Added `--platform` option to `build` command

2 files changed, 9 insertions, 0 deletions

diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index decdca06bb..eaf8573d8f 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -1,11 +1,16 @@
 # frozen_string_literal: true
 require 'rubygems/command'
 require 'rubygems/package'
+require 'rubygems/version_option'
 
 class Gem::Commands::BuildCommand < Gem::Command
+  include Gem::VersionOption
+
   def initialize
     super 'build', 'Build a gem from a gemspec'
 
+    add_platform_option
+
     add_option '--force', 'skip validation of the spec' do |value, options|
       options[:force] = true
     end
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index 883cad35f9..dc93adb5ab 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -1991,6 +1991,10 @@ class Gem::Specification < Gem::BasicSpecification
     self.name = name if name
     self.version = version if version
 
+    if platform = Gem.platforms.last and platform != Gem::Platform::RUBY and platform != Gem::Platform.local
+      self.platform = platform
+    end
+
     yield self if block_given?
   end