Adds most of the toolsHEADmaster

4 files changed, 882 insertions, 0 deletions

diff --git a/v_windows/v/cmd/tools/modules/scripting/scripting.v b/v_windows/v/cmd/tools/modules/scripting/scripting.v
new file mode 100644
index 0000000..342b9b7
--- /dev/null
+++ b/v_windows/v/cmd/tools/modules/scripting/scripting.v
@@ -0,0 +1,183 @@
+module scripting
+
+import os
+import term
+import time
+
+const (
+	term_colors = term.can_show_color_on_stdout()
+)
+
+pub fn set_verbose(on bool) {
+	// setting a global here would be the obvious solution,
+	// but V does not have globals normally.
+	if on {
+		os.setenv('VERBOSE', '1', true)
+	} else {
+		os.unsetenv('VERBOSE')
+	}
+}
+
+pub fn cprint(omessage string) {
+	mut message := omessage
+	if scripting.term_colors {
+		message = term.cyan(message)
+	}
+	print(message)
+}
+
+pub fn cprint_strong(omessage string) {
+	mut message := omessage
+	if scripting.term_colors {
+		message = term.bright_green(message)
+	}
+	print(message)
+}
+
+pub fn cprintln(omessage string) {
+	cprint(omessage)
+	println('')
+}
+
+pub fn cprintln_strong(omessage string) {
+	cprint_strong(omessage)
+	println('')
+}
+
+pub fn verbose_trace(label string, message string) {
+	if os.getenv('VERBOSE').len > 0 {
+		slabel := '$time.now().format_ss_milli() $label'
+		cprintln('# ${slabel:-43s} : $message')
+	}
+}
+
+pub fn verbose_trace_strong(label string, omessage string) {
+	if os.getenv('VERBOSE').len > 0 {
+		slabel := '$time.now().format_ss_milli() $label'
+		mut message := omessage
+		if scripting.term_colors {
+			message = term.bright_green(message)
+		}
+		cprintln('# ${slabel:-43s} : $message')
+	}
+}
+
+pub fn verbose_trace_exec_result(x os.Result) {
+	if os.getenv('VERBOSE').len > 0 {
+		cprintln('#   cmd.exit_code : ${x.exit_code.str():-4s}  cmd.output:')
+		mut lnum := 1
+		lines := x.output.split_into_lines()
+		for oline in lines {
+			mut line := oline
+			if scripting.term_colors {
+				line = term.bright_green(line)
+			}
+			cprintln('# ${lnum:3d}: $line')
+			lnum++
+		}
+		cprintln('# ----------------------------------------------------------------------')
+	}
+}
+
+fn modfn(mname string, fname string) string {
+	return '${mname}.$fname'
+}
+
+pub fn chdir(path string) {
+	verbose_trace_strong(modfn(@MOD, @FN), 'cd $path')
+	os.chdir(path) or {
+		verbose_trace(modfn(@MOD, @FN), '## failed.')
+		return
+	}
+}
+
+pub fn mkdir(path string) ? {
+	verbose_trace_strong(modfn(@MOD, @FN), 'mkdir $path')
+	os.mkdir(path) or {
+		verbose_trace(modfn(@MOD, @FN), '## failed.')
+		return err
+	}
+}
+
+pub fn mkdir_all(path string) ? {
+	verbose_trace_strong(modfn(@MOD, @FN), 'mkdir -p $path')
+	os.mkdir_all(path) or {
+		verbose_trace(modfn(@MOD, @FN), '## failed.')
+		return err
+	}
+}
+
+pub fn rmrf(path string) {
+	verbose_trace_strong(modfn(@MOD, @FN), 'rm -rf $path')
+	if os.exists(path) {
+		if os.is_dir(path) {
+			os.rmdir_all(path) or { panic(err) }
+		} else {
+			os.rm(path) or { panic(err) }
+		}
+	}
+}
+
+// execute a command, and return a result, or an error, if it failed in any way.
+pub fn exec(cmd string) ?os.Result {
+	verbose_trace_strong(modfn(@MOD, @FN), cmd)
+	x := os.execute(cmd)
+	if x.exit_code != 0 {
+		verbose_trace(modfn(@MOD, @FN), '## failed.')
+		return error(x.output)
+	}
+	verbose_trace_exec_result(x)
+	return x
+}
+
+// run a command, tracing its results, and returning ONLY its output
+pub fn run(cmd string) string {
+	verbose_trace_strong(modfn(@MOD, @FN), cmd)
+	x := os.execute(cmd)
+	if x.exit_code < 0 {
+		verbose_trace(modfn(@MOD, @FN), '## failed.')
