parse ... in variants

jscomp/syntax/src/res_core.ml

@@ -4730,6 +4730,12 @@ and parseTypeConstructorDeclaration ~startPos p =
   Parser.leaveBreadcrumb p Grammar.ConstructorDeclaration;
   let attrs = parseAttributes p in
   match p.Parser.token with
+  | DotDotDot ->
+    Parser.next p;
+    let name = Location.mkloc "..." (mkLoc startPos p.prevEndPos) in
+    let typ = parsePolyTypeExpr p in
+    let loc = mkLoc startPos typ.ptyp_loc.loc_end in
+    Ast_helper.Type.constructor ~loc ~attrs ~args:(Pcstr_tuple [typ]) name
   | Uident uident ->
     let uidentLoc = mkLoc p.startPos p.endPos in
     Parser.next p;

jscomp/syntax/src/res_printer.ml

@@ -1442,16 +1442,17 @@ and printConstructorDeclarations ~state ~privateFlag
 and printConstructorDeclaration2 ~state i
     (cd : Parsetree.constructor_declaration) cmtTbl =
   let attrs = printAttributes ~state cd.pcd_attributes cmtTbl in
+  let isDotDotDot = cd.pcd_name.txt = "..." in
   let bar =
-    if i > 0 || cd.pcd_attributes <> [] then Doc.text "| "
+    if i > 0 || cd.pcd_attributes <> [] || isDotDotDot then Doc.text "| "
     else Doc.ifBreaks (Doc.text "| ") Doc.nil
   in
   let constrName =
     let doc = Doc.text cd.pcd_name.txt in
     printComments doc cmtTbl cd.pcd_name.loc
   in
   let constrArgs =
-    printConstructorArguments ~state ~indent:true cd.pcd_args cmtTbl
+    printConstructorArguments ~isDotDotDot ~state ~indent:true cd.pcd_args cmtTbl
   in
   let gadt =
     match cd.pcd_res with
@@ -1473,15 +1474,15 @@ and printConstructorDeclaration2 ~state i
            ]);
     ]
 
-and printConstructorArguments ~state ~indent
+and printConstructorArguments ?(isDotDotDot = false) ~state ~indent
     (cdArgs : Parsetree.constructor_arguments) cmtTbl =
   match cdArgs with
   | Pcstr_tuple [] -> Doc.nil
   | Pcstr_tuple types ->
     let args =
       Doc.concat
         [
-          Doc.lparen;
+          (if isDotDotDot then Doc.nil else Doc.lparen);
           Doc.indent
             (Doc.concat
                [
@@ -1494,7 +1495,7 @@ and printConstructorArguments ~state ~indent
                ]);
           Doc.trailingComma;
           Doc.softLine;
-          Doc.rparen;
+          (if isDotDotDot then Doc.nil else Doc.rparen);
         ]
     in
     Doc.group (if indent then Doc.indent args else args)

jscomp/syntax/tests/printer/typeDef/expected/variant.res.txt

@@ -107,3 +107,10 @@ type color =
   | @rgb Red
   | @rgb Blue
   | @rgb Green
+
+// Spreads
+module S = {
+  type s = Five | Six
+}
+type aa = One | Two
+type bb = | ...aa | Three | Four | ...S.s

jscomp/syntax/tests/printer/typeDef/variant.res

@@ -94,3 +94,10 @@ type color =
   | @rgb Red
   | @rgb Blue
   | @rgb Green
+
+// Spreads
+module S = {
+  type s = Five | Six
+}
+type aa = One | Two
+type bb = | ...aa | Three | Four | ...S.s