Fix type aliases with fixed-length tuples (#14184)

Fix type aliases like these:
```
T = tuple[int, str]
```
Type applications involving fixed-length tuples still don't fully work.
The inferred type is a variable-length tuple when constructing a tuple
using a type application, e.g. `tuple[int, str]((1, ""))`. This seems a
pretty low-priority issue, whereas the type alias use case seems common.

Most of the work was by @sobolevn originally in #12134. I just finished
it up.

Fixes #11098.

mypy/checkexpr.py

@@ -3969,6 +3969,9 @@ def apply_type_arguments_to_callable(
 
         if isinstance(tp, CallableType):
             if len(tp.variables) != len(args):
+                if tp.is_type_obj() and tp.type_object().fullname == "builtins.tuple":
+                    # TODO: Specialize the callable for the type arguments
+                    return tp
                 self.msg.incompatible_type_application(len(tp.variables), len(args), ctx)
                 return AnyType(TypeOfAny.from_error)
             return self.apply_generic_arguments(tp, args, ctx)

test-data/unit/check-type-aliases.test

@@ -993,3 +993,35 @@ x_bad: A[bytes]  # E: Value of type variable "S" of "A" cannot be "bytes"
 B = List[C[U]]
 y: B[int]
 y_bad: B[str]  # E: Type argument "str" of "B" must be a subtype of "int"
+
+[case testTupleWithDifferentArgsPy38]
+# flags: --python-version 3.8
+NotYet1 = tuple[float]  # E: "tuple" is not subscriptable
+NotYet2 = tuple[float, float]  # E: "tuple" is not subscriptable
+NotYet3 = tuple[float, ...]  # E: Unexpected "..." \
+                             # E: "tuple" is not subscriptable
+NotYet4 = tuple[float, float, ...]  # E: Unexpected "..." \
+                                    # E: "tuple" is not subscriptable
+[builtins fixtures/tuple.pyi]
+
+[case testTupleWithDifferentArgsStub]
+# https://github.com/python/mypy/issues/11098
+import tup
+
+[file tup.pyi]
+Correct1 = str | tuple[float, float, str]
+Correct2 = tuple[float] | str
+Correct3 = tuple[float, ...] | str
+Correct4 = tuple[float, str] | str
+Correct5 = tuple[int, str]
+Correct6 = tuple[int, ...]
+
+RHSAlias1: type = tuple[int, int]
+RHSAlias2: type = tuple[int]
+RHSAlias3: type = tuple[int, ...]
+
+# Wrong:
+
+WrongTypeElement = str | tuple[float, 1]  # E: Invalid type: try using Literal[1] instead?
+WrongEllipsis = str | tuple[float, float, ...]  # E: Unexpected "..."
+[builtins fixtures/tuple.pyi]

test-data/unit/pythoneval.test

@@ -1816,3 +1816,45 @@ def foo(k: str) -> TD:
     return x.get(k, {})
 [out]
 _testTypedDictUnionGetFull.py:11: note: Revealed type is "TypedDict('_testTypedDictUnionGetFull.TD', {'x'?: builtins.int, 'y'?: builtins.int})"
+
+[case testTupleWithDifferentArgsPy310]
+# https://github.com/python/mypy/issues/11098
+# flags: --python-version 3.10
+Correct1 = str | tuple[float, float, str]
+Correct2 = tuple[float] | str
+Correct3 = tuple[float, ...] | str
+Correct4 = tuple[float, str]
+Correct5 = tuple[float, ...]
+Correct6 = list[tuple[int, str]]
+c1: Correct1
+c2: Correct2
+c3: Correct3
+c4: Correct4
+c5: Correct5
+c6: Correct6
+reveal_type(c1)
+reveal_type(c2)
+reveal_type(c3)
+reveal_type(c4)
+reveal_type(c5)
+reveal_type(c6)
+
+RHSAlias1: type = tuple[int, int]
+RHSAlias2: type = tuple[int]
+RHSAlias3: type = tuple[int, ...]
+
+WrongTypeElement = str | tuple[float, 1]  # Error
+WrongEllipsis = tuple[float, float, ...] | str  # Error
+
+# TODO: This should produce a fixed-length tuple
+reveal_type(tuple[int, str]((1, "x")))
+[out]
+_testTupleWithDifferentArgsPy310.py:15: note: Revealed type is "Union[builtins.str, Tuple[builtins.float, builtins.float, builtins.str]]"
+_testTupleWithDifferentArgsPy310.py:16: note: Revealed type is "Union[Tuple[builtins.float], builtins.str]"
+_testTupleWithDifferentArgsPy310.py:17: note: Revealed type is "Union[builtins.tuple[builtins.float, ...], builtins.str]"
+_testTupleWithDifferentArgsPy310.py:18: note: Revealed type is "Tuple[builtins.float, builtins.str]"
+_testTupleWithDifferentArgsPy310.py:19: note: Revealed type is "builtins.tuple[builtins.float, ...]"
+_testTupleWithDifferentArgsPy310.py:20: note: Revealed type is "builtins.list[Tuple[builtins.int, builtins.str]]"
+_testTupleWithDifferentArgsPy310.py:26: error: Invalid type: try using Literal[1] instead?
+_testTupleWithDifferentArgsPy310.py:27: error: Unexpected "..."
+_testTupleWithDifferentArgsPy310.py:30: note: Revealed type is "builtins.tuple[builtins.object, ...]"