From d7049ae2dadf410c7b79b69056fb972d5e4ac09d Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 8 Mar 2021 20:52:13 +0200
Subject: [PATCH] os: deprecate os.exec (returning ?os.Result), in favour of
 os.execute, which returns os.Result (#8974)

---
 .github/workflows/ci.yml                      |  4 +-
 CHANGELOG.md                                  |  1 +
 cmd/tools/fast/fast.v                         |  6 +-
 cmd/tools/fast/fast_job.v                     | 10 ++-
 cmd/tools/gen_vc.v                            | 13 +--
 cmd/tools/modules/scripting/scripting.v       | 13 ++-
 cmd/tools/modules/testing/common.v            |  8 +-
 cmd/tools/oldv.v                              | 12 ++-
 cmd/tools/repeat.v                            | 11 ++-
 cmd/tools/test_if_v_test_system_works.v       |  4 +-
 cmd/tools/vcheck-md.v                         |  7 +-
 cmd/tools/vcreate.v                           |  3 +-
 cmd/tools/vdoctor.v                           | 89 +++++++++----------
 cmd/tools/vfmt.v                              |  5 +-
 cmd/tools/vpm.v                               | 21 ++---
 cmd/tools/vrepl.v                             |  7 +-
 cmd/tools/vself.v                             |  2 +-
 cmd/tools/vsetup-freetype.v                   | 11 ++-
 cmd/tools/vsymlink.v                          |  2 +-
 cmd/tools/vtest-parser.v                      | 14 ++-
 cmd/tools/vup.v                               | 44 ++++-----
 cmd/tools/vvet/vet_test.v                     |  5 +-
 cmd/v/help/help_test.v                        |  6 +-
 examples/dynamic_library_loading/use_test.v   |  8 +-
 vlib/builtin/bare/syscallwrapper_test.v       | 14 +--
 vlib/gg/text_rendering.v                      | 12 ++-
 vlib/os/os.v                                  | 19 ++++
 vlib/os/os_nix.c.v                            | 14 +--
 vlib/os/os_windows.c.v                        | 25 ++++--
 vlib/term/term_nix.c.v                        |  9 +-
 vlib/v/builder/cc.v                           | 76 ++++------------
 vlib/v/builder/compile.v                      |  6 +-
 vlib/v/builder/js.v                           |  7 +-
 vlib/v/builder/msvc.v                         | 16 ++--
 vlib/v/compiler_errors_test.v                 |  7 +-
 vlib/v/fmt/fmt_keep_test.v                    |  5 +-
 vlib/v/gen/js/jsgen_test.v                    |  2 +-
 vlib/v/gen/x64/tests/x64_test.v               | 17 ++--
 vlib/v/live/executable/reloader.v             |  5 +-
 vlib/v/tests/array_init_test.v                | 79 ++++++++--------
 vlib/v/tests/blank_ident_test.v               | 21 ++++-
 vlib/v/tests/goto_test.v                      |  7 +-
 vlib/v/tests/inout/compiler_test.v            | 13 +--
 .../vmodules_overrides_test.v                 |  4 +-
 vlib/v/tests/named_break_continue_test.v      | 37 +++++---
 vlib/v/tests/profile/profile_test.v           |  2 +-
 vlib/v/tests/repl/repl_test.v                 |  9 +-
 vlib/v/tests/repl/runner/runner.v             | 10 ++-
 vlib/v/tests/run_v_code_from_stdin_test.v     |  2 +-
 vlib/v/tests/valgrind/valgrind_test.v         | 12 +--
 vlib/v/util/diff.v                            | 17 +++-
 vlib/v/util/util.v                            | 14 +--
 52 files changed, 423 insertions(+), 344 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1c68319bb0..b1d298f885 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1015,5 +1015,5 @@ jobs:
         run: git clone --depth 1 https://github.com/vlang/vab
       - name: Build vab
         run: cd vab; ../v ./vab.v ; cd ..
-      - name: Build vab with -prod
-        run: cd vab; ../v -prod ./vab.v ; cd ..
+      - name: Build vab with
+        run: cd vab; ../v ./vab.v ; cd ..
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5bee0cd6ea..e884c78018 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -29,6 +29,7 @@ from local variables.
 - Support for compile time environment variables via `$env('ENV_VAR')`.
 - Allow method declaration of `==` and `<` operators and auto generate `!=`, `>`, `<=` and `>=`.
 - support `dump(expr)`, i.e. tracing of both the location, name and value of an expression
+- deprecate os.exec in favour of os.executable() which does *NOT* return an option, when the command was not found
 
 ## V 0.2.1
 *30 Dec 2020*
diff --git a/cmd/tools/fast/fast.v b/cmd/tools/fast/fast.v
index 3d061a54ea..9baa19fe74 100644
--- a/cmd/tools/fast/fast.v
+++ b/cmd/tools/fast/fast.v
@@ -50,7 +50,7 @@ fn main() {
 	date := time.unix(commit_date.int())
 	mut out := os.create('table.html') ?
 	// Place the new row on top
-	table =
+	table = 
 		'<tr>
 		<td>$date.format()</td>
 		<td><a target=_blank href="https://github.com/vlang/v/commit/$commit">$commit</a></td>
@@ -81,7 +81,7 @@ fn main() {
 }
 
 fn exec(s string) string {
-	e := os.exec(s) or { panic(err) }
+	e := os.execute_or_panic(s)
 	return e.output.trim_right('\r\n')
 }
 
@@ -111,7 +111,7 @@ fn measure(cmd string, description string) int {
 }
 
 fn measure_steps(vdir string) (int, int, int) {
-	resp := os.exec('$vdir/vprod -o v.c -show-timings $vdir/cmd/v') or { panic(err) }
+	resp := os.execute_or_panic('$vdir/vprod -o v.c -show-timings $vdir/cmd/v')
 	lines := resp.output.split_into_lines()
 	if lines.len != 3 {
 		return 0, 0, 0
diff --git a/cmd/tools/fast/fast_job.v b/cmd/tools/fast/fast_job.v
index ed72a7431e..01c5a0bb69 100644
--- a/cmd/tools/fast/fast_job.v
+++ b/cmd/tools/fast/fast_job.v
@@ -17,20 +17,22 @@ fn main() {
 		return
 	}
 	for {
-		os.exec('git pull --rebase') or {
+		res_pull := os.execute('git pull --rebase')
+		if res_pull.exit_code != 0 {
 			println('failed to git pull. uncommitted changes?')
 			return
 		}
 		// println('running fast')
-		resp := os.exec('./fast') or {
-			println(err)
+		resp := os.execute('./fast')
+		if resp.exit_code < 0 {
+			println(resp.output)
 			return
 		}
 		if resp.exit_code != 0 {
 			println('resp != 0, skipping')
 		} else {
 			os.chdir('website')
-			os.exec('git checkout gh-pages') ?
+			os.execute_or_panic('git checkout gh-pages')
 			os.cp('../index.html', 'index.html') ?
 			os.system('git commit -am "update benchmark"')
 			os.system('git push origin gh-pages')
diff --git a/cmd/tools/gen_vc.v b/cmd/tools/gen_vc.v
index 82cb8d855b..f924dbd828 100644
--- a/cmd/tools/gen_vc.v
+++ b/cmd/tools/gen_vc.v
@@ -43,13 +43,13 @@ const (
 	// version
 	app_version          = '0.1.2'
 	// description
-	app_description      = "This tool regenerates V\'s bootstrap .c files every time the V master branch is updated."
+	app_description      = "This tool regenerates V's bootstrap .c files every time the V master branch is updated."
 	// assume something went wrong if file size less than this
 	too_short_file_limit = 5000
 	// create a .c file for these os's
 	vc_build_oses        = [
 		'nix',
-		/* all nix based os */
+		// all nix based os
 		'windows',
 	]
 )
@@ -188,8 +188,8 @@ fn parse_flags(mut fp flag.FlagParser) FlagOptions {
 		work_dir: fp.string('work-dir', 0, work_dir, 'gen_vc working directory')
 		purge: fp.bool('purge', 0, false, 'force purge the local repositories')
 		port: fp.int('port', 0, server_port, 'port for web server to listen on')
-		log_to: fp.string('log-to', 0, log_to, "log to is \'file\' or \'terminal\'")
-		log_file: fp.string('log-file', 0, log_file, "log file to use when log-to is \'file\'")
+		log_to: fp.string('log-to', 0, log_to, "log to is 'file' or 'terminal'")
+		log_file: fp.string('log-file', 0, log_file, "log file to use when log-to is 'file'")
 		dry_run: fp.bool('dry-run', 0, dry_run, 'when specified dont push anything to remote repo')
 		force: fp.bool('force', 0, false, 'force update even if already up to date')
 	}
@@ -318,9 +318,10 @@ fn (mut gen_vc GenVC) command_execute(cmd string, dry bool) string {
 		return gen_vc.command_execute_dry(cmd)
 	}
 	gen_vc.logger.info('cmd: $cmd')
-	r := os.exec(cmd) or {
+	r := os.execute(cmd)
+	if r.exit_code < 0 {
 		gen_vc.logger.error('$err_msg_cmd_x: "$cmd" could not start.')
-		gen_vc.logger.error(err.msg)
+		gen_vc.logger.error(r.output)
 		// something went wrong, better start fresh next time
 		gen_vc.purge_repos()
 		gen_vc.gen_error = true
diff --git a/cmd/tools/modules/scripting/scripting.v b/cmd/tools/modules/scripting/scripting.v
index 19d7c0ae36..f9589118f7 100644
--- a/cmd/tools/modules/scripting/scripting.v
+++ b/cmd/tools/modules/scripting/scripting.v
@@ -60,19 +60,23 @@ pub fn rmrf(path string) {
 	}
 }
 
