Compilation failed on Visual Studio 2019

[holywyvern]

Summary

Compiling using Visual Studio 16.0, throws the following unresolved external symbols:

libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_free referenced in function onig_regexp_free
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_search referenced in function onig_match_common
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_region_new referenced in function create_onig_region
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_region_free referenced in function match_data_free
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_region_copy referenced in function match_data_copy
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_name_to_backref_number referenced in function append_replace_str
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_get_encoding referenced in function onig_regexp_inspect
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_get_options referenced in function onig_regexp_casefold_p
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_version referenced in function onig_regexp_version
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigEncodingASCII
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigEncodingUTF_8
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigSyntaxRuby
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigDefaultSyntax
mrbtest.exe : fatal error LNK1120: 15 unresolved externals
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_error_code_to_str referenced in function onig_match_common
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_new referenced in function onig_regexp_initialize
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_free referenced in function onig_regexp_free
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_search referenced in function onig_match_common
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_region_new referenced in function create_onig_region
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_region_free referenced in function match_data_free
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_region_copy referenced in function match_data_copy
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_name_to_backref_number referenced in function append_replace_str
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_get_encoding referenced in function onig_regexp_inspect
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_get_options referenced in function onig_regexp_casefold_p
libmruby.lib(mruby_onig_regexp.obj) : error LNK2019: unresolved external symbol onig_version referenced in function onig_regexp_version
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigEncodingASCII
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigEncodingUTF_8
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigSyntaxRuby
libmruby.lib(mruby_onig_regexp.obj) : error LNK2001: unresolved external symbol OnigDefaultSyntax

Environment

Visual studio version: 16 (VS 2019)
Arch: x86_64
Mruby version: 2.1.2
Build config:

MRuby::Build.new do |conf|
  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
    conf.toolchain :visualcpp
  else
    conf.toolchain :gcc
  end

  conf.gembox 'default'
  conf.gem github: 'mattn/mruby-onig-regexp'

  conf.enable_test

  if ENV['DEBUG'] == 'true'
    conf.enable_debug
    conf.cc.defines = %w[MRB_ENABLE_DEBUG_HOOK]
    conf.gem core: 'mruby-bin-debugger'
  end