feat: new mypyc primitive for weakref.ref (#19099)

This PR adds a new mypyc primitive for `weakref.ref`

I wasn't able to figure out what name mypyc expects for `weakref.proxy`,
so I took that out and will keep that for a separate PR later on. ref is
more commonly used than proxy anyway.

for later, I tried:
- weakref.proxy
- weakref.ProxyType
- weakref.weakproxy

no luck with those

also for later, I'll need to finish #19145 to add a primitive for
`weakref.ref.__call__`

Author: BobTheBuidler

mypyc/primitives/registry.py

@@ -371,4 +371,5 @@ def load_address_op(name: str, type: RType, src: str) -> LoadAddressDescription:
 import mypyc.primitives.list_ops
 import mypyc.primitives.misc_ops
 import mypyc.primitives.str_ops
-import mypyc.primitives.tuple_ops  # noqa: F401
+import mypyc.primitives.tuple_ops
+import mypyc.primitives.weakref_ops  # noqa: F401

mypyc/primitives/weakref_ops.py

@@ -0,0 +1,22 @@
+from mypyc.ir.ops import ERR_MAGIC
+from mypyc.ir.rtypes import object_rprimitive, pointer_rprimitive
+from mypyc.primitives.registry import function_op
+
+# Weakref operations
+
+new_ref_op = function_op(
+    name="weakref.ReferenceType",
+    arg_types=[object_rprimitive],
+    return_type=object_rprimitive,
+    c_function_name="PyWeakref_NewRef",
+    extra_int_constants=[(0, pointer_rprimitive)],
+    error_kind=ERR_MAGIC,
+)
+
+new_ref__with_callback_op = function_op(
+    name="weakref.ReferenceType",
+    arg_types=[object_rprimitive, object_rprimitive],
+    return_type=object_rprimitive,
+    c_function_name="PyWeakref_NewRef",
+    error_kind=ERR_MAGIC,
+)

mypyc/test-data/irbuild-weakref.test

@@ -0,0 +1,51 @@
+[case testWeakrefRef]
+import weakref
+from typing import Any, Callable
+def f(x: object) -> object:
+    return weakref.ref(x)
+
+[out]
+def f(x):
+    x, r0 :: object
+L0:
+    r0 = PyWeakref_NewRef(x, 0)
+    return r0
+
+[case testWeakrefRefCallback]
+import weakref
+from typing import Any, Callable
+def f(x: object, cb: Callable[[object], Any]) -> object:
+    return weakref.ref(x, cb)
+
+[out]
+def f(x, cb):
+    x, cb, r0 :: object
+L0:
+    r0 = PyWeakref_NewRef(x, cb)
+    return r0
+
+[case testFromWeakrefRef]
+from typing import Any, Callable
+from weakref import ref
+def f(x: object) -> object:
+    return ref(x)
+
+[out]
+def f(x):
+    x, r0 :: object
+L0:
+    r0 = PyWeakref_NewRef(x, 0)
+    return r0
+
+[case testFromWeakrefRefCallback]
+from typing import Any, Callable
+from weakref import ref
+def f(x: object, cb: Callable[[object], Any]) -> object:
+    return ref(x, cb)
+
+[out]
+def f(x, cb):
+    x, cb, r0 :: object
+L0:
+    r0 = PyWeakref_NewRef(x, cb)
+    return r0

mypyc/test-data/run-weakref.test

@@ -0,0 +1,30 @@
+# Test cases for weakrefs (compile and run)
+
+[case testWeakrefRef]
+from weakref import ref
+from mypy_extensions import mypyc_attr
+
+@mypyc_attr(native_class=False)
+class Object:
+    """some random weakreffable object"""
+    pass
+
+def test_weakref_ref():
+    obj = Object()
+    r = ref(obj)
+    assert r() is obj
+    obj = None
+    assert r() is None, r()
+
+def test_weakref_ref_with_callback():
+    obj = Object()
+    r = ref(obj, lambda x: x)
+    assert r() is obj
+    obj = None
+    assert r() is None, r()
+
+[file driver.py]
+from native import test_weakref_ref, test_weakref_ref_with_callback
+
+test_weakref_ref()
+test_weakref_ref_with_callback()

mypyc/test/test_irbuild.py

@@ -53,6 +53,7 @@
     "irbuild-constant-fold.test",
     "irbuild-glue-methods.test",
     "irbuild-math.test",
+    "irbuild-weakref.test",
 ]
 
 if sys.version_info >= (3, 10):

mypyc/test/test_run.py

@@ -70,6 +70,7 @@
     "run-singledispatch.test",
     "run-attrs.test",
     "run-signatures.test",
+    "run-weakref.test",
     "run-python37.test",
     "run-python38.test",
 ]

test-data/unit/lib-stub/weakref.pyi

@@ -0,0 +1,11 @@
+from collections.abc import Callable
+from typing import Any, Generic, TypeVar
+from typing_extensions import Self
+
+_T = TypeVar("_T")
+
+class ReferenceType(Generic[_T]):  # "weakref"
+    __callback__: Callable[[Self], Any]
+    def __new__(cls, o: _T, callback: Callable[[Self], Any] | None = ..., /) -> Self: ...
+
+ref = ReferenceType