diagnostic: add doctor check for CPU arch on Linux

Library/Homebrew/extend/os/linux/diagnostic.rb

@@ -2,6 +2,7 @@
 
 require "tempfile"
 require "utils/shell"
+require "hardware"
 require "os/linux/diagnostic"
 require "os/linux/glibc"
 require "os/linux/kernel"
@@ -13,6 +14,7 @@ def supported_configuration_checks
         %w[
           check_glibc_minimum_version
           check_kernel_minimum_version
+          check_supported_architecture
         ].freeze
       end
 
@@ -71,6 +73,16 @@ def check_umask_not_zero
         EOS
       end
 
+      def check_supported_architecture
+        return if Hardware::CPU.arch == :x86_64
+
+        <<~EOS
+          Your CPU architecture (#{Hardware::CPU.arch}) is not supported. We only support
+          x86_64 CPU architectures. You will be unable to use binary packages (bottles).
+          #{please_create_pull_requests}
+        EOS
+      end
+
       def check_glibc_minimum_version
         return unless OS::Linux::Glibc.below_minimum_version?
 

Library/Homebrew/test/os/linux/diagnostic_spec.rb

@@ -3,6 +3,13 @@
 require "diagnostic"
 
 describe Homebrew::Diagnostic::Checks do
+  specify "#check_supported_architecture" do
+    allow(Hardware::CPU).to receive(:type).and_return(:arm64)
+
+    expect(subject.check_supported_architecture)
+      .to match(/Your CPU architecture .+ is not supported/)
+  end
+
   specify "#check_glibc_minimum_version" do
     allow(OS::Linux::Glibc).to receive(:below_minimum_version?).and_return(true)