+		return ''
+	}
+	verbose_trace_exec_result(x)
+	if x.exit_code == 0 {
+		return x.output.trim_right('\r\n')
+	}
+	return ''
+}
+
+pub fn exit_0_status(cmd string) bool {
+	verbose_trace_strong(modfn(@MOD, @FN), cmd)
+	x := os.execute(cmd)
+	if x.exit_code < 0 {
+		verbose_trace(modfn(@MOD, @FN), '## failed.')
+		return false
+	}
+	verbose_trace_exec_result(x)
+	if x.exit_code == 0 {
+		return true
+	}
+	return false
+}
+
+pub fn tool_must_exist(toolcmd string) {
+	verbose_trace(modfn(@MOD, @FN), toolcmd)
+	if exit_0_status('type $toolcmd') {
+		return
+	}
+	eprintln('Missing tool: $toolcmd')
+	eprintln('Please try again after you install it.')
+	exit(1)
+}
+
+pub fn used_tools_must_exist(tools []string) {
+	for t in tools {
+		tool_must_exist(t)
+	}
+}
+
+pub fn show_sizes_of_files(files []string) {
+	for f in files {
+		size := os.file_size(f)
+		println('$size $f') // println('${size:10d} $f')
+	}
+}
diff --git a/v_windows/v/cmd/tools/modules/testing/common.v b/v_windows/v/cmd/tools/modules/testing/common.v
new file mode 100644
index 0000000..7f9de79
--- /dev/null
+++ b/v_windows/v/cmd/tools/modules/testing/common.v
@@ -0,0 +1,488 @@
+module testing
+
+import os
+import time
+import term
+import benchmark
+import sync.pool
+import v.pref
+import v.util.vtest
+
+const github_job = os.getenv('GITHUB_JOB')
+
+const show_start = os.getenv('VTEST_SHOW_START') == '1'
+
+const hide_skips = os.getenv('VTEST_HIDE_SKIP') == '1'
+
+const hide_oks = os.getenv('VTEST_HIDE_OK') == '1'
+
+pub struct TestSession {
+pub mut:
+	files         []string
+	skip_files    []string
+	vexe          string
+	vroot         string
+	vtmp_dir      string
+	vargs         string
+	failed        bool
+	benchmark     benchmark.Benchmark
+	rm_binaries   bool = true
+	silent_mode   bool
+	progress_mode bool
+	root_relative bool // used by CI runs, so that the output is stable everywhere
+	nmessages     chan LogMessage // many publishers, single consumer/printer
+	nmessage_idx  int      // currently printed message index
+	nprint_ended  chan int // read to block till printing ends, 1:1
+	failed_cmds   shared []string
+}
+
+enum MessageKind {
+	ok
+	fail
+	skip
+	info
+	sentinel
+}
+
+struct LogMessage {
+	message string
+	kind    MessageKind
+}
+
+pub fn (mut ts TestSession) add_failed_cmd(cmd string) {
+	lock ts.failed_cmds {
+		ts.failed_cmds << cmd
+	}
+}
+
+pub fn (mut ts TestSession) show_list_of_failed_tests() {
+	for i, cmd in ts.failed_cmds {
+		eprintln(term.failed('Failed command ${i + 1}:') + '    $cmd')
+	}
+}
+
+pub fn (mut ts TestSession) append_message(kind MessageKind, msg string) {
+	ts.nmessages <- LogMessage{
+		message: msg
+		kind: kind
+	}
+}
+
+pub fn (mut ts TestSession) print_messages() {
+	empty := term.header(' ', ' ')
+	mut print_msg_time := time.new_stopwatch()
+	for {
+		// get a message from the channel of messages to be printed:
+		mut rmessage := <-ts.nmessages
+		if rmessage.kind == .sentinel {
+			// a sentinel for stopping the printing thread
+			if !ts.silent_mode && ts.progress_mode {
+				eprintln('')
+			}
+			ts.nprint_ended <- 0
+			return
+		}
+		if rmessage.kind != .info {
+			ts.nmessage_idx++
+		}
+		msg := rmessage.message.replace_each([
+			'TMP1',
+			'${ts.nmessage_idx:1d}',
+			'TMP2',
+			'${ts.nmessage_idx:2d}',
+			'TMP3',
+			'${ts.nmessage_idx:3d}',
+			'TMP4',
+			'${ts.nmessage_idx:4d}',
+		])
+		is_ok := rmessage.kind == .ok
+		//
+		time_passed := print_msg_time.elapsed().seconds()
+		if time_passed > 10 && ts.silent_mode && is_ok {
+			// Even if OK tests are suppressed,
+			// show *at least* 1 result every 10 seconds,
+			// otherwise the CI can seem stuck ...
