fix(python): make class declarations and references agree on type names

src/Fable.Transforms/FSharp2Fable.Util.fs

@@ -676,7 +676,11 @@ module Helpers =
 
         let sanitizedName =
             match com.Options.Language with
-            | Python -> Fable.Py.Naming.sanitizeIdent Fable.Py.Naming.pyBuiltins.Contains name part
+            | Python ->
+                // Python classes are declared with PascalCase names (PEP 8), so entity
+                // references must use the same casing as the declaration
+                let name = Fable.Py.Naming.toPascalCase name
+                Fable.Py.Naming.sanitizeIdent Fable.Py.Naming.pyBuiltins.Contains name part
             | Rust -> (entityName |> cleanNameAsRustIdentifier)
             | Dart -> Naming.sanitizeDartIdent (fun _ -> false) name part
             | _ -> Naming.sanitizeJsIdent (fun _ -> false) name part
@@ -768,7 +772,12 @@ module Helpers =
                     | Some _ -> name
                     | _ -> Fable.Py.Naming.toPythonNaming name
 
+                // Reference sites re-case the full composed name, so apply the naming
+                // convention to the composed name here as well. Otherwise a lowercase
+                // member name with an overload suffix is declared with the suffix
+                // preserved but referenced with it snake_cased
                 Fable.Py.Naming.sanitizeIdent Fable.Py.Naming.pyBuiltins.Contains name part
+                |> Fable.Py.Naming.toPythonNaming
             | Rust -> Naming.buildNameWithoutSanitation name part
             | Dart -> Naming.sanitizeDartIdent (fun _ -> false) name part
             | _ -> Naming.sanitizeJsIdent (fun _ -> false) name part

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

@@ -727,13 +727,20 @@ let makeEntityTypeAnnotation com ctx (entRef: Fable.EntityRef) genArgs repeatedG
                             // Inside base class or not a union - use as-is
                             id
 
-                    // Import the type if it's from another file
-                    if ent.IsFSharpUnion then
-                        match ent.Ref.SourcePath with
-                        | Some path when path <> com.CurrentFile ->
-                            let importPath = Path.getRelativeFileOrDirPath false com.CurrentFile false path
-                            com.GetImportExpr(ctx, importPath, annotationName) |> ignore
-                        | _ -> ()
+                    // Import the type if it's from another file. The import may be aliased when the
+                    // name clashes with a local declaration, so use the returned local identifier
+                    let annotationName =
+                        if ent.IsFSharpUnion then
+                            match ent.Ref.SourcePath with
+                            | Some path when path <> com.CurrentFile ->
+                                let importPath = Path.getRelativeFileOrDirPath false com.CurrentFile false path
+
+                                match com.GetImportExpr(ctx, importPath, annotationName) with
+                                | Expression.Name { Id = Identifier localId } -> localId
+                                | _ -> annotationName
+                            | _ -> annotationName
+                        else
+                            annotationName
 
                     makeGenericTypeAnnotation com ctx annotationName genArgs repeatedGenerics, stmts
                 // TODO: Resolve references to types in nested modules

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

@@ -3355,7 +3355,7 @@ let declareDataClassType
                     |> List.filter (fun genArg ->
                         match genArg with
                         | Fable.DeclaredType({ FullName = fullName }, _) ->
-                            Helpers.removeNamespace (fullName) <> entName
+                            Naming.toPascalCase (Helpers.removeNamespace fullName) <> entName
                         | _ -> true
                     )
 
@@ -3628,7 +3628,8 @@ let declareClassType
                 int.GenericArgs
                 |> List.filter (fun genArg ->
                     match genArg with
-                    | Fable.DeclaredType({ FullName = fullName }, _) -> Helpers.removeNamespace (fullName) <> entName
+                    | Fable.DeclaredType({ FullName = fullName }, _) ->
+                        Naming.toPascalCase (Helpers.removeNamespace fullName) <> entName
                     | _ -> true
                 )
 

tests/Python/Misc/Util2.fs

@@ -12,6 +12,13 @@ type Helper3(i: int) =
 
 type H = Helper3
 
+// Lowercase type name at the root of the file: the Python class declaration and
+// its references from other files must agree on the name
+type shape(size: int) =
+    member _.Size = size
+
+type Direction = | Up
+
 
 module Extensions =
     type String with

tests/Python/TestMisc.fs

@@ -958,6 +958,19 @@
 let ``test Naming values with same name as module works`` () =
     equal 30 Same.Same.shouldEqual30
 
+[<Fact>]
+let ``test Lowercase type name from another file works`` () =
+    let s = Util2.shape (4)
+    s.Size |> equal 4
+
+[<AttachMembers>]
+type Direction() =
+    static member Up = Util2.Direction.Up
+
+[<Fact>]
+let ``test Type with same name as type from another file works`` () =
+    Direction.Up |> equal Util2.Direction.Up
+
 [<Fact>]
 let ``test Can access nested recursive function with mangled name`` () =
     Util.Bar.nestedRecursive 3 |> equal 10
@@ -1179,7 +1192,7 @@
     | 2 -> x <- "2"
     | 3 | 4 -> x <- "3" // Multiple cases are allowed
     // | 5 | 6 as j -> x <- string j // This prevents the optimization
     | 4 -> x <- "4" // Unreachable cases are removed
     | _ -> x <- "?"
     equal "3" x