Allow type checkers to infer more precise types for tuples (#2194)

davidhalter · AlexWaygood · web-flow · commit 6b1a64cfbfab · 2026-02-27T13:25:22.000-08:00
Co-authored-by: Alex Waygood &lt;Alex.Waygood@Gmail.com&gt;
diff --git a/conformance/results/pyrefly/aliases_explicit.toml b/conformance/results/pyrefly/aliases_explicit.toml
@@ -4,7 +4,7 @@ errors_diff = """
 """
 output = """
 ERROR aliases_explicit.py:67:9-28: `TypeAlias[GoodTypeAlias2, type[int | None]]` is not subscriptable [unsupported-operation]
-ERROR aliases_explicit.py:68:9-28: `TypeAlias[GoodTypeAlias3, type[list[GoodTypeAlias2]]]` is not subscriptable [unsupported-operation]
+ERROR aliases_explicit.py:68:9-28: `TypeAlias[GoodTypeAlias3, type[list[int | None]]]` is not subscriptable [unsupported-operation]
 ERROR aliases_explicit.py:69:9-33: Expected 1 type argument for `GoodTypeAlias4`, got 2 [bad-specialization]
 ERROR aliases_explicit.py:70:9-33: Expected 1 type argument for `GoodTypeAlias8`, got 2 [bad-specialization]
 ERROR aliases_explicit.py:71:9-33: Expected a valid ParamSpec expression, got `int` [invalid-param-spec]
diff --git a/conformance/results/pyrefly/aliases_recursive.toml b/conformance/results/pyrefly/aliases_recursive.toml
@@ -14,4 +14,5 @@ ERROR aliases_recursive.py:63:30-43: `list[list[float] | str | GenericTypeAlias1
 ERROR aliases_recursive.py:69:35-64: `list[int | list[int | list[int | list[float] | str | GenericTypeAlias2[str, int]] | str | GenericTypeAlias2[str, int]] | str | GenericTypeAlias2[str, int]]` is not assignable to `list[int | str | GenericTypeAlias2[str, int]]` [bad-assignment]
 ERROR aliases_recursive.py:72:29-57: Found cyclic self-reference in `RecursiveUnion` [invalid-type-alias]
 ERROR aliases_recursive.py:75:31-61: Found cyclic self-reference in `MutualReference1` [invalid-type-alias]
+ERROR aliases_recursive.py:75:93-123: Found cyclic self-reference in `MutualReference2` [invalid-type-alias]
 """
diff --git a/conformance/results/pyrefly/aliases_type_statement.toml b/conformance/results/pyrefly/aliases_type_statement.toml
@@ -31,5 +31,6 @@ ERROR aliases_type_statement.py:77:7-41: `str` is not assignable to upper bound
 ERROR aliases_type_statement.py:79:7-41: `int` is not assignable to upper bound `str` of type variable `T` [bad-specialization]
 ERROR aliases_type_statement.py:82:28-47: Found cyclic self-reference in `RecursiveTypeAlias3` [invalid-type-alias]
 ERROR aliases_type_statement.py:84:31-59: Found cyclic self-reference in `RecursiveTypeAlias4` [invalid-type-alias]
+ERROR aliases_type_statement.py:88:28-47: Found cyclic self-reference in `RecursiveTypeAlias6` [invalid-type-alias]
 ERROR aliases_type_statement.py:89:28-47: Found cyclic self-reference in `RecursiveTypeAlias7` [invalid-type-alias]
 """
diff --git a/conformance/results/pyrefly/aliases_typealiastype.toml b/conformance/results/pyrefly/aliases_typealiastype.toml
@@ -1,21 +1,16 @@
-conformant = "Partial"
-notes = """
-Does not detect circular definitions.
-"""
-conformance_automated = "Fail"
+conformance_automated = "Pass"
 errors_diff = """
-Line 48: Expected 1 errors
-Line 66: Expected 1 errors
 """
 output = """
 ERROR aliases_typealiastype.py:32:7-30: Object of class `TypeAliasType` has no attribute `other_attrib` [missing-attribute]
 ERROR aliases_typealiastype.py:40:5-30: `int` is not assignable to upper bound `str` of type variable `TStr` [bad-specialization]
 ERROR aliases_typealiastype.py:43:13-66: Type variable `S` is out of scope for this `TypeAliasType` [invalid-type-alias]
 ERROR aliases_typealiastype.py:44:13-48: Type variable `S` is out of scope for this `TypeAliasType` [invalid-type-alias]
 ERROR aliases_typealiastype.py:45:45-65: Value for argument `type_params` must be a tuple literal [invalid-type-alias]
-ERROR aliases_typealiastype.py:46:41-50: Found cyclic self-reference in `BadAlias4` [invalid-type-alias]
-ERROR aliases_typealiastype.py:47:40-60: Found cyclic self-reference in `BadAlias5` [invalid-type-alias]
-ERROR aliases_typealiastype.py:49:40-49: Found cyclic self-reference in `BadAlias7` [invalid-type-alias]
+ERROR aliases_typealiastype.py:46:13-52: Found cyclic self-reference in `BadAlias4` [invalid-type-alias]
+ERROR aliases_typealiastype.py:47:13-79: Found cyclic self-reference in `BadAlias5` [invalid-type-alias]
+ERROR aliases_typealiastype.py:48:13-52: Found cyclic self-reference in `BadAlias6` [invalid-type-alias]
