From a4465d41d49637b007e2002d6a039f9b6a4e6388 Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <cristianoc@users.noreply.github.com>
Date: Wed, 24 Jul 2024 17:11:01 +0200
Subject: [PATCH] Fix issue with uninitialized `_param` in recursive functions
 with unit argument.

Fixes https://github.com/rescript-lang/rescript-compiler/issues/6719
---
 CHANGELOG.md                | 1 +
 jscomp/core/lam_compile.ml  | 1 +
 jscomp/test/uncurry_test.js | 1 -
 3 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e692a5f1c..b79f0e2d78 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@
 - Ignore `@uncurry` attribute in uncurried mode, to avoid generating calls to `Curry` at runtime. https://github.com/rescript-lang/rescript-compiler/pull/6869
 - Avoid generating calls to Curry when adjusting arity of uncurried functions. https://github.com/rescript-lang/rescript-compiler/pull/6870
 - Fix build after calling without `-warn-error`, see https://github.com/rescript-lang/rescript-compiler/issues/6868 for more details. https://github.com/rescript-lang/rescript-compiler/pull/6877
+- Fix issue with uninitialized `_param` in recursive functions with unit argument. https://github.com/rescript-lang/rescript-compiler/pull/6907
 
 # 11.1.3-rc.1
 
diff --git a/jscomp/core/lam_compile.ml b/jscomp/core/lam_compile.ml
index 70a10fc9fb..9f7ced71f3 100644
--- a/jscomp/core/lam_compile.ml
+++ b/jscomp/core/lam_compile.ml
@@ -328,6 +328,7 @@ and compile_recursive_let ~all_bindings (cxt : Lam_compile_context.t)
          ]}
           [Alias] may not be exact
       *)
+      let params = if oneUnitArg then [] else params in
       let ret : Lam_compile_context.return_label =
         {
           id;
diff --git a/jscomp/test/uncurry_test.js b/jscomp/test/uncurry_test.js
index cbce7ce877..bca59b1ade 100644
--- a/jscomp/test/uncurry_test.js
+++ b/jscomp/test/uncurry_test.js
@@ -28,7 +28,6 @@ console.log([
 
 function xx() {
   while(true) {
-    _param = undefined;
     continue ;
   };
 }