[Rust] Fixed generic interface implementation types (#3787)

Author: ncave

src/Fable.Cli/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * [JS/TS] Fixed `DateTime.Add` for `DateTimeKind.Unspecified` (by @ncave)
 * [Rust] Fixed deprecated `NaiveDateTime` usage in `DateTime` (by @ncave)
+* [Rust] Fixed generic interface implementation types (by @ncave)
 
 ### Added
 

src/Fable.Transforms/Rust/Fable2Rust.fs

@@ -4459,16 +4459,14 @@ module Util =
 
             [ ctorItem ]
 
-    let makeInterfaceTraitImpls (com: IRustCompiler) ctx entName genArgs ifcEntRef memberItems =
+    let makeInterfaceTraitImpls (com: IRustCompiler) ctx entName genArgs (ifc: Fable.DeclaredType) memberItems =
         let genArgsOpt = transformGenArgs com ctx genArgs
         let traitBound = mkTypeTraitGenericBound [ entName ] genArgsOpt
         let ty = mkTraitTy [ traitBound ]
         let generics = makeGenerics com ctx genArgs
 
-        let ifcEnt = com.GetEntity(ifcEntRef)
-        let ifcFullName = getInterfaceImportName com ctx ifcEntRef
-        let ifcGenArgs = FSharp2Fable.Util.getEntityGenArgs ifcEnt
-        let ifcGenArgsOpt = transformGenArgs com ctx ifcGenArgs
+        let ifcFullName = ifc.Entity |> getInterfaceImportName com ctx
+        let ifcGenArgsOpt = ifc.GenericArgs |> transformGenArgs com ctx
 
         let path = makeFullNamePath ifcFullName ifcGenArgsOpt
         let ofTrait = mkTraitRef path |> Some
@@ -4549,16 +4547,17 @@ module Util =
 
         let interfaces =
             ent.AllInterfaces
-            |> Seq.map (fun ifc -> ifc.Entity, ifc.Entity |> getInterfaceMemberNames com)
-            |> Seq.filter (fun (ifcEntRef, _) ->
+            |> Seq.filter (fun ifc ->
                 // throws out anything on the ignored interfaces list
-                not (Set.contains ifcEntRef.FullName ignoredInterfaceNames)
+                not (Set.contains ifc.Entity.FullName ignoredInterfaceNames)
             )
             |> Seq.toList
 
         let interfaceTraitImpls =
             interfaces
-            |> List.collect (fun (ifcEntRef, ifcMemberNames) ->
+            |> List.collect (fun ifc ->
+                let ifcMemberNames = ifc.Entity |> getInterfaceMemberNames com
+
                 let memberItems =
                     interfaceMembers
                     |> List.filter (fun (d, m) ->
@@ -4570,7 +4569,7 @@ module Util =
                 if List.isEmpty memberItems then
                     []
                 else
-                    makeInterfaceTraitImpls com ctx entName genArgs ifcEntRef memberItems
+                    makeInterfaceTraitImpls com ctx entName genArgs ifc memberItems
             )
 
         nonInterfaceImpls @ displayTraitImpls @ operatorTraitImpls @ interfaceTraitImpls