+			eprintln(msg)
+			print_msg_time.restart()
+			continue
+		}
+		if ts.progress_mode {
+			// progress mode, the last line is rewritten many times:
+			if is_ok && !ts.silent_mode {
+				print('\r$empty\r$msg')
+			} else {
+				// the last \n is needed, so SKIP/FAIL messages
+				// will not get overwritten by the OK ones
+				eprint('\r$empty\r$msg\n')
+			}
+			continue
+		}
+		if !ts.silent_mode || !is_ok {
+			// normal expanded mode, or failures in -silent mode
+			eprintln(msg)
+			continue
+		}
+	}
+}
+
+pub fn new_test_session(_vargs string, will_compile bool) TestSession {
+	mut skip_files := []string{}
+	if will_compile {
+		$if msvc {
+			skip_files << 'vlib/v/tests/const_comptime_eval_before_vinit_test.v' // _constructor used
+		}
+		$if solaris {
+			skip_files << 'examples/gg/gg2.v'
+			skip_files << 'examples/pico/pico.v'
+			skip_files << 'examples/sokol/fonts.v'
+			skip_files << 'examples/sokol/drawing.v'
+		}
+		$if macos {
+			skip_files << 'examples/database/mysql.v'
+			skip_files << 'examples/database/orm.v'
+			skip_files << 'examples/database/psql/customer.v'
+		}
+		$if windows {
+			skip_files << 'examples/database/mysql.v'
+			skip_files << 'examples/database/orm.v'
+			skip_files << 'examples/websocket/ping.v' // requires OpenSSL
+			skip_files << 'examples/websocket/client-server/client.v' // requires OpenSSL
+			skip_files << 'examples/websocket/client-server/server.v' // requires OpenSSL
+			$if tinyc {
+				skip_files << 'examples/database/orm.v' // try fix it
+			}
+		}
+		if testing.github_job != 'sokol-shaders-can-be-compiled' {
+			// These examples need .h files that are produced from the supplied .glsl files,
+			// using by the shader compiler tools in https://github.com/floooh/sokol-tools-bin/archive/pre-feb2021-api-changes.tar.gz
+			skip_files << 'examples/sokol/02_cubes_glsl/cube_glsl.v'
+			skip_files << 'examples/sokol/03_march_tracing_glsl/rt_glsl.v'
+			skip_files << 'examples/sokol/04_multi_shader_glsl/rt_glsl.v'
+			skip_files << 'examples/sokol/05_instancing_glsl/rt_glsl.v'
+			// Skip obj_viewer code in the CI
+			skip_files << 'examples/sokol/06_obj_viewer/show_obj.v'
+		}
+		if testing.github_job != 'ubuntu-tcc' {
+			skip_files << 'examples/c_interop_wkhtmltopdf.v' // needs installation of wkhtmltopdf from https://github.com/wkhtmltopdf/packaging/releases
+			// the ttf_test.v is not interactive, but needs X11 headers to be installed, which is done only on ubuntu-tcc for now
+			skip_files << 'vlib/x/ttf/ttf_test.v'
+			skip_files << 'vlib/vweb/vweb_app_test.v' // imports the `sqlite` module, which in turn includes sqlite3.h
+		}
+		if testing.github_job != 'audio-examples' {
+			skip_files << 'examples/sokol/sounds/melody.v'
+			skip_files << 'examples/sokol/sounds/wav_player.v'
+			skip_files << 'examples/sokol/sounds/simple_sin_tones.v'
+		}
+	}
+	vargs := _vargs.replace('-progress', '').replace('-progress', '')
+	vexe := pref.vexe_path()
+	vroot := os.dir(vexe)
+	new_vtmp_dir := setup_new_vtmp_folder()
+	if term.can_show_color_on_stderr() {
+		os.setenv('VCOLORS', 'always', true)
+	}
+	return TestSession{
+		vexe: vexe
+		vroot: vroot
+		skip_files: skip_files
+		vargs: vargs
+		vtmp_dir: new_vtmp_dir
+		silent_mode: _vargs.contains('-silent')
+		progress_mode: _vargs.contains('-progress')
+	}
+}
+
+pub fn (mut ts TestSession) init() {
+	ts.files.sort()
+	ts.benchmark = benchmark.new_benchmark_no_cstep()
+}
+
+pub fn (mut ts TestSession) add(file string) {
+	ts.files << file
+}
+
+pub fn (mut ts TestSession) test() {
+	// Ensure that .tmp.c files generated from compiling _test.v files,
+	// are easy to delete at the end, *without* affecting the existing ones.
