Document TypeVarTuple failure

Summary: For this one, instead of solving equality constraints, do we want to solve consistency constraints? that sounds challanging.

Reviewed By: grievejia

Differential Revision: D91708623

fbshipit-source-id: 3e1504b68a5f52445a544eccfc3dd416c48008b4

Author: migeed-z

pyrefly/lib/test/type_var_tuple.rs

@@ -310,3 +310,17 @@ def test[T, *Ts](t1: tuple[T, *Ts], t2: tuple[*Ts, T]):
     t2 = (*t1[1:], t1[0])
 "#,
 );
+
+testcase!(
+    bug = "conformance: TypeVarTuple should allow compatible tuple types when solving (maybe related to issue 105)",
+    test_typevartuple_compatible_tuple_types,
+    r#"
+from typing import TypeVarTuple
+
+Ts = TypeVarTuple("Ts")
+
+def func2(arg1: tuple[*Ts], arg2: tuple[*Ts]) -> tuple[*Ts]: ...
+
+func2((0,), (0.0,))  # E: Argument `tuple[float]` is not assignable to parameter `arg2` with type `tuple[int]`
+"#,
+);