+// 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(@FN, cmd)
-	x := os.exec(cmd) or {
+	x := os.execute(cmd)
+	if x.exit_code != 0 {
 		verbose_trace(@FN, '## failed.')
-		return err
+		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(@FN, cmd)
-	x := os.exec(cmd) or {
+	x := os.execute(cmd)
+	if x.exit_code < 0 {
 		verbose_trace(@FN, '## failed.')
 		return ''
 	}
@@ -85,7 +89,8 @@ pub fn run(cmd string) string {
 
 pub fn exit_0_status(cmd string) bool {
 	verbose_trace(@FN, cmd)
-	x := os.exec(cmd) or {
+	x := os.execute(cmd)
+	if x.exit_code < 0 {
 		verbose_trace(@FN, '## failed.')
 		return false
 	}
diff --git a/cmd/tools/modules/testing/common.v b/cmd/tools/modules/testing/common.v
index 3cf4e846bf..70fdeb6e0d 100644
--- a/cmd/tools/modules/testing/common.v
+++ b/cmd/tools/modules/testing/common.v
@@ -287,7 +287,8 @@ fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
 		if testing.show_start {
 			ts.append_message(.info, '                 starting $relative_file ...')
 		}
-		r := os.exec(cmd) or {
+		r := os.execute(cmd)
+		if r.exit_code < 0 {
 			ts.failed = true
 			ts.benchmark.fail()
 			tls_bench.fail()
@@ -387,7 +388,10 @@ pub fn v_build_failing_skipped(zargs string, folder string, oskipped []string) b
 }
 
 pub fn build_v_cmd_failed(cmd string) bool {
-	res := os.exec(cmd) or { return true }
+	res := os.execute(cmd)
+	if res.exit_code < 0 {
+		return true
+	}
 	if res.exit_code != 0 {
 		eprintln('')
 		eprintln(res.output)
diff --git a/cmd/tools/oldv.v b/cmd/tools/oldv.v
index afdbb8f121..d9f99733bb 100644
--- a/cmd/tools/oldv.v
+++ b/cmd/tools/oldv.v
@@ -29,10 +29,10 @@ const (
 
 struct Context {
 mut:
-	vgo           vgit.VGitOptions
-	commit_v      string = 'master'
+	vgo      vgit.VGitOptions
+	commit_v string = 'master'
 	// the commit from which you want to produce a working v compiler (this may be a commit-ish too)
-	commit_vc     string = 'master'
+	commit_vc string = 'master'
 	// this will be derived from commit_v
 	commit_v_hash string // this will be filled from the commit-ish commit_v using rev-list. It IS a commit hash.
 	path_v        string // the full path to the v folder inside workdir.
@@ -40,7 +40,7 @@ mut:
 	cmd_to_run    string // the command that you want to run *in* the oldv repo
 	cc            string = 'cc'
 	// the C compiler to use for bootstrapping.
-	cleanup       bool // should the tool run a cleanup first
+	cleanup bool // should the tool run a cleanup first
 }
 
 fn (mut c Context) compile_oldv_if_needed() {
@@ -100,9 +100,7 @@ fn main() {
 	scripting.cprintln('#     v commit hash: $context.commit_v_hash')
 	scripting.cprintln('#   checkout folder: $context.path_v')
 	if context.cmd_to_run.len > 0 {
-		cmdres := os.exec(context.cmd_to_run) or {
-			panic(err)
-		}
+		cmdres := os.execute_or_panic(context.cmd_to_run)
 		scripting.cprintln('#           command: ${context.cmd_to_run:-34s} exit code: ${cmdres.exit_code:-4d}  result:')
 		println(cmdres.output)
 		exit(cmdres.exit_code)
diff --git a/cmd/tools/repeat.v b/cmd/tools/repeat.v
index 3553a9e82d..c5a19e9c98 100644
--- a/cmd/tools/repeat.v
+++ b/cmd/tools/repeat.v
@@ -42,7 +42,7 @@ mut:
 }
 
 struct Aints {
-	values  []int
+	values []int
 mut:
 	imin    int
 	imax    int
@@ -206,7 +206,10 @@ fn (mut context Context) run() {
 				for i in 1 .. context.warmup + 1 {
 					print('${context.cgoback}warming up run: ${i:4}/${context.warmup:-4} for ${cmd:-50s} took ${duration:6} ms ...')
 					mut sw := time.new_stopwatch({})
-					os.exec(cmd) or { continue }
+					res := os.execute(cmd)
+					if res.exit_code != 0 {
+						continue
+					}
 					duration = int(sw.elapsed().milliseconds())
 				}
 				run_warmups++
@@ -225,8 +228,8 @@ fn (mut context Context) run() {
 					eprintln('${i:10} non 0 exit code for cmd: $cmd')
 					continue
 				}
-				context.results[icmd].outputs <<
-					res.output.trim_right('\r\n').replace('\r\n', '\n').split('\n')
+				context.results[icmd].outputs << res.output.trim_right('\r\n').replace('\r\n',
+					'\n').split('\n')
 				context.results[icmd].timings << duration
 				sum += duration
 				runs++
diff --git a/cmd/tools/test_if_v_test_system_works.v b/cmd/tools/test_if_v_test_system_works.v
index 11596cee27..a86abd8b99 100644
--- a/cmd/tools/test_if_v_test_system_works.v
+++ b/cmd/tools/test_if_v_test_system_works.v
@@ -55,7 +55,7 @@ fn main() {
 
 fn check_ok(cmd string) string {
 	println('>   check_ok cmd: $cmd')
-	res := os.exec(cmd) or { panic(err) }
+	res := os.execute(cmd)
 	if res.exit_code != 0 {
 		eprintln('>   check_ok failed.\n$res.output')
 		exit(1)
@@ -65,7 +65,7 @@ fn check_ok(cmd string) string {
 
 fn check_fail(cmd string) string {
 	println('> check_fail cmd: $cmd')
-	res := os.exec(cmd) or { panic(err) }
+	res := os.execute(cmd)
 	if res.exit_code == 0 {
 		eprintln('> check_fail succeeded, but it should have failed.\n$res.output')
 		exit(1)
diff --git a/cmd/tools/vcheck-md.v b/cmd/tools/vcheck-md.v
index 59698486a0..2b30efd22b 100644
--- a/cmd/tools/vcheck-md.v
+++ b/cmd/tools/vcheck-md.v
@@ -211,7 +211,10 @@ fn (mut f MDFile) debug() {
 }
 
 fn cmdexecute(cmd string) int {
-	res := os.exec(cmd) or { return 1 }
+	res := os.execute(cmd)
+	if res.exit_code < 0 {
+		return 1
+	}
 	if res.exit_code != 0 {
 		eprint(res.output)
 	}
@@ -219,7 +222,7 @@ fn cmdexecute(cmd string) int {
 }
 
 fn silent_cmdexecute(cmd string) int {
-	res := os.exec(cmd) or { return 1 }
+	res := os.execute(cmd)
 	return res.exit_code
 }
 
diff --git a/cmd/tools/vcreate.v b/cmd/tools/vcreate.v
index e6a069adde..ec3cc155b4 100644
--- a/cmd/tools/vcreate.v
+++ b/cmd/tools/vcreate.v
@@ -81,7 +81,8 @@ fn (c &Create) write_main(new bool) {
 fn (c &Create) create_git_repo(dir string) {
 	// Create Git Repo and .gitignore file
 	if !os.is_dir('$dir/.git') {
-		os.exec('git init $dir') or {
+		res := os.execute('git init $dir')
+		if res.exit_code != 0 {
 			cerror('Unable to create git repo')
 			exit(4)
 		}
diff --git a/cmd/tools/vdoctor.v b/cmd/tools/vdoctor.v
index 644f2a8fba..6effed5873 100644
--- a/cmd/tools/vdoctor.v
+++ b/cmd/tools/vdoctor.v
@@ -30,9 +30,9 @@ fn (mut a App) collect_info() {
 		arch_details << 'little endian'
 	}
 	if os_kind == 'macos' {
-		arch_details << a.cmd({
+		arch_details << a.cmd(
 			command: 'sysctl -n machdep.cpu.brand_string'
-		})
+		)
 	}
 	if os_kind == 'linux' {
 		mut cpu_details := ''
@@ -48,16 +48,16 @@ fn (mut a App) collect_info() {
 		arch_details << cpu_details
 	}
 	if os_kind == 'windows' {
-		arch_details << a.cmd({
+		arch_details << a.cmd(
 			command: 'wmic cpu get name /format:table'
 			line: 1
-		})
+		)
 	}
 	//
 	mut os_details := ''
-	wsl_check := a.cmd({
+	wsl_check := a.cmd(
 		command: 'cat /proc/sys/kernel/osrelease'
-	})
+	)
 	if os_kind == 'linux' {
 		os_details = a.get_linux_os_name()
 		if 'hypervisor' in a.cpu_info('flags') {
@@ -75,26 +75,27 @@ fn (mut a App) collect_info() {
 			os_details += ' (WSL)'
 		}
 		// From https://unix.stackexchange.com/a/14346
-		if a.cmd(command: '[ "$(awk \'\$5=="/" {print \$1}\' </proc/1/mountinfo)" != "$(awk \'\$5=="/" {print \$1}\' </proc/$$/mountinfo)" ] ; echo \$?') == '0' {
+		awk_cmd := '[ "$(awk \'\$5=="/" {print \$1}\' </proc/1/mountinfo)" != "$(awk \'\$5=="/" {print \$1}\' </proc/$$/mountinfo)" ] ; echo \$?'
+		if a.cmd(command: awk_cmd) == '0' {
 			os_details += ' (chroot)'
 		}
 	} else if os_kind == 'macos' {
 		mut details := []string{}
-		details << a.cmd({
+		details << a.cmd(
 			command: 'sw_vers -productName'
-		})
-		details << a.cmd({
+		)
+		details << a.cmd(
 			command: 'sw_vers -productVersion'
-		})
-		details << a.cmd({
+		)
+		details << a.cmd(
 			command: 'sw_vers -buildVersion'
-		})
+		)
 		os_details = details.join(', ')
 	} else if os_kind == 'windows' {
-		wmic_info := a.cmd({
+		wmic_info := a.cmd(
 			command: 'wmic os get * /format:value'
 			line: -1
-		})
+		)
 		p := a.parse(wmic_info, '=')
 		caption, build_number, os_arch := p['caption'], p['buildnumber'], p['osarchitecture']
 		os_details = '$caption v$build_number $os_arch'
@@ -104,15 +105,15 @@ fn (mut a App) collect_info() {
 	}
 	a.line('OS', '$os_kind, $os_details')
 	a.line('Processor', arch_details.join(', '))
-	a.line('CC version', a.cmd({
+	a.line('CC version', a.cmd(
 		command: 'cc --version'
-	}))
+	))
 	a.println('')
 	getwd := os.getwd()
 	vmodules := os.vmodules_dir()
 	vexe := os.getenv('VEXE')
 	vroot := os.dir(vexe)
-	os.chdir(vroot)	
+	os.chdir(vroot)
 	a.line('getwd', getwd)
 	a.line('vmodules', vmodules)
 	a.line('vroot', vroot)
@@ -130,9 +131,9 @@ fn (mut a App) collect_info() {
 		a.line('env VFLAGS', '"$vflags"')
 	}
 	a.println('')
-	a.line('Git version', a.cmd({
+	a.line('Git version', a.cmd(
 		command: 'git --version'
-	}))
+	))
 	a.line('Git vroot status', a.git_info())
 	a.line('.git/config present', os.is_file('.git/config').str())
 	//
@@ -145,7 +146,8 @@ struct CmdConfig {
 }
 
 fn (mut a App) cmd(c CmdConfig) string {
-	x := os.exec(c.command) or {
+	x := os.execute(c.command)
+	if x.exit_code < 0 {
 		return 'N/A'
 	}
 	if x.exit_code == 0 {
@@ -189,9 +191,7 @@ fn (mut a App) get_linux_os_name() string {
 				if !os.is_file('/etc/os-release') {
 					continue
 				}
-				lines := os.read_file('/etc/os-release') or {
-					continue
-				}
+				lines := os.read_file('/etc/os-release') or { continue }
 				vals := a.parse(lines, '=')
 				if vals['PRETTY_NAME'] == '' {
 					continue
@@ -200,24 +200,24 @@ fn (mut a App) get_linux_os_name() string {
 				break
 			}
 			'lsb_release' {
-				exists := a.cmd({
+				exists := a.cmd(
 					command: 'type lsb_release'
-				})
+				)
 				if exists.starts_with('Error') {
 					continue
 				}
-				os_details = a.cmd({
+				os_details = a.cmd(
 					command: 'lsb_release -d -s'
-				})
+				)
 				break
 			}
 			'kernel' {
 				if !os.is_file('/proc/version') {
 					continue
 				}
-				os_details = a.cmd({
+				os_details = a.cmd(
 					command: 'cat /proc/version'
-				})
+				)
 				break
 			}
 			'uname' {
@@ -235,22 +235,23 @@ fn (mut a App) cpu_info(key string) string {
 	if a.cached_cpuinfo.len > 0 {
 		return a.cached_cpuinfo[key]
 	}
-	info := os.exec('cat /proc/cpuinfo') or {
-		return a.cached_cpuinfo[key]
+	info := os.execute('cat /proc/cpuinfo')
+	if info.exit_code != 0 {
+		return '`cat /proc/cpuinfo` could not run'
 	}
 	a.cached_cpuinfo = a.parse(info.output, ':')
 	return a.cached_cpuinfo[key]
 }
 
