From f1ddd583b8e1ff303bd5f8b456198a8e0a4393ab 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/ocaml_re_test.js | 1 -
 jscomp/test/uncurry_test.js  | 1 -
 lib/es6/stream.js            | 1 -
 lib/js/stream.js             | 1 -
 6 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ba2a0b5c2b..2bfd8916f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -49,6 +49,7 @@
 - Avoid generation of `Curry` with reverse application `|>`. https://github.com/rescript-lang/rescript-compiler/pull/6876
 - Fix issue where the internal ppx for pipe `->` would not use uncurried application in uncurried mode. https://github.com/rescript-lang/rescript-compiler/pull/6878
 - 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
 
 #### :house: Internal
 
diff --git a/jscomp/core/lam_compile.ml b/jscomp/core/lam_compile.ml
index 4065d9c27f..b782e12966 100644
--- a/jscomp/core/lam_compile.ml
+++ b/jscomp/core/lam_compile.ml
@@ -327,6 +327,7 @@ and compile_recursive_let ~all_bindings (cxt : Lam_compile_context.t)
          ]}
           [Alias] may not be exact
       *)
+      let params = if one_unit_arg then [] else params in
       let ret : Lam_compile_context.return_label =
         {
           id;
diff --git a/jscomp/test/ocaml_re_test.js b/jscomp/test/ocaml_re_test.js
index dfcd0828f2..4ec6be2f10 100644
--- a/jscomp/test/ocaml_re_test.js
+++ b/jscomp/test/ocaml_re_test.js
@@ -4187,7 +4187,6 @@ function parse(multiline, dollar_endonly, dotall, ungreedy, s) {
         return epsilon;
       }
       i.contents = i.contents + 1 | 0;
-      _param = undefined;
       continue;
     };
   };
diff --git a/jscomp/test/uncurry_test.js b/jscomp/test/uncurry_test.js
index 80632c7bcc..d88d252252 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;
   };
 }
diff --git a/lib/es6/stream.js b/lib/es6/stream.js
index 5d6058b378..a6bf804d7b 100644
--- a/lib/es6/stream.js
+++ b/lib/es6/stream.js
@@ -266,7 +266,6 @@ function iter(f, strm) {
       }
       junk(strm);
       f(Caml_option.valFromOption(a));
-      _param = undefined;
       continue;
     };
   };
diff --git a/lib/js/stream.js b/lib/js/stream.js
index 2ee0c6b4be..c8db66eb78 100644
--- a/lib/js/stream.js
+++ b/lib/js/stream.js
@@ -266,7 +266,6 @@ function iter(f, strm) {
       }
       junk(strm);
       f(Caml_option.valFromOption(a));
-      _param = undefined;
       continue;
     };
   };