[build] Remove two constants from python's version.bzl

bindings/pydrake/BUILD.bazel

@@ -510,7 +510,7 @@ install(
         ":pydrake_pyi",
         ":pydrake_typed",
     ],
-    data_dest = "@PYTHON_SITE_PACKAGES@",
+    data_dest = "lib/python@PYTHON_VERSION@/site-packages",
     visibility = ["//visibility:public"],
     deps = get_drake_py_installs(PY_LIBRARIES_WITH_INSTALL) + [
         # These three modules are a special case.

tools/install/install.bzl

@@ -1,4 +1,4 @@
-load("@python//:version.bzl", "PYTHON_SITE_PACKAGES_RELPATH", "PYTHON_VERSION")
+load("@python//:version.bzl", "PYTHON_VERSION")
 load("@rules_license//rules:providers.bzl", "LicenseInfo")
 load("//tools/skylark:cc.bzl", "CcInfo")
 load("//tools/skylark:drake_java.bzl", "MainClassInfo")
@@ -120,13 +120,10 @@ def _install_action(
     else:
         dest = dests
 
-    dest_replacements = (
-        ("@WORKSPACE@", _workspace(ctx)),
-        ("@PYTHON_SITE_PACKAGES@", PYTHON_SITE_PACKAGES_RELPATH),
-    )
-    for old, new in dest_replacements:
-        if old in dest:
-            dest = dest.replace(old, new)
+    if "@WORKSPACE@" in dest:
+        dest = dest.replace("@WORKSPACE@", _workspace(ctx))
+    if "@PYTHON_VERSION@" in dest:
+        dest = dest.replace("@PYTHON_VERSION@", PYTHON_VERSION)
 
     if type(strip_prefixes) == "dict":
         strip_prefix = strip_prefixes.get(
@@ -590,7 +587,9 @@ _install_rule = rule(
         "runtime_strip_prefix": attr.string_list(),
         "java_dest": attr.string(default = "share/java"),
         "java_strip_prefix": attr.string_list(),
-        "py_dest": attr.string(default = "@PYTHON_SITE_PACKAGES@"),
+        "py_dest": attr.string(
+            default = "lib/python@PYTHON_VERSION@/site-packages",
+        ),
         "py_strip_prefix": attr.string_list(),
         "rename": attr.string_dict(),
         "install_tests": attr.label_list(
@@ -636,8 +635,7 @@ Destination paths may include the following placeholders:
 
 * ``@WORKSPACE@``, replaced with ``workspace`` (if specified) or the name of
   the workspace which invokes ``install``.
-* ``@PYTHON_SITE_PACKAGES``, replaced with the Python version-specific path of
-  "site-packages".
+* ``@PYTHON_VERSION@``, replaced with the Python major.minor version.
 
 Note:
     By default, headers and resource files to be installed must be explicitly

tools/install/libdrake/BUILD.bazel

@@ -4,11 +4,7 @@ load(
     "@drake//tools/workspace:cmake_configure_file.bzl",
     "cmake_configure_file",
 )
-load(
-    "@python//:version.bzl",
-    "PYTHON_SITE_PACKAGES_RELPATH",
-    "PYTHON_VERSION",
-)
+load("@python//:version.bzl", "PYTHON_VERSION")
 load(
     "//third_party:com_github_bazelbuild_rules_cc/whole_archive.bzl",
     "cc_whole_archive_library",
@@ -63,7 +59,6 @@ cmake_configure_file(
     atonly = True,
     cmakelists = ["stamp_version.cmake"],
     defines = [
-        "PYTHON_SITE_PACKAGES_RELPATH=" + PYTHON_SITE_PACKAGES_RELPATH,
         "PYTHON_VERSION=" + PYTHON_VERSION,
     ],
 )

tools/install/libdrake/drake-config.cmake.in

@@ -97,7 +97,7 @@ set(${CMAKE_FIND_PACKAGE_NAME}_VERSION_PATCH "@DRAKE_VERSION_PATCH@")
 set(${CMAKE_FIND_PACKAGE_NAME}_VERSION_TWEAK "@DRAKE_VERSION_TWEAK@")
 
