[ty] Recurse into tuples and nested tuples when applying special-cased validation of isinstance() and issubclass() (#23607)

## Summary

Refactor the validation logic for `isinstance()` and `issubclass()`
calls to support checking tuples (both literal and non-literal) that
contain invalid types like protocol classes, TypedDicts, `typing.Any`,
and invalid `UnionType` instances.

Previously, validation only worked when these invalid types were passed
directly as the second argument. Now we recursively validate each
element in tuples, enabling detection of errors in cases like:
- `isinstance(obj, (int, SomeProtocol))`
- `isinstance(obj, (int, SomeTypedDict))`
- `isinstance(obj, (int, typing.Any))`
- `isinstance(obj, (int, list[int] | bytes))`

This fixes astral-sh/ty#1600 and improves our
typing conformance score

## Test Plan

mdtests and snapshots extended and updated

Author: AlexWaygood

crates/ty_python_semantic/resources/mdtest/annotations/any.md

@@ -185,8 +185,19 @@ And `Any` cannot be used in `isinstance()` checks:
 isinstance("", Any)
 ```
 
+The same applies when `Any` is nested inside a tuple, including non-literal tuples:
+
+```py
+isinstance("", (int, Any))  # error: [invalid-argument-type]
+isinstance("", (int, (str, Any)))  # error: [invalid-argument-type]
+classes = (int, Any)
+isinstance("", classes)  # error: [invalid-argument-type]
+```
+
 But `issubclass()` checks are fine:
 
 ```py
 issubclass(object, Any)  # no error!
+issubclass(object, (int, Any))  # no error!
+issubclass(object, (int, (str, Any)))  # no error!
 ```

crates/ty_python_semantic/resources/mdtest/call/builtins.md

@@ -164,6 +164,11 @@ isinstance("", t.Callable | t.Deque)
 # `Any` is valid in `issubclass()` calls but not `isinstance()` calls
 issubclass(list, t.Any)
 issubclass(list, t.Any | t.Dict)
+
+# The same works in tuples
+isinstance("", (int, t.Dict))
+isinstance("", (int, t.Callable))
+issubclass(list, (int, t.Any))
 ```
 
 But for other special forms that are not permitted as the second argument, we still emit an error:
@@ -173,6 +178,9 @@ isinstance("", t.TypeGuard)  # error: [invalid-argument-type]
 isinstance("", t.ClassVar)  # error: [invalid-argument-type]
 isinstance("", t.Final)  # error: [invalid-argument-type]
 isinstance("", t.Any)  # error: [invalid-argument-type]
+
+# The same applies when `Any` is nested inside a tuple
+isinstance("", (int, t.Any))  # error: [invalid-argument-type]
 ```
 
 ## The builtin `NotImplemented` constant is not callable

crates/ty_python_semantic/resources/mdtest/narrow/isinstance.md

@@ -128,6 +128,41 @@ def _(x: int | list[int] | bytes):
         reveal_type(x)  # revealed: int | list[int] | bytes
 ```
 
+The same validation also applies when an invalid `UnionType` is nested inside a tuple:
+
+```py
+def _(x: int | list[int] | bytes):
+    # error: [invalid-argument-type]
+    if isinstance(x, (int, list[int] | bytes)):
+        reveal_type(x)  # revealed: int | list[int] | bytes
+    else:
+        reveal_type(x)  # revealed: int | list[int] | bytes
+```
+
+Including nested tuples:
+
+```py
+def _(x: int | list[int] | bytes):
+    # error: [invalid-argument-type]
+    if isinstance(x, (int, (str, list[int] | bytes))):
+        reveal_type(x)  # revealed: int | list[int] | bytes
+    else:
+        reveal_type(x)  # revealed: int | list[int] | bytes
+```
+
+And non-literal tuples:
+
+```py
+classes = (int, list[int] | bytes)
+
+def _(x: int | list[int] | bytes):
+    # error: [invalid-argument-type]
+    if isinstance(x, classes):
+        reveal_type(x)  # revealed: int | list[int] | bytes
+    else:
+        reveal_type(x)  # revealed: int | list[int] | bytes
+```
+
 ## PEP-604 unions on Python \<3.10
 
