[ruby/set] Expose Set::VERSION

https://github.com/ruby/set/commit/d39b33f463

lib/set.rb

@@ -216,6 +216,9 @@
 #   has been modified while an element in the set.
 #
 class Set
+
+  VERSION = "1.0.3"
+
   include Enumerable
 
   # Creates a new set containing the given objects.

lib/set/set.gemspec

@@ -1,6 +1,13 @@
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
 Gem::Specification.new do |spec|
-  spec.name          = "set"
-  spec.version       = "1.0.3"
+  spec.name          = name
+  spec.version       = version
   spec.authors       = ["Akinori MUSHA"]
   spec.email         = ["knu@idaemons.org"]