Improve pip package build (#5965)

Summary:
Addressing comments in #5961.

* Separate out `executorch-wheel-config.cmake` from `executorch-config.cmake`.
* Hardcode the envrionment variable `SETUPTOOLS_EXT_SUFFIX` in `setup.py`.

Pull Request resolved: #5965

Reviewed By: dbort

Differential Revision: D64017947

Pulled By: larryliu0820

fbshipit-source-id: 0bdff5e2d2ec5873540d1b701595c7a316e84e80

Author: larryliu0820

build/executorch-config.cmake

@@ -1,3 +1,4 @@
+
 # Copyright (c) Meta Platforms, Inc. and affiliates.
 # All rights reserved.
 #

build/executorch-wheel-config.cmake

@@ -0,0 +1,40 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# Config defining how CMake should find ExecuTorch package. CMake will search
+# for this file and find ExecuTorch package if it is installed. Typical usage
+# is:
+#
+# find_package(executorch REQUIRED)
+# -------
+#
+# Finds the ExecuTorch library
+#
+# This will define the following variables:
+#
+#   EXECUTORCH_FOUND        -- True if the system has the ExecuTorch library
+#   EXECUTORCH_INCLUDE_DIRS -- The include directories for ExecuTorch
+#   EXECUTORCH_LIBRARIES    -- Libraries to link against
+#
+cmake_minimum_required(VERSION 3.19)
+
+# Find prebuilt _portable_lib.so. This file should be installed under
+# <site-packages>/executorch/share/cmake
+find_library(_portable_lib_LIBRARY _portable_lib.so PATHS "${CMAKE_CURRENT_LIST_DIR}/../../extension/pybindings/")
+set(EXECUTORCH_LIBRARIES)
+set(EXECUTORCH_FOUND OFF)
+if(_portable_lib_LIBRARY)
+  set(EXECUTORCH_FOUND ON)
+  message(STATUS "ExecuTorch portable library is found at ${_portable_lib_LIBRARY}")
+  list(APPEND EXECUTORCH_LIBRARIES _portable_lib)
+  add_library(_portable_lib STATIC IMPORTED)
+  set(EXECUTORCH_INCLUDE_DIRS ${CMAKE_CURRENT_LIST_DIR}/include)
+  set_target_properties(_portable_lib PROPERTIES
+    IMPORTED_LOCATION "${_portable_lib_LIBRARY}"
+    INTERFACE_INCLUDE_DIRECTORIES "${EXECUTORCH_INCLUDE_DIRS}"
+    CXX_STANDARD 17
+  )
+endif()

build/packaging/env_var_script_linux.sh

@@ -11,10 +11,6 @@
 # Enable pybindings so that users can execute ExecuTorch programs from python.
 export EXECUTORCH_BUILD_PYBIND=1
 
-# Override extension suffix to be ".so", skipping package info such as
-# "cpython-311-x86_64-linux-gnu"
-export SETUPTOOLS_EXT_SUFFIX=".so"
-
 # Ensure that CMAKE_ARGS is defined before referencing it. Defaults to empty
 # if not defined.
 export CMAKE_ARGS="${CMAKE_ARGS:-}"

build/packaging/env_var_script_m1.sh

@@ -11,10 +11,6 @@
 # Enable pybindings so that users can execute ExecuTorch programs from python.
 export EXECUTORCH_BUILD_PYBIND=1
 
-# Override extension suffix to be ".so", skipping package info such as
-# "cpython-311-darwin"
-export SETUPTOOLS_EXT_SUFFIX=".so"
-
 # Ensure that CMAKE_ARGS is defined before referencing it. Defaults to empty
 # if not defined.
 export CMAKE_ARGS="${CMAKE_ARGS:-}"

setup.py

@@ -423,10 +423,10 @@ def run(self):
                 "devtools/bundled_program/schema/scalar_type.fbs",
                 "devtools/bundled_program/serialize/scalar_type.fbs",
             ),
-            # Install executorch-config.cmake to the root of the package.
+            # Install executorch-wheel-config.cmake to pip package.
             (
-                "build/executorch-config.cmake",
-                "executorch-config.cmake",
+                "build/executorch-wheel-config.cmake",
+                "share/cmake/executorch-config.cmake",
             ),
         ]
         for src, dst in src_to_dst:
@@ -668,6 +668,10 @@ def get_ext_modules() -> List[Extension]:
     return ext_modules
 
 
+# Override extension suffix to be ".so", skipping package info such as
+# "cpython-311-darwin"
+os.environ["SETUPTOOLS_EXT_SUFFIX"] = ".so"
+
 setup(
     version=Version.string(),
     # TODO(dbort): Could use py_modules to restrict the set of modules we