1 files changed, 43 insertions, 19 deletions
diff --git a/ext/etc/extconf.rb b/ext/etc/extconf.rb
index dbd0672545..497303a4fa 100644
--- a/ext/etc/extconf.rb
+++ b/ext/etc/extconf.rb
@@ -1,10 +1,16 @@
+# frozen_string_literal: true
 require 'mkmf'
 
+headers = []
+%w[sys/utsname.h].each {|h|
+  if have_header(h, headers)
+    headers << h
+  end
+}
 have_library("sun", "getpwnam")	# NIS (== YP) interface for IRIX 4
-a = have_func("getlogin")
-b = have_func("getpwent")
-c = have_func("getgrent")
-if  a or b or c
+have_func("uname((struct utsname *)NULL)", headers)
+have_func("getlogin")
+if have_func("getpwent")
   have_struct_member('struct passwd', 'pw_gecos', 'pwd.h')
   have_struct_member('struct passwd', 'pw_change', 'pwd.h')
   have_struct_member('struct passwd', 'pw_quota', 'pwd.h')
@@ -23,21 +29,39 @@ if  a or b or c
   have_struct_member('struct passwd', 'pw_comment', 'pwd.h') unless /cygwin/ === RUBY_PLATFORM
   have_struct_member('struct passwd', 'pw_expire', 'pwd.h')
   have_struct_member('struct passwd', 'pw_passwd', 'pwd.h')
+end
+if have_func("getgrent")
   have_struct_member('struct group', 'gr_passwd', 'grp.h')
-  [%w"uid_t pwd.h", %w"gid_t grp.h"].each do |t, *h|
-    h.unshift("sys/types.h")
-    f = "INT2NUM"
-    if have_type(t, h)
-      if try_static_assert("sizeof(#{t}) > sizeof(long)", h)
-	f = "LL2NUM"
-      end
-      if try_static_assert("(#{t})-1 > 0", h)
-	f = "U#{f}"
-      end
-    end
-    t = t.chomp('_t').upcase
-    $defs.push("-DPW_#{t}2VAL=#{f}")
-    $defs.push("-DPW_VAL2#{t}=#{f.sub(/([A-Z]+)2(NUM)/, '\22\1')}")
+end
+
+if (sysconfdir = RbConfig::CONFIG["sysconfdir"] and
+    !RbConfig.expand(sysconfdir.dup, "prefix"=>"", "DESTDIR"=>"").empty?)
+  $defs.push("-DSYSCONFDIR=#{Shellwords.escape(sysconfdir.dump)}")
+end
+
+have_func("sysconf")
+have_func("confstr")
+have_func("fpathconf")
+
+# for https://github.com/ruby/etc
+srcdir = File.expand_path("..", __FILE__)
+constdefs = "#{srcdir}/constdefs.h"
+if !File.exist?(constdefs)
+  ruby = RbConfig.ruby
+  if File.file?(ruby)
+    ruby = [ruby]
+  else
+    require "shellwords"
+    ruby = Shellwords.split(ruby)
   end
-  create_makefile("etc")
+  system(*ruby, "#{srcdir}/mkconstants.rb", "-o", constdefs)
 end
+
+# TODO: remove when dropping 2.7 support, as exported since 3.0
+have_func('rb_deprecate_constant(Qnil, "None")')
+
+have_func("rb_io_descriptor", "ruby/io.h")
+
+$distcleanfiles << "constdefs.h"
+
+create_makefile("etc")