Pun record declaration fields when possible.

src/napkin_printer.ml

@@ -1420,13 +1420,32 @@ and printLabelDeclaration (ld : Parsetree.label_declaration) cmtTbl =
     let doc = printIdentLike ld.pld_name.txt in
     printComments doc cmtTbl ld.pld_name.loc
   in
+  let typeDoc = match (ld.pld_name, ld.pld_type) with
+  | (
+      {txt = key; loc = keyLoc},
+      {
+        ptyp_desc = Ptyp_constr (({txt = Lident constr}), []);
+        ptyp_attributes = [];
+        ptyp_loc = typLoc
+      }
+    ) when key = constr && keyLoc.loc_start.pos_cnum == typLoc.loc_start.pos_cnum ->
+    (* we detect punning by checking:
+     *  - is the key and the name of the constructor the same
+     *  - is the start of the location of the key and the constructor the same
+     * By doing this we make a difference between {a, b}  and {a: a, b: b} *)
+    Doc.nil
+  | _ ->
+    Doc.concat [
+      Doc.text ": ";
+      printTypExpr ld.pld_type cmtTbl;
+    ]
+  in
   Doc.group (
     Doc.concat [
       attrs;
       mutableFlag;
       name;
-      Doc.text ": ";
-      printTypExpr ld.pld_type cmtTbl;
+      typeDoc;
     ]
   )
 

tests/conversion/reason/__snapshots__/render.spec.js.snap

@@ -1173,6 +1173,11 @@ let () = switch [Color.red, Color.blue, Color.green] {
 "
 `;
 
+exports[`record.re 1`] = `
+"type r = {a, b}
+"
+`;
+
 exports[`recursiveType.ml 1`] = `
 "type rec tree = {\\"label\\": string, \\"left\\": option<tree>, \\"right\\": option<tree>}
 "

tests/conversion/reason/record.re

@@ -0,0 +1 @@
+type r = { a, b }

tests/printer/typeDef/__snapshots__/render.spec.js.snap

@@ -180,6 +180,20 @@ type user = {
   @attrSuperLongNaaaaaaaaaaaaaaameSooooooooLong
   hairStyle: Hair.t,
 }
+
+type punned = {
+  name,
+  @attr name2,
+  mutable name3,
+  name4: @attrNotPunned name4,
+  name5: name5<int>,
+}
+
+// not punned, user wrote typexpr
+type t = {a: a, b: b}
+
+// punned, user only wrote key
+type t = {a, b}
 "
 `;
 

tests/printer/typeDef/record.js

@@ -51,3 +51,17 @@ type user = {
   hairStyle: Hair.t,
   @attrAbove @attrSuperLongNaaaaaaaaaaaaaaameSooooooooLong @attrSuperLongNaaaaaaaaaaaaaaameSooooooooLong hairStyle: Hair.t
 }
+
+type punned = {
+  name,
+  @attr name2,
+  mutable name3
+  name4: @attrNotPunned name4
+  name5: name5<int>
+}
+
+// not punned, user wrote typexpr
+type t = {a: a, b: b}
+
+// punned, user only wrote key
+type t = {a, b}