Use RUBY_ENGINE instead of RUBY_PLATFORM

Author: hsbt

bundler/lib/bundler/stub_specification.rb

@@ -40,7 +40,7 @@ def ignored?
 
       # If we share GEM_HOME for all of Ruby platform, the platform specific gem always warn that specification.
       # ex `jruby-launcher` and CRuby
-      if platform == Gem::Platform::RUBY && RUBY_PLATFORM != Gem::Platform::JAVA
+      if platform == Gem::Platform::RUBY && RUBY_ENGINE != 'jruby'
         warn "Source #{source} is ignoring #{self} because it is missing extensions"
       end
 

lib/rubygems/basic_specification.rb

@@ -75,7 +75,7 @@ def contains_requirable_file?(file)
       if platform == Gem::Platform::RUBY || Gem::Platform.local === platform
         # RubyGems warns gem specification of C extensions. But JRuby couldn't
         # rebuild with `gem pristine` command. So, we skip the warning.
-        if RUBY_PLATFORM != "java" # JRuby
+        if RUBY_ENGINE != 'jruby'
           warn "Ignoring #{full_name} because its extensions are not built. " \
               "Try: gem pristine #{name} --version #{version}"
         end

test/rubygems/test_gem.rb

@@ -1308,7 +1308,7 @@ def test_self_try_activate_missing_extensions
       refute Gem.try_activate "nonexistent"
     end
 
-    expected = if RUBY_PLATFORM == "java"
+    expected = if RUBY_ENGINE == 'jruby'
       ""
     else
       "Ignoring ext-1 because its extensions are not built. " \

test/rubygems/test_gem_specification.rb

@@ -1557,7 +1557,7 @@ def test_contains_requirable_file_eh_extension
       refute @ext.contains_requirable_file? "nonexistent"
     end
 
-    expected = if RUBY_PLATFORM == "java"
+    expected = if RUBY_ENGINE == 'jruby'
       ""
     else
       "Ignoring ext-1 because its extensions are not built. " \