```
% bundle                
Fetching gem metadata from https://rubygems.org/........
Using rake 12.3.1
Using concurrent-ruby 1.1.3
Using i18n 0.9.5
Using minitest 5.11.3
Using thread_safe 0.3.6
Using tzinfo 1.2.5
Using activesupport 4.2.11
Using builder 3.2.3
Using erubis 2.7.0
Using mini_portile2 2.3.0
Using nokogiri 1.8.5
Using rails-deprecated_sanitizer 1.0.3
Using rails-dom-testing 1.0.9
Using crass 1.0.4
Using loofah 2.2.3
Using rails-html-sanitizer 1.0.4
Using actionview 4.2.11
Using rack 1.6.11
Using rack-test 0.6.3
Using actionpack 4.2.11
Using globalid 0.4.1
Using activejob 4.2.11
Using mini_mime 1.0.1
Using mail 2.7.1
Using actionmailer 4.2.11
Using activemodel 4.2.11
Using active_model_serializers 0.8.4
Using arel 6.0.4
Using activerecord 4.2.11
Using public_suffix 3.0.3
Using addressable 2.5.2
Using annotate 2.7.4
Using coderay 1.1.2
Using erubi 1.7.1
Using better_errors 2.5.0
Using debug_inspector 0.0.3
Using binding_of_caller 0.8.0
Using thor 0.19.4
Using railties 4.2.11
Using bootstrap-multiselect-rails 0.0.4
Using sass 3.2.19
Using bootstrap-sass 3.0.2.1
Using buftok 0.2.0
Using bundler 1.17.1
Using mime-types-data 3.2018.0812
Using mime-types 3.2.2
Using xpath 2.1.0
Using capybara 2.4.4
Using json 2.1.0
Fetching capybara-webkit 1.6.0
Installing capybara-webkit 1.6.0 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0
/Users/horaotoko/.rbenv/versions/2.5.3/bin/ruby -r ./siteconf20181206-16364-1ey59t7.rb extconf.rb
Info: creating stash file /Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0/.qmake.stash
cd src/ && ( test -e Makefile.webkit_server || /usr/local/opt/qt@5.5/bin/qmake
/Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0/src/webkit_server.pro -o Makefile.webkit_server )
&& /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile.webkit_server
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -pipe -O2 -isysroot
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -mmacosx-version-min=10.7 -Wall -W
-fPIC -DQT_NO_DEBUG -DQT_WEBKITWIDGETS_LIB -DQT_WIDGETS_LIB -DQT_WEBKIT_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I.
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWebKitWidgets.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWidgets.framework/Headers -I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWebKit.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtGui.framework/Headers -I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtNetwork.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtCore.framework/Headers -Ibuild
-I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/OpenGL.framework/Headers
-I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/AGL.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/mkspecs/macx-clang -F/usr/local/Cellar/qt@5.5/5.5.1_1/lib -x c++-header -c stable.h -o
build/webkit_server/c++.pch
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard library instead
[-Wstdlibcxx-not-found]
In file included from stable.h:1:
In file included from /usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWidgets.framework/Headers/QApplication:1:
In file included from /usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWidgets.framework/Headers/qapplication.h:37:
In file included from /usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtCore.framework/Headers/qcoreapplication.h:37:
/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtCore.framework/Headers/qglobal.h:39:12: fatal error: 'cstddef' file not found
#  include <cstddef>
           ^~~~~~~~~
1 warning and 1 error generated.
