[JS/TS] Fix regression, generate let variable when using import o…

…n a private mutable variable (#3941)

src/Fable.Cli/CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * [Rust] Fixed try finally handler order of execution (by @ncave)
 * [JS/TS/Python/Rust] Fixed String.StartsWith/EndsWith (#3934) (by @ncave)
 * [All/Rust] Removed Regex.Replace from hot paths (by @ncave)
+* [JS] Fix regression, generate `let` variable when using `import` on a private mutable variable (by @MangelMaxime)
 
 ## 4.22.0 - 2024-10-02
 

src/Fable.Transforms/FSharp2Fable.fs

@@ -1579,7 +1579,7 @@ let private transformImportValue com r typ name (memb: FSharpMemberOrFunctionOrV
         "Imported members cannot be mutable and public, please make it private: " + name
         |> addError com [] None
 
-    let memberRef = Fable.GeneratedMember.Value(name, typ)
+    let memberRef = Fable.GeneratedMember.Value(name, typ, isMutable = memb.IsMutable)
     transformImport com r typ name [] memberRef selector path
 
 let private transformMemberValue

tests/Integration/Integration/data/import/PrivateMutableImport.fs

@@ -0,0 +1,12 @@
+module PrivateMutableImport
+
+open Fable.Core.JsInterop
+
+type ToastrOptions =
+    abstract Thing : string with get, set
+
+[<RequireQualifiedAccess>]
+module Toastr =
+    let mutable private theOptions: ToastrOptions =
+        //()
+        import "path" "toastr"

tests/Integration/Integration/data/import/PrivateMutableImport.js.expected

@@ -0,0 +1,4 @@
+import { path } from "toastr";
+
+export let Toastr_theOptions = path;
+

tests/Integration/Integration/data/import/import.fsproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <RollForward>Major</RollForward>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="PrivateMutableImport.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Fable.Core" Version="4.2.0" />
+  </ItemGroup>
+
+</Project>