chore(python): cover overloaded-ctor casing on lowercase types

src/Fable.Transforms/FSharp2Fable.Util.fs

@@ -767,15 +767,24 @@ module Helpers =
             match com.Options.Language with
             | Python ->
                 let name =
-                    // Don't apply Python naming convention if member has compiled name attribute
+                    // Don't snake_case the prefix for [<CompiledName>] members. This is
+                    // largely subsumed by the re-casing of the whole composed name below,
+                    // but keeps the intent explicit at this step.
                     match memb.Attributes |> Helpers.tryFindAttrib Atts.compiledName with
                     | 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
+                // Import/reference sites re-case the full composed name unconditionally
+                // (see the imports printer in Fable2Python.Transforms), so re-case it here
+                // too to keep declarations and references in agreement. This is what makes
+                // a lowercase member with an overload suffix, e.g. `foo__ctor_Z<hash>`, be
+                // both declared and imported as `foo__ctor_z<hash>`.
+                //
+                // Caveat: being unconditional, this also overrides the [<CompiledName>] skip
+                // above when the composed name has no uppercase entity/module prefix, i.e. a
+                // root-level compiled name starting lowercase is snake_cased. Prefixed names
+                // (class / nested-module members) keep their uppercase prefix, so toPythonNaming
+                // is a no-op there and the compiled name survives.
                 Fable.Py.Naming.sanitizeIdent Fable.Py.Naming.pyBuiltins.Contains name part
                 |> Fable.Py.Naming.toPythonNaming
             | Rust -> Naming.buildNameWithoutSanitation name part

tests/Python/Misc/Util2.fs

@@ -15,6 +15,10 @@ 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) =
+    // Overloaded constructors are emitted as module-level names with an overload
+    // suffix (e.g. `shape__ctor_Z<hash>`) and imported across files. The declaration
+    // and the import must agree on the suffix casing too, not just the base name.
+    new(label: string) = shape(label.Length)
     member _.Size = size
 
 type Direction = | Up

tests/Python/TestMisc.fs

@@ -963,6 +963,14 @@
     let s = Util2.shape (4)
     s.Size |> equal 4
 
+[<Fact>]
+let ``test Overloaded constructor on lowercase type from another file works`` () =
+    // Exercises the `shape__ctor_Z<hash>` overload-suffix casing across files
+    let s1 = Util2.shape (4)
+    let s2 = Util2.shape ("abc")
+    s1.Size |> equal 4
+    s2.Size |> equal 3
+
 [<AttachMembers>]
 type Direction() =
     static member Up = Util2.Direction.Up
@@ -1192,7 +1200,7 @@
     | 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