 
-set(${CMAKE_FIND_PACKAGE_NAME}_PYTHON_DIR "${${CMAKE_FIND_PACKAGE_NAME}_IMPORT_PREFIX}/@PYTHON_SITE_PACKAGES_RELPATH@")
+set(${CMAKE_FIND_PACKAGE_NAME}_PYTHON_DIR "${${CMAKE_FIND_PACKAGE_NAME}_IMPORT_PREFIX}/lib/python@PYTHON_VERSION@/site-packages")
 # Allow users to easily check Drake's expected CPython version.
 set(${CMAKE_FIND_PACKAGE_NAME}_PYTHON_VERSION "@PYTHON_VERSION@")
 

tools/skylark/pybind.bzl

@@ -1,5 +1,4 @@
 load("@cc//:compiler.bzl", "COMPILER_ID")
-load("@python//:version.bzl", "PYTHON_EXTENSION_SUFFIX")
 load("//tools/install:install.bzl", "install")
 load("//tools/skylark:cc.bzl", "CcInfo", "cc_binary")
 load("//tools/skylark:drake_cc.bzl", "drake_cc_binary", "drake_cc_googletest")
@@ -57,7 +56,7 @@ def pybind_py_library(
 
     # TODO(eric.cousineau): See if we can keep non-`*.so` target name, but
     # output a *.so, so that the target name is similar to what is provided.
-    cc_so_target = cc_so_name + PYTHON_EXTENSION_SUFFIX
+    cc_so_target = cc_so_name + ".so"
 
     # Add C++ shared library.
     cc_binary_rule(
@@ -232,7 +231,7 @@ def get_pybind_package_info(base_package, sub_package = None):
     package_info = _get_package_info(base_package, sub_package)
     return struct(
         py_imports = [package_info.base_path_rel],
-        py_dest = "@PYTHON_SITE_PACKAGES@/{}".format(
+        py_dest = "lib/python@PYTHON_VERSION@/site-packages/{}".format(
             package_info.sub_path_rel,
         ),
     )

tools/workspace/lcm/package.BUILD.bazel

@@ -11,7 +11,6 @@ load(
     "generate_export_header",
 )
 load("@drake//tools/workspace:generate_file.bzl", "generate_file")
-load("@python//:version.bzl", "PYTHON_EXTENSION_SUFFIX")
 
 licenses([
     "notice",  # BSD-3-Clause
@@ -180,7 +179,7 @@ cc_binary(
 )
 
 cc_binary(
-    name = "_lcm" + PYTHON_EXTENSION_SUFFIX,
+    name = "_lcm.so",
     srcs = [
         "lcm-python/module.c",
         "lcm-python/pyeventlog.c",
@@ -230,20 +229,19 @@ generate_file(
     content = """
 import ctypes
 import os.path
-ctypes.cdll.LoadLibrary(os.path.realpath(
-     __path__[0] + '/_lcm{extension_suffix}'))
+ctypes.cdll.LoadLibrary(os.path.realpath(__path__[0] + '/_lcm.so'))
 _filename = __path__[0] + \"/lcm-python/lcm/__init__.py\"
 with open(_filename) as f:
     _code = compile(f.read(), _filename, 'exec')
     exec(_code)
-""".format(extension_suffix = PYTHON_EXTENSION_SUFFIX),
+""",
     visibility = ["//visibility:private"],
 )
 
 py_library(
     name = "lcm-python-upstream",
     srcs = ["lcm-python/lcm/__init__.py"],  # Actual code from upstream.
-    data = [":_lcm" + PYTHON_EXTENSION_SUFFIX],
+    data = [":_lcm.so"],
     visibility = ["//visibility:private"],
 )
 