+	current_wd := os.getwd()
+	if current_wd == os.wd_at_startup && current_wd == ts.vroot {
+		ts.root_relative = true
+	}
+	//
+	ts.init()
+	mut remaining_files := []string{}
+	for dot_relative_file in ts.files {
+		relative_file := dot_relative_file.replace('./', '')
+		file := os.real_path(relative_file)
+		$if windows {
+			if file.contains('sqlite') || file.contains('httpbin') {
+				continue
+			}
+		}
+		$if !macos {
+			if file.contains('customer') {
+				continue
+			}
+		}
+		$if msvc {
+			if file.contains('asm') {
+				continue
+			}
+		}
+		remaining_files << dot_relative_file
+	}
+	remaining_files = vtest.filter_vtest_only(remaining_files, fix_slashes: false)
+	ts.files = remaining_files
+	ts.benchmark.set_total_expected_steps(remaining_files.len)
+	mut pool_of_test_runners := pool.new_pool_processor(callback: worker_trunner)
+	// for handling messages across threads
+	ts.nmessages = chan LogMessage{cap: 10000}
+	ts.nprint_ended = chan int{cap: 0}
+	ts.nmessage_idx = 0
+	go ts.print_messages()
+	pool_of_test_runners.set_shared_context(ts)
+	pool_of_test_runners.work_on_pointers(unsafe { remaining_files.pointers() })
+	ts.benchmark.stop()
+	ts.append_message(.sentinel, '') // send the sentinel
+	_ := <-ts.nprint_ended // wait for the stop of the printing thread
+	eprintln(term.h_divider('-'))
+	// cleanup generated .tmp.c files after successfull tests:
+	if ts.benchmark.nfail == 0 {
+		if ts.rm_binaries {
+			os.rmdir_all(ts.vtmp_dir) or { panic(err) }
+		}
+	}
+	ts.show_list_of_failed_tests()
+}
+
+fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
+	mut ts := &TestSession(p.get_shared_context())
+	tmpd := ts.vtmp_dir
+	show_stats := '-stats' in ts.vargs.split(' ')
+	// tls_bench is used to format the step messages/timings
+	mut tls_bench := &benchmark.Benchmark(p.get_thread_context(idx))
+	if isnil(tls_bench) {
+		tls_bench = benchmark.new_benchmark_pointer()
+		tls_bench.set_total_expected_steps(ts.benchmark.nexpected_steps)
+		p.set_thread_context(idx, tls_bench)
+	}
+	tls_bench.no_cstep = true
+	dot_relative_file := p.get_item<string>(idx)
+	mut relative_file := dot_relative_file.replace('./', '')
+	mut cmd_options := [ts.vargs]
+	if relative_file.contains('global') && !ts.vargs.contains('fmt') {
+		cmd_options << ' -enable-globals'
+	}
+	if ts.root_relative {
+		relative_file = relative_file.replace(ts.vroot + os.path_separator, '')
+	}
+	file := os.real_path(relative_file)
+	normalised_relative_file := relative_file.replace('\\', '/')
+	// Ensure that the generated binaries will be stored in the temporary folder.
+	// Remove them after a test passes/fails.
+	fname := os.file_name(file)
+	generated_binary_fname := if os.user_os() == 'windows' {
+		fname.replace('.v', '.exe')
+	} else {
+		fname.replace('.v', '')
+	}
+	generated_binary_fpath := os.join_path(tmpd, generated_binary_fname)
+	if os.exists(generated_binary_fpath) {
+		if ts.rm_binaries {
+			os.rm(generated_binary_fpath) or { panic(err) }
+		}
+	}
+	if !ts.vargs.contains('fmt') {
+		cmd_options << ' -o "$generated_binary_fpath"'
+	}
+	cmd := '"$ts.vexe" ' + cmd_options.join(' ') + ' "$file"'
+	ts.benchmark.step()
+	tls_bench.step()
+	if relative_file.replace('\\', '/') in ts.skip_files {
+		ts.benchmark.skip()
+		tls_bench.skip()
+		if !testing.hide_skips {
+			ts.append_message(.skip, tls_bench.step_message_skip(normalised_relative_file))
+		}
+		return pool.no_result
+	}
+	if show_stats {
+		ts.append_message(.ok, term.h_divider('-'))
+		status := os.system(cmd)
+		if status == 0 {
+			ts.benchmark.ok()
+			tls_bench.ok()
+		} else {
+			ts.failed = true
+			ts.benchmark.fail()
+			tls_bench.fail()
+			ts.add_failed_cmd(cmd)
+			return pool.no_result
+		}
+	} else {
+		if testing.show_start {
+			ts.append_message(.info, '                 starting $relative_file ...')
