Source maps: use ignoreList to hide runtime files

The generated code is also hidden by using a dummy file.

Author: vouillon

compiler/bin-js_of_ocaml/compile.ml

@@ -79,7 +79,9 @@ let find_source file =
   match Builtins.find file with
   | Some f -> Some (Source_map.Source_content.create (Builtins.File.content f))
   | None ->
-      if Sys.file_exists file && not (Sys.is_directory file)
+      if String.equal file Js_output.blackbox_filename
+      then Some (Source_map.Source_content.create "(* generated code *)")
+      else if Sys.file_exists file && not (Sys.is_directory file)
       then
         let content = Fs.read_file file in
         Some (Source_map.Source_content.create content)
@@ -99,9 +101,18 @@ let sourcemap_section_of_info
         | None -> filename
         | Some _ -> Filename.concat "/builtin" filename)
   in
+  let ignore_list =
+    List.filter sources ~f:(fun filename -> String.is_prefix ~prefix:"/builtin/" filename)
+  in
   let offset, mappings = Source_map.Mappings.encode_with_offset mappings in
   let map =
-    { (base : Source_map.Standard.t) with sources; sources_content; names; mappings }
+    { (base : Source_map.Standard.t) with
+      sources
+    ; sources_content
+    ; names
+    ; mappings
+    ; ignore_list
+    }
   in
   { Source_map.Index.offset; map }
 

compiler/lib/js_output.ml

@@ -133,6 +133,8 @@ module Make (D : sig
 
   val get_name_index : string -> int
 
+  val hidden_location : Source_map.map
+
   val source_map_enabled : bool
 
   val accept_unnamed_var : bool
@@ -167,7 +169,7 @@ struct
          then
            match loc with
            | N | U | Pi { Parse_info.src = None | Some ""; _ } ->
-               push_mapping (PP.pos f) (Source_map.Gen { gen_line = -1; gen_col = -1 })
+               push_mapping (PP.pos f) hidden_location
            | Pi { Parse_info.src = Some file; line; col; _ } ->
                push_mapping
                  (PP.pos f)
@@ -209,10 +211,15 @@ struct
         (match loc with
         | None | Some { Parse_info.src = Some "" | None; _ } ->
             (* Use a dummy location. It is going to be ignored anyway *)
+            let ori_source =
+              match hidden_location with
+              | Source_map.Gen_Ori { ori_source; _ } -> ori_source
+              | _ -> 0
+            in
             Source_map.Gen_Ori_Name
               { gen_line = -1
               ; gen_col = -1
-              ; ori_source = 0
+              ; ori_source
               ; ori_line = 1
               ; ori_col = 0
               ; ori_name = get_name_index nm
@@ -2042,6 +2049,8 @@ let hashtbl_to_list htb =
   |> List.sort ~cmp:(fun (_, a) (_, b) -> compare a b)
   |> List.map ~f:fst
 
+let blackbox_filename = "/builtin/blackbox.ml"
+
 let program ?(accept_unnamed_var = false) ?(source_map = false) f p =
   let temp_mappings = ref [] in
   let files = Hashtbl.create 17 in
@@ -2061,13 +2070,24 @@ let program ?(accept_unnamed_var = false) ?(source_map = false) f p =
           Hashtbl.add names name pos;
           pos )
   in
+  let hidden_location =
+    Source_map.Gen_Ori
+      { gen_line = -1
+      ; gen_col = -1
+      ; ori_source = get_file_index blackbox_filename
+      ; ori_line = 1
+      ; ori_col = 0
+      }
+  in
   let module O = Make (struct
     let push_mapping = push_mapping
 
     let get_name_index = get_name_index
 
     let get_file_index = get_file_index
 
+    let hidden_location = hidden_location
+
     let source_map_enabled = source_map
 
     let accept_unnamed_var = accept_unnamed_var

compiler/lib/js_output.mli

@@ -24,3 +24,5 @@ val program :
   -> Pretty_print.t
   -> Javascript.program
   -> Source_map.info
+
+val blackbox_filename : string

compiler/lib/source_map.ml

@@ -294,6 +294,11 @@ let string_of_stringlit (`Stringlit s) =
   | `String s -> s
   | _ -> invalid ()
 
+let int_of_intlit (`Intlit s) =
+  match Yojson.Safe.from_string s with
+  | `Int s -> s
+  | _ -> invalid ()
+
 let stringlit name rest : [ `Stringlit of string ] option =
   try
     match List.assoc name rest with
@@ -325,6 +330,17 @@ let list_stringlit_opt name rest =
     | _ -> invalid ()
   with Not_found -> None
 