+ERROR aliases_typealiastype.py:49:13-50: Found cyclic self-reference in `BadAlias7` [invalid-type-alias]
 ERROR aliases_typealiastype.py:52:40-80: Function call cannot be used in annotations [invalid-annotation]
 ERROR aliases_typealiastype.py:53:40-50: List literal cannot be used in annotations [invalid-annotation]
 ERROR aliases_typealiastype.py:54:42-55: Tuple literal cannot be used in annotations [invalid-annotation]
@@ -31,4 +26,5 @@ ERROR aliases_typealiastype.py:61:42-46: Bool literal cannot be used in annotati
 ERROR aliases_typealiastype.py:62:42-43: Number literal cannot be used in annotations [invalid-annotation]
 ERROR aliases_typealiastype.py:63:42-53: Boolean operation cannot be used in annotations [invalid-annotation]
 ERROR aliases_typealiastype.py:64:42-52: F-string cannot be used in annotations [invalid-annotation]
+ERROR aliases_typealiastype.py:66:14-59: Found cyclic self-reference in `BadAlias21` [invalid-type-alias]
 """
diff --git a/conformance/results/pyrefly/generics_scoping.toml b/conformance/results/pyrefly/generics_scoping.toml
@@ -4,13 +4,9 @@ Does not implement several scoping checks/restrictions for generics
 """
 conformance_automated = "Fail"
 errors_diff = """
-Line 61: Expected 1 errors
-Line 65: Expected 1 errors
 Line 86: Expected 1 errors
 Line 89: Expected 1 errors
 Line 98: Expected 1 errors
-Line 105: Expected 1 errors
-Line 106: Expected 1 errors
 Line 107: Expected 1 errors
 """
 output = """
@@ -19,5 +15,9 @@ ERROR generics_scoping.py:20:12-38: assert_type(str, Literal['a']) failed [asser
 ERROR generics_scoping.py:34:10-13: Argument `Literal['a']` is not assignable to parameter `x` with type `int` in function `MyClass.meth_2` [bad-argument-type]
 ERROR generics_scoping.py:50:12-48: assert_type(str, Literal['abc']) failed [assert-type]
 ERROR generics_scoping.py:54:12-50: assert_type(bytes, Literal[b'abc']) failed [assert-type]
+ERROR generics_scoping.py:61:8-15: Type variable `S` is not in scope [invalid-type-var]
+ERROR generics_scoping.py:65:14-21: Type variable `S` is not in scope [invalid-type-var]
 ERROR generics_scoping.py:76:11-20: Redundant type parameter declaration [invalid-type-var]
+ERROR generics_scoping.py:105:14-15: Type variable `T` is not in scope [invalid-type-var]
+ERROR generics_scoping.py:106:14-21: Type variable `T` is not in scope [invalid-type-var]
 """
diff --git a/conformance/results/pyrefly/generics_typevartuple_args.toml b/conformance/results/pyrefly/generics_typevartuple_args.toml
@@ -3,8 +3,8 @@ conformance_automated = "Pass"
 errors_diff = """
 """
 output = """
-ERROR generics_typevartuple_args.py:33:8-19: Unpacked argument `tuple[Literal[0], Literal['']]` is not assignable to parameter `*args` with type `tuple[*@_, Env]` in function `exec_le` [bad-argument-type]
-ERROR generics_typevartuple_args.py:34:8-30: Unpacked argument `tuple[Literal[0], Literal['']]` is not assignable to parameter `*args` with type `tuple[*@_, Env]` in function `exec_le` [bad-argument-type]
+ERROR generics_typevartuple_args.py:33:12-23: Unpacked argument `tuple[Literal[0], Literal['']]` is not assignable to parameter `*args` with type `tuple[*@_, Env]` in function `exec_le` [bad-argument-type]
+ERROR generics_typevartuple_args.py:34:12-34: Unpacked argument `tuple[Literal[0], Literal['']]` is not assignable to parameter `*args` with type `tuple[*@_, Env]` in function `exec_le` [bad-argument-type]
 ERROR generics_typevartuple_args.py:48:6-17: Unpacked argument `tuple[Literal[1], Literal['2'], Literal[3]]` is not assignable to parameter `*args` with type `tuple[int, ...]` in function `func1` [bad-argument-type]
 ERROR generics_typevartuple_args.py:57:6-16: Unpacked argument `tuple[Literal[1], Literal[1], Literal['']]` is not assignable to parameter `*args` with type `tuple[int, *tuple[str, ...], str]` in function `func2` [bad-argument-type]
 ERROR generics_typevartuple_args.py:58:6-9: Unpacked argument `tuple[Literal[1]]` is not assignable to parameter `*args` with type `tuple[int, *tuple[str, ...], str]` in function `func2` [bad-argument-type]
diff --git a/conformance/results/pyrefly/version.toml b/conformance/results/pyrefly/version.toml
@@ -1 +1 @@
-version = "pyrefly 0.53.0"
+version = "pyrefly 0.54.0"
diff --git a/conformance/results/pyright/generics_typevartuple_args.toml b/conformance/results/pyright/generics_typevartuple_args.toml
