1 files changed, 35 insertions, 0 deletions
diff --git a/lib/rubygems/errors.rb b/lib/rubygems/errors.rb
new file mode 100644
index 0000000000..950b34d744
--- /dev/null
+++ b/lib/rubygems/errors.rb
@@ -0,0 +1,35 @@
+class Gem::ErrorReason; end
+
+# Generated when trying to lookup a gem to indicate that the gem
+# was found, but that it isn't usable on the current platform.
+#
+# fetch and install read these and report them to the user to aid
+# in figuring out why a gem couldn't be installed.
+#
+class Gem::PlatformMismatch < Gem::ErrorReason
+
+  attr_reader :name
+  attr_reader :version
+  attr_reader :platforms
+
+  def initialize(name, version)
+    @name = name
+    @version = version
+    @platforms = []
+  end
+
+  def add_platform(platform)
+    @platforms << platform
+  end
+
+  def wordy
+    prefix = "Found #{@name} (#{@version})"
+
+    if @platforms.size == 1
+      "#{prefix}, but was for platform #{@platforms[0]}"
+    else
+      "#{prefix}, but was for platforms #{@platforms.join(' ,')}"
+    end
+  end
+
+end