 PEP-604 unions were added in Python 3.10, so attempting to use them on Python 3.9 does not lead to
@@ -312,6 +347,15 @@ def _(flag: bool):
         reveal_type(x)  # revealed: Literal[1, "a"]
 ```
 
+## Splatted calls with invalid `classinfo`
+
+Diagnostics are still emitted for invalid `classinfo` types when the arguments are splatted:
+
+```py
+args = (object(), int | list[str])
+isinstance(*args)  # error: [invalid-argument-type]
+```
+
 ## Generic aliases are not supported as second argument
 
 The `classinfo` argument cannot be a generic alias:

crates/ty_python_semantic/resources/mdtest/narrow/issubclass.md

@@ -181,6 +181,41 @@ def _(x: type[int | list | bytes]):
         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
 ```
 
+The same validation also applies when an invalid `UnionType` is nested inside a tuple:
+
+```py
+def _(x: type[int | list | bytes]):
+    # error: [invalid-argument-type]
+    if issubclass(x, (int, list[int] | bytes)):
+        reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+    else:
+        reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+```
+
+Including nested tuples:
+
+```py
+def _(x: type[int | list | bytes]):
+    # error: [invalid-argument-type]
+    if issubclass(x, (int, (str, list[int] | bytes))):
+        reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+    else:
+        reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+```
+
+And non-literal tuples:
+
+```py
+classes = (int, list[int] | bytes)
+
+def _(x: type[int | list | bytes]):
+    # error: [invalid-argument-type]
+    if issubclass(x, classes):
+        reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+    else:
+        reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+```
+
 ## PEP-604 unions on Python \<3.10
 
 PEP-604 unions were added in Python 3.10, so attempting to use them on Python 3.9 does not lead to

crates/ty_python_semantic/resources/mdtest/protocols.md

@@ -2601,6 +2601,41 @@ def f(arg1: type):
         reveal_type(arg1)  # revealed: type & ~type[OnlyClassmethodMembers]
 ```
 
+The same diagnostics are also emitted when protocol classes appear inside a tuple passed as the
+second argument to `isinstance()` or `issubclass()`:
+
+```py
+def g(arg: object, arg2: type):
+    isinstance(arg, (HasX, RuntimeCheckableHasX))  # error: [isinstance-against-protocol]
+    isinstance(arg, (HasX, int))  # error: [isinstance-against-protocol]
+
+    # error: [isinstance-against-protocol]
+    # error: [isinstance-against-protocol]
+    issubclass(arg2, (HasX, RuntimeCheckableHasX))
+
+    issubclass(arg2, (HasX, OnlyMethodMembers))  # error: [isinstance-against-protocol]
+```
+
+This includes nested tuples:
+
+```py
+def g2(arg: object, arg2: type):
+    isinstance(arg, (int, (HasX, str)))  # error: [isinstance-against-protocol]
+
+    # error: [isinstance-against-protocol]
+    # error: [isinstance-against-protocol]
+    issubclass(arg2, (int, (HasX, RuntimeCheckableHasX)))
+```
+
+This also works when the tuple is not a literal in the source:
+
+```py
+classes = (HasX, int)
+
+def h(arg: object):
+    isinstance(arg, classes)  # error: [isinstance-against-protocol]
+```
+
 ## Match class patterns and protocols
 
 <!-- snapshot-diagnostics -->
@@ -3049,11 +3084,13 @@ static_assert(not is_disjoint_from(Proto, Nominal))
 This snippet caused us to panic on an early version of the implementation for protocols.
 
 ```py
-from typing import Protocol
+from typing import Protocol, runtime_checkable
 
+@runtime_checkable
 class A(Protocol):
     def x(self) -> "B | A": ...
 