@@ -1,8 +1,8 @@
 conformant = "Pass"
 output = """
-generics_typevartuple_args.py:33:16 - error: Argument of type "Literal['']" cannot be assigned to parameter of type "Env" in function "exec_le"
+generics_typevartuple_args.py:33:20 - error: Argument of type "Literal['']" cannot be assigned to parameter of type "Env" in function "exec_le"
   "Literal['']" is not assignable to "Env" (reportArgumentType)
-generics_typevartuple_args.py:34:16 - error: Argument of type "Literal['']" cannot be assigned to parameter of type "Env" in function "exec_le"
+generics_typevartuple_args.py:34:20 - error: Argument of type "Literal['']" cannot be assigned to parameter of type "Env" in function "exec_le"
   "Literal['']" is not assignable to "Env" (reportArgumentType)
 generics_typevartuple_args.py:48:10 - error: Argument of type "Literal['2']" cannot be assigned to parameter of type "int" in function "func1"
   "Literal['2']" is not assignable to "int" (reportArgumentType)
diff --git a/conformance/results/results.html b/conformance/results/results.html
@@ -176,9 +176,9 @@ <h3>Python Type System Conformance Test Results</h3>
 </th>
 <th class='tc-header'><div class='tc-name'>pyright 1.1.408</div>
 </th>
-<th class='tc-header'><div class='tc-name'>zuban 0.6.0</div>
+<th class='tc-header'><div class='tc-name'>zuban 0.6.1</div>
 </th>
-<th class='tc-header'><div class='tc-name'>pyrefly 0.53.0</div>
+<th class='tc-header'><div class='tc-name'>pyrefly 0.54.0</div>
 </th>
 </tr>
 <tr><th class="column" colspan="5">
@@ -307,7 +307,7 @@ <h3>Python Type System Conformance Test Results</h3>
 <tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;generics_scoping</th>
 <th class="column col2 conformant">Pass</th>
 <th class="column col2 conformant">Pass</th>
-<th class="column col2 partially-conformant">Partial</th>
+<th class="column col2 conformant">Pass</th>
 <th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Does not implement several scoping checks/restrictions for generics</p></span></div></th>
 </tr>
 <tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;generics_self_advanced</th>
@@ -503,7 +503,7 @@ <h3>Python Type System Conformance Test Results</h3>
 <th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Incorrectly rejects some recursive type aliases using TypeAliasType.</p><p>Incorrectly rejects the use of a class-scoped TypeVar in a TypeAliasType definition.</p></span></div></th>
 <th class="column col2 conformant">Pass</th>
 <th class="column col2 conformant">Pass</th>
-<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Does not detect circular definitions.</p></span></div></th>
+<th class="column col2 conformant">Pass</th>
 </tr>
 <tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;aliases_variance</th>
 <th class="column col2 conformant">Pass</th>
diff --git a/conformance/results/zuban/generics_scoping.toml b/conformance/results/zuban/generics_scoping.toml
@@ -1,13 +1,12 @@
-conformance_automated = "Fail"
-conformant = "Partial"
+conformance_automated = "Pass"
 errors_diff = """
-Lines 15, 16: Expected error (tag 'fun1')
-Lines 19, 20: Expected error (tag 'fun2')
-Lines 49, 50: Expected error (tag 'method-str')
-Lines 53, 54: Expected error (tag 'method-bytes')
 """
 output = """
+generics_scoping.py:15: error: Expression is of type "Literal[1]", not "int"  [misc]
+generics_scoping.py:19: error: Expression is of type "Literal['a']", not "str"  [misc]
 generics_scoping.py:34: error: Argument 1 to "meth_2" of "MyClass" has incompatible type "str"; expected "int"  [arg-type]
+generics_scoping.py:49: error: Expression is of type "Literal['abc']", not "str"  [misc]
+generics_scoping.py:53: error: Expression is of type "Literal[b'abc']", not "bytes"  [misc]
 generics_scoping.py:61: error: Type variable "generics_scoping.S" is unbound  [misc]
 generics_scoping.py:61: note: (Hint: Use "Generic[S]" or "Protocol[S]" base class to bind "S" inside a class)
 generics_scoping.py:61: note: (Hint: Use "S" in function signature to bind "S" inside a function)
diff --git a/conformance/results/zuban/version.toml b/conformance/results/zuban/version.toml
@@ -1 +1 @@
-version = "zuban 0.6.0"
+version = "zuban 0.6.1"
diff --git a/conformance/tests/generics_typevartuple_args.py b/conformance/tests/generics_typevartuple_args.py
@@ -17,9 +17,6 @@ def args_to_tuple(*args: *Ts) -> tuple[*Ts]:
     raise NotImplementedError
 