+		}
+		r := os.execute(cmd)
+		if r.exit_code < 0 {
+			ts.failed = true
+			ts.benchmark.fail()
+			tls_bench.fail()
+			ts.append_message(.fail, tls_bench.step_message_fail(normalised_relative_file))
+			ts.add_failed_cmd(cmd)
+			return pool.no_result
+		}
+		if r.exit_code != 0 {
+			ts.failed = true
+			ts.benchmark.fail()
+			tls_bench.fail()
+			ending_newline := if r.output.ends_with('\n') { '\n' } else { '' }
+			ts.append_message(.fail, tls_bench.step_message_fail('$normalised_relative_file\n$r.output.trim_space()$ending_newline'))
+			ts.add_failed_cmd(cmd)
+		} else {
+			ts.benchmark.ok()
+			tls_bench.ok()
+			if !testing.hide_oks {
+				ts.append_message(.ok, tls_bench.step_message_ok(normalised_relative_file))
+			}
+		}
+	}
+	if os.exists(generated_binary_fpath) {
+		if ts.rm_binaries {
+			os.rm(generated_binary_fpath) or { panic(err) }
+		}
+	}
+	return pool.no_result
+}
+
+pub fn vlib_should_be_present(parent_dir string) {
+	vlib_dir := os.join_path(parent_dir, 'vlib')
+	if !os.is_dir(vlib_dir) {
+		eprintln('$vlib_dir is missing, it must be next to the V executable')
+		exit(1)
+	}
+}
+
+pub fn v_build_failing(zargs string, folder string) bool {
+	return v_build_failing_skipped(zargs, folder, [])
+}
+
+pub fn prepare_test_session(zargs string, folder string, oskipped []string, main_label string) TestSession {
+	vexe := pref.vexe_path()
+	parent_dir := os.dir(vexe)
+	vlib_should_be_present(parent_dir)
+	vargs := zargs.replace(vexe, '')
+	eheader(main_label)
+	if vargs.len > 0 {
+		eprintln('v compiler args: "$vargs"')
+	}
+	mut session := new_test_session(vargs, true)
+	files := os.walk_ext(os.join_path(parent_dir, folder), '.v')
+	mut mains := []string{}
+	mut skipped := oskipped.clone()
+	next_file: for f in files {
+		fnormalised := f.replace('\\', '/')
+		// NB: a `testdata` folder, is the preferred name of a folder, containing V code,
+		// that you *do not want* the test framework to find incidentally for various reasons,
+		// for example module import tests, or subtests, that are compiled/run by other parent tests
+		// in specific configurations, etc.
+		if fnormalised.contains('testdata/') || fnormalised.contains('modules/')
+			|| f.contains('preludes/') {
+			continue
+		}
+		$if windows {
+			// skip pico and process/command examples on windows
+			if fnormalised.ends_with('examples/pico/pico.v')
+				|| fnormalised.ends_with('examples/process/command.v') {
+				continue
+			}
+		}
+		c := os.read_file(f) or { panic(err) }
+		maxc := if c.len > 300 { 300 } else { c.len }
+		start := c[0..maxc]
+		if start.contains('module ') && !start.contains('module main') {
+			skipped_f := f.replace(os.join_path(parent_dir, ''), '')
+			skipped << skipped_f
+		}
+		for skip_prefix in oskipped {
+			if f.starts_with(skip_prefix) {
+				continue next_file
+			}
+		}
+		mains << f
+	}
+	session.files << mains
+	session.skip_files << skipped
+	return session
+}
+
+pub fn v_build_failing_skipped(zargs string, folder string, oskipped []string) bool {
+	main_label := 'Building $folder ...'
