Update ambiguity rule.

Author: rchen152

conformance/results/mypy/overloads_evaluation.toml

@@ -24,7 +24,6 @@ Line 268: Unexpected errors ['overloads_evaluation.py:268: error: Expression is
 Line 284: Unexpected errors ['overloads_evaluation.py:284: error: Expression is of type "list[Any]", not "Any"  [assert-type]']
 Line 306: Unexpected errors ['overloads_evaluation.py:306: error: Expression is of type "Any", not "float"  [assert-type]']
 Line 350: Unexpected errors ['overloads_evaluation.py:350: error: Expression is of type "list[Any]", not "Any"  [assert-type]']
-Line 395: Unexpected errors ['overloads_evaluation.py:395: error: Expression is of type "Any", not "int"  [assert-type]']
 Line 439: Unexpected errors ['overloads_evaluation.py:439: error: Expression is of type "Any", not "bool"  [assert-type]']
 """
 output = """
@@ -58,6 +57,5 @@ overloads_evaluation.py:268: error: Expression is of type "list[Any]", not "Any"
 overloads_evaluation.py:284: error: Expression is of type "list[Any]", not "Any"  [assert-type]
 overloads_evaluation.py:306: error: Expression is of type "Any", not "float"  [assert-type]
 overloads_evaluation.py:350: error: Expression is of type "list[Any]", not "Any"  [assert-type]
-overloads_evaluation.py:395: error: Expression is of type "Any", not "int"  [assert-type]
 overloads_evaluation.py:439: error: Expression is of type "Any", not "bool"  [assert-type]
 """

conformance/results/pycroscope/overloads_evaluation.toml

@@ -1,7 +1,6 @@
 conformance_automated = "Fail"
 errors_diff = """
 Line 371: Unexpected errors ['./overloads_evaluation.py:371:16:   Any[multiple_overload_matches] is not equivalent to bool']
-Line 395: Unexpected errors ['./overloads_evaluation.py:395:16:   Any[multiple_overload_matches] is not equivalent to int']
 Line 400: Unexpected errors ['./overloads_evaluation.py:400:16:   Any[multiple_overload_matches] is not equivalent to bool']
 Line 420: Unexpected errors ['./overloads_evaluation.py:420:16:   Any[multiple_overload_matches] is not equivalent to bool']
 Line 439: Unexpected errors ['./overloads_evaluation.py:439:16:   Any[multiple_overload_matches] is not equivalent to bool']
@@ -14,7 +13,6 @@ output = """
 ./overloads_evaluation.py:51:0: Cannot call overloaded function [incompatible_argument]
 ./overloads_evaluation.py:116:4: Cannot call overloaded function [incompatible_argument]
 ./overloads_evaluation.py:371:16:   Any[multiple_overload_matches] is not equivalent to bool
-./overloads_evaluation.py:395:16:   Any[multiple_overload_matches] is not equivalent to int
 ./overloads_evaluation.py:400:16:   Any[multiple_overload_matches] is not equivalent to bool
 ./overloads_evaluation.py:420:16:   Any[multiple_overload_matches] is not equivalent to bool
 ./overloads_evaluation.py:439:16:   Any[multiple_overload_matches] is not equivalent to bool

conformance/results/pyrefly/overloads_evaluation.toml

@@ -1,10 +1,12 @@
 conformant = "Pass"
-conformance_automated = "Pass"
+conformance_automated = "Fail"
 errors_diff = """
+Line 395: Unexpected errors ['assert_type(int, Any) failed [assert-type]']
 """
 output = """
 ERROR overloads_evaluation.py:38:11-13: No matching overload found for function `example1_1` called with arguments: () [no-matching-overload]
 ERROR overloads_evaluation.py:46:15-16: Argument `Literal[1]` is not assignable to parameter `y` with type `str` in function `example1_1` [bad-argument-type]
 ERROR overloads_evaluation.py:51:12-13: Argument `Literal[1]` is not assignable to parameter `x` with type `str` in function `example1_1` [bad-argument-type]
 ERROR overloads_evaluation.py:116:13-22: No matching overload found for function `example2` called with arguments: (int | str, int | str, Literal[1]) [no-matching-overload]
+ERROR overloads_evaluation.py:395:16-27: assert_type(int, Any) failed [assert-type]
 """

