Fix issue with uninitialized _param in recursive functions with unit argument.

Fixes #6719

Author: cristianoc

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
 

jscomp/core/lam_compile.ml

@@ -357,7 +357,7 @@ and compile_recursive_let ~all_bindings (cxt : Lam_compile_context.t)
              it will be renamed into [method]
              when it is detected by a primitive
           *)
-            ~return_unit ~async ~one_unit_arg ?directive ~immutable_mask:ret.immutable_mask
+            ~return_unit ~async ~one_unit_arg:false  ?directive ~immutable_mask:ret.immutable_mask
             (Ext_list.map params (fun x ->
                  Map_ident.find_default ret.new_params x x))
             [
@@ -1465,7 +1465,6 @@ and compile_apply (appinfo : Lam.apply) (lambda_cxt : Lam_compile_context.t) =
             *)
           (* TODO: use [fold]*)
           let _, assigned_params, new_params =
-            let args = if ret.params = [] then [] else args in
             Ext_list.fold_left2 ret.params args (0, [], Map_ident.empty)
               (fun param arg (i, assigns, new_params) ->
                 match arg with

jscomp/test/ocaml_re_test.js

@@ -258,19 +258,17 @@ function empty(s) {
 }
 
 function iter(f, strm) {
-  let do_rec = function () {
-    while(true) {
-      let a = peek(strm);
-      if (a === undefined) {
-        return;
-      }
-      junk(strm);
-      f(Caml_option.valFromOption(a));
-      _param = undefined;
-      continue;
-    };
+  let _param;
+  while(true) {
+    let a = peek(strm);
+    if (a === undefined) {
+      return;
+    }
+    junk(strm);
+    f(Caml_option.valFromOption(a));
+    _param = undefined;
+    continue;
   };
-  do_rec();
 }
 
 function from(f) {

jscomp/test/uncurry_test.js

@@ -258,19 +258,17 @@ function empty(s) {
 }
 
 function iter(f, strm) {
-  let do_rec = function () {
-    while(true) {
-      let a = peek(strm);
-      if (a === undefined) {
-        return;
-      }
-      junk(strm);
-      f(Caml_option.valFromOption(a));
-      _param = undefined;
-      continue;
-    };
+  let _param;
+  while(true) {
+    let a = peek(strm);
+    if (a === undefined) {
+      return;
+    }
+    junk(strm);
+    f(Caml_option.valFromOption(a));
+    _param = undefined;
+    continue;
   };
-  do_rec();
 }
 
 function from(f) {