+	finish_label := 'building $folder'
+	mut session := prepare_test_session(zargs, folder, oskipped, main_label)
+	session.test()
+	eprintln(session.benchmark.total_message(finish_label))
+	return session.failed
+}
+
+pub fn build_v_cmd_failed(cmd string) bool {
+	res := os.execute(cmd)
+	if res.exit_code < 0 {
+		return true
+	}
+	if res.exit_code != 0 {
+		eprintln('')
+		eprintln(res.output)
+		return true
+	}
+	return false
+}
+
+pub fn building_any_v_binaries_failed() bool {
+	eheader('Building V binaries...')
+	eprintln('VFLAGS is: "' + os.getenv('VFLAGS') + '"')
+	vexe := pref.vexe_path()
+	parent_dir := os.dir(vexe)
+	vlib_should_be_present(parent_dir)
+	os.chdir(parent_dir) or { panic(err) }
+	mut failed := false
+	v_build_commands := ['$vexe -o v_g             -g  cmd/v', '$vexe -o v_prod_g  -prod -g  cmd/v',
+		'$vexe -o v_cg            -cg cmd/v', '$vexe -o v_prod_cg -prod -cg cmd/v',
+		'$vexe -o v_prod    -prod     cmd/v',
+	]
+	mut bmark := benchmark.new_benchmark()
+	for cmd in v_build_commands {
+		bmark.step()
+		if build_v_cmd_failed(cmd) {
+			bmark.fail()
+			failed = true
+			eprintln(bmark.step_message_fail('command: $cmd . See details above ^^^^^^^'))
+			eprintln('')
+			continue
+		}
+		bmark.ok()
+		if !testing.hide_oks {
+			eprintln(bmark.step_message_ok('command: $cmd'))
+		}
+	}
+	bmark.stop()
+	eprintln(term.h_divider('-'))
+	eprintln(bmark.total_message('building v binaries'))
+	return failed
+}
+
+pub fn eheader(msg string) {
+	eprintln(term.header_left(msg, '-'))
+}
+
+pub fn header(msg string) {
+	println(term.header_left(msg, '-'))
+}
+
+pub fn setup_new_vtmp_folder() string {
+	now := time.sys_mono_now()
+	new_vtmp_dir := os.join_path(os.temp_dir(), 'v', 'test_session_$now')
+	os.mkdir_all(new_vtmp_dir) or { panic(err) }
+	os.setenv('VTMP', new_vtmp_dir, true)
+	return new_vtmp_dir
+}
diff --git a/v_windows/v/cmd/tools/modules/vgit/vgit.v b/v_windows/v/cmd/tools/modules/vgit/vgit.v
new file mode 100644
index 0000000..efa2e8a
--- /dev/null
+++ b/v_windows/v/cmd/tools/modules/vgit/vgit.v
@@ -0,0 +1,197 @@
+module vgit
+
+import os
+import flag
+import scripting
+
+pub fn check_v_commit_timestamp_before_self_rebuilding(v_timestamp int) {
+	if v_timestamp >= 1561805697 {
+		return
+	}
+	eprintln('##################################################################')
+	eprintln('# WARNING: v self rebuilding, before 5b7a1e8 (2019-06-29 12:21)  #')
+	eprintln('#          required the v executable to be built *inside*        #')
+	eprintln('#          the toplevel compiler/ folder.                        #')
+	eprintln('#                                                                #')
+	eprintln('#          That is not supported by this tool.                   #')
+	eprintln('#          You will have to build it manually there.             #')
+	eprintln('##################################################################')
+}
+
+pub fn validate_commit_exists(commit string) {
+	if commit.len == 0 {
+		return
+	}
+	cmd := "git cat-file -t '$commit' "
+	if !scripting.exit_0_status(cmd) {
+		eprintln('Commit: "$commit" does not exist in the current repository.')
+		exit(3)
+	}
+}
+
+pub fn line_to_timestamp_and_commit(line string) (int, string) {
+	parts := line.split(' ')
+	return parts[0].int(), parts[1]
+}
+
+pub fn normalized_workpath_for_commit(workdir string, commit string) string {
+	nc := 'v_at_' + commit.replace('^', '_').replace('-', '_').replace('/', '_')
+	return os.real_path(workdir + os.path_separator + nc)
+}
+
+fn get_current_folder_commit_hash() string {
+	vline := scripting.run('git rev-list -n1 --timestamp HEAD')
+	_, v_commithash := line_to_timestamp_and_commit(vline)
+	return v_commithash
+}
+
+pub fn prepare_vc_source(vcdir string, cdir string, commit string) (string, string) {
+	scripting.chdir(cdir)
+	// Building a historic v with the latest vc is not always possible ...
