[GR-15191] Make StringIO available by default because RubyGems requires it.

PullRequest: truffleruby/859

Author: eregon

CHANGELOG.md

@@ -21,6 +21,7 @@ Compatibility
 * `Hash#merge` now preserves the key order from the original hash for merged values (#1650).
 * Coerce values given to `FFI::Pointer` methods.
 * `FrozenError` is now defined and is used for `can't modify frozen` object exceptions.
+* `StringIO` is now available by default like in MRI, because it is required by RubyGems.
 
 Changes:
 

lib/truffle/truffle/lazy-rubygems.rb

@@ -38,6 +38,9 @@ class Object
       autoload :RbConfig, 'rbconfig'
       # Defined by RbConfig
       autoload :CROSS_COMPILING, 'rbconfig'
+
+      # StringIO is required by RubyGems
+      autoload :StringIO, 'stringio'
     end
   end
 end

spec/tags/truffle/lazy_rubygems_tags.txt

@@ -1,3 +1,4 @@
 slow:RubyGems is not loaded until needed
 slow:RubyGems is loaded when accessing Gem
 slow:RubyGems is loaded by a failing require
+slow:Lazy RubyGems defines StringIO like RubyGems which requires it eagerly

spec/truffle/lazy_rubygems_spec.rb

@@ -26,3 +26,10 @@
     $?.success?.should == true
   end
 end
+
+describe "Lazy RubyGems" do
+  # See https://github.com/rubygems/rubygems/issues/2772
+  it "defines StringIO like RubyGems which requires it eagerly" do
+    ruby_exe('puts StringIO').should == "StringIO\n"
+  end
+end