 
-assert_type(args_to_tuple(1, "a"), tuple[int, str])
-
-
 class Env:
     ...
 
@@ -28,10 +25,13 @@ def exec_le(path: str, *args: * tuple[*Ts, Env], env: Env | None = None) -> tupl
     raise NotImplementedError
 
 
-assert_type(exec_le("", Env()), tuple[()])  # OK
-assert_type(exec_le("", 0, "", Env()), tuple[int, str])  # OK
-exec_le("", 0, "")  # E
-exec_le("", 0, "", env=Env())  # E
+def has_int_and_str(x: int, y: str):
+    assert_type(args_to_tuple(x, y), tuple[int, str])
+
+    assert_type(exec_le("", Env()), tuple[()])  # OK
+    assert_type(exec_le(y, x, y, Env()), tuple[int, str])  # OK
+    exec_le("", 0, "")  # E
+    exec_le("", 0, "", env=Env())  # E
 
 
 # > Using an unpacked unbounded tuple is equivalent to the
diff --git a/conformance/tests/generics_typevartuple_callable.py b/conformance/tests/generics_typevartuple_callable.py
@@ -46,4 +46,5 @@ def func3(*args: * tuple[int, *Ts, T]) -> tuple[T, *Ts]:
     raise NotImplementedError
 
 
-assert_type(func3(1, "", 3j, 3.4), tuple[float, str, complex])
+def has_int_and_str(a: int, b: str, c: float, d: complex):
+    assert_type(func3(a, b, c, d), tuple[float, str, complex])

Original file line number	Diff line number	Diff line change
`@@ -1 +1 @@`
`1`		`-version = "pyrefly 0.53.0"`
	`1`	`+version = "pyrefly 0.54.0"`