From 31d0d7e37b4c63dcd3627ca6ba4dda3055bf2870 Mon Sep 17 00:00:00 2001
From: Zhongpeng Lin <zplin@uber.com>
Date: Wed, 2 Mar 2022 09:34:22 -0800
Subject: [PATCH] Added support for Apple Silicon (#272)

* Added support for Apple Sillicon

* support arm64 for released versions only

* Printing out Bazel version

* Checking operation system

* Fixed tests for darwin arm64

* Address comments
---
 bazelisk.py      | 35 ++++++++++++++++++++++++++++++-----
 bazelisk_test.sh | 12 ++++++------
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/bazelisk.py b/bazelisk.py
index b6fab96e..08c5929e 100755
--- a/bazelisk.py
+++ b/bazelisk.py
@@ -206,16 +206,16 @@ def determine_executable_filename_suffix():
 
 
 def determine_bazel_filename(version):
+    operating_system = get_operating_system()
+    supported_machines = get_supported_machine_archs(version, operating_system)
     machine = normalized_machine_arch_name()
-    if machine != "x86_64":
+    if machine not in supported_machines:
         raise Exception(
-            'Unsupported machine architecture "{}". Bazel currently only supports x86_64.'.format(
-                machine
+            'Unsupported machine architecture "{}". Bazel {} only supports {} on {}.'.format(
+                machine, version, ", ".join(supported_machines), operating_system.capitalize()
             )
         )
 
-    operating_system = get_operating_system()
-
     filename_suffix = determine_executable_filename_suffix()
     bazel_flavor = "bazel"
     if os.environ.get("BAZELISK_NOJDK", "0") != "0":
@@ -223,6 +223,31 @@ def determine_bazel_filename(version):
     return "{}-{}-{}-{}{}".format(bazel_flavor, version, operating_system, machine, filename_suffix)
 
 
+def get_supported_machine_archs(version, operating_system):
+    supported_machines = ["x86_64"]
+    versions = version.split(".")[:2]
+    if len(versions) == 2:
+        # released version
+        major, minor = int(versions[0]), int(versions[1])
+        if (
+            operating_system == "darwin"
+            and (major > 4 or major == 4 and minor >= 1)
+            or operating_system == "linux"
+            and (major > 3 or major == 3 and minor >= 4)
+        ):
+            # Linux arm64 was supported since 3.4.0.
+            # Darwin arm64 was supported since 4.1.0.
+            supported_machines.append("arm64")
+    elif operating_system in ("darwin", "linux"):
+        # This is needed to run bazelisk_test.sh on Linux and Darwin arm64 machines, which are
+        # becoming more and more popular.
+        # It works because all recent commits of Bazel support arm64 on Darwin and Linux.
+        # However, this would add arm64 by mistake if the commit is too old, which should be
+        # a rare scenario.
+        supported_machines.append("arm64")
+    return supported_machines
+
+
 def normalized_machine_arch_name():
     machine = platform.machine().lower()
     if machine == "amd64":
diff --git a/bazelisk_test.sh b/bazelisk_test.sh
index 9002979e..09733bab 100755
--- a/bazelisk_test.sh
+++ b/bazelisk_test.sh
@@ -108,12 +108,12 @@ function test_bazel_version_go() {
 function test_bazel_version_from_environment() {
   setup
 
-  USE_BAZEL_VERSION="0.20.0" \
+  USE_BAZEL_VERSION="5.0.0" \
       BAZELISK_HOME="$BAZELISK_HOME" \
       bazelisk version 2>&1 | tee log
 
-  grep "Build label: 0.20.0" log || \
-      (echo "FAIL: Expected to find 'Build label: 0.20.0' in the output of 'bazelisk version'"; exit 1)
+  grep "Build label: 5.0.0" log || \
+      (echo "FAIL: Expected to find 'Build label: 5.0.0' in the output of 'bazelisk version'"; exit 1)
 }
 
 function test_bazel_version_prefer_environment_to_bazeliskrc() {
@@ -157,13 +157,13 @@ function test_bazel_version_prefer_bazeliskrc_to_bazelversion_file() {
 function test_bazel_version_from_file() {
   setup
 
-  echo "0.19.0" > .bazelversion
+  echo "5.0.0" > .bazelversion
 
   BAZELISK_HOME="$BAZELISK_HOME" \
       bazelisk version 2>&1 | tee log
 
-  grep "Build label: 0.19.0" log || \
-      (echo "FAIL: Expected to find 'Build label: 0.19.0' in the output of 'bazelisk version'"; exit 1)
+  grep "Build label: 5.0.0" log || \
+      (echo "FAIL: Expected to find 'Build label: 5.0.0' in the output of 'bazelisk version'"; exit 1)
 }
 
 function test_bazel_version_from_url() {