Commit 77be60c3 breaks installation with homebrew system libraries and pkg_config

[xeron]

Gem installation fails for me starting from 1.8.3. I started to check commits and this is what I found:

When I'm on b5b97bc bundle exec rake succeeds.
When I'm on 77be60c bundle exec rake fails.

Making following change on the latest master fixes the issue:

diff --git a/ext/nokogiri/extconf.rb b/ext/nokogiri/extconf.rb
index 1b0ca4ed..ae89b019 100644
--- a/ext/nokogiri/extconf.rb
+++ b/ext/nokogiri/extconf.rb
@@ -434,7 +434,7 @@ end
 
 if RbConfig::MAKEFILE_CONFIG['CC'] =~ /gcc/
   $CFLAGS << " -O3" unless $CFLAGS[/-O\d/]
-  $CFLAGS << " -Wall -Wcast-qual -Wwrite-strings -Wextra -Wmissing-noreturn -Winline"
+  $CFLAGS << " -Wall -Wcast-qual -Wwrite-strings -Wconversion -Wmissing-noreturn -Winline"
 end
 
 case

My setup:

• macOS 10.13.6
• Xcode 9.4.1
• homebrew latest version
• libxml2: stable 2.9.7 (bottled) – FORCE LINKED
• libxslt: stable 1.1.32 – FORCE LINKED
• brew link libxml2 libxslt --force
• My $CPPFLAGS env variable: -I/opt/brew/include
• My $LDFLAGS env variable: -L/opt/brew/lib
• My $NOKOGIRI_USE_SYSTEM_LIBRARIES env variable: Y

Rake log:

$ bundle exec rake
cd tmp/x86_64-darwin17/nokogiri/2.5.1
/Users/ilarionov/.rvm/rubies/ruby-2.5.1/bin/ruby -I. ../../../../ext/nokogiri/extconf.rb 
checking if the C compiler accepts ... yes
checking if the C compiler accepts -Wno-error=unused-command-line-argument-hard-error-in-future... no
Building nokogiri using system libraries.
pkg-config could not be used to find libxml-2.0
Please install either `pkg-config` or the pkg-config gem per

    gem install pkg-config -v "~> 1.1"

pkg-config could not be used to find libxslt
Please install either `pkg-config` or the pkg-config gem per

    gem install pkg-config -v "~> 1.1"

pkg-config could not be used to find libexslt
Please install either `pkg-config` or the pkg-config gem per

    gem install pkg-config -v "~> 1.1"

ERROR: cannot discover where libxml2 is located on your system. please make sure `pkg-config` is installed.
rake aborted!
Command failed with status (1): [/Users/ilarionov/.rvm/rubies/ruby-2.5.1/bi...]
/Users/ilarionov/workspace/devel/nokogiri/.bundle/vendor/ruby/2.5.0/gems/rake-compiler-1.0.4/lib/rake/extensiontask.rb:205:in `block (2 levels) in define_compile_tasks'
/Users/ilarionov/workspace/devel/nokogiri/.bundle/vendor/ruby/2.5.0/gems/rake-compiler-1.0.4/lib/rake/extensiontask.rb:202:in `block in define_compile_tasks'
/Users/ilarionov/workspace/devel/nokogiri/.bundle/vendor/ruby/2.5.0/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/cli/exec.rb:74:in `load'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/cli/exec.rb:74:in `kernel_load'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/cli/exec.rb:28:in `run'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/cli.rb:424:in `exec'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/vendor/thor/lib/thor.rb:387:in `dispatch'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/cli.rb:27:in `dispatch'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/vendor/thor/lib/thor/base.rb:466:in `start'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/cli.rb:18:in `start'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/exe/bundle:30:in `block in <top (required)>'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/lib/bundler/friendly_errors.rb:124:in `with_friendly_errors'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/gems/bundler-1.16.3/exe/bundle:22:in `<top (required)>'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/bin/bundle:23:in `load'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/bin/bundle:23:in `<main>'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/bin/ruby_executable_hooks:24:in `eval'
/Users/ilarionov/.rvm/gems/ruby-2.5.1/bin/ruby_executable_hooks:24:in `<main>'
Tasks: TOP => default => test => compile => compile:x86_64-darwin17 => compile:nokogiri:x86_64-darwin17 => copy:nokogiri:x86_64-darwin17:2.5.1 => tmp/x86_64-darwin17/nokogiri/2.5.1/nokogiri.bundle => tmp/x86_64-darwin17/nokogiri/2.5.1/Makefile
(See full trace by running task with --trace)

pkg_config output:

$ pkg-config --cflags libxml-2.0
-I/opt/brew/Cellar/libxml2/2.9.7/include/libxml2
$ pkg-config --libs libxml-2.0
-L/opt/brew/Cellar/libxml2/2.9.7/lib -lxml2
$ pkg-config --libs libxslt
-L/opt/brew/Cellar/libxslt/1.1.32/lib -L/opt/brew/Cellar/libxml2/2.9.7/lib -lxslt -lxml2 -lz -lpthread -liconv -lm -lxml2
$ pkg-config --cflags libxslt
-I/opt/brew/Cellar/libxslt/1.1.32/include -I/opt/brew/Cellar/libxml2/2.9.7/include/libxml2

Attached mkmf.log when trying to install 1.8.4 using rubygems:

mkmf.log

[xeron]

Same issue with macports and:

$ sudo port installed | grep libx
  libxml2 @2.9.7_0 (active)
  libxslt @1.1.32_0 (active)
$ echo $CPPFLAGS
-I/opt/local/include
$ echo $LDFLAGS
-L/opt/local/lib
$ echo $NOKOGIRI_USE_SYSTEM_LIBRARIES 
Y

[flavorjones]

Hi, this appears to be a duplicate of #1772 related to #1731. Closing, please follow on #1772.