From b274e17764743b985b7262e779046b48b2be0748 Mon Sep 17 00:00:00 2001
From: Jules Aguillon <jules@j3s.fr>
Date: Fri, 24 Mar 2023 21:57:26 +0100
Subject: [PATCH 1/2] Add failing test

---
 tests/passing/js-let.ml | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tests/passing/js-let.ml b/tests/passing/js-let.ml
index 7065f9c4..fc9b9d5a 100644
--- a/tests/passing/js-let.ml
+++ b/tests/passing/js-let.ml
@@ -40,3 +40,20 @@ let parenthesized_let_tweak =
           S.S.g s.S.s ~s
         in
         y)
+
+let indentation_after_fun =
+  fun foo ->
+  bar
+
+let indentation_after_fun =
+  let f =
+    fun foo ->
+      bar
+  in
+  ()
+
+module M = struct
+  let indentation_after_fun =
+    fun foo ->
+      bar
+end

From ffc678c7d908eeccf50d583cd028dccbff668b7b Mon Sep 17 00:00:00 2001
From: Jules Aguillon <jules@j3s.fr>
Date: Sat, 25 Mar 2023 00:49:28 +0100
Subject: [PATCH 2/2] Consistent indentation of `fun` after `let`

Apply the same indentation for:

    let f =
      fun x ->
      y

and:

    let _ =
      let f =
        fun x ->
        y
      in
      ()

The reason for this change is that a top-level-`let` can be interpreted
as a `LetIn`, for example:

    module M = struct
      let indentation_after_fun =
        fun foo ->
        bar
    end
---
 src/indentBlock.ml      | 5 +++--
 tests/passing/js-let.ml | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/indentBlock.ml b/src/indentBlock.ml
index 9933965b..c1852094 100644
--- a/src/indentBlock.ml
+++ b/src/indentBlock.ml
@@ -1177,7 +1177,7 @@ let rec update_path config block stream tok =
             | KParen | KBegin | KBracket | KBrace | KBracketBar
             | KWith(KMatch|KTry) | KBar(KMatch|KTry) | KArrow(KMatch|KTry)
             | KFun
-            | KBody(KType|KExternal) | KColon
+            | KBody(KType|KExternal|KLet) | KColon
             | KStruct | KSig | KObject
             | KExtendedItem _ | KExtendedExpr _ -> true
             | _ -> false)
@@ -1187,10 +1187,11 @@ let rec update_path config block stream tok =
         | {kind=KFun} :: ({kind=KExpr i} as e) :: path when i = prio_flatop ->
             (* eg '>>= fun x ->': indent like the top of the expression *)
             {e with kind = KExpr 0} :: path
-        | {kind=KFun; line } :: {kind=KBody KLet; line=letline} :: _
+        | {kind=KFun; line } :: {kind=KBody(KLet|KLetIn); line=letline} :: _
           when next_offset tok stream = None
             && line = current_line && line <> letline
           ->
+            (* Special indentation of [fun] inside a [let]. *)
             append (KArrow KFun) L ~pad:0 (reset_line_indent config line path)
         | {kind=KFun; line; _ } :: _
           when next_offset tok stream = None
diff --git a/tests/passing/js-let.ml b/tests/passing/js-let.ml
index fc9b9d5a..1855ff70 100644
--- a/tests/passing/js-let.ml
+++ b/tests/passing/js-let.ml
@@ -48,12 +48,13 @@ let indentation_after_fun =
 let indentation_after_fun =
   let f =
     fun foo ->
-      bar
+    bar
   in
   ()
 
+(* Let is wrongly interpreted as LetIn *)
 module M = struct
   let indentation_after_fun =
     fun foo ->
-      bar
+    bar
 end