Improve formatting of the generated JS code (#6932)

* Fix js dump

* Commit compiled test files

* Update change log

* Fix space in front comma for for in loop

* Commit test output

* Return spaces around () in for loop

* Commit tests output

* Add space around brackets in while loop

* Commit test outputs

* Reduce tabulation of switch case items

* Commit tests output

* Remove empty default from generated Js code

* Commit test outputs

* Remove tabulation from throw new Error generated code

* Commit test output

* Update changelog

* Revert formatting changes in changelog file

* Commit output of genType tests

Author: DZakh

CHANGELOG.md

@@ -12,6 +12,17 @@
 
 # 12.0.0-alpha.2 (Unreleased)
 
+#### :nail_care: Polish
+
+- Improve formatting in the generated js code. https://github.com/rescript-lang/rescript-compiler/pull/6932
+  - `}\ncatch{` -> `} catch {`
+  - `for(let i = 0 ,i_finish = r.length; i < i_finish; ++i){` -> `for (let i = 0, i_finish = r.length; i < i_finish; ++i) {`
+  - `while(true) {` -> `while (true) {`
+  - Fixed tabulation for `switch case` bodies
+  - Fixed tabulation for `throw new Error` bodies
+  - Removed empty line at the end of `switch` statement
+  - Removed empty `default` case from `switch` statement in the generated code
+
 # 12.0.0-alpha.1
 
 #### :rocket: New Feature

jscomp/core/js_dump.ml

@@ -248,7 +248,6 @@ let debugger_nl f =
 
 let break_nl f =
   P.string f L.break;
-  P.space f;
   semi f;
   P.newline f
 
@@ -430,17 +429,18 @@ 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)) ->
+  P.newline f;
   let cxt =
     P.group f 1 (fun _ ->
-        P.group f 1 (fun _ ->
+        P.group f 0 (fun _ ->
             P.string f L.case;
             P.space f;
             pp_comment_option f comment;
             pp_cond f switch_case;
             (* could be integer or string *)
             P.space f;
             P.string f L.colon);
-        P.group f 1 (fun _ ->
+        P.group f 0 (fun _ ->
             let cxt =
               match switch_body with
               | [] -> cxt
@@ -454,7 +454,6 @@ and pp_one_case_clause :
               semi f);
             cxt))
   in
-  P.newline f;
   cxt
 
 and loop_case_clauses :
@@ -858,11 +857,11 @@ and expression_desc cxt ~(level : int) f x : cxt =
           cxt)
   | New (e, el) ->
       P.cond_paren_group f (level > 15) (fun _ ->
-          P.group f 1 (fun _ ->
+          P.group f 0 (fun _ ->
               P.string f L.new_;
               P.space f;
               let cxt = expression ~level:16 cxt f e in
-              P.paren_group f 1 (fun _ ->
+              P.paren_group f 0 (fun _ ->
                   match el with Some el -> arguments cxt f el | None -> cxt)))
   | Cond (e, e1, e2) ->
       let action () =
@@ -1045,13 +1044,15 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
         match e.expression_desc with
         | Number (Int { i = 1l }) ->
             P.string f L.while_;
+            P.space f;
             P.string f L.lparen;
             P.string f L.true_;
             P.string f L.rparen;
             P.space f;
             cxt
         | _ ->
             P.string f L.while_;
+            P.space f;
             let cxt =
               P.paren_group f 1 (fun _ -> expression ~level:0 cxt f e)
             in
@@ -1068,7 +1069,8 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
               P.group f 0 (fun _ ->
                   (* The only place that [semi] may have semantics here *)
                   P.string f L.for_;
-                  P.paren_group f 1 (fun _ ->
+                  P.space f;
+                  let ctx  = P.paren_group f 1 (fun _ ->
                       let cxt, new_id =
                         match
                           (for_ident_expression, finish.expression_desc)
@@ -1081,8 +1083,8 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
                             let cxt =
                               expression ~level:1 cxt f ident_expression
                             in
-                            P.space f;
                             comma f;
+                            P.space f;
                             let id =
                               Ext_ident.create (Ident.name id ^ "_finish")
                             in
@@ -1128,7 +1130,9 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
                       semi f;
                       P.space f;
                       pp_direction f direction;
-                      Ext_pp_scope.ident cxt f id))
+                      Ext_pp_scope.ident cxt f id) in
+                      P.space f;
+                      ctx)
             in
             brace_block cxt f s)
       in
@@ -1177,6 +1181,7 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
           match def with
           | None -> cxt
           | Some def ->
+              P.newline f;
               P.group f 1 (fun _ ->
                   P.string f L.default;
                   P.string f L.colon;
@@ -1195,6 +1200,7 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
           match def with
           | None -> cxt
           | Some def ->
+              P.newline f;
               P.group f 1 (fun _ ->
                   P.string f L.default;
                   P.string f L.colon;
@@ -1224,10 +1230,9 @@ and statement_desc top cxt f (s : J.statement_desc) : cxt =
             match ctch with
             | None -> cxt
             | Some (i, b) ->
-                P.newline f;
-                P.string f "catch (";
+                P.string f " catch (";
                 let cxt = Ext_pp_scope.ident cxt f i in
-                P.string f ")";
+                P.string f ") ";
                 brace_block cxt f b
           in
           match fin with

