1 files changed, 14 insertions, 19 deletions
diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index 6d1a057dfa..2ec8324141 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -1,31 +1,37 @@
 # frozen_string_literal: true
-require_relative '../command'
-require_relative '../package'
-require_relative '../version_option'
+
+require_relative "../command"
+require_relative "../gemspec_helpers"
+require_relative "../package"
+require_relative "../version_option"
 
 class Gem::Commands::BuildCommand < Gem::Command
   include Gem::VersionOption
+  include Gem::GemspecHelpers
 
   def initialize
-    super 'build', 'Build a gem from a gemspec'
+    super "build", "Build a gem from a gemspec"
 
     add_platform_option
 
-    add_option '--force', 'skip validation of the spec' do |value, options|
+    add_option "--force", "skip validation of the spec" do |_value, options|
       options[:force] = true
     end
 
-    add_option '--strict', 'consider warnings as errors when validating the spec' do |value, options|
+    add_option "--strict", "consider warnings as errors when validating the spec" do |_value, options|
       options[:strict] = true
     end
 
-    add_option '-o', '--output FILE', 'output gem with the given filename' do |value, options|
+    add_option "-o", "--output FILE", "output gem with the given filename" do |value, options|
       options[:output] = value
     end
 
-    add_option '-C PATH', 'Run as if gem build was started in <PATH> instead of the current working directory.' do |value, options|
+    add_option "-C PATH", "Run as if gem build was started in <PATH> instead of the current working directory." do |value, options|
       options[:build_path] = value
     end
+    deprecate_option "-C",
+                     version: "4.0",
+                     extra_msg: "-C is a global flag now. Use `gem -C PATH build GEMSPEC_FILE [options]` instead"
   end
 
   def arguments # :nodoc:
@@ -71,17 +77,6 @@ Gems can be saved to a specified filename with the output option:
 
   private
 
-  def find_gemspec(glob = "*.gemspec")
-    gemspecs = Dir.glob(glob).sort
-
-    if gemspecs.size > 1
-      alert_error "Multiple gemspecs found: #{gemspecs}, please specify one"
-      terminate_interaction(1)
-    end
-
-    gemspecs.first
-  end
-
   def build_gem
     gemspec = resolve_gem_name