+@runtime_checkable
 class B(Protocol):
     def y(self): ...
 

crates/ty_python_semantic/resources/mdtest/snapshots/isinstance.md_-_Narrowing_for_`isins…_-_`classinfo`_is_an_in…_(eeef56c0ef87a30b).snap

@@ -27,6 +27,26 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/narrow/isinstance.md
 12 |         reveal_type(x)  # revealed: int | list[int] | bytes
 13 |     else:
 14 |         reveal_type(x)  # revealed: int | list[int] | bytes
+15 | def _(x: int | list[int] | bytes):
+16 |     # error: [invalid-argument-type]
+17 |     if isinstance(x, (int, list[int] | bytes)):
+18 |         reveal_type(x)  # revealed: int | list[int] | bytes
+19 |     else:
+20 |         reveal_type(x)  # revealed: int | list[int] | bytes
+21 | def _(x: int | list[int] | bytes):
+22 |     # error: [invalid-argument-type]
+23 |     if isinstance(x, (int, (str, list[int] | bytes))):
+24 |         reveal_type(x)  # revealed: int | list[int] | bytes
+25 |     else:
+26 |         reveal_type(x)  # revealed: int | list[int] | bytes
+27 | classes = (int, list[int] | bytes)
+28 | 
+29 | def _(x: int | list[int] | bytes):
+30 |     # error: [invalid-argument-type]
+31 |     if isinstance(x, classes):
+32 |         reveal_type(x)  # revealed: int | list[int] | bytes
+33 |     else:
+34 |         reveal_type(x)  # revealed: int | list[int] | bytes
 ```
 
 # Diagnostics
@@ -87,3 +107,58 @@ info: Element `<special-form 'typing.Any'>` in the union, and 2 more elements, a
 info: rule `invalid-argument-type` is enabled by default
 
 ```
+
+```
+error[invalid-argument-type]: Invalid second argument to `isinstance`
+  --> src/mdtest_snippet.py:17:8
+   |
+15 | def _(x: int | list[int] | bytes):
+16 |     # error: [invalid-argument-type]
+17 |     if isinstance(x, (int, list[int] | bytes)):
+   |        ^^^^^^^^^^^^^^^^^^^^-----------------^^
+   |                            |
+   |                            This `UnionType` instance contains non-class elements
+18 |         reveal_type(x)  # revealed: int | list[int] | bytes
+19 |     else:
+   |
+info: A `UnionType` instance can only be used as the second argument to `isinstance` if all elements are class objects
+info: Element `<class 'list[int]'>` in the union is not a class object
+info: rule `invalid-argument-type` is enabled by default
+
+```
+
+```
+error[invalid-argument-type]: Invalid second argument to `isinstance`
+  --> src/mdtest_snippet.py:23:8
+   |
+21 | def _(x: int | list[int] | bytes):
+22 |     # error: [invalid-argument-type]
+23 |     if isinstance(x, (int, (str, list[int] | bytes))):
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------^^^
+   |                                  |
+   |                                  This `UnionType` instance contains non-class elements
+24 |         reveal_type(x)  # revealed: int | list[int] | bytes
+25 |     else:
+   |
+info: A `UnionType` instance can only be used as the second argument to `isinstance` if all elements are class objects
+info: Element `<class 'list[int]'>` in the union is not a class object
+info: rule `invalid-argument-type` is enabled by default
+
+```
+
+```
+error[invalid-argument-type]: Invalid second argument to `isinstance`
+  --> src/mdtest_snippet.py:31:8
+   |
+29 | def _(x: int | list[int] | bytes):
+30 |     # error: [invalid-argument-type]
+31 |     if isinstance(x, classes):
+   |        ^^^^^^^^^^^^^^^^^^^^^^
+32 |         reveal_type(x)  # revealed: int | list[int] | bytes
+33 |     else:
+   |
+info: A `UnionType` instance can only be used as the second argument to `isinstance` if all elements are class objects
+info: Element `<class 'list[int]'>` in the union `list[int] | bytes` is not a class object
+info: rule `invalid-argument-type` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/issubclass.md_-_Narrowing_for_`issub…_-_`classinfo`_is_an_in…_(7bb66a0f412caac1).snap

