Avoid diffutils 3.8 bug#61193 [ci skip]

tool/enc-unicode.rb

@@ -10,9 +10,22 @@
 # ruby1.9 tool/enc-unicode.rb data_dir > enc/unicode/name2ctype.kwd
 # You can get source file for gperf.  After this, simply make ruby.
 
-if ARGV[0] == "--header"
-  header = true
-  ARGV.shift
+while arg = ARGV.shift
+  case arg
+  when "--"
+    break
+  when "--header"
+    header = true
+  when "--diff"
+    diff = ARGV.shift or abort "#{$0}: --diff=DIFF-COMMAND"
+  when /\A--diff=(.+)/m
+    diff = $1
+  when /\A-/
+    abort "#{$0}: unknown option #{arg}"
+  else
+    ARGV.unshift(arg)
+    break
+  end
 end
 unless ARGV.size == 2
   abort "Usage: #{$0} data_directory emoji_data_directory"
@@ -544,6 +557,47 @@ output.restore
 if header
   require 'tempfile'
 
+  def diff_args(diff)
+    ok = IO.popen([diff, "-DDIFF_TEST", IO::NULL, "-"], "r+") do |f|
+      f.puts "Test for diffutils 3.8"
+      f.close_write
+      /^#if/ =~ f.read
+    end
+    if ok
+      proc {|macro, *inputs|
+        [diff, "-D#{macro}", *inputs]
+      }
+    else
+      IO.popen([diff, "--old-group-format=%<", "--new-group-format=%>", IO::NULL, IO::NULL], err: %i[child out], &:read)
+      unless $?.success?
+        abort "#{$0}: #{diff} -D does not work"
+      end
+      warn "Avoiding diffutils 3.8 bug#61193"
+      proc {|macro, *inputs|
+        [diff] + [
+          "--old-group-format=" \
+	  "#ifndef @\n" \
+	  "%<" \
+	  "#endif /* ! @ */\n",
+
+          "--new-group-format=" \
+	  "#ifdef @\n" \
+	  "%>" \
+	  "#endif /* @ */\n",
+
+	  "--changed-group-format=" \
+	  "#ifndef @\n" \
+	  "%<" \
+	  "#else /* @ */\n" \
+	  "%>" \
+	  "#endif /* @ */\n"
+        ].map {|opt| opt.gsub(/@/) {macro}} + inputs
+      }
+    end
+  end
+
+  ifdef = diff_args(diff || "diff")
+
   NAME2CTYPE = %w[gperf -7 -c -j1 -i1 -t -C -P -T -H uniname2ctype_hash -Q uniname2ctype_pool -N uniname2ctype_p]
 
   fds = []
@@ -554,8 +608,8 @@ if header
   end while syms.pop
   fds.each(&:close)
   ff = nil
-  IO.popen(%W[diff -DUSE_UNICODE_AGE_PROPERTIES #{fds[1].path} #{fds[0].path}], "r") {|age|
-    IO.popen(%W[diff -DUSE_UNICODE_PROPERTIES #{fds[2].path} -], "r", in: age) {|f|
+  IO.popen(ifdef["USE_UNICODE_AGE_PROPERTIES", fds[1].path, fds[0].path], "r") {|age|
+    IO.popen(ifdef["USE_UNICODE_PROPERTIES", fds[2].path, "-"], "r", in: age) {|f|
       ansi = false
       f.each {|line|
         if /ANSI-C code produced by gperf/ =~ line