
+        of_sexp_errorf sexp
+          "if you meant for this to be executed with bash, write (bash \"...\") instead"
+      | List _ -> Ast.t String_with_vars.t String_with_vars.t sexp
+
     let fold_vars t ~init ~f =
       Ast.fold t ~init ~f:(fun acc pat ->
         String_with_vars.fold ~init:acc pat ~f)

src/gen_rules.ml

@@ -241,6 +241,8 @@ module Gen(P : Params) = struct
       List.map (Lib_db.resolve_selects t ~from:dir lib_deps) ~f:(fun { dst_fn; src_fn } ->
         let src = Path.relative dir src_fn in
         let dst = Path.relative dir dst_fn in
+        Build.path src
+        >>>
         Build.action ~targets:[dst]
           (Copy_and_add_line_directive (src, dst)))