[MLIR][Python] use `FetchContent_Declare` for nanobind and remove pybind (#161230)

Inspired by this comment
https://github.com/llvm/llvm-project/pull/157930#issuecomment-3346634290
(and long-standing issues related to finding nanobind/pybind in the
right place), this PR moves to using `FetchContent_Declare` to get the
nanobind dependency. This is pretty standard (see e.g.,
[IREE](https://github.com/iree-org/iree/blob/cf60359b7443b0e92e15fb6ffc011525dc40e772/CMakeLists.txt#L842-L848)).
This PR also removes pybind which has been deprecated for almost a year
(https://github.com/llvm/llvm-project/pull/117922) and which isn't
compatible (for whatever reason) with `FetchContent_Declare`.

---------

Co-authored-by: Jacques Pienaar <jpienaar@google.com>

1 files changed, 0 insertions, 118 deletions

diff --git a/mlir/test/python/lib/PythonTestModulePybind11.cpp b/mlir/test/python/lib/PythonTestModulePybind11.cpp
deleted file mode 100644
index 94a5f5178d16..000000000000
--- a/mlir/test/python/lib/PythonTestModulePybind11.cpp
+++ /dev/null
@@ -1,118 +0,0 @@
-//===- PythonTestModule.cpp - Python extension for the PythonTest dialect -===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-// This is the pybind11 edition of the PythonTest dialect module.
-//===----------------------------------------------------------------------===//
-
-#include "PythonTestCAPI.h"
-#include "mlir-c/BuiltinAttributes.h"
-#include "mlir-c/BuiltinTypes.h"
-#include "mlir-c/IR.h"
-#include "mlir/Bindings/Python/PybindAdaptors.h"
-
-namespace py = pybind11;
-using namespace mlir::python::adaptors;
-using namespace pybind11::literals;
-
-static bool mlirTypeIsARankedIntegerTensor(MlirType t) {
-  return mlirTypeIsARankedTensor(t) &&
-         mlirTypeIsAInteger(mlirShapedTypeGetElementType(t));
-}
-
-PYBIND11_MODULE(_mlirPythonTestPybind11, m) {
-  m.def(
-      "register_python_test_dialect",
-      [](MlirContext context, bool load) {
-        MlirDialectHandle pythonTestDialect =
-            mlirGetDialectHandle__python_test__();
-        mlirDialectHandleRegisterDialect(pythonTestDialect, context);
-        if (load) {
-          mlirDialectHandleLoadDialect(pythonTestDialect, context);
-        }
-      },
-      py::arg("context"), py::arg("load") = true);
-
-  m.def(
-      "register_dialect",
-      [](MlirDialectRegistry registry) {
-        MlirDialectHandle pythonTestDialect =
-            mlirGetDialectHandle__python_test__();
-        mlirDialectHandleInsertDialect(pythonTestDialect, registry);
-      },
-      py::arg("registry"));
-
-  mlir_attribute_subclass(m, "TestAttr",
-                          mlirAttributeIsAPythonTestTestAttribute,
-                          mlirPythonTestTestAttributeGetTypeID)
-      .def_classmethod(
-          "get",
-          [](const py::object &cls, MlirContext ctx) {
-            return cls(mlirPythonTestTestAttributeGet(ctx));
-          },
-          py::arg("cls"), py::arg("context") = py::none());
-
-  mlir_type_subclass(m, "TestType", mlirTypeIsAPythonTestTestType,
-                     mlirPythonTestTestTypeGetTypeID)
-      .def_classmethod(
-          "get",
-          [](const py::object &cls, MlirContext ctx) {
-            return cls(mlirPythonTestTestTypeGet(ctx));
-          },
-          py::arg("cls"), py::arg("context") = py::none());
-
-  auto typeCls =
-      mlir_type_subclass(m, "TestIntegerRankedTensorType",
-                         mlirTypeIsARankedIntegerTensor,
-                         py::module::import(MAKE_MLIR_PYTHON_QUALNAME("ir"))
-                             .attr("RankedTensorType"))
-          .def_classmethod(
-              "get",
-              [](const py::object &cls, std::vector<int64_t> shape,
-                 unsigned width, MlirContext ctx) {
-                MlirAttribute encoding = mlirAttributeGetNull();
-                return cls(mlirRankedTensorTypeGet(
-                    shape.size(), shape.data(), mlirIntegerTypeGet(ctx, width),
-                    encoding));
-              },
-              "cls"_a, "shape"_a, "width"_a, "context"_a = py::none());
-
-  assert(py::hasattr(typeCls.get_class(), "static_typeid") &&
-         "TestIntegerRankedTensorType has no static_typeid");
-
-  MlirTypeID mlirRankedTensorTypeID = mlirRankedTensorTypeGetTypeID();
-
-  py::module::import(MAKE_MLIR_PYTHON_QUALNAME("ir"))
-      .attr(MLIR_PYTHON_CAPI_TYPE_CASTER_REGISTER_ATTR)(mlirRankedTensorTypeID,
-                                                        "replace"_a = true)(
-          pybind11::cpp_function([typeCls](const py::object &mlirType) {
-            return typeCls.get_class()(mlirType);
-          }));
-
-  auto valueCls = mlir_value_subclass(m, "TestTensorValue",
-                                      mlirTypeIsAPythonTestTestTensorValue)
-                      .def("is_null", [](MlirValue &self) {
-                        return mlirValueIsNull(self);
-                      });
-
-  py::module::import(MAKE_MLIR_PYTHON_QUALNAME("ir"))
-      .attr(MLIR_PYTHON_CAPI_VALUE_CASTER_REGISTER_ATTR)(
-          mlirRankedTensorTypeID)(
-          pybind11::cpp_function([valueCls](const py::object &valueObj) {
-            py::object capsule = mlirApiObjectToCapsule(valueObj);
-            MlirValue v = mlirPythonCapsuleToValue(capsule.ptr());
-            MlirType t = mlirValueGetType(v);
-            // This is hyper-specific in order to exercise/test registering a
-            // value caster from cpp (but only for a single test case; see
-            // testTensorValue python_test.py).
-            if (mlirShapedTypeHasStaticShape(t) &&
-                mlirShapedTypeGetDimSize(t, 0) == 1 &&
-                mlirShapedTypeGetDimSize(t, 1) == 2 &&
-                mlirShapedTypeGetDimSize(t, 2) == 3)
-              return valueCls.get_class()(valueObj);
-            return valueObj;
-          }));
-}