+let list_intlit name rest =
+  try
+    match List.assoc name rest with
+    | `List l ->
+        Some
+          (List.map l ~f:(function
+              | `Intlit _ as s -> s
+              | _ -> invalid ()))
+    | _ -> invalid ()
+  with Not_found -> None
+
 module Standard = struct
   type t =
     { version : int
@@ -334,6 +350,7 @@ module Standard = struct
     ; sources_content : Source_content.t option list option
     ; names : string list
     ; mappings : Mappings.t
+    ; ignore_list : string list
     }
 
   let empty ~inline_source_content =
@@ -344,6 +361,7 @@ module Standard = struct
     ; sources_content = (if inline_source_content then Some [] else None)
     ; names = []
     ; mappings = Mappings.empty
+    ; ignore_list = []
     }
 
   let maps ~sources_offset ~names_offset x =
@@ -472,6 +490,21 @@ module Standard = struct
                      (List.map l ~f:(function
                          | None -> `Null
                          | Some x -> Source_content.to_json x))) )
+         ; ( "ignoreList"
+           , match t.ignore_list with
+             | [] -> None
+             | _ ->
+                 Some
+                   (`List
+                     (let s = StringSet.of_list t.ignore_list in
+                      List.filter_map
+                        ~f:(fun x -> x)
+                        (List.mapi
+                           ~f:(fun i nm ->
+                             if StringSet.mem nm s
+                             then Some (`Intlit (string_of_int i))
+                             else None)
+                           t.sources))) )
          ])
 
   let of_json (json : Yojson.Raw.t) =
@@ -505,13 +538,25 @@ module Standard = struct
           | None -> Mappings.empty
           | Some s -> Mappings.of_string_unsafe s
         in
+        let ignore_list =
+          let s =
+            IntSet.of_list
+              (List.map
+                 ~f:int_of_intlit
+                 (Option.value ~default:[] (list_intlit "ignoreList" rest)))
+          in
+          List.filter_map
+            ~f:(fun x -> x)
+            (List.mapi ~f:(fun i nm -> if IntSet.mem i s then Some nm else None) sources)
+        in
         { version = int_of_string version
         ; file
         ; sourceroot
         ; names
         ; sources_content
         ; sources
         ; mappings
+        ; ignore_list
         }
     | _ -> invalid ()
 
@@ -520,7 +565,8 @@ module Standard = struct
   let to_file m file = Yojson.Raw.to_file file (json m)
 
   let invariant
-      { version; file = _; sourceroot = _; names; sources_content; sources; mappings } =
+      { version; file = _; sourceroot = _; names; sources_content; sources; mappings; _ }
+      =
     if not (version_is_valid version)
     then invalid_arg "Source_map.Standard.invariant: invalid version";
     match sources_content with

compiler/lib/source_map.mli

@@ -98,6 +98,7 @@ module Standard : sig
           (** Left uninterpreted, since most useful operations can be performed efficiently
           directly on the encoded form, and a full decoding can be costly for big
           sourcemaps. *)
+    ; ignore_list : string list
     }
 
   val filter_map : t -> f:(int -> int option) -> t

compiler/tests-compiler/build_path_prefix_map.ml

@@ -48,5 +48,6 @@ let%expect_test _ =
     file: test.js
     sourceRoot: <none>
     sources:
+    - /builtin/blackbox.ml
     - /dune-root/test.ml
     |}]

compiler/tests-compiler/sourcemap.ml

@@ -83,14 +83,14 @@ let%expect_test _ =
        11:   (globalThis));
        12:
        13: //# sourceMappingURL=test.map
-      /dune-root/test.ml:1:0 -> 5:7
-      null -> 5:17
+      /builtin/blackbox.ml:1:0 -> 5:7
+      /builtin/blackbox.ml:1:0 -> 5:17
       /dune-root/test.ml:1:4 -> 6:12
       /dune-root/test.ml:1:7 -> 6:15
       /dune-root/test.ml:1:11 -> 6:18
       /dune-root/test.ml:1:12 -> 6:28
       /dune-root/test.ml:1:12 -> 7:7
-      null -> 7:14
+      /builtin/blackbox.ml:1:0 -> 7:14
     |}]
 
 let%expect_test _ =

compiler/tests-sourcemap/dump.reference

@@ -1,5 +1,4 @@
 sourcemap for test.bc.js
-/my/sourceRoot#b.ml:1:0 -> 7:   var <>runtime = globalThis.jsoo_runtime;
 /my/sourceRoot#b.ml:1:4 -> 12:   function <>f(x){return x - 1 | 0; }
 /my/sourceRoot#b.ml:1:6 -> 14:   function f(<>x){return x - 1 | 0; }
 /my/sourceRoot#b.ml:1:10 -> 17:   function f(x){<>return x - 1 | 0; }