Add extension_linker_flags to Python toolchain

Summary:
Add a new `extension_linker_flags` to the Python toolchain, which
allows specifying linker flags that only affect native extensions (e.g.
`cxx_python_extension`).

Reviewed By: Yingquan-Y

Differential Revision: D62672175

fbshipit-source-id: 5dee8200d99f294be4b53b6e7760fb26244cc4ab

prelude/python/cxx_python_extension.bzl

@@ -60,7 +60,7 @@ load(
 )
 load("@prelude//linking:types.bzl", "Linkage")
 load("@prelude//os_lookup:defs.bzl", "OsLookup")
-load("@prelude//python:toolchain.bzl", "PythonPlatformInfo", "get_platform_attr")
+load("@prelude//python:toolchain.bzl", "PythonPlatformInfo", "PythonToolchainInfo", "get_platform_attr")
 load("@prelude//unix:providers.bzl", "UnixEnv", "create_unix_env_info")
 load("@prelude//utils:expect.bzl", "expect")
 load("@prelude//utils:utils.bzl", "value_or")
@@ -110,6 +110,8 @@ def cxx_python_extension_impl(ctx: AnalysisContext) -> list[Provider]:
         preprocessor_for_tests = False,
     )
 
+    python_toolchain = ctx.attrs._python_toolchain[PythonToolchainInfo]
+
     impl_params = CxxRuleConstructorParams(
         build_empty_so = True,
         rule_type = "cxx_python_extension",
@@ -122,6 +124,7 @@ def cxx_python_extension_impl(ctx: AnalysisContext) -> list[Provider]:
         compiler_flags = ctx.attrs.compiler_flags,
         lang_compiler_flags = ctx.attrs.lang_compiler_flags,
         platform_compiler_flags = ctx.attrs.platform_compiler_flags,
+        extra_link_flags = python_toolchain.extension_linker_flags,
         lang_platform_compiler_flags = ctx.attrs.lang_platform_compiler_flags,
         preprocessor_flags = ctx.attrs.preprocessor_flags,
         lang_preprocessor_flags = ctx.attrs.lang_preprocessor_flags,

prelude/python/python_wheel.bzl

@@ -35,6 +35,7 @@ load(
 )
 load("@prelude//python:manifest.bzl", "create_manifest_for_entries")
 load("@prelude//python:python.bzl", "PythonLibraryInfo")
+load("@prelude//python:toolchain.bzl", "PythonToolchainInfo")
 load("@prelude//utils:expect.bzl", "expect")
 load(
     "@prelude//utils:graph_utils.bzl",
@@ -112,6 +113,7 @@ def _impl(ctx: AnalysisContext) -> list[Provider]:
             expect(not manifests.resources[1])
             srcs.append(manifests.resources[0])
         if manifests.extensions != None:
+            python_toolchain = ctx.attrs._python_toolchain[PythonToolchainInfo]
             toolchain_info = get_cxx_toolchain_info(ctx)
             items = manifests.extensions.items()
             expect(len(items) == 1)
@@ -148,7 +150,10 @@ def _impl(ctx: AnalysisContext) -> list[Provider]:
                 ctx = ctx,
                 output = extension,
                 opts = link_options(
-                    links = [LinkArgs(infos = inputs)],
+                    links = [
+                        LinkArgs(flags = python_toolchain.extension_linker_flags),
+                        LinkArgs(infos = inputs),
+                    ],
                     category_suffix = "native_extension",
                     identifier = extension,
                     link_execution_preference = LinkExecutionPreference("any"),
@@ -222,5 +227,6 @@ python_wheel = rule(
         prefer_stripped_objects = attrs.default_only(attrs.bool(default = False)),
         _wheel = attrs.default_only(attrs.exec_dep(default = "prelude//python/tools:wheel")),
         _cxx_toolchain = toolchains_common.cxx(),
+        _python_toolchain = toolchains_common.python(),
     ),
 )

prelude/python/toolchain.bzl

@@ -56,6 +56,7 @@ PythonToolchainInfo = provider(
         "native_link_strategy": provider_field(typing.Any, default = None),
         "linker_flags": provider_field(typing.Any, default = None),
         "binary_linker_flags": provider_field(typing.Any, default = None),
+        "extension_linker_flags": provider_field(typing.Any, default = None),
         "generate_static_extension_info": provider_field(typing.Any, default = None),
         "parse_imports": provider_field(typing.Any, default = None),
         "traverse_dep_manifest": provider_field(typing.Any, default = None),