Fix emitting unary minus for floats in case of negative constants.

CHANGELOG.md

@@ -35,6 +35,7 @@
 - Fix issue where formatter erases tail comments inside JSX tag https://github.com/rescript-lang/syntax/issues/663
 - Fix issue where the JSX prop has type annotation of the first class module https://github.com/rescript-lang/syntax/pull/666
 - Fix issue where an empty record literal {} expected to have a non-record type would type check https://github.com/rescript-lang/rescript-compiler/pull/5729
+- Fix emitting unary minus for floats in case of negative constants https://github.com/rescript-lang/rescript-compiler/pull/5737
 
 #### :eyeglasses: Spec Compliance
 

jscomp/core/js_dump.ml

@@ -666,7 +666,10 @@ and expression_desc cxt ~(level : int) f x : cxt =
       expression ~level:13 cxt f e
   | Bin
       ( Minus,
-        { expression_desc = Number (Int { i = 0l; _ } | Float { f = "0." }) },
+        {
+          expression_desc =
+            Number ((Int { i = 0l; _ } | Float { f = "0." }) as desc);
+        },
         e )
   (* TODO:
      Handle multiple cases like
@@ -675,7 +678,7 @@ and expression_desc cxt ~(level : int) f x : cxt =
      {[ 0.000 - x ]}
   *) ->
       P.cond_paren_group f (level > 13) 1 (fun _ ->
-          P.string f "-";
+          P.string f (match desc with Float _ -> "- " | _ -> "-");
           expression ~level:13 cxt f e)
   | Bin (op, e1, e2) ->
       let out, lft, rght = Js_op_util.op_prec op in
@@ -718,8 +721,10 @@ and expression_desc cxt ~(level : int) f x : cxt =
                 Js_op.Lit (Ext_ident.convert x))))
   (*name convention of Record is slight different from modules*)
   | Caml_block (el, mutable_flag, _, Blk_record { fields; record_repr }) -> (
-      if Array.length fields <> 0 && Ext_array.for_alli fields (fun i v -> string_of_int i = v) then
-        expression_desc cxt ~level f (Array (el, mutable_flag))
+      if
+        Array.length fields <> 0
+        && Ext_array.for_alli fields (fun i v -> string_of_int i = v)
+      then expression_desc cxt ~level f (Array (el, mutable_flag))
       else
         match record_repr with
         | Record_regular ->

jscomp/test/format_test.js

@@ -189,6 +189,10 @@ List.iter((function (param) {
         scan_float("File \"format_test.ml\", line 122, characters 13-20", param[1], param[0]);
       }), literals);
 
+var f1 = - -9.9;
+
+eq("File \"format_test.ml\", line 128, characters 5-12", f1, 9.9);
+
 Mt.from_pair_suites("Format_test", suites.contents);
 
 exports.suites = suites;

jscomp/test/format_test.ml

@@ -122,6 +122,9 @@ let () =
   scan_float __LOC__ b a 
   ) literals
 
-
+let () =
+  let f = -9.9 in
+  let f1 = -.f in
+  eq __LOC__ f1 9.9
 
 let () = Mt.from_pair_suites __MODULE__ !suites