From 9cf524c66ce973b3bd2d4023774e5af1607eb74f Mon Sep 17 00:00:00 2001
From: Christoph Knittel <ck@cca.io>
Date: Thu, 24 Mar 2022 19:29:58 +0100
Subject: [PATCH 1/3] Print punned fields

---
 src/res_printer.ml                            | 37 +++++++++++++------
 .../reason/expected/bracedJsx.re.txt          |  2 +-
 .../conversion/reason/expected/braces.re.txt  |  2 +-
 tests/printer/expr/expected/block.res.txt     |  2 +-
 tests/printer/expr/expected/record.res.txt    |  9 +++++
 tests/printer/expr/record.res                 | 10 +++++
 6 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/src/res_printer.ml b/src/res_printer.ml
index e68b25f7..bdd8b424 100644
--- a/src/res_printer.ml
+++ b/src/res_printer.ml
@@ -2807,6 +2807,10 @@ and printExpression (e : Parsetree.expression) cmtTbl =
     let forceBreak =
       e.pexp_loc.loc_start.pos_lnum < e.pexp_loc.loc_end.pos_lnum
     in
+    let punningAllowed = match spreadExpr with
+    | Some(_) -> true
+    | None -> List.length rows > 1
+    in
     Doc.breakableGroup ~forceBreak (
       Doc.concat([
         Doc.lbrace;
@@ -2815,7 +2819,7 @@ and printExpression (e : Parsetree.expression) cmtTbl =
             Doc.softLine;
             spread;
             Doc.join ~sep:(Doc.concat [Doc.text ","; Doc.line])
-              (List.map (fun row -> printRecordRow row cmtTbl) rows)
+              (List.map (fun row -> printRecordRow row cmtTbl punningAllowed) rows)
           ]
         );
         Doc.trailingComma;
@@ -4818,17 +4822,28 @@ and printDirectionFlag flag = match flag with
   | Asttypes.Downto -> Doc.text " downto "
   | Asttypes.Upto -> Doc.text " to "
 
-and printRecordRow (lbl, expr) cmtTbl =
+and printRecordRow (lbl, expr) cmtTbl punningAllowed =
   let cmtLoc = {lbl.loc with loc_end = expr.pexp_loc.loc_end} in
-  let doc = Doc.group (Doc.concat [
-    printLidentPath lbl cmtTbl;
-    Doc.text ": ";
-    (let doc = printExpressionWithComments expr cmtTbl in
-    match Parens.expr expr with
-    | Parens.Parenthesized -> addParens doc
-    | Braced braces -> printBraces doc expr braces
-    | Nothing -> doc);
-  ]) in
+  let doc = Doc.group (
+    match expr.pexp_desc with
+    | Pexp_ident({txt = Lident key; loc = keyLoc}) when (
+      punningAllowed && 
+      Longident.last lbl.txt = key &&
+      lbl.loc.loc_start.pos_cnum == keyLoc.loc_start.pos_cnum
+    ) ->
+      (* print punned field *)
+      printLidentPath lbl cmtTbl;
+    | _ ->
+      Doc.concat [
+      printLidentPath lbl cmtTbl;
+      Doc.text ": ";
+      (let doc = printExpressionWithComments expr cmtTbl in
+      match Parens.expr expr with
+      | Parens.Parenthesized -> addParens doc
+      | Braced braces -> printBraces doc expr braces
+      | Nothing -> doc);
+    ]
+  ) in
   printComments doc cmtTbl cmtLoc
 
 and printBsObjectRow (lbl, expr) cmtTbl =
diff --git a/tests/conversion/reason/expected/bracedJsx.re.txt b/tests/conversion/reason/expected/bracedJsx.re.txt
index 27f93d34..b49e82fe 100644
--- a/tests/conversion/reason/expected/bracedJsx.re.txt
+++ b/tests/conversion/reason/expected/bracedJsx.re.txt
@@ -91,7 +91,7 @@ let make = () => {
           ],
         ),
       }
-    | SetValue(input) => {...state, input: input}
+    | SetValue(input) => {...state, input}
     }
   , {history: [], input: ""})
 