jscomp/core/lam_compile.ml

@@ -584,7 +584,10 @@ and compile_general_cases :
             | Complete -> None
             | NonComplete -> None
             | Default lam ->
-                Some (Js_output.output_as_block (compile_lambda cxt lam))
+                let statements = Js_output.output_as_block (compile_lambda cxt lam) in
+                match statements with
+                | [] -> None
+                | _ -> Some statements
           in
           let body =
             group_apply ~merge_cases cases (fun last (switch_case, lam) ->

jscomp/gentype_tests/typescript-react-example/src/NestedVariants.res.js

@@ -25,7 +25,7 @@ o runtime/caml_exceptions.cmj : cc_cmi runtime/caml_exceptions.res | runtime/cam
 o runtime/caml_exceptions.cmi : cc runtime/caml_exceptions.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_float.cmj : cc_cmi runtime/caml_float.res | runtime/caml_float.cmi runtime/caml_float_extern.cmj
 o runtime/caml_float.cmi : cc runtime/caml_float.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
-o runtime/caml_format.cmj : cc_cmi runtime/caml_format.res | runtime/caml_float.cmj runtime/caml_float_extern.cmj runtime/caml_format.cmi runtime/caml_int64.cmj runtime/caml_int64_extern.cmj runtime/caml_nativeint_extern.cmj runtime/caml_string_extern.cmj
+o runtime/caml_format.cmj : cc_cmi runtime/caml_format.res | runtime/caml.cmj runtime/caml_float.cmj runtime/caml_float_extern.cmj runtime/caml_format.cmi runtime/caml_int64.cmj runtime/caml_int64_extern.cmj runtime/caml_nativeint_extern.cmj runtime/caml_string_extern.cmj
 o runtime/caml_format.cmi : cc runtime/caml_format.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_hash.cmj : cc_cmi runtime/caml_hash.res | runtime/caml_hash.cmi runtime/caml_hash_primitive.cmj runtime/caml_nativeint_extern.cmj
 o runtime/caml_hash.cmi : cc runtime/caml_hash.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
@@ -41,7 +41,7 @@ o runtime/caml_md5.cmj : cc_cmi runtime/caml_md5.res | runtime/caml_array_extern
 o runtime/caml_md5.cmi : cc runtime/caml_md5.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_module.cmj : cc_cmi runtime/caml_module.res | runtime/caml_array_extern.cmj runtime/caml_module.cmi runtime/caml_obj.cmj
 o runtime/caml_module.cmi : cc runtime/caml_module.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
-o runtime/caml_obj.cmj : cc_cmi runtime/caml_obj.res | runtime/caml_array_extern.cmj runtime/caml_obj.cmi runtime/caml_option.cmj
+o runtime/caml_obj.cmj : cc_cmi runtime/caml_obj.res | runtime/caml.cmj runtime/caml_array_extern.cmj runtime/caml_obj.cmi runtime/caml_option.cmj
 o runtime/caml_obj.cmi : cc runtime/caml_obj.resi | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_option.cmj : cc_cmi runtime/caml_option.res | runtime/caml_option.cmi runtime/caml_undefined_extern.cmj
 o runtime/caml_option.cmi : cc runtime/caml_option.resi | runtime/bs_stdlib_mini.cmi runtime/caml_undefined_extern.cmj runtime/js.cmi runtime/js.cmj
@@ -57,7 +57,7 @@ o runtime/caml_array_extern.cmi runtime/caml_array_extern.cmj : cc runtime/caml_
 o runtime/caml_bigint_extern.cmi runtime/caml_bigint_extern.cmj : cc runtime/caml_bigint_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_float_extern.cmi runtime/caml_float_extern.cmj : cc runtime/caml_float_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_int64_extern.cmi runtime/caml_int64_extern.cmj : cc runtime/caml_int64_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
-o runtime/caml_js_exceptions.cmi runtime/caml_js_exceptions.cmj : cc runtime/caml_js_exceptions.res | runtime/bs_stdlib_mini.cmi runtime/caml_exceptions.cmj runtime/js.cmi runtime/js.cmj
+o runtime/caml_js_exceptions.cmi runtime/caml_js_exceptions.cmj : cc runtime/caml_js_exceptions.res | runtime/bs_stdlib_mini.cmi runtime/caml_exceptions.cmj runtime/caml_option.cmj runtime/js.cmi runtime/js.cmj
 o runtime/caml_nativeint_extern.cmi runtime/caml_nativeint_extern.cmj : cc runtime/caml_nativeint_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_string_extern.cmi runtime/caml_string_extern.cmj : cc runtime/caml_string_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 o runtime/caml_undefined_extern.cmi runtime/caml_undefined_extern.cmj : cc runtime/caml_undefined_extern.res | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj