Added testing support for cross-MinGW builds.

This adds a build_config that will cross-build a Windows executable
using the MinGW cross-compiler and will also run the unit (i.e.
'rake test') using Wine.

For this to work, I made some modifications to the underlying test
scripts as well as some minor changes to a couple of the tests
themselves.

7 files changed, 204 insertions, 6 deletions

diff --git a/build_config/cross-mingw-winetest.rb b/build_config/cross-mingw-winetest.rb
new file mode 100644
index 000000000..fad06b265
--- /dev/null
+++ b/build_config/cross-mingw-winetest.rb
@@ -0,0 +1,91 @@
+
+# Cross-compile using MinGW and test using Wine.
+#
+# Steps:
+#
+#   1. Install MinGW; 64-bit target seems to work best.
+#
+#   2. Install Wine.
+#
+#   3. Run command:
+#
+#           wine cmd /c echo "Hello world"'
+#
+#      This will confirm that Wine works and will trigger standard
+#      Wine setup, which is slow.
+#
+#   4. Confirm that drive 'z:' is mapped to your root filesystem.
+#      (This is supposed to be a default but it helps to
+#      double-check.)  To confirm, run:
+#
+#           wine cmd /c dir 'z:\\'
+#
+#      This should give you a DOS-style equivalent of 'ls /'.  If not,
+#      you'll need to fix that with winecfg or by adding a symlink to
+#      '~/.wine/dosdevices'.
+#
+#   5. You will likely need to tweak the settings below to work with
+#      your configuration unless it is exactly like one of the platforms
+#      I've tested on (Ubuntu 20.04 or macOS using brew.)
+#
+#   6. Run the build command:
+#
+#           MRUBY_CONFIG=build_config/cross-mingw-winetest.rb rake test
+#
+#      If all goes well, you should now have Windows executables and a
+#      set of passing tests.
+#
+#
+#  Caveats:
+#
+#    1. This works by using a helper script that rewrites test output
+#       to make it look *nix-like and then handing it back to the test
+#       cases.  Some of the existing tests were (slightly) modified to
+#       make this easier but only for the 'full-core' gembox.  Other
+#       gems' bintests may or may not work with the helper script and
+#       may or may not be fixable by extending the script.
+#
+#   2.  MinGW and Wine are both complex and not very consistent so you
+#       will likely need to do some fiddling to get things to work.
+#
+#   3.  This script assumes you are running it on a *nix-style OS.
+#
+#   4.  I recommend building 64-bit targets only.  Building a 32-bit
+#       Windows binary with i686-w64-mingw32 seems to work (at least,
+#       it did for me) but the resulting executable failed a number of
+#       unit tests due to small errors in some floating point
+#       operations.  It's unclear if this indicates more serious problems.
+#
+
+
+MRuby::CrossBuild.new("cross-mingw-winetest") do |conf|
+  conf.toolchain :gcc
+
+  conf.host_target = "x86_64-w64-mingw32"
+
+  # Ubuntu 20
+  conf.cc.command = "#{conf.host_target}-gcc-posix"
+
+  # macOS+Wine from brew
+  #conf.cc.command = "#{conf.host_target}-gcc"
+
+  conf.linker.command = conf.cc.command
+  conf.archiver.command = "#{conf.host_target}-gcc-ar"
+  conf.exts.executable = ".exe"
+
+  # By default, we compile as static as possible to remove runtime
+  # MinGW dependencies; they are probably fixable but it gets
+  # complicated.
+  conf.cc.flags = ['-static']
+  conf.linker.flags += ['-static']
+
+  conf.test_runner do |t|
+    thisdir = File.absolute_path( File.dirname(__FILE__) )
+    t.command = File.join(thisdir, * %w{ helpers wine_runner.rb})
+  end
+
+  conf.gembox "full-core"
+
+  conf.enable_bintest
+  conf.enable_test
+end
diff --git a/build_config/helpers/wine_runner.rb b/build_config/helpers/wine_runner.rb
new file mode 100755
index 000000000..9a7eb46b0
--- /dev/null
+++ b/build_config/helpers/wine_runner.rb
@@ -0,0 +1,71 @@
+#!/usr/bin/env ruby
+
+# Wrapper for running tests for cross-compiled Windows builds in Wine.
+
+require 'open3'
+
+DOSROOT = 'z:'
+
+# Rewrite test output to replace DOS-isms with Unix-isms.
+def clean(output, stderr = false)
+  ends_with_newline = !!(output =~ /\n$/)
+  executable = ARGV[0].gsub(/\.exe\z/i, '')
+
+  # Fix line-ends
+  output = output.gsub(/\r\n/, "\n")
+
+  # Strip out Wine messages
+
+
+  results = output.split(/\n/).map do |line|
+    # Fix file paths
+    if line =~ /#{DOSROOT}\\/i
+      line.gsub!(/#{DOSROOT}([^:]*)/i) { |path|
+        path.gsub!(/^#{DOSROOT}/i, '')
+        path.gsub!(%r{\\}, '/')
+        path
+      }
+    end
+
+    # strip '.exe' off the end of the executable's name if needed
+    line.gsub!(/(#{Regexp.escape executable})\.exe/i, '\1')
+
+    line
+  end
+
+  result_text = results.join("\n")
+  result_text += "\n" if ends_with_newline
+  return result_text
+end
+
+
+def main
+  if ARGV.empty? || ARGV[0] =~ /^- (-?) (\?|help|h) $/x
+    puts "#{$0} <command-line>"
+    exit 0
+  end
+
+  # For simplicity, just read all of stdin into memory and pass that
+  # as an argument when invoking wine.  (Skipped if STDIN was not
+  # redirected.)
+  if !STDIN.tty?
+    input = STDIN.read
+  else
+    input = ""
+  end
+
+  # Disable all Wine messages so they don't interfere with the output
+  ENV['WINEDEBUG'] = 'err-all,warn-all,fixme-all,trace-all'
+
+  # Run the program in wine and capture the output
+  output, errormsg, status = Open3.capture3('wine', *ARGV, :stdin_data => input)
+
+  # Clean and print the results.
+  STDOUT.write clean(output)
+  STDERR.write clean(errormsg)
+
+  exit(status.exitstatus)
+end
+
+
+main()
diff --git a/lib/mruby/build.rb b/lib/mruby/build.rb
index 67267ab46..66005a6df 100644
--- a/lib/mruby/build.rb
+++ b/lib/mruby/build.rb
@@ -541,6 +541,23 @@ EOS
       end
     end
 