make[1]: *** [build/webkit_server/c++.pch] Error 1
make: *** [sub-src-webkit_server-pro-make_first-ordered] Error 2
Command 'make' failed

current directory: /Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0
make "DESTDIR=" clean
cd src/ && ( test -e Makefile.webkit_server || /usr/local/opt/qt@5.5/bin/qmake
/Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0/src/webkit_server.pro -o Makefile.webkit_server )
&& /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile.webkit_server clean
rm -f qrc_webkit_server.cpp
rm -f build/moc_BlockUrl.cpp build/moc_AllowUrl.cpp build/moc_SetUnknownUrlMode.cpp build/moc_FindModal.cpp build/moc_AcceptAlert.cpp
build/moc_GoForward.cpp build/moc_GoBack.cpp build/moc_WindowMaximize.cpp build/moc_WindowSize.cpp build/moc_WindowCommand.cpp
build/moc_WindowOpen.cpp build/moc_WindowClose.cpp build/moc_Version.cpp build/moc_EnableLogging.cpp build/moc_Authenticate.cpp
build/moc_SetConfirmAction.cpp build/moc_SetPromptAction.cpp build/moc_SetPromptText.cpp build/moc_ClearPromptText.cpp
build/moc_JavascriptAlertMessages.cpp build/moc_JavascriptConfirmMessages.cpp build/moc_JavascriptPromptMessages.cpp
build/moc_IgnoreSslErrors.cpp build/moc_WindowResize.cpp build/moc_CurrentUrl.cpp build/moc_ConsoleMessages.cpp build/moc_WebPage.cpp
build/moc_Server.cpp build/moc_Connection.cpp build/moc_Command.cpp build/moc_SocketCommand.cpp build/moc_Visit.cpp build/moc_Reset.cpp
build/moc_Node.cpp build/moc_JavascriptInvocation.cpp build/moc_Evaluate.cpp build/moc_Execute.cpp build/moc_FrameFocus.cpp
build/moc_Response.cpp build/moc_NetworkAccessManager.cpp build/moc_NetworkCookieJar.cpp build/moc_Header.cpp build/moc_Render.cpp
build/moc_Body.cpp build/moc_Status.cpp build/moc_Headers.cpp build/moc_UnsupportedContentHandler.cpp build/moc_SetCookie.cpp
build/moc_ClearCookies.cpp build/moc_GetCookies.cpp build/moc_CommandParser.cpp build/moc_CommandFactory.cpp build/moc_SetProxy.cpp
build/moc_NullCommand.cpp build/moc_PageLoadingCommand.cpp build/moc_SetSkipImageLoading.cpp build/moc_WebPageManager.cpp
build/moc_WindowFocus.cpp build/moc_GetWindowHandles.cpp build/moc_GetWindowHandle.cpp build/moc_GetTimeout.cpp build/moc_SetTimeout.cpp
build/moc_TimeoutCommand.cpp build/moc_SetUrlBlacklist.cpp build/moc_NoOpReply.cpp build/moc_JsonSerializer.cpp
build/moc_ErrorMessage.cpp build/moc_Title.cpp build/moc_FindCss.cpp build/moc_JavascriptCommand.cpp build/moc_FindXpath.cpp
build/moc_NetworkReplyProxy.cpp build/moc_StdinNotifier.cpp build/moc_RequestHandler.cpp
rm -f build/BlockUrl.o build/AllowUrl.o build/SetUnknownUrlMode.o build/FindModal.o build/AcceptAlert.o build/GoForward.o build/GoBack.o
build/WindowMaximize.o build/WindowSize.o build/WindowCommand.o build/WindowOpen.o build/WindowClose.o build/Version.o
build/EnableLogging.o build/Authenticate.o build/SetConfirmAction.o build/SetPromptAction.o build/SetPromptText.o
build/ClearPromptText.o build/JavascriptAlertMessages.o build/JavascriptConfirmMessages.o build/JavascriptPromptMessages.o
build/IgnoreSslErrors.o build/WindowResize.o build/CurrentUrl.o build/ConsoleMessages.o build/main.o build/WebPage.o build/Server.o
build/Connection.o build/Command.o build/SocketCommand.o build/Visit.o build/Reset.o build/Node.o build/JavascriptInvocation.o
build/Evaluate.o build/Execute.o build/FrameFocus.o build/Response.o build/NetworkAccessManager.o build/NetworkCookieJar.o
build/Header.o build/Render.o build/body.o build/Status.o build/Headers.o build/UnsupportedContentHandler.o build/SetCookie.o
build/ClearCookies.o build/GetCookies.o build/CommandParser.o build/CommandFactory.o build/SetProxy.o build/NullCommand.o
build/PageLoadingCommand.o build/SetTimeout.o build/GetTimeout.o build/SetSkipImageLoading.o build/WebPageManager.o build/WindowFocus.o
build/GetWindowHandles.o build/GetWindowHandle.o build/TimeoutCommand.o build/SetUrlBlacklist.o build/NoOpReply.o build/JsonSerializer.o
build/InvocationResult.o build/ErrorMessage.o build/Title.o build/FindCss.o build/JavascriptCommand.o build/FindXpath.o
build/NetworkReplyProxy.o build/IgnoreDebugOutput.o build/StdinNotifier.o build/RequestHandler.o build/BlacklistedRequestHandler.o
build/MissingContentHeaderRequestHandler.o build/CustomHeadersRequestHandler.o build/NetworkRequestFactory.o build/UnknownUrlHandler.o
build/qrc_webkit_server.o build/moc_BlockUrl.o build/moc_AllowUrl.o build/moc_SetUnknownUrlMode.o build/moc_FindModal.o
build/moc_AcceptAlert.o build/moc_GoForward.o build/moc_GoBack.o build/moc_WindowMaximize.o build/moc_WindowSize.o
