Introduce Sourcemap (#8393)

* introduce linked external source map

* Remove marker entries after lookup

* Preserve relative source paths in maps

* Change sourceMap field schema to false or object

* sourcemap schema in rescript.json

* Add source map enabled policy

* Preserve source map markers across package targets

* Add comments

* Add mapping %debugger statement

* Refactor source maps to use JS IR source locations

* Add inline and hidden source map modes

* Reject sourceMap true during config parsing

* Expand source map coverage across modes

* Expand source map test coverage

* format

* Invalidate dependency builds on sourcemap changes

* fix test in windows

* Avoid source map work when disabled

* Remove direct internal source map flag test

* changelog

Author: mununki

CHANGELOG.md

@@ -18,6 +18,8 @@
 
 #### :rocket: New Feature
 
+- Add source map support with linked, inline, and hidden modes. https://github.com/rescript-lang/rescript/pull/8393
+
 #### :bug: Bug fix
 
 #### :memo: Documentation

compiler/bsc/rescript_compiler_main.ml

@@ -209,6 +209,25 @@ let[@inline] string_optional_set s : Bsc_args.spec =
 let[@inline] unit_call s : Bsc_args.spec = Unit (Unit_call s)
 let[@inline] string_list_add s : Bsc_args.spec = String (String_list_add s)
 
+let parse_source_map value =
+  Js_config.source_map :=
+    match String.lowercase_ascii value with
+    | "linked" -> Linked
+    | "inline" -> Inline
+    | "hidden" -> Hidden
+    | "false" | "none" -> No_source_map
+    | value ->
+      Bsc_args.bad_arg
+        ("Unsupported sourceMap value: " ^ value
+       ^ ". Expected linked, inline, hidden, false, or none")
+
+let parse_bool_ref target value =
+  target :=
+    match String.lowercase_ascii value with
+    | "true" -> true
+    | "false" -> false
+    | value -> Bsc_args.bad_arg ("Expected true or false, got: " ^ value)
+
 (* mostly common used to list in the beginning to make search fast
 *)
 let command_line_flags : (string * Bsc_args.spec * string) array =
@@ -259,6 +278,15 @@ let command_line_flags : (string * Bsc_args.spec * string) array =
       string_call ignore,
       "*internal* Set jsx mode, this is no longer used and is a no-op." );
     ("-bs-jsx-preserve", set Js_config.jsx_preserve, "*internal* Preserve jsx");
+    ( "-bs-source-map",
+      string_call parse_source_map,
+      "*internal* Configure source map output" );
+    ( "-bs-source-map-sources-content",
+      string_call (parse_bool_ref Js_config.source_map_sources_content),
+      "*internal* Include original source text in source maps" );
+    ( "-bs-source-map-root",
+      string_call (fun value -> Js_config.source_map_root := value),
+      "*internal* Set sourceRoot in source maps" );
     ( "-bs-package-output",
       string_call Js_packages_state.update_npm_package_path,
       "*internal* Set npm-output-path: [opt_module]:path, for example: \

compiler/common/js_config.ml

@@ -26,6 +26,7 @@
 
 type jsx_version = Jsx_v4
 type jsx_module = React | Generic of {module_name: string}
+type source_map = No_source_map | Linked | Inline | Hidden
 
 let no_version_header = ref false
 
@@ -53,6 +54,9 @@ let jsx_version = ref None
 let jsx_module = ref React
 let jsx_preserve = ref false
 let js_stdout = ref true
+let source_map = ref No_source_map
+let source_map_sources_content = ref false
+let source_map_root = ref ""
 let all_module_aliases = ref false
 let no_stdlib = ref false
 let no_export = ref false

compiler/common/js_config.mli

@@ -24,6 +24,7 @@
 
 type jsx_version = Jsx_v4
 type jsx_module = React | Generic of {module_name: string}
+type source_map = No_source_map | Linked | Inline | Hidden
 
