[Python] Type annotation fixes (#4330)

Author: dbrattli

pyrightconfig.ci.json

@@ -3,10 +3,8 @@
   "exclude": [
     "**/.venv/**",
     "**/node_modules/**",
-    "temp/fable-library-py/fable_library/list.py",
     "temp/tests/Python/test_applicative.py",
     "temp/tests/Python/test_misc.py",
-    "temp/tests/Python/test_type.py",
     "temp/tests/Python/fable_modules/thoth_json_python/encode.py"
   ]
 }

src/Fable.Transforms/Python/Fable2Python.Annotation.fs

@@ -71,6 +71,27 @@ let getGenericArgs (typ: Fable.Type) : Fable.Type list =
 let containsGenericParams (t: Fable.Type) =
     FSharp2Fable.Util.getGenParamNames [ t ] |> List.isEmpty |> not
 
+/// Check if a type contains Option nested inside a container (Array, List, Tuple).
+/// When Options are inside invariant containers, we must use Option[T] form consistently
+/// to match function signatures that use generic type parameters.
+let rec hasOptionInContainer (t: Fable.Type) : bool =
+    match t with
+    | Fable.Array(elementType, _) -> containsOptionType elementType
+    | Fable.List elementType -> containsOptionType elementType
+    | Fable.Tuple(genArgs, _) -> genArgs |> List.exists containsOptionType
+    | Fable.DeclaredType(_, genArgs) -> genArgs |> List.exists containsOptionType
+    | _ -> false
+
+/// Check if a type is or contains an Option type
+and containsOptionType (t: Fable.Type) : bool =
+    match t with
+    | Fable.Option _ -> true
+    | Fable.Array(elementType, _) -> containsOptionType elementType
+    | Fable.List elementType -> containsOptionType elementType
+    | Fable.Tuple(genArgs, _) -> genArgs |> List.exists containsOptionType
+    | Fable.DeclaredType(_, genArgs) -> genArgs |> List.exists containsOptionType
+    | _ -> false
+
 /// Check if a type is a callable type (Lambda or Delegate)
 let isCallableType (t: Fable.Type) =
     match t with
@@ -472,6 +493,8 @@ let makeImportTypeAnnotation com ctx genArgs moduleName typeName =
 let makeEntityTypeAnnotation com ctx (entRef: Fable.EntityRef) genArgs repeatedGenerics =
     // printfn "DeclaredType: %A" entRef.FullName
     match entRef.FullName, genArgs with
+    // Python's BaseException - used for catch-all exception handlers
+    | "BaseException", _ -> Expression.name "BaseException", []
     | Types.result, _ ->
         let resolved, stmts = resolveGenerics com ctx genArgs repeatedGenerics
         fableModuleAnnotation com ctx "result" "FSharpResult_2" resolved, stmts
@@ -630,8 +653,13 @@ let makeBuiltinTypeAnnotation com ctx typ repeatedGenerics kind =
     match kind with
     | Replacements.Util.BclGuid -> stdlibModuleTypeHint com ctx "uuid" "UUID" [] repeatedGenerics
     | Replacements.Util.FSharpReference genArg ->
-        let resolved, stmts = resolveGenerics com ctx [ genArg ] repeatedGenerics
-        fableModuleAnnotation com ctx "core" "FSharpRef" resolved, stmts
+        // In F#, struct instance method's `this` parameter is represented as inref<StructType>,
+        // but in Python the struct is passed directly, not wrapped in FSharpRef.
+        if isInRefOrAnyType com typ then
+            typeAnnotation com ctx repeatedGenerics genArg
+        else
+            let resolved, stmts = resolveGenerics com ctx [ genArg ] repeatedGenerics
+            fableModuleAnnotation com ctx "core" "FSharpRef" resolved, stmts
     (*
     | Replacements.Util.BclTimeSpan -> NumberTypeAnnotation
     | Replacements.Util.BclDateTime -> makeSimpleTypeAnnotation com ctx "Date"

src/Fable.Transforms/Python/Fable2Python.Bases.fs

@@ -278,6 +278,46 @@ let generatePythonProtocolDunders (com: IPythonCompiler) ctx (classEnt: Fable.En
     // a collection is either a mapping or a set, not both
     mappingDunders @ mutableMappingDunders @ setDunders @ mutableSetDunders
 
+/// Known core interfaces and their method members.
+/// These interfaces are injected by the compiler and their entities may not be available.
+/// Maps interface full name -> set of method member names.
+let knownInterfaceMethods =
+    Map
+        [
+            "Fable.Core.IGenericAdder`1", set [ "GetZero"; "Add" ]
+            "Fable.Core.IGenericAverager`1", set [ "GetZero"; "Add"; "DivideByInt" ]
+            "System.Collections.Generic.IComparer`1", set [ "Compare" ]
+            "System.Collections.Generic.IEqualityComparer`1", set [ "Equals"; "GetHashCode" ]
+        ]
+
+/// All known method names from core interfaces (for untyped object expressions).
+let knownInterfaceMethodNames =
+    knownInterfaceMethods |> Map.values |> Seq.collect id |> Set.ofSeq
+
+/// Check if the interface member is a method (vs property).
+/// Methods have parameters; properties (even returning functions) don't.
+/// Used in object expression code generation to determine whether to emit
+/// a method or a @property decorator.
+let isInterfaceMethod (com: Compiler) (typ: Fable.Type) (memberName: string) : bool =
+    match typ with
+    | Fable.DeclaredType(entRef, _) ->
+        // Check known interfaces first (handles compiler-injected interfaces)
+        match knownInterfaceMethods.TryFind entRef.FullName with
+        | Some methods -> methods.Contains memberName
+        | None ->
+            // Not a known interface, try entity lookup for user-defined interfaces
+            match com.TryGetEntity entRef with
+            | Some ent ->
+                ent.MembersFunctionsAndValues
+                |> Seq.tryFind (fun m -> m.DisplayName = memberName || m.CompiledName = memberName)
+                |> Option.map (fun m -> m.CurriedParameterGroups |> List.exists (not << List.isEmpty))
+                |> Option.defaultValue false
+            | None -> false
+    | Fable.Any ->
+        // For untyped object expressions (compiler-injected), check known method names
+        knownInterfaceMethodNames.Contains memberName
+    | _ -> false
+
 /// Utilities for interface and abstract class member naming.
 module InterfaceNaming =
     /// Computes the overload suffix for an interface/abstract class member based on parameter types.