 fn (mut a App) git_info() string {
-	mut out := a.cmd({
+	mut out := a.cmd(
 		command: 'git -C . describe --abbrev=8 --dirty --always --tags'
-	}).trim_space()
-	os.exec('git -C . remote add V_REPO https://github.com/vlang/v') or { } // ignore failure (i.e. remote exists)
-	os.exec('git -C . fetch V_REPO') or { }
-	commit_count := a.cmd({
+	).trim_space()
+	os.execute('git -C . remote add V_REPO https://github.com/vlang/v') // ignore failure (i.e. remote exists)
+	os.execute('git -C . fetch V_REPO')
+	commit_count := a.cmd(
 		command: 'git rev-list @{0}...V_REPO/master --right-only --count'
-	}).int()
+	).int()
 	if commit_count > 0 {
 		out += ' ($commit_count commit(s) behind V master)'
 	}
@@ -262,12 +263,12 @@ fn (mut a App) report_tcc_version(tccfolder string) {
 		a.line(tccfolder, 'N/A')
 		return
 	}
-	tcc_branch_name := a.cmd({
+	tcc_branch_name := a.cmd(
 		command: 'git -C $tccfolder rev-parse --abbrev-ref HEAD'
-	})
-	tcc_commit := a.cmd({
+	)
+	tcc_commit := a.cmd(
 		command: 'git -C $tccfolder describe --abbrev=8 --dirty --always --tags'
-	})
+	)
 	a.line('$tccfolder status', '$tcc_branch_name $tcc_commit')
 }
 
@@ -278,9 +279,7 @@ fn (mut a App) report_info() {
 }
 
 fn is_writable_dir(path string) bool {
-	res := os.is_writable_folder(path) or {
-		false
-	}
+	res := os.is_writable_folder(path) or { false }
 	return res
 }
 
diff --git a/cmd/tools/vfmt.v b/cmd/tools/vfmt.v
index 01b06c5047..1d10e5ea29 100644
--- a/cmd/tools/vfmt.v
+++ b/cmd/tools/vfmt.v
@@ -117,7 +117,8 @@ fn main() {
 		if foptions.is_verbose {
 			eprintln('vfmt worker_cmd: $worker_cmd')
 		}
-		worker_result := os.exec(worker_cmd) or {
+		worker_result := os.execute(worker_cmd)
+		if worker_result.exit_code != 0 {
 			errors++
 			continue
 		}
@@ -277,7 +278,7 @@ fn (foptions &FormatOptions) post_process_file(file string, formatted_file_path
 }
 
 fn (f FormatOptions) str() string {
-	return
+	return 
 		'FormatOptions{ is_l: $f.is_l, is_w: $f.is_w, is_diff: $f.is_diff, is_verbose: $f.is_verbose,' +
 		' is_all: $f.is_all, is_worker: $f.is_worker, is_debug: $f.is_debug, is_noerror: $f.is_noerror,' +
 		' is_verify: $f.is_verify" }'
diff --git a/cmd/tools/vpm.v b/cmd/tools/vpm.v
index f196e52d5d..27510bde11 100644
--- a/cmd/tools/vpm.v
+++ b/cmd/tools/vpm.v
@@ -193,13 +193,7 @@ fn vpm_install(module_names []string) {
 		vcs_install_cmd := supported_vcs_install_cmds[vcs]
 		cmd := '$vcs_install_cmd "$mod.url" "$final_module_path"'
 		verbose_println('      command: $cmd')
-		cmdres := os.exec(cmd) or {
-			errors++
-			println('Could not install module "$name" to "$final_module_path" .')
-			verbose_println('Error command: $cmd')
-			verbose_println('Error details: $err')
-			continue
-		}
+		cmdres := os.execute(cmd)
 		if cmdres.exit_code != 0 {
 			errors++
 			println('Failed installing module "$name" to "$final_module_path" .')
@@ -232,13 +226,7 @@ fn vpm_update(m []string) {
 		vcs := vcs_used_in_dir(final_module_path) or { continue }
 		vcs_cmd := supported_vcs_update_cmds[vcs[0]]
 		verbose_println('    command: $vcs_cmd')
-		vcs_res := os.exec('$vcs_cmd') or {
-			errors++
-			println('Could not update module "$name".')
-			verbose_println('Error command: $vcs_cmd')
-			verbose_println('Error details:\n$err')
-			continue
-		}
+		vcs_res := os.execute('$vcs_cmd')
 		if vcs_res.exit_code != 0 {
 			errors++
 			println('Failed updating module "$name".')
@@ -265,9 +253,10 @@ fn get_outdated() ?[]string {
 		vcs_cmd_steps := supported_vcs_outdated_steps[vcs[0]]
 		mut outputs := []string{}
 		for step in vcs_cmd_steps {
-			res := os.exec(step) or {
+			res := os.execute(step)
+			if res.exit_code < 0 {
 				verbose_println('Error command: $step')
-				verbose_println('Error details:\n$err')
+				verbose_println('Error details:\n$res.output')
 				return error('Error while checking latest commits for "$name".')
 			}
 			if vcs[0] == 'hg' {
diff --git a/cmd/tools/vrepl.v b/cmd/tools/vrepl.v
index 0c8754f9aa..bad89e66aa 100644
--- a/cmd/tools/vrepl.v
+++ b/cmd/tools/vrepl.v
@@ -381,9 +381,10 @@ fn repl_run_vfile(file string) ?os.Result {
 	$if trace_repl_temp_files ? {
 		eprintln('>> repl_run_vfile file: $file')
 	}
-	s := os.exec('"$vexe" -repl run "$file"') or {
-		rerror(err.msg)
-		return err
+	s := os.execute('"$vexe" -repl run "$file"')
+	if s.exit_code < 0 {
+		rerror(s.output)
+		return error(s.output)
 	}
 	return s
 }
diff --git a/cmd/tools/vself.v b/cmd/tools/vself.v
index 9bf7269332..a21de12c95 100644
--- a/cmd/tools/vself.v
+++ b/cmd/tools/vself.v
@@ -32,7 +32,7 @@ fn main() {
 }
 
 fn compile(vroot string, cmd string) {
-	result := os.exec(cmd) or { panic(err) }
+	result := os.execute_or_panic(cmd)
 	if result.exit_code != 0 {
 		eprintln('cannot compile to `$vroot`: \n$result.output')
 		exit(1)
diff --git a/cmd/tools/vsetup-freetype.v b/cmd/tools/vsetup-freetype.v
index 0d4b33f14e..c17ee6746a 100644
--- a/cmd/tools/vsetup-freetype.v
+++ b/cmd/tools/vsetup-freetype.v
@@ -3,16 +3,21 @@ module main
 import os
 import v.pref
 
+const freetype_repo_url = 'https://github.com/ubawurinna/freetype-windows-binaries'
+
+const freetype_folder = os.join_path('thirdparty', 'freetype')
+
 fn main() {
 	$if windows {
 		println('Setup freetype...')
 		vroot := os.dir(pref.vexe_path())
 		os.chdir(vroot)
-		if os.is_dir('./thirdparty/freetype') {
+		if os.is_dir(freetype_folder) {
 			println('Thirdparty "freetype" is already installed.')
 		} else {
-			s := os.exec('git clone --depth=1 https://github.com/ubawurinna/freetype-windows-binaries ./thirdparty/freetype/') or {
-				panic(err)
+			s := os.execute('git clone --depth=1 $freetype_repo_url $freetype_folder')
+			if s.exit_code != 0 {
+				panic(s.output)
 			}
 			println(s.output)
 			println('Thirdparty "freetype" installed successfully.')
diff --git a/cmd/tools/vsymlink.v b/cmd/tools/vsymlink.v
index 881da93d57..3c058c152d 100644
--- a/cmd/tools/vsymlink.v
+++ b/cmd/tools/vsymlink.v
@@ -31,7 +31,7 @@ fn setup_symlink_unix(vexe string) {
 		}
 		link_path = link_dir + '/v'
 	}
-	ret := os.exec('ln -sf $vexe $link_path') or { panic(err) }
+	ret := os.execute_or_panic('ln -sf $vexe $link_path')
 	if ret.exit_code == 0 {
 		println('Symlink "$link_path" has been created')
 	} else {
diff --git a/cmd/tools/vtest-parser.v b/cmd/tools/vtest-parser.v
index d3a21671cb..c6c7b2b556 100644
--- a/cmd/tools/vtest-parser.v
+++ b/cmd/tools/vtest-parser.v
@@ -13,11 +13,10 @@ const (
 	support_color = term.can_show_color_on_stderr() && term.can_show_color_on_stdout()
 	ecode_timeout = 101
 	ecode_memout  = 102
-	ecode_exec    = 103
 	ecode_details = map{
-		'101': 'too slow'
-		'102': 'too memory hungry'
-		'103': 'worker executable not found'
+		-1:  'worker executable not found'
+		101: 'too slow'
+		102: 'too memory hungry'
 	}
 )
 
@@ -217,10 +216,7 @@ fn (mut context Context) process_whole_file_in_worker(path string) (int, int) {
 		context.cut_index = i // needed for the progress bar
 		cmd := '"$context.myself" $verbosity --worker --timeout_ms ${context.timeout_ms:5} --cut_index ${i:5} --path "$path" '
 		context.log(cmd)
-		res := os.exec(cmd) or { os.Result{
-			output: err.msg
-			exit_code: ecode_exec
-		} }
+		mut res := os.execute(cmd)
 		context.log('worker exit_code: $res.exit_code | worker output:\n$res.output')
 		if res.exit_code != 0 {
 			fails++
@@ -236,7 +232,7 @@ fn (mut context Context) process_whole_file_in_worker(path string) (int, int) {
 			err := if is_panic {
 				red('parser failure: panic')
 			} else {
-				red('parser failure: crash, ${ecode_details[res.exit_code.str()]}')
+				red('parser failure: crash, ${ecode_details[res.exit_code]}')
 			}
 			path_to_line := bold('$path:$line:$col:')
 			err_line := last_line.trim_left('\t')
diff --git a/cmd/tools/vup.v b/cmd/tools/vup.v
index 7ff83b8f69..d019c50e59 100644
--- a/cmd/tools/vup.v
+++ b/cmd/tools/vup.v
@@ -41,7 +41,7 @@ fn main() {
 		app.backup('cmd/tools/vup.exe')
 	}
 	app.recompile_v()
-	os.exec('"$app.vexe" cmd/tools/vup.v') or { panic(err) }
+	os.execute_or_panic('"$app.vexe" cmd/tools/vup.v')
 	app.show_current_v_version()
 }
 