 (* val get_packages_info :
    unit -> Js_packages_info.t *)
@@ -86,6 +87,12 @@ val jsx_preserve : bool ref
 
 val js_stdout : bool ref
 
+val source_map : source_map ref
+
+val source_map_sources_content : bool ref
+
+val source_map_root : string ref
+
 val all_module_aliases : bool ref
 
 val no_stdlib : bool ref

compiler/core/dune

@@ -5,7 +5,7 @@
   (backend bisect_ppx))
  (flags
   (:standard -w +a-4-9-27-30-40-41-42-48-70))
- (libraries depends ext flow_parser frontend gentype))
+ (libraries depends ext flow_parser frontend gentype yojson))
 
 (rule
  (target js_name_of_module_id.ml)

compiler/core/j.ml

@@ -251,6 +251,7 @@ and case_clause = {
   should_break: bool;
   (* true means break *)
   comment: string option;
+  source_loc: Location.t option;
 }
 
 and string_clause = Ast_untagged_variants.tag_type * case_clause
@@ -295,8 +296,17 @@ and statement_desc =
   | Try of block * (exception_ident * block) option * block option
   | Debugger
 
-and expression = {expression_desc: expression_desc; comment: string option}
-and statement = {statement_desc: statement_desc; comment: string option}
+and expression = {
+  expression_desc: expression_desc;
+  comment: string option;
+  source_loc: Location.t option;
+}
+
+and statement = {
+  statement_desc: statement_desc;
+  comment: string option;
+  source_loc: Location.t option;
+}
 
 and variable_declaration = {
   ident: ident;

compiler/core/js_analyzer.ml

@@ -281,7 +281,7 @@ let rev_flatten_seq (x : J.expression) =
   let rec aux acc (x : J.expression) : J.block =
     match x.expression_desc with
     | Seq (a, b) -> aux (aux acc a) b
-    | _ -> {statement_desc = Exp x; comment = None} :: acc
+    | _ -> {statement_desc = Exp x; comment = None; source_loc = None} :: acc
   in
   aux [] x
 

compiler/core/js_dump.ml

@@ -463,14 +463,16 @@ and pp_function ~return_unit ~async ~is_method ?directive cxt (f : P.t)
 and pp_one_case_clause :
     'a. _ -> P.t -> (P.t -> 'a -> unit) -> 'a * J.case_clause -> _ =
  fun cxt f pp_cond
-     (switch_case, ({switch_body; should_break; comment} : J.case_clause)) ->
+     ( switch_case,
+       ({switch_body; should_break; comment; source_loc} : J.case_clause) ) ->
   P.newline f;
   let cxt =
     P.group f 1 (fun _ ->
         P.group f 0 (fun _ ->
             P.string f L.case;
             P.space f;
             pp_comment_option f comment;
+            Js_source_map.mark_source_loc f source_loc;
             pp_cond f switch_case;
             (* could be integer or string *)
             P.space f;
@@ -517,6 +519,7 @@ and vident cxt f (v : J.vident) =
 (* The higher the level, the more likely that inner has to add parens *)
 and expression ~level:l cxt f (exp : J.expression) : cxt =
   pp_comment_option f exp.comment;
+  Js_source_map.mark_source_loc f exp.source_loc;
   expression_desc cxt ~level:l f exp.expression_desc
 
 and expression_desc cxt ~(level : int) f x : cxt =
@@ -1367,6 +1370,8 @@ and variable_declaration top cxt f (variable : J.variable_declaration) : cxt =
     | _ -> (
       match e.expression_desc with
       | Fun {is_method; params; body; env; return_unit; async; directive} ->
+        pp_comment_option f e.comment;
+        Js_source_map.mark_source_loc f e.source_loc;
         pp_function ?directive ~is_method ~return_unit ~async
           ~fn_state:(if top then Name_top name else Name_non_top name)
           cxt f params body env
@@ -1407,8 +1412,10 @@ and pp_comment_option f comment =
   | None -> ()
   | Some x -> pp_comment f x
 
-and statement top cxt f ({statement_desc = s; comment; _} : J.statement) : cxt =
+and statement top cxt f
+    ({statement_desc = s; comment; source_loc} : J.statement) : cxt =
   pp_comment_option f comment;
+  Js_source_map.mark_source_loc f source_loc;
   statement_desc top cxt f s
 
 and statement_desc top cxt f (s : J.statement_desc) : cxt =