fix: print module expr attributes

CHANGES.md

@@ -34,6 +34,8 @@
   [#2797](https://github.com/reasonml/reason/pull/2797))
 - Fix formatting of callbacks with sequence expressions (@anmonteiro,
   [#2799](https://github.com/reasonml/reason/pull/2799))
+- Fix printing of attributes on module expressions (@anmonteiro,
+  [#2803](https://github.com/reasonml/reason/pull/2803))
 
 ## 3.12.0
 

src/reason-parser/reason_pprint_ast.ml

@@ -9296,6 +9296,9 @@ let createFormatter () =
          *)
 
         method let_module_binding prefixText bindingName moduleExpr =
+          let { Reason_attributes.stdAttrs; _ } =
+            Reason_attributes.partitionAttributes moduleExpr.pmod_attributes
+          in
           let argsList, return =
             self#curriedFunctorPatternsAndReturnStruct moduleExpr
           in
@@ -9317,6 +9320,7 @@ let createFormatter () =
               (Some (true, includingEqual))
               ( [ self#moduleExpressionToFormattedApplicationItems
                     unconstrainedRetTerm
+                  |> self#attach_std_item_attrs stdAttrs
                 ]
               , None )
           (* Simple module with type no constraint, no functor args. *)
@@ -9325,7 +9329,10 @@ let createFormatter () =
               prefixText
               bindingName
               None
-              ([ self#moduleExpressionToFormattedApplicationItems return ], None)
+              ( [ self#moduleExpressionToFormattedApplicationItems return
+                  |> self#attach_std_item_attrs stdAttrs
+                ]
+              , None )
           | _, _ ->
             (* A functor *)
             let argsWithConstraint, actualReturn =
@@ -9346,7 +9353,9 @@ let createFormatter () =
               ~arrow:"=>"
               (makeList [ bindingName; atom " =" ])
               argsWithConstraint
-              ( [ self#moduleExpressionToFormattedApplicationItems actualReturn ]
+              ( [ self#moduleExpressionToFormattedApplicationItems actualReturn
+                  |> self#attach_std_item_attrs stdAttrs
+                ]
               , None )
 
         method class_opening class_keyword name pci_virt ls =

test/modules.t/input.re

@@ -572,3 +572,17 @@ module type t3 = t with module type x = { type t }
 module type t' = t with module type x := x
 
 module type t4 = t with module type x := { type t }
+
+module Foo =
+[@someattr]
+{
+  type t = string
+};
+
+let x = {
+  let module Foo =
+    [@someattr] {
+      type t = string
+    };
+  ()
+};

test/modules.t/run.t

@@ -752,4 +752,19 @@ Format modules
     t with module type x := {
                              type t;
                            };
+
+  module Foo =
+    [@someattr]
+    {
+      type t = string;
+    };
+
+  let x = {
+    module Foo =
+      [@someattr]
+      {
+        type t = string;
+      };
+    ();
+  };
 /* From http://stackoverflow.com/questions/1986374/  higher-order-type-constructors-and-functors-in-ocaml */