diff --git a/tests/conversion/reason/expected/braces.re.txt b/tests/conversion/reason/expected/braces.re.txt
index cf164c93..0a3e335d 100644
--- a/tests/conversion/reason/expected/braces.re.txt
+++ b/tests/conversion/reason/expected/braces.re.txt
@@ -20,5 +20,5 @@ let getDailyNewCases = x =>
   | Pair({prevRecord, record}) =>
     let confirmed = record.confirmed - prevRecord.confirmed
     let deaths = record.deaths - prevRecord.deaths
-    {confirmed: confirmed, deaths: deaths}
+    {confirmed, deaths}
   }
diff --git a/tests/printer/expr/expected/block.res.txt b/tests/printer/expr/expected/block.res.txt
index 8333405a..d7d8068b 100644
--- a/tests/printer/expr/expected/block.res.txt
+++ b/tests/printer/expr/expected/block.res.txt
@@ -60,7 +60,7 @@ React.useEffect0(() => {
     switch videoContainerRect {
     | Some(videoContainerRect) =>
       let newChapter = ({startTime: percent *. duration}: Video.chapter)
-      {a: a, b: b}->onChange
+      {a, b}->onChange
     | _ => ()
     }
   }}
diff --git a/tests/printer/expr/expected/record.res.txt b/tests/printer/expr/expected/record.res.txt
index 9226003d..e977aa83 100644
--- a/tests/printer/expr/expected/record.res.txt
+++ b/tests/printer/expr/expected/record.res.txt
@@ -39,3 +39,12 @@ let user = {
 }
 // braced + constrained expr
 let user = {name: {(ceo.name: string)}}
+
+// Punning
+let r = {a} // actually not a record, just an expression in braces
+let r = {a, b}
+let r = {a, b, c: 42}
+let r = {A.a, b}
+let r = {A.a: a, b}
+let r = {a: a, b}
+let r = {a, b: b}
diff --git a/tests/printer/expr/record.res b/tests/printer/expr/record.res
index 55e655e8..0d460829 100644
--- a/tests/printer/expr/record.res
+++ b/tests/printer/expr/record.res
@@ -28,3 +28,13 @@ let user = {name: {
 }}
 // braced + constrained expr
 let user = {name: {(ceo.name: string)}}
+
+
+// Punning
+let r = {a} // actually not a record, just an expression in braces
+let r = {a, b}
+let r = {a, b, c: 42}
+let r = {A.a, b}
+let r = {A.a: a, b}
+let r = {a: a, b}
+let r = {a, b: b}
\ No newline at end of file

From 9baf3c11ff024962f6cbc875ec1ac2e950d2389e Mon Sep 17 00:00:00 2001
From: Christoph Knittel <ck@cca.io>
Date: Fri, 25 Mar 2022 07:18:05 +0100
Subject: [PATCH 2/3] Avoid List.length

---
 src/res_printer.ml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/res_printer.ml b/src/res_printer.ml
index bdd8b424..5506039d 100644
--- a/src/res_printer.ml
+++ b/src/res_printer.ml
@@ -2807,9 +2807,9 @@ and printExpression (e : Parsetree.expression) cmtTbl =
     let forceBreak =
       e.pexp_loc.loc_start.pos_lnum < e.pexp_loc.loc_end.pos_lnum
     in
-    let punningAllowed = match spreadExpr with
-    | Some(_) -> true
-    | None -> List.length rows > 1
+    let punningAllowed = match spreadExpr, rows with
+    | (None, [_]) -> false (* disallow punning for single-element records *)
+    | _ -> true
     in
     Doc.breakableGroup ~forceBreak (
       Doc.concat([

From dee565d3650659ca5176975de840648b0f6fc38c Mon Sep 17 00:00:00 2001
From: Christoph Knittel <ck@cca.io>
Date: Mon, 28 Mar 2022 16:35:00 +0200
Subject: [PATCH 3/3] Add test cases for punning + comments

---
 tests/printer/expr/expected/record.res.txt | 23 ++++++++++++++++++++
 tests/printer/expr/record.res              | 25 +++++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/tests/printer/expr/expected/record.res.txt b/tests/printer/expr/expected/record.res.txt
index e977aa83..576cd48c 100644
--- a/tests/printer/expr/expected/record.res.txt
+++ b/tests/printer/expr/expected/record.res.txt
@@ -48,3 +48,26 @@ let r = {A.a, b}
 let r = {A.a: a, b}
 let r = {a: a, b}
 let r = {a, b: b}
+
+// Punning + comments
+let r = {
+  // a
+  a,
+  // b
+  b,
+}
+let r = {
+  a, // a
+  b, // b
+}
+let r = {
+  /* a */
+  a,
+  /* b */
+  b,
+}
+let r = {
+  a /* a */,
+  b /* b */,
+}
+let r = {a /* a */, b /* b */}
diff --git a/tests/printer/expr/record.res b/tests/printer/expr/record.res
index 0d460829..4cb993c9 100644
--- a/tests/printer/expr/record.res
+++ b/tests/printer/expr/record.res
@@ -37,4 +37,27 @@ let r = {a, b, c: 42}
 let r = {A.a, b}
 let r = {A.a: a, b}
 let r = {a: a, b}
-let r = {a, b: b}
\ No newline at end of file
+let r = {a, b: b}
+
+// Punning + comments
+let r = {
+  // a
+  a,
+  // b
+  b,
+}
+let r = {
+  a, // a
+  b, // b
+}
+let r = {
+  /* a */
+  a,
+  /* b */
+  b,
+}
+let r = {
+  a /* a */,
+  b /* b */,
+}
+let r = {a /* a */, b /* b */}