@@ -13,12 +13,32 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/narrow/issubclass.md
 ## mdtest_snippet.py
 
 ```
-1 | def _(x: type[int | list | bytes]):
-2 |     # error: [invalid-argument-type]
-3 |     if issubclass(x, int | list[int]):
-4 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
-5 |     else:
-6 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+ 1 | def _(x: type[int | list | bytes]):
+ 2 |     # error: [invalid-argument-type]
+ 3 |     if issubclass(x, int | list[int]):
+ 4 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+ 5 |     else:
+ 6 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+ 7 | def _(x: type[int | list | bytes]):
+ 8 |     # error: [invalid-argument-type]
+ 9 |     if issubclass(x, (int, list[int] | bytes)):
+10 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+11 |     else:
+12 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+13 | def _(x: type[int | list | bytes]):
+14 |     # error: [invalid-argument-type]
+15 |     if issubclass(x, (int, (str, list[int] | bytes))):
+16 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+17 |     else:
+18 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+19 | classes = (int, list[int] | bytes)
+20 | 
+21 | def _(x: type[int | list | bytes]):
+22 |     # error: [invalid-argument-type]
+23 |     if issubclass(x, classes):
+24 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+25 |     else:
+26 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
 ```
 
 # Diagnostics
@@ -41,3 +61,58 @@ info: Element `<class 'list[int]'>` in the union is not a class object
 info: rule `invalid-argument-type` is enabled by default
 
 ```
+
+```
+error[invalid-argument-type]: Invalid second argument to `issubclass`
+  --> src/mdtest_snippet.py:9:8
+   |
+ 7 | def _(x: type[int | list | bytes]):
+ 8 |     # error: [invalid-argument-type]
+ 9 |     if issubclass(x, (int, list[int] | bytes)):
+   |        ^^^^^^^^^^^^^^^^^^^^-----------------^^
+   |                            |
+   |                            This `UnionType` instance contains non-class elements
+10 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+11 |     else:
+   |
+info: A `UnionType` instance can only be used as the second argument to `issubclass` if all elements are class objects
+info: Element `<class 'list[int]'>` in the union is not a class object
+info: rule `invalid-argument-type` is enabled by default
+
+```
+
+```
+error[invalid-argument-type]: Invalid second argument to `issubclass`
+  --> src/mdtest_snippet.py:15:8
+   |
+13 | def _(x: type[int | list | bytes]):
+14 |     # error: [invalid-argument-type]
+15 |     if issubclass(x, (int, (str, list[int] | bytes))):
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------^^^
+   |                                  |
+   |                                  This `UnionType` instance contains non-class elements
+16 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+17 |     else:
+   |
+info: A `UnionType` instance can only be used as the second argument to `issubclass` if all elements are class objects
+info: Element `<class 'list[int]'>` in the union is not a class object
+info: rule `invalid-argument-type` is enabled by default
+
+```
+
+```
+error[invalid-argument-type]: Invalid second argument to `issubclass`
+  --> src/mdtest_snippet.py:23:8
+   |
+21 | def _(x: type[int | list | bytes]):
+22 |     # error: [invalid-argument-type]
+23 |     if issubclass(x, classes):
+   |        ^^^^^^^^^^^^^^^^^^^^^^
+24 |         reveal_type(x)  # revealed: type[int | list[Unknown] | bytes]
+25 |     else:
+   |
+info: A `UnionType` instance can only be used as the second argument to `issubclass` if all elements are class objects
+info: Element `<class 'list[int]'>` in the union `list[int] | bytes` is not a class object
+info: rule `invalid-argument-type` is enabled by default
+
+```