iconv deprecation warning with ruby 1.9.3 - ruby-on-rails

Question

I'm getting this warning when I run rspec:
/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `block in require': iconv will be deprecated in the future, use String#encode instead.
I get the same warning with rails 3.1.0, 3.1.1, 3.1.2.rc2 versions. Seems it's related to sqlite3 gem, but I'm not sure. There are no warnings with ruby 1.9.2
Any suggestions how to deal with it?

Answer 1

You are getting this deprecation notice cause a library somewhere is requiring iconv.
iconv is a gem created by Matz that can be used to convert strings from one format to another.
For example this is often used:
Iconv.iconv('UTF-8//IGNORE', 'UTF-8', content) this little bit of magic takes a UTF-8 string that may have invalid chars and converts it to a proper UTF-8 string.
It has been decided that in Ruby 1.9.3 we should not be using iconv any more and instead use the built-in String#encode. encode is more powerful and allows you more flexibility.
The theory is that the above example could be replaced with:
string.encode("UTF-8", :invalid => :replace, :undef => :replace, :replace => "?")
In practice it seems this is imperfect.
This also leads to a less than easy story for gem creators who wish to support 1.8:
content = RUBY_VERSION.to_f < 1.9 ?
Iconv.iconv('UTF-8//IGNORE', 'UTF-8', "content") :
"#{content}".encode(Encoding::UTF_8, :invalid => :replace, :undef => :replace, :replace => '')
So, you have a gem somewhere that is requiring iconv, to find it:
Assuming your error message is: /gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240
Open up /gems/activesupport-3.1.0/lib/active_support/dependencies.rb on line 240:
Add the line:
p caller if file =~ /iconv/
(just after: load_dependency(file) { result = super })
You will get a big fat stack trace:
rake --tasks
/home/sam/.rvm/gems/ruby-1.9.3-p125/gems/activesupport-3.2.6/lib/active_support/dependencies.rb:251:in `block in require': iconv will be deprecated in the future, use String#encode instead.
["/home/sam/.rvm/gems/ruby-1.9.3-p125/gems/calais-0.0.13/lib/calais.rb:5:in `'",
.. more omitted ..
This tells me it is the calais gem. Looking through pull requests, I am not the first. The pull has not been yanked in.
Depending on the gem, there may be an upgraded version that does not have this error, so I would recommend you upgrade your gems first. If you are unlucky you may be stuck with the unfortunate task of forking a gem to get rid of this (if for example your pull request to fix it languishes)

Answer 2

If you're seeing this, it's very probably not Rails. If you look at the method surrounding the line being referred to in the error you posted, you'll see the following:
def require(file, *)
result = false
load_dependency(file) { result = super }
result
end
I'm not saying it's your code, necessarily, but I'm certain that it's not actually the line in question where iconv is being called. In my case, I found that my project's code actually contained a reference to iconv.
If you want to check your code for such a reference, try grep -ir iconv ./ in your project directory.
When iconv is actually in a library it can be harder to find. By temporarily changing the above method to:
def require(file, *)
result = false
puts
puts caller.reverse
load_dependency(file) { result = super }
result
end
You can then easily run your code and grep out the relevant lines of the backtrace to find the root cause of the warning.
ruby your/code.rb 2>&1 | grep -B 5 iconv

Answer 3

Add this to the start of your program:
oldverb = $VERBOSE; $VERBOSE = nil
require 'iconv'
$VERBOSE = oldverb
and curse the people who think this is a professional way to handle deprecation.

Answer 4

You can pin down the exact location of the warning by generating exceptions for ActiveSupport::Deprecation, instead of just printing to the log. At the top of application.rb:
ActiveSupport::Deprecation.behavior = Proc.new do |message, backtrace|
raise message
end
Once you've figured out where the warning is coming from (by inspecting the full backtrace), remove this again.

Answer 5

To remove this warning...
go to your .rvm directory and find iconv.c (mine was at ~/.rvm/src/ruby-1.9.3-p125/ext/iconv/iconv.c)
edit that file are remove or comment out the call to warn_deprecated() (should be near the bottom)
from that file's directory, run ruby extconf.rb
then make
then make install
Should do the trick