Error on compile rugged_diff.c in manjaro

Start by reproducing the native-extension build with Ruby 2.6.0 and the Manjaro setup shown in the report. Inspect rugged_diff.c around the rb_funcall calls at lines 427 and 463; done means rugged 0.19.0 compiles successfully and the reported make error no longer occurs.

I'm having the following error when installing rugged 0.19.0 from the ready (Stable version):

Fetching rugged 0.19.0
Installing rugged 0.19.0 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/home/marlon/.rvm/gems/ruby-2.6.0/gems/rugged-0.19.0/ext/rugged
/home/marlon/.rvm/rubies/ruby-2.6.0/bin/ruby -I
/home/marlon/.rvm/rubies/ruby-2.6.0/lib/ruby/2.6.0 -r
./siteconf20190129-2478-5d96n4.rb extconf.rb
checking for gmake... no
checking for make... yes
 -- /usr/bin/make -f Makefile.embed
checking for -lgit2_embed... yes
checking for git2.h... yes
creating Makefile

current directory: /home/marlon/.rvm/gems/ruby-2.6.0/gems/rugged-0.19.0/ext/rugged
make "DESTDIR=" clean

current directory: /home/marlon/.rvm/gems/ruby-2.6.0/gems/rugged-0.19.0/ext/rugged
make "DESTDIR="
compiling rugged.c
rugged.c: In function ‘rugged_exception_raise’:
rugged.c:282:6: warning: function might be candidate for attribute ‘noreturn’
[-Wsuggest-attribute=noreturn]
 void rugged_exception_raise(void)
      ^~~~~~~~~~~~~~~~~~~~~~
rugged.c: At top level:
cc1: warning: unrecognized command line option ‘-Wno-self-assign’
cc1: warning: unrecognized command line option ‘-Wno-parentheses-equality’
cc1: warning: unrecognized command line option ‘-Wno-constant-logical-operand’
compiling rugged_blob.c
compiling rugged_branch.c
compiling rugged_commit.c
compiling rugged_config.c
compiling rugged_diff.c
In file included from
/home/marlon/.rvm/rubies/ruby-2.6.0/include/ruby-2.6.0/ruby.h:33,
                 from rugged.h:33,
                 from rugged_diff.c:25:
In function ‘rb_git_diff_each_delta.part.0’,
    inlined from ‘rb_git_diff_each_delta’ at rugged_diff.c:456:14:
/home/marlon/.rvm/rubies/ruby-2.6.0/include/ruby-2.6.0/ruby/ruby.h:1850:3: error:
call to ‘rb_varargs_bad_length’ declared with attribute error:  argument length
doesn't match
   rb_varargs_bad_length(argc, vargc)), \
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/marlon/.rvm/rubies/ruby-2.6.0/include/ruby-2.6.0/ruby/ruby.h:2603:6: note:
in expansion of macro ‘rb_varargs_argc_check’
      rb_varargs_argc_check(rb_funcall_argc, rb_funcall_nargs), \
      ^~~~~~~~~~~~~~~~~~~~~
rugged_diff.c:463:10: note: in expansion of macro ‘rb_funcall’
   return rb_funcall(self, rb_intern("to_enum"), 1, CSTR2SYM("each_delta"), self);
          ^~~~~~~~~~
In function ‘rb_git_diff_each_patch.part.1’,
    inlined from ‘rb_git_diff_each_patch’ at rugged_diff.c:420:14:
/home/marlon/.rvm/rubies/ruby-2.6.0/include/ruby-2.6.0/ruby/ruby.h:1850:3: error:
call to ‘rb_varargs_bad_length’ declared with attribute error:  argument length
doesn't match
   rb_varargs_bad_length(argc, vargc)), \
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/marlon/.rvm/rubies/ruby-2.6.0/include/ruby-2.6.0/ruby/ruby.h:2603:6: note:
in expansion of macro ‘rb_varargs_argc_check’
      rb_varargs_argc_check(rb_funcall_argc, rb_funcall_nargs), \
      ^~~~~~~~~~~~~~~~~~~~~
rugged_diff.c:427:10: note: in expansion of macro ‘rb_funcall’
   return rb_funcall(self, rb_intern("to_enum"), 1, CSTR2SYM("each_patch"), self);
          ^~~~~~~~~~
rugged_diff.c: At top level:
cc1: warning: unrecognized command line option ‘-Wno-self-assign’
cc1: warning: unrecognized command line option ‘-Wno-parentheses-equality’
cc1: warning: unrecognized command line option ‘-Wno-constant-logical-operand’
make: *** [Makefile:244: rugged_diff.o] Error 1

make failed, exit code 2

Gem files will remain installed in
/home/marlon/.rvm/gems/ruby-2.6.0/gems/rugged-0.19.0 for inspection.
Results logged to
/home/marlon/.rvm/gems/ruby-2.6.0/extensions/x86_64-linux/2.6.0/rugged-0.19.0/gem_make.out

An error occurred while installing rugged (0.19.0), and Bundler cannot
continue.
Make sure that `gem install rugged -v '0.19.0' --source 'https://rubygems.org/'`
succeeds before bundling.

In Gemfile:
  pronto was resolved to 0.2.6, which depends on
    rugged

Setup

• Ruby 2.6.0
• Pronto Stable (Rugged 0.19.0 required)