Bug #13060: pkg_config breaks when adding '-Wconversion' to $CFLAGS

• Status: Closed
• Assignee: -
• Target version: 2.4
• ruby -v: ruby 2.4.0rc1 (2016-12-12 trunk 57064) [x86_64-linux]

[hone (Terence Lee)]

When compiling the nokogiri gem, you can opt to use system libraries which uses pkg_config. When I add '-Wconversion' to $CFLAGS, it causes 'pkg_config('libxml-2.0')' to return nil. This is not the case in Ruby 2.3.3.

This will affect anyone using nokogiri with Ruby 2.4.0 on Heroku.

test script:

require 'mkmf'

puts RUBY_DESCRIPTION
puts "pkg_config('libxml-2.0'): #{pkg_config('libxml-2.0').inspect}"
puts "Adding -Wconversion to $CFLAGS"
$CFLAGS << " -Wconversion"
puts "pkg_config('libxml-2.0'): #{pkg_config('libxml-2.0').inspect}"

ruby 2.3.3 output:

ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-linux]
pkg_config('libxml-2.0'): ["", "", "-lxml2"]
Adding -Wconversion to $CFLAGS
pkg_config('libxml-2.0'): ["", "", "-lxml2"]

ruby 2.4.0-rc1 output:

ruby 2.4.0rc1 (2016-12-12 trunk 57064) [x86_64-linux]
pkg_config('libxml-2.0'): ["", "", "-lxml2"]
Adding -Wconversion to $CFLAGS
pkg_config('libxml-2.0'): nil

[hone (Terence Lee)]

I was able to track it down to this commit using git bisect, https://github.com/ruby/ruby/commit/feaa82a42ba238d9192d219f72229f4c3948957f.

[naruse (Yui NARUSE)]

• Status changed from Open to Closed

Applied in changeset r57150.

---

suppress warning: implicit conversion changes signedness

It causes [Bug #13060]

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)