Can't install on Ubuntu Linux Subsystem.

[amadeuspagel]

I get this error:

current directory: /home/amadeus/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/rankable_graph-0.2.3/ext/rankable_graph
/home/amadeus/.rbenv/versions/2.5.0/bin/ruby -r ./siteconf20180531-3415-1ypgfap.rb extconf.rb
/home/amadeus/.rbenv/versions/2.5.0/lib/ruby/2.5.0/mkmf.rb:1553: warning: Insecure world writable dir /home/amadeus/.rbenv/versions in PATH, mode 040777
creating Makefile

current directory: /home/amadeus/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/rankable_graph-0.2.3/ext/rankable_graph
make "DESTDIR=" clean

current directory: /home/amadeus/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/rankable_graph-0.2.3/ext/rankable_graph
make "DESTDIR="
compiling rankable_graph.c
rankable_graph.c: In function ‘update_in_links’:
rankable_graph.c:69:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   GArray* in_links_for_to = g_ptr_array_index(rn->in_links, to);
   ^
rankable_graph.c: In function ‘update_number_out_links’:
rankable_graph.c:75:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   gint* current_value = (gint *)g_ptr_array_index(rn->number_out_links, from);
   ^
rankable_graph.c:76:18: warning: operation on ‘*current_value’ may be undefined [-Wsequence-point]
   *current_value = (*current_value)++;
                  ^
rankable_graph.c: At top level:
rankable_graph.c:97:14: error: conflicting types for ‘link’
 static VALUE link(VALUE self, VALUE from, VALUE to){
              ^
In file included from /home/amadeus/.rbenv/versions/2.5.0/include/ruby-2.5.0/ruby/defines.h:143:0,
                 from /home/amadeus/.rbenv/versions/2.5.0/include/ruby-2.5.0/ruby/ruby.h:29,
                 from /home/amadeus/.rbenv/versions/2.5.0/include/ruby-2.5.0/ruby.h:33,
                 from rankable_graph.c:1:
/usr/include/unistd.h:793:12: note: previous declaration of ‘link’ was here
 extern int link (const char *__from, const char *__to)
            ^
rankable_graph.c: In function ‘link’:
rankable_graph.c:101:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   gint from_as_index = key_as_array_index(rn, from);
   ^
rankable_graph.c: In function ‘calculate_dangling_nodes’:
rankable_graph.c:121:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(i = 0; i < rn->number_out_links->len; i++){
                ^
rankable_graph.c: In function ‘step’:
rankable_graph.c:134:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(i = 0; i < dangling_nodes->len; i++){
                ^
rankable_graph.c:137:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   const gfloat inner_product_over_size = inner_product / (gfloat)size;
   ^
rankable_graph.c:146:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(j = 0; j < in_links_for_i->len; j++){
                  ^
rankable_graph.c:155:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
   const gfloat inverse_of_vsum = 1 / vsum;
   ^
rankable_graph.c: In function ‘rank’:
rankable_graph.c:167:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
     const gint size = g_hash_table_size(rn->key_to_index);
     ^
rankable_graph.c:173:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
     GArray* dangling_nodes = calculate_dangling_nodes(rn);
     ^
rankable_graph.c:180:5: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
     gfloat* new_p;
     ^
rankable_graph.c: At top level:
cc1: warning: unrecognized command line option ‘-Wno-self-assign’
cc1: warning: unrecognized command line option ‘-Wno-constant-logical-operand’
cc1: warning: unrecognized command line option ‘-Wno-parentheses-equality’
cc1: warning: unrecognized command line option ‘-Wno-tautological-compare’
Makefile:241: recipe for target 'rankable_graph.o' failed
make: *** [rankable_graph.o] Error 1

make failed, exit code 2