[torchgen] Introduce Executorch types and signatures (pytorch#90591)

Retry of pytorch#89595. Accidentally closed.

## Forked `BaseCppType`

Created a module for Executorch: `torchgen.executorch`.

In `torchgen.executorch.api.types.types`:
* Define `BaseCppType` with `torch::executor` namespace.

In `torchgen.executorch.api.et_cpp`:
* Help generate `NamedCType` for `ExecutorchCppSignature` arguments.

In `torchgen.executorch.api.types.signatures`:
* Define the signature using these types. (`ExecutorchCppSignature`)

In `torchgen.executorch.api.types.__init__`:
* Suppress flake8 error for `import *`.

Differential Revision: [D41501836](https://our.internmc.facebook.com/intern/diff/D41501836/)
Pull Request resolved: pytorch#90591
Approved by: https://github.com/iseeyuan

.flake8

@@ -12,7 +12,11 @@ ignore =
     B007,B008,
     # these ignores are from flake8-comprehensions; please fix!
     C400,C401,C402,C403,C404,C405,C407,C411,C413,C414,C415
-per-file-ignores = __init__.py: F401 torch/utils/cpp_extension.py: B950 torchgen/api/types/__init__.py: F401,F403
+per-file-ignores =
+    __init__.py: F401
+    torch/utils/cpp_extension.py: B950
+    torchgen/api/types/__init__.py: F401,F403
+    torchgen/executorch/api/types/__init__.py: F401,F403
 optional-ascii-coding = True
 exclude =
     ./.git,

tools/test/test_executorch_types.py

@@ -0,0 +1,109 @@
+import unittest
+
+from torchgen import local
+from torchgen.api.types import (
+    BaseCType,
+    ConstRefCType,
+    CType,
+    longT,
+    MutRefCType,
+    NamedCType,
+    OptionalCType,
+    TupleCType,
+    VectorCType,
+    voidT,
+)
+from torchgen.executorch.api.et_cpp import argument_type, return_type, returns_type
+from torchgen.executorch.api.types import ArrayRefCType, scalarT, tensorListT, tensorT
+from torchgen.model import Argument, FunctionSchema, Return
+
+
+class ExecutorchCppTest(unittest.TestCase):
+    """
+    Test torchgen.executorch.api.cpp
+    """
+
+    def _test_argumenttype_type(self, arg_str: str, expected: NamedCType) -> None:
+        arg = Argument.parse(arg_str)
+        self.assertEqual(str(argument_type(arg, binds=arg.name)), str(expected))
+
+    @local.parametrize(
+        use_const_ref_for_mutable_tensors=False, use_ilistref_for_tensor_lists=False
+    )
+    def test_argumenttype_type(self) -> None:
+        data = [
+            ("Tensor self", NamedCType("self", ConstRefCType(BaseCType(tensorT)))),
+            ("Tensor(a!) out", NamedCType("out", MutRefCType(BaseCType(tensorT)))),
+            (
+                "Tensor? opt",
+                NamedCType("opt", ConstRefCType(OptionalCType(BaseCType(tensorT)))),
+            ),
+            ("Scalar scalar", NamedCType("scalar", ConstRefCType(BaseCType(scalarT)))),
+            (
+                "Scalar? scalar",
+                NamedCType("scalar", ConstRefCType(OptionalCType(BaseCType(scalarT)))),
+            ),
+            ("int[] size", NamedCType("size", ArrayRefCType(BaseCType(longT)))),
+            ("int? dim", NamedCType("dim", OptionalCType(BaseCType(longT)))),
+            ("Tensor[] weight", NamedCType("weight", BaseCType(tensorListT))),
+            (
+                "Scalar[] spacing",
+                NamedCType("spacing", ArrayRefCType(ConstRefCType(BaseCType(scalarT)))),
+            ),
+            (
+                "Tensor?[] weight",
+                NamedCType("weight", ArrayRefCType(OptionalCType(BaseCType(tensorT)))),
+            ),
+            (
+                "SymInt[]? output_size",
+                NamedCType(
+                    "output_size", OptionalCType(ArrayRefCType(BaseCType(longT)))
+                ),
+            ),
+            (
+                "int[]? dims",
+                NamedCType("dims", OptionalCType(ArrayRefCType(BaseCType(longT)))),
+            ),
+        ]
+        for d in data:
+            self._test_argumenttype_type(*d)
+
+    def _test_returntype_type(self, ret_str: str, expected: CType) -> None:
+        ret = Return.parse(ret_str)
+        self.assertEqual(str(return_type(ret)), str(expected))
+
+    @local.parametrize(
+        use_const_ref_for_mutable_tensors=False, use_ilistref_for_tensor_lists=False
+    )
+    def test_returntype_type(self) -> None:
+        data = [
+            ("Tensor", BaseCType(tensorT)),
+            ("Tensor(a!)", MutRefCType(BaseCType(tensorT))),
+            ("Tensor[]", VectorCType(BaseCType(tensorT))),
+        ]
+        for d in data:
+            self._test_returntype_type(*d)
+
+    @local.parametrize(
+        use_const_ref_for_mutable_tensors=False, use_ilistref_for_tensor_lists=False
+    )
+    def test_returns_type(self) -> None:
+        func = FunctionSchema.parse(
+            "min.dim(Tensor self, int dim, bool keepdim=False) -> (Tensor values, Tensor indices)"
+        )
+        expected = TupleCType([BaseCType(tensorT), BaseCType(tensorT)])
+        self.assertEqual(str(returns_type(func.returns)), str(expected))
+
+    @local.parametrize(
+        use_const_ref_for_mutable_tensors=False, use_ilistref_for_tensor_lists=False
+    )
+    def test_void_return_type(self) -> None:
+        func = FunctionSchema.parse(
+            "_foreach_add_.Scalar(Tensor(a!)[] self, Scalar scalar) -> ()"
+        )
+        expected = BaseCType(voidT)
+        self.assertEqual(str(returns_type(func.returns)), str(expected))
+
+
+if __name__ == "__main__":
+    unittest.main()