build/moc_WindowCommand.o build/moc_WindowOpen.o build/moc_WindowClose.o build/moc_Version.o build/moc_EnableLogging.o
build/moc_Authenticate.o build/moc_SetConfirmAction.o build/moc_SetPromptAction.o build/moc_SetPromptText.o build/moc_ClearPromptText.o
build/moc_JavascriptAlertMessages.o build/moc_JavascriptConfirmMessages.o build/moc_JavascriptPromptMessages.o
build/moc_IgnoreSslErrors.o build/moc_WindowResize.o build/moc_CurrentUrl.o build/moc_ConsoleMessages.o build/moc_WebPage.o
build/moc_Server.o build/moc_Connection.o build/moc_Command.o build/moc_SocketCommand.o build/moc_Visit.o build/moc_Reset.o
build/moc_Node.o build/moc_JavascriptInvocation.o build/moc_Evaluate.o build/moc_Execute.o build/moc_FrameFocus.o build/moc_Response.o
build/moc_NetworkAccessManager.o build/moc_NetworkCookieJar.o build/moc_Header.o build/moc_Render.o build/moc_Body.o build/moc_Status.o
build/moc_Headers.o build/moc_UnsupportedContentHandler.o build/moc_SetCookie.o build/moc_ClearCookies.o build/moc_GetCookies.o
build/moc_CommandParser.o build/moc_CommandFactory.o build/moc_SetProxy.o build/moc_NullCommand.o build/moc_PageLoadingCommand.o
build/moc_SetSkipImageLoading.o build/moc_WebPageManager.o build/moc_WindowFocus.o build/moc_GetWindowHandles.o
build/moc_GetWindowHandle.o build/moc_GetTimeout.o build/moc_SetTimeout.o build/moc_TimeoutCommand.o build/moc_SetUrlBlacklist.o
build/moc_NoOpReply.o build/moc_JsonSerializer.o build/moc_ErrorMessage.o build/moc_Title.o build/moc_FindCss.o
build/moc_JavascriptCommand.o build/moc_FindXpath.o build/moc_NetworkReplyProxy.o build/moc_StdinNotifier.o build/moc_RequestHandler.o
rm -f build/webkit_server/c.pch build/webkit_server/c++.pch build/webkit_server/objective-c.pch build/webkit_server/objective-c++.pch
rm -f *~ core *.core

current directory: /Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0
make "DESTDIR="
cd src/ && ( test -e Makefile.webkit_server || /usr/local/opt/qt@5.5/bin/qmake
/Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0/src/webkit_server.pro -o Makefile.webkit_server )
&& /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile.webkit_server
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -pipe -O2 -isysroot
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -mmacosx-version-min=10.7 -Wall -W
-fPIC -DQT_NO_DEBUG -DQT_WEBKITWIDGETS_LIB -DQT_WIDGETS_LIB -DQT_WEBKIT_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I.
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWebKitWidgets.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWidgets.framework/Headers -I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWebKit.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtGui.framework/Headers -I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtNetwork.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtCore.framework/Headers -Ibuild
-I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/OpenGL.framework/Headers
-I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/AGL.framework/Headers
-I/usr/local/Cellar/qt@5.5/5.5.1_1/mkspecs/macx-clang -F/usr/local/Cellar/qt@5.5/5.5.1_1/lib -x c++-header -c stable.h -o
build/webkit_server/c++.pch
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard library instead
[-Wstdlibcxx-not-found]
In file included from stable.h:1:
In file included from /usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWidgets.framework/Headers/QApplication:1:
In file included from /usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtWidgets.framework/Headers/qapplication.h:37:
In file included from /usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtCore.framework/Headers/qcoreapplication.h:37:
/usr/local/Cellar/qt@5.5/5.5.1_1/lib/QtCore.framework/Headers/qglobal.h:39:12: fatal error: 'cstddef' file not found
#  include <cstddef>
           ^~~~~~~~~
1 warning and 1 error generated.
make[1]: *** [build/webkit_server/c++.pch] Error 1
make: *** [sub-src-webkit_server-pro-make_first-ordered] Error 2

make failed, exit code 2

Gem files will remain installed in /Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/gems/capybara-webkit-1.6.0 for inspection.
Results logged to
/Users/horaotoko/.rbenv/versions/2.5.3/lib/ruby/gems/2.5.0/extensions/x86_64-darwin-17/2.5.0-static/capybara-webkit-1.6.0/gem_make.out

An error occurred while installing capybara-webkit (1.6.0), and Bundler cannot continue.
Make sure that `gem install capybara-webkit -v '1.6.0' --source 'https://rubygems.org/'` succeeds before bundling.

In Gemfile:
  capybara-webkit
```