+    def run_bintest
+      puts ">>> Bintest #{name} <<<"
+      targets = @gems.select { |v| File.directory? "#{v.dir}/bintest" }.map { |v| filename v.dir }
+      targets << filename(".") if File.directory? "./bintest"
+      mrbc = @gems["mruby-bin-mrbc"] ? exefile("#{@build_dir}/bin/mrbc") : mrbcfile
+
+      emulator = @test_runner.command
+      emulator = @test_runner.shellquote(emulator) if emulator
+
+      env = {
+        "BUILD_DIR" => @build_dir,
+        "MRBCFILE" => mrbc,
+        "EMULATOR" => @test_runner.emulator,
+      }
+      sh env, "ruby test/bintest.rb#{verbose_flag} #{targets.join ' '}"
+    end
+
     protected
 
     def create_mrbc_build; end
diff --git a/lib/mruby/build/command.rb b/lib/mruby/build/command.rb
index c93d08ea7..31a595ef0 100644
--- a/lib/mruby/build/command.rb
+++ b/lib/mruby/build/command.rb
@@ -363,6 +363,11 @@ module MRuby
       @flags = []
     end
 
+    def emulator
+      return "" unless @command
+      return [@command, *@flags].map{|c| shellquote(c)}.join(' ')
+    end
+
     def run(testbinfile)
       puts "TEST for " + @build.name
       _run runner_options, { :flags => [flags, verbose_flag].flatten.join(' '), :infile => testbinfile }
diff --git a/mrbgems/mruby-bin-mrbc/bintest/mrbc.rb b/mrbgems/mruby-bin-mrbc/bintest/mrbc.rb
index f4d9208b3..90bbd123f 100644
--- a/mrbgems/mruby-bin-mrbc/bintest/mrbc.rb
+++ b/mrbgems/mruby-bin-mrbc/bintest/mrbc.rb
@@ -7,7 +7,7 @@ assert('Compiling multiple files without new line in last line. #2361') do
   b.write('module B; end')
   b.flush
   result = `#{cmd('mrbc')} -c -o #{out.path} #{a.path} #{b.path} 2>&1`
-  assert_equal "#{cmd('mrbc')}:#{a.path}:Syntax OK", result.chomp
+  assert_equal "#{cmd_bin('mrbc')}:#{a.path}:Syntax OK", result.chomp
   assert_equal 0, $?.exitstatus
 end
 
@@ -16,7 +16,7 @@ assert('parsing function with void argument') do
   a.write('f ()')
   a.flush
   result = `#{cmd('mrbc')} -c -o #{out.path} #{a.path} 2>&1`
-  assert_equal "#{cmd('mrbc')}:#{a.path}:Syntax OK", result.chomp
+  assert_equal "#{cmd_bin('mrbc')}:#{a.path}:Syntax OK", result.chomp
   assert_equal 0, $?.exitstatus
 end
 
diff --git a/mrbgems/mruby-bin-mruby/bintest/mruby.rb b/mrbgems/mruby-bin-mruby/bintest/mruby.rb
index bc25f18c1..a626a13cd 100644
--- a/mrbgems/mruby-bin-mruby/bintest/mruby.rb
+++ b/mrbgems/mruby-bin-mruby/bintest/mruby.rb
@@ -2,7 +2,7 @@ require 'tempfile'
 require 'open3'
 
 def assert_mruby(exp_out, exp_err, exp_success, args)
-  out, err, stat = Open3.capture3(cmd("mruby"), *args)
+  out, err, stat = Open3.capture3( *(cmd_list("mruby") + args))
   assert "assert_mruby" do
     assert_operator(exp_out, :===, out, "standard output")
     assert_operator(exp_err, :===, err, "standard error")
@@ -87,7 +87,7 @@ assert('mruby -e option (no code specified)') do
 end
 
 assert('mruby -h option') do
-  assert_mruby(/\AUsage: #{Regexp.escape cmd("mruby")} .*/m, "", true, %w[-h])
+  assert_mruby(/\AUsage: #{Regexp.escape cmd_bin("mruby")} .*/m, "", true, %w[-h])
 end
 
 assert('mruby -r option') do
diff --git a/test/bintest.rb b/test/bintest.rb
index a6888c9fb..773d61edc 100644
--- a/test/bintest.rb
+++ b/test/bintest.rb
@@ -3,13 +3,27 @@ require 'test/assert.rb'
 
 GEMNAME = ""
 
-def cmd(s)
+def cmd_list(s)
   path = s == "mrbc" ? ENV['MRBCFILE'] : "#{ENV['BUILD_DIR']}/bin/#{s}"
   path = path.sub(/\.exe\z/, "")
   if /mswin(?!ce)|mingw|bccwin/ =~ RbConfig::CONFIG['host_os']
     path = "#{path}.exe".tr("/", "\\")
   end
-  path
+
+  path_list = [path]
+
+  emu = ENV['EMULATOR']
+  path_list.unshift emu if emu && !emu.empty?
+
+  path_list
+end
+
+def cmd(s)
+  return cmd_list(s).join(' ')
+end
+
+def cmd_bin(s)
+  return cmd_list(s).pop
 end
 
 def shellquote(s)