@@ -71,14 +71,13 @@ fn (app App) recompile_v() {
 	opts := if app.is_prod { '-prod' } else { '' }
 	vself := '"$app.vexe" $opts self'
 	app.vprintln('> recompiling v itself with `$vself` ...')
-	if self_result := os.exec(vself) {
-		if self_result.exit_code == 0 {
-			println(self_result.output.trim_space())
-			return
-		} else {
-			app.vprintln('`$vself` failed, running `make`...')
-			app.vprintln(self_result.output.trim_space())
-		}
+	self_result := os.execute(vself)
+	if self_result.exit_code == 0 {
+		println(self_result.output.trim_space())
+		return
+	} else {
+		app.vprintln('`$vself` failed, running `make`...')
+		app.vprintln(self_result.output.trim_space())
 	}
 	app.make(vself)
 }
@@ -88,19 +87,19 @@ fn (app App) make(vself string) {
 	$if windows {
 		make = 'make.bat'
 	}
-	make_result := os.exec(make) or { panic(err) }
+	make_result := os.execute_or_panic(make)
 	app.vprintln(make_result.output)
 }
 
 fn (app App) show_current_v_version() {
-	if vout := os.exec('"$app.vexe" version') {
+	vout := os.execute('"$app.vexe" version')
+	if vout.exit_code >= 0 {
 		mut vversion := vout.output.trim_space()
 		if vout.exit_code == 0 {
 			latest_v_commit := vversion.split(' ').last().all_after('.')
-			if latest_v_commit_time := os.exec('git show -s --format=%ci $latest_v_commit') {
-				if latest_v_commit_time.exit_code == 0 {
-					vversion += ', timestamp: ' + latest_v_commit_time.output.trim_space()
-				}
+			latest_v_commit_time := os.execute('git show -s --format=%ci $latest_v_commit')
+			if latest_v_commit_time.exit_code == 0 {
+				vversion += ', timestamp: ' + latest_v_commit_time.output.trim_space()
 			}
 		}
 		println('Current V version:')
@@ -118,10 +117,11 @@ fn (app App) backup(file string) {
 
 fn (app App) git_command(command string) {
 	app.vprintln('git_command: git $command')
-	git_result := os.exec('git $command') or {
+	git_result := os.execute('git $command')
+	if git_result.exit_code < 0 {
 		app.get_git()
 		// Try it again with (maybe) git installed
-		os.exec('git $command') or { panic(err) }
+		os.execute_or_panic('git $command')
 	}
 	if git_result.exit_code != 0 {
 		eprintln(git_result.output)
@@ -134,13 +134,15 @@ fn (app App) get_git() {
 	$if windows {
 		println('Downloading git 32 bit for Windows, please wait.')
 		// We'll use 32 bit because maybe someone out there is using 32-bit windows
-		os.exec('bitsadmin.exe /transfer "vgit" https://github.com/git-for-windows/git/releases/download/v2.30.0.windows.2/Git-2.30.0.2-32-bit.exe "$os.getwd()/git32.exe"') or {
+		res_download := os.execute('bitsadmin.exe /transfer "vgit" https://github.com/git-for-windows/git/releases/download/v2.30.0.windows.2/Git-2.30.0.2-32-bit.exe "$os.getwd()/git32.exe"')
+		if res_download.exit_code != 0 {
 			eprintln('Unable to install git automatically: please install git manually')
-			panic(err)
+			panic(res_download.output)
 		}
-		os.exec('$os.getwd()/git32.exe') or {
+		res_git32 := os.execute('$os.getwd()/git32.exe')
+		if res_git32.exit_code != 0 {
 			eprintln('Unable to install git automatically: please install git manually')
-			panic(err)
+			panic(res_git32.output)
 		}
 	} $else { // Probably some kind of *nix, usually need to get using a package manager.
 		eprintln("error: Install `git` using your system's package manager")
diff --git a/cmd/tools/vvet/vet_test.v b/cmd/tools/vvet/vet_test.v
index 6209f9168c..fd62ce93e6 100644
--- a/cmd/tools/vvet/vet_test.v
+++ b/cmd/tools/vvet/vet_test.v
@@ -34,7 +34,10 @@ fn check_path(vexe string, dir string, tests []string) int {
 		program := path
 		print(path + ' ')
 		// -force is needed so that `v vet` would not skip the regression files
-		res := os.exec('$vexe vet -force $program') or { panic(err) }
+		res := os.execute('$vexe vet -force $program')
+		if res.exit_code < 0 {
+			panic(res.output)
+		}
 		mut expected := os.read_file(program.replace('.vv', '') + '.out') or { panic(err) }
 		expected = clean_line_endings(expected)
 		found := clean_line_endings(res.output)
diff --git a/cmd/v/help/help_test.v b/cmd/v/help/help_test.v
index 78cf6d6e4b..ac395b6577 100644
--- a/cmd/v/help/help_test.v
+++ b/cmd/v/help/help_test.v
@@ -2,21 +2,21 @@ import os
 
 fn test_help() {
 	vexe := os.getenv('VEXE')
-	res := os.exec('"$vexe" help') or { panic(err) }
+	res := os.execute('"$vexe" help')
 	assert res.exit_code == 0
 	assert res.output.starts_with('V is a tool for managing V source code.')
 }
 
 fn test_help_as_short_option() {
 	vexe := os.getenv('VEXE')
-	res := os.exec('"$vexe" -h') or { panic(err) }
+	res := os.execute('"$vexe" -h')
 	assert res.exit_code == 0
 	assert res.output.starts_with('V is a tool for managing V source code.')
 }
 
 fn test_help_as_long_option() {
 	vexe := os.getenv('VEXE')
-	res := os.exec('"$vexe" --help') or { panic(err) }
+	res := os.execute('"$vexe" --help')
 	assert res.exit_code == 0
 	assert res.output.starts_with('V is a tool for managing V source code.')
 }
diff --git a/examples/dynamic_library_loading/use_test.v b/examples/dynamic_library_loading/use_test.v
index 5e36b05be7..e468cc1d28 100644
--- a/examples/dynamic_library_loading/use_test.v
+++ b/examples/dynamic_library_loading/use_test.v
@@ -40,13 +40,13 @@ fn test_can_compile_main_program() {
 fn v_compile(vopts string) os.Result {
 	cmd := '"$vexe" -showcc $vopts'
 	dump(cmd)
-	res := os.exec(cmd) or { panic(err) }
+	res := os.execute_or_panic(cmd)
 	dump(res)
 	// assert res.exit_code == 0
-	$if !windows {
-		os.system('ls -al $cfolder')
-	} $else {
+	$if windows {
 		os.system('dir $cfolder /a')
+	} $else {
+		os.system('ls -al $cfolder')
 	}
 	return res
 }
diff --git a/vlib/builtin/bare/syscallwrapper_test.v b/vlib/builtin/bare/syscallwrapper_test.v
index b293978c8e..0f80b05f2f 100644
--- a/vlib/builtin/bare/syscallwrapper_test.v
+++ b/vlib/builtin/bare/syscallwrapper_test.v
@@ -1,22 +1,24 @@
 import os
 
 fn test_syscallwrappers() {
-	if true { return }
+	if true {
+		return
+	}
 	$if linux {
 		$if x64 {
 			exe := os.executable()
 			vdir := os.dir(exe)
 			if vdir.len > 1 {
-				dot_checks := vdir + "/.checks"
+				dot_checks := vdir + '/.checks'
 				assert os.is_dir(dot_checks)
 
 				os.chdir(dot_checks)
-				checks_v := "checks.v"
+				checks_v := 'checks.v'
 				assert os.exists(checks_v)
-				rc := os.exec("v run $checks_v") or { panic(err) }
-				assert !rc.output.contains("V panic: An assertion failed.")
-				assert !rc.output.contains("failed")
+				rc := os.execute_or_panic('v run $checks_v')
 				assert rc.exit_code == 0
+				assert !rc.output.contains('V panic: An assertion failed.')
+				assert !rc.output.contains('failed')
 			} else {
 				panic("Can't find test directory")
 			}
diff --git a/vlib/gg/text_rendering.v b/vlib/gg/text_rendering.v
index d3678e9a0f..2ee791d7a3 100644
--- a/vlib/gg/text_rendering.v
+++ b/vlib/gg/text_rendering.v
@@ -107,8 +107,11 @@ fn new_ft(c FTConfig) ?&FT {
 			return none
 		}
 	}
-	bold_path := if c.custom_bold_font_path != '' { c.custom_bold_font_path } else { get_font_path_variant(c.font_path,
-			.bold) }
+	bold_path := if c.custom_bold_font_path != '' {
+		c.custom_bold_font_path
+	} else {
+		get_font_path_variant(c.font_path, .bold)
+	}
 	bytes_bold := os.read_bytes(bold_path) or {
 		debug_font_println('failed to load font "$bold_path"')
 		bytes
@@ -290,7 +293,10 @@ pub fn system_font_path() string {
 			}
 		}
 	}
-	s := os.exec('fc-list') or { panic('failed to fetch system fonts') }
+	s := os.execute('fc-list')
+	if s.exit_code != 0 {
+		panic('failed to fetch system fonts')
+	}
 	system_fonts := s.output.split('\n')
 	for line in system_fonts {
 		for font in fonts {
diff --git a/vlib/os/os.v b/vlib/os/os.v
index b2011fe351..a06b61caa0 100644
--- a/vlib/os/os.v
+++ b/vlib/os/os.v
@@ -596,3 +596,22 @@ pub mut:
 	version  string
 	machine  string
 }
+
+[deprecated: 'use os.execute or os.execute_or_panic instead']
+pub fn exec(cmd string) ?Result {
+	res := execute(cmd)
+	if res.exit_code < 0 {
+		return error_with_code(res.output, -1)
+	}
+	return res
+}
+
+pub fn execute_or_panic(cmd string) Result {
+	res := execute(cmd)
+	if res.exit_code != 0 {
+		eprintln('failed    cmd: $cmd')
+		eprintln('failed   code: $res.exit_code')
+		panic(res.output)
+	}
+	return res
+}
diff --git a/vlib/os/os_nix.c.v b/vlib/os/os_nix.c.v
index 368113adc6..b99f5f348b 100644
--- a/vlib/os/os_nix.c.v
+++ b/vlib/os/os_nix.c.v
@@ -156,15 +156,18 @@ pub fn mkdir(path string) ?bool {
 	return true
 }
 
-// exec starts the specified command, waits for it to complete, and returns its output.
-pub fn exec(cmd string) ?Result {
+// execute starts the specified command, waits for it to complete, and returns its output.
+pub fn execute(cmd string) Result {
 	// if cmd.contains(';') || cmd.contains('&&') || cmd.contains('||') || cmd.contains('\n') {
-	// return error(';, &&, || and \\n are not allowed in shell commands')
+	// return Result{ exit_code: -1, output: ';, &&, || and \\n are not allowed in shell commands' }
 	// }
 	pcmd := '$cmd 2>&1'
 	f := vpopen(pcmd)
 	if isnil(f) {
-		return error('exec("$cmd") failed')
+		return Result{
+			exit_code: -1
+			output: 'exec("$cmd") failed'
+		}
 	}
 	buf := [4096]byte{}
 	mut res := strings.new_builder(1024)
@@ -177,9 +180,6 @@ pub fn exec(cmd string) ?Result {
 	soutput := res.str()
 	// res.free()
 	exit_code := vpclose(f)
-	if exit_code == 127 {
-		return error_with_code(soutput, 127)
-	}
 	return Result{
 		exit_code: exit_code
 		output: soutput
diff --git a/vlib/os/os_windows.c.v b/vlib/os/os_windows.c.v
index b9945d8110..88bbd550b7 100644
--- a/vlib/os/os_windows.c.v
+++ b/vlib/os/os_windows.c.v
@@ -221,10 +221,13 @@ pub fn get_error_msg(code int) string {
 	return unsafe { string_from_wide(ptr_text) }
 }
 
