Remove unsafe overlap in overload example.

Author: rchen152

conformance/results/pyright/overloads_evaluation.toml

@@ -23,6 +23,5 @@ overloads_evaluation.py:116:17 - error: Argument of type "int | str" cannot be a
   Type "int | str" is not assignable to type "int"
     "str" is not assignable to "int" (reportArgumentType)
 overloads_evaluation.py:284:17 - error: "assert_type" mismatch: expected "Any" but received "list[int]" (reportAssertTypeFailure)
-overloads_evaluation.py:354:5 - error: Overload 1 for "example8" overlaps overload 2 and returns an incompatible type (reportOverlappingOverload)
 overloads_evaluation.py:398:17 - error: "assert_type" mismatch: expected "A[Any]" but received "A[None]" (reportAssertTypeFailure)
 """

conformance/tests/overloads_evaluation.py

@@ -351,15 +351,15 @@ def check_example7(v1: list[Any], v2: Any) -> None:
 
 
 @overload
-def example8(x: str, y: Literal['o1']) -> str: ...  # E? some type checkers report unsafe overlap between example8's overloads
+def example8(x: str, y: Literal['o1']) -> bool: ...
 
 
 @overload
 def example8(x: str, y: str) -> int: ...
 
 
-def example8(x: str, y: str) -> str | int:
-    return x if y == 'o1' else 0
+def example8(x: str, y: str) -> bool | int:
+    return True
 
 
 def check_example8(x: Any):
@@ -368,7 +368,7 @@ def check_example8(x: Any):
     # `Literal['o1']` match the first overload, so the second overload can be
     # eliminated.
     ret = example8(x, 'o1')
-    assert_type(ret, str)
+    assert_type(ret, bool)
 
 
 class A[T]:

docs/spec/overload.rst

@@ -295,7 +295,7 @@ Consider the following examples::
 and::
 
   @overload
-  def example2(x: str, y: Literal['o1']) -> str: ...
+  def example2(x: str, y: Literal['o1']) -> bool: ...
   @overload
   def example2(x: str, y: str) -> int: ...