conformance/results/pyright/overloads_evaluation.toml

@@ -10,6 +10,7 @@ Does not evaluate `Any` in some cases where overload is ambiguous.
 conformance_automated = "Fail"
 errors_diff = """
 Line 284: Unexpected errors ['overloads_evaluation.py:284:17 - error: "assert_type" mismatch: expected "Any" but received "list[int]" (reportAssertTypeFailure)']
+Line 395: Unexpected errors ['overloads_evaluation.py:395:17 - error: "assert_type" mismatch: expected "Any" but received "int" (reportAssertTypeFailure)']
 Line 468: Unexpected errors ['overloads_evaluation.py:468:17 - error: "assert_type" mismatch: expected "A[Any]" but received "A[None]" (reportAssertTypeFailure)']
 """
 output = """
@@ -27,5 +28,6 @@ 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:395:17 - error: "assert_type" mismatch: expected "Any" but received "int" (reportAssertTypeFailure)
 overloads_evaluation.py:468:17 - error: "assert_type" mismatch: expected "A[Any]" but received "A[None]" (reportAssertTypeFailure)
 """

conformance/results/ty/overloads_evaluation.toml

@@ -4,14 +4,12 @@ Returns Any instead of most general return type for ambiguous calls.
 """
 conformance_automated = "Fail"
 errors_diff = """
-Line 395: Unexpected errors ['overloads_evaluation.py:395:5: error[type-assertion-failure] Type `Unknown` does not match asserted type `int`']
 Line 468: Unexpected errors ['overloads_evaluation.py:468:5: error[type-assertion-failure] Type `Unknown` does not match asserted type `A[Any]`']
 """
 output = """
 overloads_evaluation.py:38:1: error[no-matching-overload] No overload of function `example1_1` matches arguments
 overloads_evaluation.py:46:15: error[invalid-argument-type] Argument to function `example1_1` is incorrect: Expected `str`, found `Literal[1]`
 overloads_evaluation.py:51:12: error[invalid-argument-type] Argument to function `example1_1` is incorrect: Expected `str`, found `Literal[1]`
 overloads_evaluation.py:116:5: error[no-matching-overload] No overload of function `example2` matches arguments
-overloads_evaluation.py:395:5: error[type-assertion-failure] Type `Unknown` does not match asserted type `int`
 overloads_evaluation.py:468:5: error[type-assertion-failure] Type `Unknown` does not match asserted type `A[Any]`
 """

conformance/results/zuban/overloads_evaluation.toml

@@ -5,7 +5,6 @@ Returns Any instead of most general return type for ambiguous calls.
 """
 conformance_automated = "Fail"
 errors_diff = """
-Line 395: Unexpected errors ['overloads_evaluation.py:395: error: Expression is of type "Any", not "int"  [misc]']
 Line 439: Unexpected errors ['overloads_evaluation.py:439: error: Expression is of type "Any", not "bool"  [misc]']
 Line 468: Unexpected errors ['overloads_evaluation.py:468: error: Expression is of type "Any", not "A[Any]"  [misc]']
 """
@@ -24,7 +23,6 @@ overloads_evaluation.py:51: note:     def example1_1(x: int, y: str) -> int
 overloads_evaluation.py:51: note:     def example1_1(x: str) -> str
 overloads_evaluation.py:116: error: Argument 1 to "example2" has incompatible type "int | str"; expected "int"  [arg-type]
 overloads_evaluation.py:116: error: Argument 2 to "example2" has incompatible type "int | str"; expected "str"  [arg-type]
-overloads_evaluation.py:395: error: Expression is of type "Any", not "int"  [misc]
 overloads_evaluation.py:439: error: Expression is of type "Any", not "bool"  [misc]
 overloads_evaluation.py:468: error: Expression is of type "Any", not "A[Any]"  [misc]
 """

conformance/tests/overloads_evaluation.py

@@ -390,9 +390,9 @@ def example9(x: str | bytes, y: str) -> bool | int:
 def check_example9(x: Any):
     # All three overloads are candidates. The parameter types corresponding to
     # argument `x` are `str` and `bytes`, which are not equivalent, so none of
-    # the overloads can be eliminated. We pick the most general return type.
+    # the overloads can be eliminated. We fall back to `Any`.
     ret1 = example9(x, 'o1')
-    assert_type(ret1, int)
+    assert_type(ret1, Any)
     # The second and third overload are candidates. The parameter type
     # corresponding to argument `x` is `bytes` in both candidates, so we can
     # eliminate the third overload.

docs/spec/overload.rst

@@ -315,9 +315,13 @@ caller eliminates types that include ``Any``.
 Once this filtering process is applied for all arguments, examine the return
 types of the remaining overloads. If these return types include type variables
 that are scoped to the called function, they should be replaced with their
-solved types. Eliminate every overload for which there exists a
-:term:`materialization <materialize>` of another overload's return type that is
-not assignable to this overload's return type.
+solved types.
+
+Next, keep only the overloads for which both of the following are true:
+* All :term:`materializations <materialize>` of every other candidate
+  overload's return type are assignable to this overload's return type, and
+* This overload's return type is assignable to every other candidate overload's
+  return type.
 
 This rule picks the most general return type, if one exists.