-// exec starts the specified command, waits for it to complete, and returns its output.
-pub fn exec(cmd string) ?Result {
+// execute starts the specified command, waits for it to complete, and returns its output.
+pub fn execute(cmd string) Result {
 	if cmd.contains(';') || cmd.contains('&&') || cmd.contains('||') || cmd.contains('\n') {
-		return error(';, &&, || and \\n are not allowed in shell commands')
+		return Result{
+			exit_code: -1
+			output: ';, &&, || and \\n are not allowed in shell commands'
+		}
 	}
 	mut child_stdin := &u32(0)
 	mut child_stdout_read := &u32(0)
@@ -237,14 +240,20 @@ pub fn exec(cmd string) ?Result {
 	if !create_pipe_ok {
 		error_num := int(C.GetLastError())
 		error_msg := get_error_msg(error_num)
-		return error_with_code('exec failed (CreatePipe): $error_msg', error_num)
+		return Result{
+			exit_code: error_num
+			output: 'exec failed (CreatePipe): $error_msg'
+		}
 	}
 	set_handle_info_ok := C.SetHandleInformation(child_stdout_read, C.HANDLE_FLAG_INHERIT,
 		0)
 	if !set_handle_info_ok {
 		error_num := int(C.GetLastError())
 		error_msg := get_error_msg(error_num)
-		return error_with_code('exec failed (SetHandleInformation): $error_msg', error_num)
+		return Result{
+			exit_code: error_num
+			output: 'exec failed (SetHandleInformation): $error_msg'
+		}
 	}
 	proc_info := ProcessInformation{}
 	start_info := StartupInfo{
@@ -264,8 +273,10 @@ pub fn exec(cmd string) ?Result {
 	if !create_process_ok {
 		error_num := int(C.GetLastError())
 		error_msg := get_error_msg(error_num)
-		return error_with_code('exec failed (CreateProcess) with code $error_num: $error_msg cmd: $cmd',
-			error_num)
+		return Result{
+			exit_code: error_num
+			output: 'exec failed (CreateProcess) with code $error_num: $error_msg cmd: $cmd'
+		}
 	}
 	C.CloseHandle(child_stdin)
 	C.CloseHandle(child_stdout_write)
diff --git a/vlib/term/term_nix.c.v b/vlib/term/term_nix.c.v
index 6dab16ae4c..ce96ca15c5 100644
--- a/vlib/term/term_nix.c.v
+++ b/vlib/term/term_nix.c.v
@@ -35,8 +35,9 @@ pub fn get_cursor_position() Coord {
 	}
 	// TODO: use termios.h, C.tcgetattr & C.tcsetattr directly,
 	// instead of using `stty`
-	oldsettings := os.exec('stty -g') or {
-		os.Result{}
+	mut oldsettings := os.execute('stty -g')
+	if oldsettings.exit_code < 0 {
+		oldsettings = os.Result{}
 	}
 	os.system('stty -echo -icanon time 0')
 	print('\033[6n')
@@ -91,7 +92,9 @@ pub fn set_terminal_title(title string) bool {
 	if is_atty(1) <= 0 || os.getenv('TERM') == 'dumb' {
 		return true
 	}
-	print('\033]0;${title}\007')
+	print('\033]0')
+	print(title)
+	print('\007')
 	return true
 }
 
diff --git a/vlib/v/builder/cc.v b/vlib/v/builder/cc.v
index cde45d1a00..771b33363b 100644
--- a/vlib/v/builder/cc.v
+++ b/vlib/v/builder/cc.v
@@ -47,7 +47,8 @@ fn (mut v Builder) find_win_cc() ? {
 	$if !windows {
 		return none
 	}
-	os.exec('$v.pref.ccompiler -v') or {
+	ccompiler_version_res := os.execute('$v.pref.ccompiler -v')
+	if ccompiler_version_res.exit_code != 0 {
 		if v.pref.is_verbose {
 			println('$v.pref.ccompiler not found, looking for msvc...')
 		}
@@ -57,7 +58,8 @@ fn (mut v Builder) find_win_cc() ? {
 			}
 			vpath := os.dir(pref.vexe_path())
 			thirdparty_tcc := os.join_path(vpath, 'thirdparty', 'tcc', 'tcc.exe')
-			os.exec('$thirdparty_tcc -v') or {
+			tcc_version_res := os.execute('$thirdparty_tcc -v')
+			if tcc_version_res.exit_code != 0 {
 				if v.pref.is_verbose {
 					println('tcc not found')
 				}
@@ -209,15 +211,14 @@ fn (mut v Builder) setup_ccompiler_options(ccompiler string) {
 	ccoptions.guessed_compiler = v.pref.ccompiler
 	if ccoptions.guessed_compiler == 'cc' && v.pref.is_prod {
 		// deliberately guessing only for -prod builds for performance reasons
-		if ccversion := os.exec('cc --version') {
-			if ccversion.exit_code == 0 {
-				if ccversion.output.contains('This is free software;')
-					&& ccversion.output.contains('Free Software Foundation, Inc.') {
-					ccoptions.guessed_compiler = 'gcc'
-				}
-				if ccversion.output.contains('clang version ') {
-					ccoptions.guessed_compiler = 'clang'
-				}
+		ccversion := os.execute('cc --version')
+		if ccversion.exit_code == 0 {
+			if ccversion.output.contains('This is free software;')
+				&& ccversion.output.contains('Free Software Foundation, Inc.') {
+				ccoptions.guessed_compiler = 'gcc'
+			}
+			if ccversion.output.contains('clang version ') {
+				ccoptions.guessed_compiler = 'clang'
 			}
 		}
 	}
@@ -528,9 +529,7 @@ fn (mut v Builder) cc() {
 		mut ccompiler := v.pref.ccompiler
 		if v.pref.os == .ios {
 			ios_sdk := if v.pref.is_ios_simulator { 'iphonesimulator' } else { 'iphoneos' }
-			ios_sdk_path_res := os.exec('xcrun --sdk $ios_sdk --show-sdk-path') or {
-				panic("Couldn't find iphonesimulator")
-			}
+			ios_sdk_path_res := os.execute_or_panic('xcrun --sdk $ios_sdk --show-sdk-path')
 			mut isysroot := ios_sdk_path_res.output.replace('\n', '')
 			ccompiler = 'xcrun --sdk iphoneos clang -isysroot $isysroot'
 		}
@@ -635,12 +634,7 @@ fn (mut v Builder) cc() {
 		// Run
 		ccompiler_label := 'C ${os.file_name(ccompiler):3}'
 		util.timing_start(ccompiler_label)
-		res := os.exec(cmd) or {
-			os.Result{
-				exit_code: 111
-				output: 'C compilation failed.\n$err.msg'
-			}
-		}
+		res := os.execute(cmd)
 		util.timing_measure(ccompiler_label)
 		if v.pref.show_c_output {
 			v.show_c_compiler_output(res)
@@ -694,28 +688,6 @@ fn (mut v Builder) cc() {
 		}
 		break
 	}
-	// Link it if we are cross compiling and need an executable
-	/*
-	if v.os == .linux && !linux_host && v.pref.build_mode != .build {
-		v.out_name = v.out_name.replace('.o', '')
-		obj_file := v.out_name + '.o'
-		println('linux obj_file=$obj_file out_name=$v.out_name')
-		ress := os.exec('/usr/local/Cellar/llvm/8.0.0/bin/ld.lld --sysroot=$sysroot ' +
-		'-v -o $v.out_name ' +
-		'-m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 ' +
-		'/usr/lib/x86_64-linux-gnu/crt1.o ' +
-		'$sysroot/lib/x86_64-linux-gnu/libm-2.28.a ' +
-		'/usr/lib/x86_64-linux-gnu/crti.o ' +
-		obj_file +
-		' /usr/lib/x86_64-linux-gnu/libc.so ' +
-		'/usr/lib/x86_64-linux-gnu/crtn.o') or {
-			verror(err.msg)
-			return
-		}
-		println(ress.output)
-		println('linux cross compilation done. resulting binary: "$v.out_name"')
-	}
-	*/
 	if v.pref.compress {
 		$if windows {
 			println('-compress does not work on Windows for now')
@@ -794,12 +766,7 @@ fn (mut b Builder) cc_linux_cross() {
 	if b.pref.show_cc {
 		println(cc_cmd)
 	}
-	cc_res := os.exec(cc_cmd) or {
-		os.Result{
-			exit_code: 1
-			output: 'no `cc` command found'
-		}
-	}
+	cc_res := os.execute(cc_cmd)
 	if cc_res.exit_code != 0 {
 		println('Cross compilation for Linux failed (first step, cc). Make sure you have clang installed.')
 		verror(cc_res.output)
@@ -817,14 +784,11 @@ fn (mut b Builder) cc_linux_cross() {
 	if b.pref.show_cc {
 		println(linker_cmd)
 	}
-	res := os.exec(linker_cmd) or {
-		println('Cross compilation for Linux failed (second step, lld).')
-		verror(err.msg)
-		return
-	}
+	res := os.execute(linker_cmd)
 	if res.exit_code != 0 {
 		println('Cross compilation for Linux failed (second step, lld).')
 		verror(res.output)
+		return
 	}
 	println(b.pref.out_name + ' has been successfully compiled')
 }
@@ -982,11 +946,7 @@ fn (mut v Builder) build_thirdparty_obj_file(path string, moduleflags []cflag.CF
 	$if trace_thirdparty_obj_files ? {
 		println('>>> build_thirdparty_obj_files cmd: $cmd')
 	}
-	res := os.exec(cmd) or {
-		eprintln('exec failed for thirdparty object build cmd:\n$cmd')
-		verror(err.msg)
-		return
-	}
+	res := os.execute(cmd)
 	os.chdir(current_folder)
 	if res.exit_code != 0 {
 		eprintln('failed thirdparty object build cmd:\n$cmd')
diff --git a/vlib/v/builder/compile.v b/vlib/v/builder/compile.v
index dd33228f0a..ea51093a7b 100644
--- a/vlib/v/builder/compile.v
+++ b/vlib/v/builder/compile.v
@@ -93,12 +93,12 @@ fn (mut b Builder) run_compiled_executable_and_exit() {
 	}
 	if b.pref.os == .ios {
 		device := '"iPhone SE (2nd generation)"'
-		os.exec('xcrun simctl boot $device') or { panic(err) }
+		os.execute_or_panic('xcrun simctl boot $device')
 		bundle_name := b.pref.out_name.split('/').last()
 		display_name := if b.pref.display_name != '' { b.pref.display_name } else { bundle_name }
-		os.exec('xcrun simctl install $device ${display_name}.app') or { panic(err) }
+		os.execute_or_panic('xcrun simctl install $device ${display_name}.app')
 		bundle_id := if b.pref.bundle_id != '' { b.pref.bundle_id } else { 'app.vlang.$bundle_name' }
-		os.exec('xcrun simctl launch $device $bundle_id') or { panic(err) }
+		os.execute_or_panic('xcrun simctl launch $device $bundle_id')
 	} else {
 		exefile := os.real_path(b.pref.out_name)
 		mut cmd := '"$exefile"'
diff --git a/vlib/v/builder/js.v b/vlib/v/builder/js.v
index 0a2b149731..ea5ae26653 100644
--- a/vlib/v/builder/js.v
+++ b/vlib/v/builder/js.v
@@ -56,9 +56,10 @@ pub fn (mut b Builder) compile_js() {
 
