Merge pull request #2080 from tweag/cg/support_macos_arm64

chore: support arm64 on MacOS

haskell/ghc_bindist.bzl

@@ -18,6 +18,7 @@ load(
     "resolve_labels",
 )
 load("//haskell:ghc.bzl", "DEFAULT_GHC_VERSION")
+load(":private/bazel_platforms.bzl", "bazel_platforms")
 
 _GHC_DEFAULT_VERSION = DEFAULT_GHC_VERSION
 
@@ -567,7 +568,7 @@ def haskell_register_ghc_bindists(
         configure_python3_toolchain(name = LOCAL_PYTHON_REPO_NAME, register = register)
 
 def _configure_python3_toolchain_impl(repository_ctx):
-    cpu = get_cpu_value(repository_ctx)
+    os_cpu = get_cpu_value(repository_ctx)
     python3_path = find_python(repository_ctx)
     if check_bazel_version("4.2.0")[0]:
         stub_shebang = """stub_shebang = "#!{python3_path}",""".format(
@@ -595,20 +596,18 @@ toolchain(
     toolchain = ":py_runtime_pair",
     toolchain_type = "@bazel_tools//tools/python:toolchain_type",
     exec_compatible_with = [
-        "@platforms//cpu:x86_64",
+        "@platforms//cpu:{cpu}",
         "@platforms//os:{os}",
     ],
     target_compatible_with = [
-        "@platforms//cpu:x86_64",
+        "@platforms//cpu:{cpu}",
         "@platforms//os:{os}",
     ],
 )
 """.format(
         python3 = python3_path,
-        os = {
-            "darwin": "osx",
-            "x64_windows": "windows",
-        }.get(cpu, "linux"),
+        os = bazel_platforms.get_os(os_cpu),
+        cpu = bazel_platforms.get_cpu(os_cpu),
         stub_shebang = stub_shebang,
     ))
 

haskell/private/bazel_platforms.bzl

@@ -0,0 +1,32 @@
+"""Module for managing/deriving official Bazel platform values."""
+
+# The expected values for os_cpu can be found by looking at the
+# implementation for get_cpu_value in lib_cc_configure.bzl.
+# https://github.com/bazelbuild/bazel/blob/e11506feaea7401c3d27f55b47183ef49bd1d5a8/tools/cpp/lib_cc_configure.bzl#L186
+
+def _get_os(os_cpu):
+    if os_cpu.find("darwin") >= 0:
+        return "osx"
+    if os_cpu.find("windows") >= 0:
+        return "windows"
+    return "linux"
+
+def _get_cpu(os_cpu):
+    # This value could appear in older versions of Bazel.
+    if os_cpu == "darwin":
+        return "x86_64"
+
+    # This handles modern os-cpu values like darwin_arm64 or darwin_x86_64.
+    if os_cpu.startswith("darwin_"):
+        return os_cpu.removeprefix("darwin_")
+    if os_cpu == "arm64_windows":
+        return "arm64"
+    if os_cpu == "x64_windows":
+        return "x86_64"
+
+    return "x86_64"
+
+bazel_platforms = struct(
+    get_os = _get_os,
+    get_cpu = _get_cpu,
+)

tests/haskell_tests/BUILD.bazel

@@ -0,0 +1,3 @@
+load(":bazel_platforms_tests.bzl", "bazel_platforms_test_suite")
+
+bazel_platforms_test_suite()

tests/haskell_tests/bazel_platforms_tests.bzl

@@ -0,0 +1,97 @@
+"""Tests for `bazel_platforms` module."""
+
+load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest")
+load("//haskell:private/bazel_platforms.bzl", "bazel_platforms")
+
+def _get_os_test(ctx):
+    env = unittest.begin(ctx)
+
+    tests = [
+        struct(
+            msg = "darwin (legacy MacOS on x86_64)",
+            os_cpu = "darwin",
+            exp = "osx",
+        ),
+        struct(
+            os_cpu = "darwin_x86_64",
+            exp = "osx",
+        ),
+        struct(
+            os_cpu = "darwin_arm64",
+            exp = "osx",
+        ),
+        struct(
+            os_cpu = "arm64_windows",
+            exp = "windows",
+        ),
+        struct(
+            os_cpu = "x64_windows",
+            exp = "windows",
+        ),
+        struct(
+            os_cpu = "freebsd",
+            exp = "linux",
+        ),
+        struct(
+            os_cpu = "openbsd",
+            exp = "linux",
+        ),
+    ]
+    for t in tests:
+        actual = bazel_platforms.get_os(t.os_cpu)
+        msg = getattr(t, "msg", t.os_cpu)
+        asserts.equals(env, t.exp, actual, msg)
+
+    return unittest.end(env)
+
+get_os_test = unittest.make(_get_os_test)
+
+def _get_cpu_test(ctx):
+    env = unittest.begin(ctx)
+
+    tests = [
+        struct(
+            msg = "darwin (legacy MacOS on x86_64)",
+            os_cpu = "darwin",
+            exp = "x86_64",
+        ),
+        struct(
+            os_cpu = "darwin_x86_64",
+            exp = "x86_64",
+        ),
+        struct(
+            os_cpu = "darwin_arm64",
+            exp = "arm64",
+        ),
+        struct(
+            os_cpu = "arm64_windows",
+            exp = "arm64",
+        ),
+        struct(
+            os_cpu = "x64_windows",
+            exp = "x86_64",
+        ),
+        struct(
+            os_cpu = "freebsd",
+            exp = "x86_64",
+        ),
+        struct(
+            os_cpu = "openbsd",
+            exp = "x86_64",
+        ),
+    ]
+    for t in tests:
+        actual = bazel_platforms.get_cpu(t.os_cpu)
+        msg = getattr(t, "msg", t.os_cpu)
+        asserts.equals(env, t.exp, actual, msg)
+
+    return unittest.end(env)
+
+get_cpu_test = unittest.make(_get_cpu_test)
+
+def bazel_platforms_test_suite(name = "bazel_platforms_tests"):
+    return unittest.suite(
+        name,
+        get_os_test,
+        get_cpu_test,
+    )

tools/os_info.bzl

@@ -16,6 +16,7 @@ def _os_info_impl(repository_ctx):
         "aarch64",
         "darwin",
         "darwin_arm64",
+        "darwin_x86_64",
         "k8",
         "x64_windows",
     ]