Print optional labels with ?.

Author: cristianoc

src/res_core.ml

@@ -161,7 +161,7 @@ let jsxAttr = (Location.mknoloc "JSX", Parsetree.PStr [])
 let uncurryAttr = (Location.mknoloc "bs", Parsetree.PStr [])
 let ternaryAttr = (Location.mknoloc "ns.ternary", Parsetree.PStr [])
 let ifLetAttr = (Location.mknoloc "ns.iflet", Parsetree.PStr [])
-let optionalAttr = (Location.mknoloc "optional", Parsetree.PStr [])
+let optionalAttr = (Location.mknoloc "ns.optional", Parsetree.PStr [])
 
 let suppressFragileMatchWarningAttr =
   ( Location.mknoloc "warning",

src/res_parsetree_viewer.ml

@@ -169,7 +169,7 @@ let filterParsingAttrs attrs =
       | ( {
             Location.txt =
               ( "ns.ternary" | "ns.braces" | "res.template" | "bs" | "ns.iflet"
-              | "ns.namedArgLoc" );
+              | "ns.namedArgLoc" | "ns.optional" );
           },
           _ ) ->
         false
@@ -304,6 +304,12 @@ let isIfLetExpr expr =
     true
   | _ -> false
 
+let rec hasOptionalAttribute attrs =
+  match attrs with
+  | [] -> false
+  | ({Location.txt = "ns.optional"}, _) :: _ -> true
+  | _ :: attrs -> hasOptionalAttribute attrs
+
 let hasAttributes attrs =
   List.exists
     (fun attr ->

src/res_parsetree_viewer.mli

@@ -83,6 +83,7 @@ val filterFragileMatchAttributes : Parsetree.attributes -> Parsetree.attributes
 
 val isJsxExpression : Parsetree.expression -> bool
 val hasJsxAttribute : Parsetree.attributes -> bool
+val hasOptionalAttribute: Parsetree.attributes -> bool
 
 val shouldIndentBinaryExpr : Parsetree.expression -> bool
 val shouldInlineRhsBinaryExpr : Parsetree.expression -> bool

src/res_printer.ml

@@ -4658,6 +4658,9 @@ and printExpressionRecordRow (lbl, expr) cmtTbl punningAllowed =
           [
             printLidentPath lbl cmtTbl;
             Doc.text ": ";
+            (if Res_parsetree_viewer.hasOptionalAttribute expr.pexp_attributes then
+             Doc.text "?"
+            else Doc.nil);
             (let doc = printExpressionWithComments expr cmtTbl in
              match Parens.expr expr with
              | Parens.Parenthesized -> addParens doc

tests/parsing/grammar/expressions/expected/record.res.txt

@@ -15,7 +15,7 @@ let r = { (make () : myRecord) with foo = bar }
 let r =
   {
     x = ((None)[@optional ]);
-    y = ((None)[@optional ]);
+    y = ((None)[@ns.optional ]);
     z = (((None : tt))[@optional ])
   }
 let z name = { name = ((name)[@optional ]); x = 3 }

tests/printer/expr/expected/record.res.txt

@@ -74,7 +74,7 @@ let r = {
 }
 let r = {a /* a */, b /* b */}
 
-let r = {x: @optional None, y: @optional None, z: (@optional None: tt)}
+let r = {x: @optional None, y: ?None, z: (@optional None: tt)}
 
 let z = name => {@optional name, x: 3}
 

tests/printer/expr/record.res

@@ -64,7 +64,7 @@ let r = {
 }
 let r = {a /* a */, b /* b */}
 
-let r = {x: @optional None, y: @optional None, z: @optional (None:tt)}
+let r = {x: @optional None, y: ?None, z: @optional (None:tt)}
 
 let z = name => { name : @optional name, x: 3}