 fn (mut b Builder) run_js() {
 	cmd := 'node ' + b.pref.out_name + '.js'
-	res := os.exec(cmd) or {
-		println('JS compilation failed.')
-		verror(err.msg)
+	res := os.execute(cmd)
+	if res.exit_code != 0 {
+		eprintln('JS compilation failed:')
+		verror(res.output)
 		return
 	}
 	println(res.output)
diff --git a/vlib/v/builder/msvc.v b/vlib/v/builder/msvc.v
index 4a259441fc..3f86446fd3 100644
--- a/vlib/v/builder/msvc.v
+++ b/vlib/v/builder/msvc.v
@@ -137,7 +137,10 @@ fn find_vs(vswhere_dir string, host_arch string, target_arch string) ?VsInstalla
 	// VSWhere is guaranteed to be installed at this location now
 	// If its not there then end user needs to update their visual studio
 	// installation!
-	res := os.exec('"$vswhere_dir\\Microsoft Visual Studio\\Installer\\vswhere.exe" -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath') ?
+	res := os.execute('"$vswhere_dir\\Microsoft Visual Studio\\Installer\\vswhere.exe" -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath')
+	if res.exit_code != 0 {
+		return error_with_code(res.output, res.exit_code)
+	}
 	res_output := res.output.trim_right('\r\n')
 	// println('res: "$res"')
 	version := os.read_file('$res_output\\VC\\Auxiliary\\Build\\Microsoft.VCToolsVersion.default.txt') or {
@@ -315,8 +318,9 @@ pub fn (mut v Builder) cc_msvc() {
 	// Also the double quotes at the start ARE needed.
 	v.show_cc(cmd, out_name_cmd_line, args)
 	util.timing_start('C msvc')
-	res := os.exec(cmd) or {
-		println(err)
+	res := os.execute(cmd)
+	if res.exit_code != 0 {
+		eprintln(res.output)
 		verror('msvc error')
 		return
 	}
@@ -367,11 +371,7 @@ fn (mut v Builder) build_thirdparty_obj_file_with_msvc(path string, moduleflags
 	$if trace_thirdparty_obj_files ? {
 		println('>>> build_thirdparty_obj_file_with_msvc cmd: $cmd')
 	}
-	res := os.exec(cmd) or {
-		println('msvc: failed to execute msvc compiler (to build a thirdparty object); cmd: $cmd')
-		verror(err.msg)
-		return
-	}
+	res := os.execute(cmd)
 	if res.exit_code != 0 {
 		println('msvc: failed to build a thirdparty object; cmd: $cmd')
 		verror(res.output)
diff --git a/vlib/v/compiler_errors_test.v b/vlib/v/compiler_errors_test.v
index bfb8e56480..bdcb2eafa5 100644
--- a/vlib/v/compiler_errors_test.v
+++ b/vlib/v/compiler_errors_test.v
@@ -177,6 +177,11 @@ fn (mut tasks Tasks) run() {
 		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_1.vv'
 		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_with_explanation_2.vv'
 	}
+	$if msvc {
+		// TODO: investigate why MSVC regressed
+		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_1.vv'
+		m_skip_files << 'vlib/v/checker/tests/missing_c_lib_header_with_explanation_2.vv'                
+	}
 	for i in 0 .. tasks.all.len {
 		if tasks.all[i].path in m_skip_files {
 			tasks.all[i].is_skipped = true
@@ -252,7 +257,7 @@ fn (mut task TaskDescription) execute() {
 	}
 	program := task.path
 	cli_cmd := '$task.vexe $task.voptions $program'
-	res := os.exec(cli_cmd) or { panic(err) }
+	res := os.execute(cli_cmd)
 	expected_out_path := program.replace('.vv', '') + task.result_extension
 	task.expected_out_path = expected_out_path
 	task.cli_cmd = cli_cmd
diff --git a/vlib/v/fmt/fmt_keep_test.v b/vlib/v/fmt/fmt_keep_test.v
index 3b130ccc73..fb4cfa1b90 100644
--- a/vlib/v/fmt/fmt_keep_test.v
+++ b/vlib/v/fmt/fmt_keep_test.v
@@ -87,7 +87,10 @@ fn fill_bin2v_keep() ? {
 	img0 := os.join_path('tutorials', 'img', 'hello.png')
 	img1 := os.join_path('tutorials', 'img', 'time.png')
 	os.rm(b2v_keep_path) ?
-	os.exec('v bin2v -w $b2v_keep_path $img0 $img1') ?
+	res := os.execute('v bin2v -w $b2v_keep_path $img0 $img1')
+	if res.exit_code < 0 {
+		return error_with_code(res.output, res.exit_code)
+	}
 }
 
 fn restore_bin2v_placeholder() ? {
diff --git a/vlib/v/gen/js/jsgen_test.v b/vlib/v/gen/js/jsgen_test.v
index 2115b8fb68..8bae0074e3 100644
--- a/vlib/v/gen/js/jsgen_test.v
+++ b/vlib/v/gen/js/jsgen_test.v
@@ -48,7 +48,7 @@ fn find_test_files() []string {
 }
 
 fn is_nodejs_working() bool {
-	node_res := os.exec('node --version') or { return false }
+	node_res := os.execute('node --version')
 	if node_res.exit_code != 0 {
 		return false
 	}
diff --git a/vlib/v/gen/x64/tests/x64_test.v b/vlib/v/gen/x64/tests/x64_test.v
index c1905481f8..8c89ac977c 100644
--- a/vlib/v/gen/x64/tests/x64_test.v
+++ b/vlib/v/gen/x64/tests/x64_test.v
@@ -28,18 +28,17 @@ fn test_x64() {
 	bench.set_total_expected_steps(tests.len)
 	for test in tests {
 		bench.step()
-		full_test_path := os.real_path(test)
-		println('x.v: $wrkdir/x.v')
-		os.system('cp $dir/$test $wrkdir/x.v') // cant run .vv file
-		os.exec('$vexe -o exe -x64 $wrkdir/x.v') or {
+		full_test_path := os.real_path(os.join_path(dir, test))
+		relative_test_path := full_test_path.replace(vroot + '/', '')
+		work_test_path := '$wrkdir/x.v'
+		os.cp(full_test_path, work_test_path) or {}
+		res_x64 := os.execute('$vexe -o exe -x64 $work_test_path')
+		if res_x64.exit_code != 0 {
 			bench.fail()
 			eprintln(bench.step_message_fail('x64 $test failed'))
 			continue
 		}
-		res := os.exec('./exe') or {
-			bench.fail()
-			continue
-		}
+		res := os.execute('./exe')
 		if res.exit_code != 0 {
 			bench.fail()
 			eprintln(bench.step_message_fail('$full_test_path failed to run'))
@@ -61,7 +60,7 @@ fn test_x64() {
 			continue
 		}
 		bench.ok()
-		eprintln(bench.step_message_ok('testing file: $test'))
+		eprintln(bench.step_message_ok(relative_test_path))
 	}
 	bench.stop()
 	eprintln(term.h_divider('-'))
diff --git a/vlib/v/live/executable/reloader.v b/vlib/v/live/executable/reloader.v
index eadcbf7fd5..a4cad91ddd 100644
--- a/vlib/v/live/executable/reloader.v
+++ b/vlib/v/live/executable/reloader.v
@@ -69,10 +69,7 @@ fn compile_lib(mut r live.LiveReloadInfo) ?string {
 	cmd := '$r.vexe $r.vopts -o $new_lib_path $r.original'
 	elog(r, '>       compilation cmd: $cmd')
 	cwatch := time.new_stopwatch({})
-	recompilation_result := os.exec(cmd) or {
-		eprintln('recompilation failed')
-		return none
-	}
+	recompilation_result := os.execute(cmd)
 	elog(r, 'compilation took: ${cwatch.elapsed().milliseconds()}ms')
 	if recompilation_result.exit_code != 0 {
 		eprintln('recompilation error:')
diff --git a/vlib/v/tests/array_init_test.v b/vlib/v/tests/array_init_test.v
index b1a06e548c..e95dd7efbf 100644
--- a/vlib/v/tests/array_init_test.v
+++ b/vlib/v/tests/array_init_test.v
@@ -8,7 +8,9 @@ fn test_array_init() {
 	a << 1
 	assert '$a, $a.len, $a.cap' == '[1], 1, 3'
 
-	c := Init{len: 3}
+	c := Init{
+		len: 3
+	}
 	mut d := []string{cap: c.len}
 	d << 'aaa'
 	d << 'bbb'
@@ -59,50 +61,50 @@ fn test_array_int_full_options() {
 	println('Test array of int values')
 
 	a := []int{len: 2, cap: 10} // this creates an array with 2 items, initial capacity 10, default value of array type
-	println('array a: length: ${a.len}, capacity: ${a.cap}, content: $a')
+	println('array a: length: $a.len, capacity: $a.cap, content: $a')
 	assert a.len == 2
 	assert a.cap == 10
 	assert a.cap >= a.len
-	assert a.str() == "[0, 0]"
+	assert a.str() == '[0, 0]'
 
 	b := []int{len: 10, cap: 100, init: 1} // this creates an array with 10 one and initial capacity 100 elements, value given
 	_ = b.clone() // discard result variable, sample
-	println('array b: length: ${b.len}, capacity: ${b.cap}, content: $b')
+	println('array b: length: $b.len, capacity: $b.cap, content: $b')
 	assert b.len == 10
 	assert b.cap == 100
 	assert b.cap >= b.len
-	assert b.str() == "[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]"
+	assert b.str() == '[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]'
 
 	mut c := []int{len: 2, cap: 10, init: 1} // this creates an array with 2 one and initial capacity 10 elements, value given
 	_ = c.clone() // discard result variable, sample
-	println('array c: length: ${c.len}, capacity: ${c.cap}, content: $c')
+	println('array c: length: $c.len, capacity: $c.cap, content: $c')
 	assert c.len == 2
 	assert c.cap == 10
 	assert c.cap >= c.len
-	assert c.str() == "[1, 1]"
+	assert c.str() == '[1, 1]'
 	// add some items to the array, to check limits
 	c << [3, 4, 5, 6, 7, 8, 9, 10] // add 8 items, from another array
 	// update one item, to have the right number in the sequence ...
 	c[1] = 2
-	println('array c: length: ${c.len}, capacity: ${c.cap}, content now: $c')
+	println('array c: length: $c.len, capacity: $c.cap, content now: $c')
 	assert c.len == 10
 	assert c.cap == 10
 	assert c.cap >= c.len
-	assert c.str() == "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"
+	assert c.str() == '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]'
 	// add some more item after initial capacity, to ensure it's expandable
 	c << [11, 12, 13, 14, 15, 16]
-	println('array c: length: ${c.len}, capacity: ${c.cap}, content now: $c')
+	println('array c: length: $c.len, capacity: $c.cap, content now: $c')
 	assert c.len == 16
 	assert c.cap >= c.len
-	assert c.str() == "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]"
+	assert c.str() == '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]'
 }
 
 fn test_array_string_full_options() {
 	println('Test array of string values')
 
