Preserve @as decorator on record fields when creating interface (#7779)

* Preserve @as decorator on record fields when creating interface

* Add CHANGELOG entry

* Always copy type declarations verbatim

* Remove unused helpers

Author: mediremi

CHANGELOG.md

@@ -23,6 +23,8 @@
 
 #### :bug: Bug fix
 
+- Preserve `@as(...)` decorator on record fields when creating interface. https://github.com/rescript-lang/rescript/pull/7779
+
 #### :memo: Documentation
 
 #### :nail_care: Polish

analysis/src/CreateInterface.ml

@@ -249,12 +249,13 @@ let printSignature ~extractor ~signature =
       in
       Buffer.add_string buf (indent ^ newItemStr ^ "\n");
       processSignature ~indent items
-    | Sig_type (id, typeDecl, resStatus) :: items ->
-      let newItemStr =
-        sigItemToString
-          (Printtyp.tree_of_type_declaration id typeDecl resStatus)
+    | Sig_type (_id, typeDecl, _recStatus) :: items ->
+      let lines =
+        let posStart, posEnd = Loc.range typeDecl.type_loc in
+        extractor |> SourceFileExtractor.extract ~posStart ~posEnd
       in
-      Buffer.add_string buf (indent ^ newItemStr ^ "\n");
+      (* Copy the type declaration verbatim to preserve attributes *)
+      Buffer.add_string buf ((lines |> String.concat "\n") ^ "\n");
       processSignature ~indent items
     | Sig_typext (id, extConstr, extStatus) :: items ->
       let newItemStr =

tests/analysis_tests/tests/src/CreateInterface.res

@@ -143,3 +143,10 @@ module Memo = {
 
   let make = React.memo(make)
 }
+
+external x: (@as("bar") ~foo: int) => unit = "myexternal"
+
+type record = {
+  @as("foo_bar")
+  fooBar: int
+}

tests/analysis_tests/tests/src/expected/CreateInterface.res.txt

@@ -109,4 +109,9 @@ module Memo: {
   @react.component
   let make: (~name: string) => React.element
 }
+external x: (@as("bar") ~foo: int) => unit = "myexternal"
+type record = {
+  @as("foo_bar")
+  fooBar: int
+}