Problem with case statement and mb_chars in Ruby-1.9.2

RoR-3.0.1

I have this case statement:

  case n.hll_normalize     when "common name"       @my_correspondent.correspondent_common_name = s     when "legal name"       . . .     else       raise ArgumentError, "#{n} attribute is not provided for."   end

hll_normalize is defined as:

  def hll_normalise     strip.squeeze(" ").mb_chars.downcase   end

I pass this case statement this value for n: "common name"

When run with Ruby-1.8.7p302 this works. The exact same code run with Ruby-1.9.2p0 yields:

common name attribute is not provided for. (ArgumentError)

When I enter rails console then I see this:

$ rails c Loading development environment (Rails 3.0.1) ruby-1.9.2-p0 > x = "common name" => "common name" ruby-1.9.2-p0 > x.mb_chars => common name ruby-1.9.2-p0 > x.mb_chars.downcase => common name ruby-1.9.2-p0 > "common name" == x.mb_chars.downcase => true ruby-1.9.2-p0 > "common name" == x.strip.squeeze(" ").mb_chars.downcase => true ruby-1.9.2-p0 > case x.strip.squeeze(" ").mb_chars.downcase ruby-1.9.2-p0 ?> when "uncommon" then puts "nothing" ruby-1.9.2-p0 ?> when "common name" then puts x ruby-1.9.2-p0 ?> end => nil ruby-1.9.2-p0 >

So, what is the case statement sensitive wrt mb_chars that changes the result of "common name" == x.strip.squeeze(" ").mb_chars.downcase when used as an argument? Is there a nil coming back from somewhere in the case statement argument evaluation when mb_chars is involved?

This is definitely related to mb_chars because this works:

ruby-1.9.2-p0 > case x.strip.squeeze(" ").downcase ruby-1.9.2-p0 ?> when "uncommon" then puts "nothing" ruby-1.9.2-p0 ?> when "common name" then puts x ruby-1.9.2-p0 ?> end common name => nil ruby-1.9.2-p0 >