 	a := []string{len: 2, cap: 10} // this creates an array with 2 items, initial capacity 10, default value of array type
-	println('array a: length: ${a.len}, capacity: ${a.cap}') // ok
-	println('array a: length: ${a.len}, capacity: ${a.cap}, content: "$a"')
+	println('array a: length: $a.len, capacity: $a.cap') // ok
+	println('array a: length: $a.len, capacity: $a.cap, content: "$a"')
 	assert a.len == 2
 	assert a.cap == 10
 	assert a.cap >= a.len
@@ -110,8 +112,8 @@ fn test_array_string_full_options() {
 
 	b := []string{len: 10, cap: 100, init: 'b'} // this creates an array with 10 'b', initial capacity 100 elements, value given
 	_ = b.clone() // discard result variable, sample
-	println('array b: length: ${b.len}, capacity: ${b.cap}') // ok
-	println('array b: length: ${b.len}, capacity: ${b.cap}, content: $b')
+	println('array b: length: $b.len, capacity: $b.cap') // ok
+	println('array b: length: $b.len, capacity: $b.cap, content: $b')
 	assert b.len == 10
 	assert b.cap == 100
 	assert b.cap >= b.len
@@ -119,7 +121,7 @@ fn test_array_string_full_options() {
 
 	mut c := []string{len: 2, cap: 10, init: 'c'} // this creates an array with 2 'c' and initial capacity 10 elements, value given
 	_ = c.clone() // discard result variable, sample
-	println('array c: length: ${c.len}, capacity: ${c.cap}, content: $c')
+	println('array c: length: $c.len, capacity: $c.cap, content: $c')
 	assert c.len == 2
 	assert c.cap == 10
 	assert c.cap >= c.len
@@ -129,7 +131,7 @@ fn test_array_string_full_options() {
 	// update some items, to have the right number in the sequence ...
 	c[0] = 'a'
 	c[1] = 'b'
-	println('array c: length: ${c.len}, capacity: ${c.cap}, content now: $c')
+	println('array c: length: $c.len, capacity: $c.cap, content now: $c')
 	assert c.len == 10
 	assert c.cap == 10
 	assert c.cap >= c.len
@@ -137,7 +139,7 @@ fn test_array_string_full_options() {
 	// add some more item after initial capacity, to ensure all is good
 	c << ['11', '12', '13', '14', '15', '16']
 	// c << ['11', nil, '13', '14', '15', '16'] // check later if/how to handle this ...
-	println('array c: length: ${c.len}, capacity: ${c.cap}, content now: $c')
+	println('array c: length: $c.len, capacity: $c.cap, content now: $c')
 	assert c.len == 16
 	assert c.cap >= c.len
 	assert c.str() == "['a', 'b', 'c', 'c', 'c', 'c', 'c', 'c', 'c', 'c', '11', '12', '13', '14', '15', '16']"
@@ -149,8 +151,8 @@ pub mut:
 }
 
 fn test_array_init_in_struct_field() {
-	m := MyStruct {
-		ar: []f32{len: 4, init:1.2}
+	m := MyStruct{
+		ar: []f32{len: 4, init: 1.2}
 	}
 	println(m)
 	assert m.ar.str() == '[1.2, 1.2, 1.2, 1.2]'
@@ -171,39 +173,42 @@ fn test_array_init_cast_type_in_struct_field() {
 }
 
 fn test_multi_dimensional_array_init() {
-	a := [][]int{len:2, init:[]int{len:4, init:2}}
+	a := [][]int{len: 2, init: []int{len: 4, init: 2}}
 	assert '$a' == '[[2, 2, 2, 2], [2, 2, 2, 2]]'
 
-	b := [][]string{len:3, init:[]string{len:2, init:'abc'}}
+	b := [][]string{len: 3, init: []string{len: 2, init: 'abc'}}
 	assert '$b' == "[['abc', 'abc'], ['abc', 'abc'], ['abc', 'abc']]"
 
-	c := [][]f64{len:2, init:[]f64{len:2, init:2.2}}
+	c := [][]f64{len: 2, init: []f64{len: 2, init: 2.2}}
 	assert '$c' == '[[2.2, 2.2], [2.2, 2.2]]'
 
-	d := [][]int{len:3, init:[]int{len:2}}
+	d := [][]int{len: 3, init: []int{len: 2}}
 	assert '$d' == '[[0, 0], [0, 0], [0, 0]]'
 
-	e := [][]string{len:2, init:[]string{len:3}}
+	e := [][]string{len: 2, init: []string{len: 3}}
 	assert '$e' == "[['', '', ''], ['', '', '']]"
 
-	f := [][]int{len:3}
+	f := [][]int{len: 3}
 	assert '$f' == '[[], [], []]'
 }
 
 fn test_array_init_direct_call() {
 	assert []int{len: 2, init: 0}.len == 2
-	assert []int{len: 3, init: 1}.map(it*2) == [2,2,2]
+	assert []int{len: 3, init: 1}.map(it * 2) == [2, 2, 2]
 }
 
 // test array init with sumtype
 type Alphabet = Abc | Xyz
+
 struct Abc {
 	val int
 }
+
 struct Xyz {
 	val int
 }
-fn test_array_init_with_sumtype () {
+
+fn test_array_init_with_sumtype() {
 	a := [Alphabet(Abc{1}), Xyz{2}]
 	a0 := a[0]
 	a1 := a[1]
@@ -228,14 +233,18 @@ fn test_array_init_with_sumtype () {
 fn test_array_init_inferred_from_optional() {
 	a := read() or { [] }
 	x := 1
-	b := read() or { match x {
-		1 {
-			[]
+	b := read() or {
+		match x {
+			1 {
+				[]
+			}
+			else {
+				[]
+			}
 		}
-		else {
-			[]
-		}
-	}}
+	}
+	println(a)
+	println(b)
 }
 
 fn read() ?[]string {
diff --git a/vlib/v/tests/blank_ident_test.v b/vlib/v/tests/blank_ident_test.v
index a526645fc2..610799c196 100644
--- a/vlib/v/tests/blank_ident_test.v
+++ b/vlib/v/tests/blank_ident_test.v
@@ -88,7 +88,9 @@ fn test_nested_for_in_array_simple() {
 
 fn test_nested_for_in_array_key() {
 	for _, v in [1, 2, 3] {
+		assert v > 0
 		for _, w in [1, 2, 3] {
+			assert w > 0
 			assert true
 		}
 	}
@@ -96,7 +98,9 @@ fn test_nested_for_in_array_key() {
 
 fn test_nested_for_in_array_val() {
 	for i, _ in [1, 2, 3] {
+		assert i > -1
 		for j, _ in [1, 2, 3] {
+			assert j > -1
 			assert true
 		}
 	}
@@ -111,7 +115,7 @@ fn test_nested_for_in_array_both() {
 }
 
 const (
-	m = {
+	m = map{
 		'key': 'value'
 	}
 )
@@ -172,12 +176,14 @@ fn fn_for_in_variadic_args_simple(arr ...string) {
 
 fn fn_for_in_variadic_args_key(arr ...string) {
 	for _, v in arr {
+		assert v > 'A'
 		assert true
 	}
 }
 
 fn fn_for_in_variadic_args_val(arr ...string) {
 	for i, _ in arr {
+		assert i > -1
 		assert true
 	}
 }
@@ -198,7 +204,9 @@ fn fn_nested_for_in_variadic_args(arr ...string) {
 
 fn fn_nested_for_in_variadic_args_key(arr ...string) {
 	for _, v in arr {
+		assert v > 'A'
 		for _, w in arr {
+			assert w > 'A'
 			assert true
 		}
 	}
@@ -206,7 +214,9 @@ fn fn_nested_for_in_variadic_args_key(arr ...string) {
 
 fn fn_nested_for_in_variadic_args_val(arr ...string) {
 	for i, _ in arr {
+		assert i > -1
 		for j, _ in arr {
+			assert j > -1
 			assert true
 		}
 	}
@@ -301,4 +311,13 @@ fn test_blank_multi_return() {
 	_, h, _ := multi_return()
 	i, _, _ := multi_return()
 	_, _, _ := multi_return()
+	assert c == 1
+	assert e == 1
+	assert i == 1
+	assert a == 2
+	assert f == 2
+	assert h == 2
+	assert b == '3'
+	assert d == '3'
+	assert g == '3'
 }
diff --git a/vlib/v/tests/goto_test.v b/vlib/v/tests/goto_test.v
index f065893953..b4654739ba 100644
--- a/vlib/v/tests/goto_test.v
+++ b/vlib/v/tests/goto_test.v
@@ -1,10 +1,13 @@
 fn test_goto() {
 	mut i := 0
-	a: b := 1
+	a:
+	b := 1
 	_ = b
 	i++
 	if i < 3 {
-		goto a
+		unsafe {
+			goto a
+		}
 	}
 	assert i == 3
 }
diff --git a/vlib/v/tests/inout/compiler_test.v b/vlib/v/tests/inout/compiler_test.v
index 6b03a72b07..9e8aea8870 100644
--- a/vlib/v/tests/inout/compiler_test.v
+++ b/vlib/v/tests/inout/compiler_test.v
@@ -1,7 +1,6 @@
 // .out file:
 // To test a panic, remove everything after the long `===` line
 // You can also remove the line with 'line:' e.g. for a builtin fn
-
 import os
 import term
 import v.util
@@ -22,19 +21,23 @@ fn test_all() {
 		println('no compiler tests found')
 		assert false
 	}
-	paths := vtest.filter_vtest_only(tests,
+	paths := vtest.filter_vtest_only(tests, 
 		basepath: dir
 	)
 	for path in paths {
 		print(path + ' ')
 		program := path
-		compilation := os.exec('$vexe -o test -cflags "-w" -cg $program') or { panic(err) }
+		compilation := os.execute('$vexe -o test -cflags "-w" -cg $program')
+		if compilation.exit_code < 0 {
+			panic(compilation.output)
+		}
 		if compilation.exit_code != 0 {
 			panic('compilation failed: $compilation.output')
 		}
-		res := os.exec('./test') or {
+		res := os.execute('./test')
+		if res.exit_code < 0 {
 			println('nope')
-			panic(err)
+			panic(res.output)
 		}
 		$if windows {
 			os.rm('./test.exe') or { }
diff --git a/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v b/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v
index 0212027941..c498792bfb 100644
--- a/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v
+++ b/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v
@@ -18,7 +18,7 @@ fn test_vexe_is_set() {
 fn test_compiling_without_vmodules_fails() {
 	os.chdir(vroot)
 	os.setenv('VMODULES', '', true)
-	res := os.exec('"$vexe" run "$mainvv"') or { panic(err) }
+	res := os.execute('"$vexe" run "$mainvv"')
 	assert res.exit_code == 1
 	assert res.output.trim_space().contains('builder error: cannot import module "yyy" (not found)')
 }
@@ -27,7 +27,7 @@ fn test_compiling_with_vmodules_works() {
 	os.chdir(vroot)
 	vmpaths := ['path1', 'path2', 'path3'].map(os.join_path(basepath, it))
 	os.setenv('VMODULES', vmpaths.join(os.path_delimiter), true)
-	res := os.exec('"$vexe" run "$mainvv"') or { panic(err) }
+	res := os.execute('"$vexe" run "$mainvv"')
 	assert res.exit_code == 0
 	assert res.output.trim_space() == "['x', 'y', 'z']"
 }
diff --git a/vlib/v/tests/named_break_continue_test.v b/vlib/v/tests/named_break_continue_test.v
index c537528fe1..39f3ebe733 100644
--- a/vlib/v/tests/named_break_continue_test.v
+++ b/vlib/v/tests/named_break_continue_test.v
@@ -1,30 +1,45 @@
 fn test_labelled_for() {
 	mut i := 4
-	goto L1
+	unsafe {
+		goto L1
+	}
 	L1: for {
 		i++
 		for {
-			if i < 7 {continue L1}
-			else {break L1}
+			if i < 7 {
+				continue L1
+			} else {
+				break L1
+			}
 		}
 	}
 	assert i == 7
 
