1 files changed, 44 insertions, 20 deletions
diff --git a/ext/etc/extconf.rb b/ext/etc/extconf.rb
index c6b41a4c92..497303a4fa 100644
--- a/ext/etc/extconf.rb
+++ b/ext/etc/extconf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'mkmf'
 
 headers = []
@@ -9,34 +10,57 @@ headers = []
 have_library("sun", "getpwnam")	# NIS (== YP) interface for IRIX 4
 have_func("uname((struct utsname *)NULL)", headers)
 have_func("getlogin")
-have_func("getpwent")
-have_func("getgrent")
-sysconfdir = RbConfig.expand(RbConfig::CONFIG["sysconfdir"].dup, "prefix"=>"", "DESTDIR"=>"")
-$defs.push("-DSYSCONFDIR=#{Shellwords.escape(sysconfdir.dump)}")
+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')
+  if have_struct_member('struct passwd', 'pw_age', 'pwd.h')
+    case what_type?('struct passwd', 'pw_age', 'pwd.h')
+    when "string"
+      f = "safe_setup_str"
+    when "long long"
+      f = "LL2NUM"
+    else
+      f = "INT2NUM"
+    end
+    $defs.push("-DPW_AGE2VAL="+f)
+  end
+  have_struct_member('struct passwd', 'pw_class', 'pwd.h')
+  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')
+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")
 
-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')
-if have_struct_member('struct passwd', 'pw_age', 'pwd.h')
-  case what_type?('struct passwd', 'pw_age', 'pwd.h')
-  when "string"
-    f = "safe_setup_str"
-  when "long long"
-    f = "LL2NUM"
+# 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
-    f = "INT2NUM"
+    require "shellwords"
+    ruby = Shellwords.split(ruby)
   end
-  $defs.push("-DPW_AGE2VAL="+f)
+  system(*ruby, "#{srcdir}/mkconstants.rb", "-o", constdefs)
 end
-have_struct_member('struct passwd', 'pw_class', 'pwd.h')
-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')
-have_struct_member('struct group', 'gr_passwd', 'grp.h')
+
+# 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"