+	// It is more likely, that the vc *at the time of the v commit*,
+	// or slightly before that time will be able to build the historic v:
+	vline := scripting.run('git rev-list -n1 --timestamp "$commit" ')
+	v_timestamp, v_commithash := line_to_timestamp_and_commit(vline)
+	scripting.verbose_trace(@FN, 'v_timestamp: $v_timestamp | v_commithash: $v_commithash')
+	check_v_commit_timestamp_before_self_rebuilding(v_timestamp)
+	scripting.chdir(vcdir)
+	scripting.run('git checkout --quiet master')
+	//
+	mut vccommit := ''
+	vcbefore_subject_match := scripting.run('git rev-list HEAD -n1 --timestamp --grep=${v_commithash[0..7]} ')
+	scripting.verbose_trace(@FN, 'vcbefore_subject_match: $vcbefore_subject_match')
+	if vcbefore_subject_match.len > 3 {
+		_, vccommit = line_to_timestamp_and_commit(vcbefore_subject_match)
+	} else {
+		scripting.verbose_trace(@FN, 'the v commit did not match anything in the vc log; try --timestamp instead.')
+		vcbefore := scripting.run('git rev-list HEAD -n1 --timestamp --before=$v_timestamp ')
+		_, vccommit = line_to_timestamp_and_commit(vcbefore)
+	}
+	scripting.verbose_trace(@FN, 'vccommit: $vccommit')
+	scripting.run('git checkout --quiet "$vccommit" ')
+	scripting.run('wc *.c')
+	scripting.chdir(cdir)
+	return v_commithash, vccommit
+}
+
+pub fn clone_or_pull(remote_git_url string, local_worktree_path string) {
+	// NB: after clone_or_pull, the current repo branch is === HEAD === master
+	if os.is_dir(local_worktree_path) && os.is_dir(os.join_path(local_worktree_path, '.git')) {
+		// Already existing ... Just pulling in this case is faster usually.
+		scripting.run('git -C "$local_worktree_path"  checkout --quiet master')
+		scripting.run('git -C "$local_worktree_path"  pull     --quiet ')
+	} else {
+		// Clone a fresh
+		scripting.run('git clone --quiet "$remote_git_url"  "$local_worktree_path" ')
+	}
+}
+
+pub struct VGitContext {
+pub:
+	cc          string = 'cc' // what compiler to use
+	workdir     string = '/tmp' // the base working folder
+	commit_v    string = 'master' // the commit-ish that needs to be prepared
+	path_v      string // where is the local working copy v repo
+	path_vc     string // where is the local working copy vc repo
+	v_repo_url  string // the remote v repo URL
+	vc_repo_url string // the remote vc repo URL
+pub mut:
+	// these will be filled by vgitcontext.compile_oldv_if_needed()
+	commit_v__hash string // the git commit of the v repo that should be prepared
+	commit_vc_hash string // the git commit of the vc repo, corresponding to commit_v__hash
+	vexename       string // v or v.exe
+	vexepath       string // the full absolute path to the prepared v/v.exe
+	vvlocation     string // v.v or compiler/ or cmd/v, depending on v version
+	make_fresh_tcc bool   // whether to do 'make fresh_tcc' before compiling an old V.