-	goto L2
-	L2: for ;; i++ {
+	unsafe {
+		goto L2
+	}
+	L2: for ; true; i++ {
 		for {
-			if i < 17 {continue L2}
-			else {break L2}
+			if i < 17 {
+				continue L2
+			} else {
+				break L2
+			}
 		}
 	}
 	assert i == 17
 
-	goto L3
-	L3: for e in [1,2,3,4] {
+	unsafe {
+		goto L3
+	}
+	L3: for e in [1, 2, 3, 4] {
 		i = e
 		for {
-			if i < 3 {continue L3}
-			else {break L3}
+			if i < 3 {
+				continue L3
+			} else {
+				break L3
+			}
 		}
 	}
 	assert i == 3
diff --git a/vlib/v/tests/profile/profile_test.v b/vlib/v/tests/profile/profile_test.v
index 9abfb6fedd..f802c7bd5b 100644
--- a/vlib/v/tests/profile/profile_test.v
+++ b/vlib/v/tests/profile/profile_test.v
@@ -12,7 +12,7 @@ fn test_vexe_exists() {
 fn test_v_profile_works() {
 	os.chdir(vroot)
 	program_source := os.join_path(vroot, 'vlib/v/tests/profile/profile_test_1.v')
-	res := os.exec('"$vexe" -profile - run $program_source') or { exit(1) }
+	res := os.execute('"$vexe" -profile - run $program_source')
 	// eprintln('res: $res')
 	assert res.exit_code == 0
 	assert res.output.len > 0
diff --git a/vlib/v/tests/repl/repl_test.v b/vlib/v/tests/repl/repl_test.v
index 33312a19cc..0634c093c9 100644
--- a/vlib/v/tests/repl/repl_test.v
+++ b/vlib/v/tests/repl/repl_test.v
@@ -12,11 +12,14 @@ fn test_the_v_compiler_can_be_invoked() {
 	println('vexecutable: $vexec')
 	assert vexec != ''
 	vcmd := '"$vexec" -version'
-	r := os.exec(vcmd) or { panic(err) }
-	// println('"$vcmd" exit_code: $r.exit_code | output: $r.output')
+	r := os.execute_or_panic(vcmd)
 	assert r.exit_code == 0
+	// println('"$vcmd" exit_code: $r.exit_code | output: $r.output')
 	vcmd_error := '"$vexec" nonexisting.v'
-	r_error := os.exec(vcmd_error) or { panic(err) }
+	r_error := os.execute(vcmd_error)
+	if r_error.exit_code < 0 {
+		panic(r_error.output)
+	}
 	// println('"$vcmd_error" exit_code: $r_error.exit_code | output: $r_error.output')
 	assert r_error.exit_code == 1
 	actual_error := r_error.output.trim_space()
diff --git a/vlib/v/tests/repl/runner/runner.v b/vlib/v/tests/repl/runner/runner.v
index 4ec542475e..7072c80b8a 100644
--- a/vlib/v/tests/repl/runner/runner.v
+++ b/vlib/v/tests/repl/runner/runner.v
@@ -50,7 +50,8 @@ pub fn run_repl_file(wd string, vexec string, file string) ?string {
 	os.write_file(input_temporary_filename, input) or { panic(err) }
 	os.write_file(os.real_path(os.join_path(wd, 'original.txt')), fcontent) or { panic(err) }
 	rcmd := '"$vexec" repl -replfolder "$wd" -replprefix "${fname}." < $input_temporary_filename'
-	r := os.exec(rcmd) or {
+	r := os.execute(rcmd)
+	if r.exit_code < 0 {
 		os.rm(input_temporary_filename) or { panic(err) }
 		return error('Could not execute: $rcmd')
 	}
@@ -73,7 +74,7 @@ pub fn run_repl_file(wd string, vexec string, file string) ?string {
 $diff
 		')
 	} else {
-		return 'Repl file $file is OK'
+		return file.replace('./', '')
 	}
 }
 
@@ -84,7 +85,10 @@ pub fn run_prod_file(wd string, vexec string, file string) ?string {
 	}
 	expected_content := f_expected_content.replace('\r', '')
 	cmd := '"$vexec" -prod run "$file"'
-	r := os.exec(cmd) or { return error('Could not execute: $cmd') }
+	r := os.execute(cmd)
+	if r.exit_code < 0 {
+		return error('Could not execute: $cmd')
+	}
 	if r.exit_code != 0 {
 		return error('$cmd return exit code: $r.exit_code')
 	}
diff --git a/vlib/v/tests/run_v_code_from_stdin_test.v b/vlib/v/tests/run_v_code_from_stdin_test.v
index fde6f33444..31de20250e 100644
--- a/vlib/v/tests/run_v_code_from_stdin_test.v
+++ b/vlib/v/tests/run_v_code_from_stdin_test.v
@@ -15,7 +15,7 @@ fn pipe_to_v_run() ? {
 	os.write_file(tmp_v_file, 'println(1 + 3)\nprintln("hello")\n') ?
 	assert os.is_file(tmp_v_file)
 	cmd := '$cat_cmd "$tmp_v_file" | "$vexe" run -'
-	res := os.exec(cmd) ?
+	res := os.execute(cmd)
 	// eprintln('>> cmd: $cmd | res: $res')
 	assert res.exit_code == 0
 	assert res.output.replace('\r', '').trim_space().split('\n') == ['4', 'hello']
diff --git a/vlib/v/tests/valgrind/valgrind_test.v b/vlib/v/tests/valgrind/valgrind_test.v
index c3110e93c1..8a71556d2d 100644
--- a/vlib/v/tests/valgrind/valgrind_test.v
+++ b/vlib/v/tests/valgrind/valgrind_test.v
@@ -73,11 +73,7 @@ fn test_all() {
 		full_path_to_source_file := os.join_path(vroot, test)
 		compile_cmd := '$vexe -o $exe_filename -cg -cflags "-w" -autofree "$full_path_to_source_file"'
 		vprintln('compile cmd: ${util.bold(compile_cmd)}')
-		res := os.exec(compile_cmd) or {
-			bench.fail()
-			eprintln(bench.step_message_fail('valgrind $test failed'))
-			continue
-		}
+		res := os.execute(compile_cmd)
 		if res.exit_code != 0 {
 			bench.fail()
 			eprintln(bench.step_message_fail('file: $test could not be compiled.'))
@@ -93,11 +89,7 @@ fn test_all() {
 		}
 		valgrind_cmd := 'valgrind --error-exitcode=1 --leak-check=full $exe_filename'
 		vprintln('valgrind cmd: ${util.bold(valgrind_cmd)}')
-		valgrind_res := os.exec(valgrind_cmd) or {
-			bench.fail()
-			eprintln(bench.step_message_fail('valgrind could not be executed'))
-			continue
-		}
+		valgrind_res := os.execute(valgrind_cmd)
 		if valgrind_res.exit_code != 0 {
 			bench.fail()
 			eprintln(bench.step_message_fail('failed valgrind check for ${util.bold(test)}'))
diff --git a/vlib/v/util/diff.v b/vlib/v/util/diff.v
index 90fe7c8c25..167f3c2c1f 100644
--- a/vlib/v/util/diff.v
+++ b/vlib/v/util/diff.v
@@ -22,7 +22,10 @@ pub fn find_working_diff_command() ?string {
 			}
 			continue
 		}
-		p := os.exec('$diffcmd --version') or { continue }
+		p := os.execute('$diffcmd --version')
+		if p.exit_code < 0 {
+			continue
+		}
 		if p.exit_code == 127 && diffcmd == env_difftool {
 			// user setup is wonky, fix it
 			return error('could not find specified VDIFF_TOOL $diffcmd')
@@ -41,9 +44,12 @@ pub fn find_working_diff_command() ?string {
 
 // determine if the FileMerge opendiff tool is available
 fn opendiff_exists() bool {
-	o := os.exec('opendiff') or { return false }
+	o := os.execute('opendiff')
+	if o.exit_code < 0 {
+		return false
+	}
 	if o.exit_code == 1 { // failed (expected), but found (i.e. not 127)
-		if o.output.contains('too few arguments') { // got some exptected output
+		if o.output.contains('too few arguments') { // got some expected output
 			return true
 		}
 	}
@@ -53,7 +59,10 @@ fn opendiff_exists() bool {
 pub fn color_compare_files(diff_cmd string, file1 string, file2 string) string {
 	if diff_cmd != '' {
 		full_cmd := '$diff_cmd --minimal --text --unified=2  --show-function-line="fn " "$file1" "$file2" '
-		x := os.exec(full_cmd) or { return 'comparison command: `$full_cmd` failed' }
+		x := os.execute(full_cmd)
+		if x.exit_code < 0 {
+			return 'comparison command: `$full_cmd` not found'
+		}
 		return x.output.trim_right('\r\n')
 	}
 	return ''
diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index ff5260e006..2ec63f6cb2 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -229,7 +229,7 @@ pub fn launch_tool(is_verbose bool, tool_name string, args []string) {
 		if is_verbose {
 			println('Compiling $tool_name with: "$compilation_command"')
 		}
-		tool_compilation := os.exec(compilation_command) or { panic(err) }
+		tool_compilation := os.execute_or_panic(compilation_command)
 		if tool_compilation.exit_code != 0 {
 			eprintln('cannot compile `$tool_source`: \n$tool_compilation.output')
 			exit(1)
@@ -428,8 +428,9 @@ pub fn check_module_is_installed(modulename string, is_verbose bool) ?bool {
 		if is_verbose {
 			eprintln('check_module_is_installed: updating with $update_cmd ...')
 		}
-		update_res := os.exec(update_cmd) or {
-			return error('can not start $update_cmd, error: $err')
+		update_res := os.execute(update_cmd)
+		if update_res.exit_code < 0 {
+			return error('can not start $update_cmd, error: $update_res.output')
 		}
 		if update_res.exit_code != 0 {
 			eprintln('Warning: `$modulename` exists, but is not updated.
@@ -446,11 +447,12 @@ and the existing module `$modulename` may still work.')
 	if is_verbose {
 		eprintln('check_module_is_installed: cloning from $murl ...')
 	}
-	cloning_res := os.exec('git clone $murl $mpath') or {
-		return error('git is not installed, error: $err')
+	cloning_res := os.execute('git clone $murl $mpath')
+	if cloning_res.exit_code < 0 {
+		return error_with_code('git is not installed, error: $cloning_res.output', cloning_res.exit_code)
 	}
 	if cloning_res.exit_code != 0 {
-		return error('cloning failed, details: $cloning_res.output')
+		return error_with_code('cloning failed, details: $cloning_res.output', cloning_res.exit_code)
 	}
 	if !os.exists(mod_v_file) {
 		return error('even after cloning, $mod_v_file is still missing')