While executing gem ... ["extconf.rb", ...] are not files - ruby

Question

I'm trying to build a ruby gem around a C extension. The C extension compiles fine using the ruby extconf.rb; make; sudo make install routine, but when I try to build a gem using rake, the process terminates with the error at the bottom of this trace.
I'm using the post here, with the same directory structure, to create the gem.
What's wrong with my configuration? My gemspec and Rakefile are below the trace (the gem is called netconf).
// Trace
** Execute copy:netconf:i686-linux:1.9.2
install -c tmp/i686-linux/netconf/1.9.2/netconf.so lib/netconf/netconf.so
** Execute compile:netconf:i686-linux
** Execute compile:i686-linux
** Execute compile
** Invoke chmod (first_time)
** Execute chmod
** Execute build
rake aborted!
ERROR: While executing gem ... (Gem::InvalidSpecificationException)
["extconf.rb", "netconf.o", "netconf.so"] are not files
// netconf.gemspec
# -*- encoding: utf-8 -*-
$:.push File.expand_path("../lib", __FILE__)
require "netconf/version"
Gem::Specification.new do |s|
s.name = "netconf"
s.version = Netconf::VERSION
s.authors = ["..."]
s.email = ["..."]
s.homepage = "..."
s.summary = %q{A tool to access and write Ubuntu network configuration}
s.description = %q{Uses ifconfig and other C system calls to access network configurations on a Ubuntu install.}
s.rubyforge_project = "netconf"
s.files = `git ls-files`.split("\n")
s.executables = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
s.require_paths = ["lib"]
s.extensions = ["ext/netconf/extconf.rb"]
end
// Rakefile
require 'rake'
require 'rake/extensiontask'
require 'bundler'
Rake::ExtensionTask.new("netconf") do |extension|
extension.lib_dir = "lib/netconf"
end
task :chmod do
File.chmod(0775, 'lib/netconf/netconf.so')
end
task :build => [:clean, :compile, :chmod]
Bundler::GemHelper.install_tasks

Answer 1

I got this error because I hadn't commited my updates with git yet.
s.files = `git ls-files`.split("\n")
That line is directly using git, and probably causing this error. Just do
git add .
git commit -a -m "init"

Answer 2

FWIW, I had a similar issue where
s.files = `git ls-files`.split("\n")
was
s.files = `git ls-files`.split('\n')
, where the single quotes were preventing the file list from splitting properly. Changing to double quotes fixed the issue for me.