+}
+
+pub fn (mut vgit_context VGitContext) compile_oldv_if_needed() {
+	vgit_context.vexename = if os.user_os() == 'windows' { 'v.exe' } else { 'v' }
+	vgit_context.vexepath = os.real_path(os.join_path(vgit_context.path_v, vgit_context.vexename))
+	mut command_for_building_v_from_c_source := ''
+	mut command_for_selfbuilding := ''
+	if 'windows' == os.user_os() {
+		command_for_building_v_from_c_source = '$vgit_context.cc -std=c99 -municode -w -o cv.exe  "$vgit_context.path_vc/v_win.c" '
+		command_for_selfbuilding = './cv.exe -o $vgit_context.vexename {SOURCE}'
+	} else {
+		command_for_building_v_from_c_source = '$vgit_context.cc -std=gnu11 -w -o cv "$vgit_context.path_vc/v.c"  -lm -lpthread'
+		command_for_selfbuilding = './cv -o $vgit_context.vexename {SOURCE}'
+	}
+	scripting.chdir(vgit_context.workdir)
+	clone_or_pull(vgit_context.v_repo_url, vgit_context.path_v)
+	clone_or_pull(vgit_context.vc_repo_url, vgit_context.path_vc)
+	scripting.chdir(vgit_context.path_v)
+	scripting.run('git checkout --quiet $vgit_context.commit_v')
+	if os.is_dir(vgit_context.path_v) && os.exists(vgit_context.vexepath) {
+		// already compiled, so no need to compile v again
+		vgit_context.commit_v__hash = get_current_folder_commit_hash()
+		return
+	}
+	v_commithash, vccommit_before := prepare_vc_source(vgit_context.path_vc, vgit_context.path_v,
+		'HEAD')
+	vgit_context.commit_v__hash = v_commithash
+	vgit_context.commit_vc_hash = vccommit_before
+	if os.exists('cmd/v') {
+		vgit_context.vvlocation = 'cmd/v'
+	} else {
+		vgit_context.vvlocation = if os.exists('v.v') { 'v.v' } else { 'compiler' }
+	}
+	if os.is_dir(vgit_context.path_v) && os.exists(vgit_context.vexepath) {
+		// already compiled, so no need to compile v again
+		return
+	}
+	// Recompilation is needed. Just to be sure, clean up everything first.
+	scripting.run('git clean -xf')
+	if vgit_context.make_fresh_tcc {
+		scripting.run('make fresh_tcc')
+	}
+	scripting.run(command_for_building_v_from_c_source)
+	build_cmd := command_for_selfbuilding.replace('{SOURCE}', vgit_context.vvlocation)
+	scripting.run(build_cmd)
+	// At this point, there exists a file vgit_context.vexepath
+	// which should be a valid working V executable.
+}
+
+pub struct VGitOptions {
+pub mut:
+	workdir     string // the working folder (typically /tmp), where the tool will write
+	v_repo_url  string // the url of the V repository. It can be a local folder path, if you want to eliminate network operations...
+	vc_repo_url string // the url of the vc repository. It can be a local folder path, if you want to eliminate network operations...
+	show_help   bool   // whether to show the usage screen
+	verbose     bool   // should the tool be much more verbose
+}
+
+pub fn add_common_tool_options(mut context VGitOptions, mut fp flag.FlagParser) []string {
+	tdir := os.temp_dir()
+	context.workdir = os.real_path(fp.string('workdir', `w`, context.workdir, 'A writable base folder. Default: $tdir'))
+	context.v_repo_url = fp.string('vrepo', 0, context.v_repo_url, 'The url of the V repository. You can clone it locally too. See also --vcrepo below.')
+	context.vc_repo_url = fp.string('vcrepo', 0, context.vc_repo_url, 'The url of the vc repository. You can clone it
+${flag.space}beforehand, and then just give the local folder
+${flag.space}path here. That will eliminate the network ops
+${flag.space}done by this tool, which is useful, if you want
+${flag.space}to script it/run it in a restrictive vps/docker.
+')
+	context.show_help = fp.bool('help', `h`, false, 'Show this help screen.')
+	context.verbose = fp.bool('verbose', `v`, false, 'Be more verbose.')
+	if context.show_help {
+		println(fp.usage())
+		exit(0)
+	}
+	if context.verbose {
+		scripting.set_verbose(true)
+	}
+	if os.is_dir(context.v_repo_url) {
+		context.v_repo_url = os.real_path(context.v_repo_url)
+	}
+	if os.is_dir(context.vc_repo_url) {
+		context.vc_repo_url = os.real_path(context.vc_repo_url)
+	}
+	commits := fp.finalize() or {
+		eprintln('Error: $err')
+		exit(1)
+	}
+	for commit in commits {
+		validate_commit_exists(commit)
+	}
+	return commits
+}
diff --git a/v_windows/v/cmd/tools/modules/vhelp/vhelp.v b/v_windows/v/cmd/tools/modules/vhelp/vhelp.v
new file mode 100644
index 0000000..347ba75
--- /dev/null
+++ b/v_windows/v/cmd/tools/modules/vhelp/vhelp.v
@@ -0,0 +1,14 @@
+module vhelp
+
+import os
+
+pub fn show_topic(topic string) {
+	vexe := os.real_path(os.getenv('VEXE'))
+	vroot := os.dir(vexe)
+	target_topic := os.join_path(vroot, 'cmd', 'v', 'help', '${topic}.txt')
+	content := os.read_file(target_topic) or {
+		eprintln('Unknown topic: $topic')
+		exit(1)
+	}
+	println(content)
+}