@@ -305,10 +303,10 @@ install_files(
 install(
     name = "install_python",
     targets = [
-        ":_lcm" + PYTHON_EXTENSION_SUFFIX,
+        ":_lcm.so",
         ":lcm-python-upstream",
     ],
-    library_dest = "@PYTHON_SITE_PACKAGES@/lcm",
+    library_dest = "lib/python@PYTHON_VERSION@/site-packages/lcm",
     py_strip_prefix = ["lcm-python"],
 )
 

tools/workspace/python/repository.bzl

@@ -65,18 +65,6 @@ def _get_python_interpreter(repo_ctx):
     ])]).stdout.strip()
     return (python, version)
 
-def _get_extension_suffix(repo_ctx, python, python_config):
-    """Returns the extension suffix, e.g. ".cpython-310-x86_64-linux-gnu.so" as
-    queried from python_config. Uses `python` only for error reporting.
-    """
-    if which(repo_ctx, python_config) == None:
-        fail(("Cannot find corresponding config executable: {}\n" +
-              "  From interpreter: {}").format(python_config, python))
-    return execute_or_fail(
-        repo_ctx,
-        [python_config, "--extension-suffix"],
-    ).stdout.strip()
-
 # TODO(jwnimmer-tri): Much of the logic for parsing includes and linkopts is
 # the same or similar to that used in pkg_config.bzl and should be refactored
 # and shared instead of being duplicated in both places.
@@ -165,11 +153,9 @@ def _impl(repo_ctx):
     # Set `python` to the the interpreter path specified by our rule attrs,
     # and `version` to its "major.minor" string.
     python, version = _get_python_interpreter(repo_ctx)
-    site_packages_relpath = "lib/python{}/site-packages".format(version)
 
-    # Get extension_suffix, includes, and linkopts from python_config.
+    # Get includes and linkopts from python_config.
     python_config = "{}-config".format(python)
-    extension_suffix = _get_extension_suffix(repo_ctx, python, python_config)
     includes = _get_includes(repo_ctx, python_config)
     linkopts = _get_linkopts(repo_ctx, python_config)
 
@@ -192,17 +178,13 @@ def _impl(repo_ctx):
 # `BUILD.bazel` or `package.BUILD.bazel` files.
 
 PYTHON_BIN_PATH = "{bin_path}"
-PYTHON_EXTENSION_SUFFIX = "{extension_suffix}"
 PYTHON_VERSION = "{version}"
-PYTHON_SITE_PACKAGES_RELPATH = "{site_packages_relpath}"
 PYTHON_INCLUDES = {includes}
 PYTHON_LINKOPTS_EMBEDDED = {linkopts_embedded}
 PYTHON_LINKOPTS_MODULE = {linkopts_module}
 """.format(
         bin_path = bin_path,
-        extension_suffix = extension_suffix,
         version = version,
-        site_packages_relpath = site_packages_relpath,
         includes = includes,
         linkopts_module = linkopts_module,
         linkopts_embedded = linkopts_embedded,
@@ -213,23 +195,21 @@ PYTHON_LINKOPTS_MODULE = {linkopts_module}
         executable = False,
     )
 
-interpreter_path_attrs = {
-    "linux_interpreter_path": attr.string(
-        default = "/usr/bin/python3",
-    ),
-    "macos_interpreter_path": attr.string(
-        # The version listed here should match what's listed in both the root
-        # CMakeLists.txt and doc/_pages/installation.md.
-        default = "{homebrew_prefix}/bin/python3.12",
-    ),
-    "requirements_flavor": attr.string(
-        default = "test",
-        values = ["build", "test"],
-    ),
-}
-
 python_repository = repository_rule(
     _impl,
-    attrs = interpreter_path_attrs,
+    attrs = {
+        "linux_interpreter_path": attr.string(
+            default = "/usr/bin/python3",
+        ),
+        "macos_interpreter_path": attr.string(
+            # The version listed here should match what's listed in both the
+            # root CMakeLists.txt and doc/_pages/installation.md.
+            default = "{homebrew_prefix}/bin/python3.12",
+        ),
+        "requirements_flavor": attr.string(
+            default = "test",
+            values = ["build", "test"],
+        ),
+    },
     configure = True,
 )