Merge pull request #3712 from chkn/fix-deref-byref-type

Fix type of dereferenced byref
fable-compiler · Jan 24, 2024 · 3a51f87 · 3a51f87
2 parents ca97ed0 + b371b08
commit 3a51f87
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Showing 2 changed files with 17 additions and 1 deletion.
diff --git a/src/Fable.Transforms/FSharp2Fable.fs b/src/Fable.Transforms/FSharp2Fable.fs
@@ -943,7 +943,12 @@ let private transformExpr
                     && com.Options.Language <> Rust
                 then
                     // Getting byref value is compiled as FSharpRef op_Dereference
-                    return Replacements.Api.getRefCell com r v.Type v
+                    return
+                        Replacements.Api.getRefCell
+                            com
+                            r
+                            (List.head v.Type.Generics)
+                            v
                 else
                     return v
 

diff --git a/tests/Js/Main/TypeTests.fs b/tests/Js/Main/TypeTests.fs
@@ -503,6 +503,12 @@ let inline callWithByrefCreatedFromByrefInlined(n: byref<int>) =
     let f = &n
     byrefFunc &f
 
+let inline inlinedFunc(n: 't[]) =
+    n.Length
+
+let genericByrefFunc(n: byref<'t[]>) =
+    inlinedFunc n
+
 let tests =
   testList "Types" [
     // TODO: This test produces different results in Fable and .NET
@@ -1100,4 +1106,9 @@ let tests =
         ignore intRef
         callWithByrefCreatedFromByrefInlined &intRef
         an_int |> equal 66
+
+    testCase "inline with generic byref works" <| fun () ->
+        let mutable arr = [| 1; 2; 3 |]
+        let result = genericByrefFunc &arr
+        result |> equal 3
   ]