scanner: guarantee an early exit when the parser/scanner is stuck

vlib/v/builder/compile.v

@@ -59,6 +59,7 @@ pub fn compile(command string, pref &pref.Preferences) {
 	if pref.is_stats {
 		println('compilation took: ${util.bold(sw.elapsed().milliseconds().str())} ms')
 	}
+	b.exit_on_invalid_syntax()
 	// running does not require the parsers anymore
 	unsafe {b.myfree()}
 	if pref.is_test || pref.is_run {
@@ -74,6 +75,21 @@ fn (mut b Builder) myfree() {
 	unsafe {b.parsed_files.free()}
 }
 
+fn (b &Builder) exit_on_invalid_syntax() {
+	// V should exit with an exit code of 1, when there are errors,
+	// even when -silent is passed in combination to -check-syntax:
+	if b.pref.only_check_syntax {
+		for pf in b.parsed_files {
+			if pf.errors.len > 0 {
+				exit(1)
+			}
+		}
+		if b.checker.nr_errors > 0 {
+			exit(1)
+		}
+	}
+}
+
 fn (mut b Builder) run_compiled_executable_and_exit() {
 	if b.pref.skip_running {
 		return

vlib/v/parser/fn.v

@@ -111,7 +111,12 @@ pub fn (mut p Parser) call_expr(language table.Language, mod string) ast.CallExp
 
 pub fn (mut p Parser) call_args() []ast.CallArg {
 	mut args := []ast.CallArg{}
+	start_pos := p.tok.position()
 	for p.tok.kind != .rpar {
+		if p.tok.kind == .eof {
+			p.error_with_pos('unexpected eof reached, while parsing call argument', start_pos)
+			break
+		}
 		is_shared := p.tok.kind == .key_shared
 		is_atomic := p.tok.kind == .key_atomic
 		is_mut := p.tok.kind == .key_mut || is_shared || is_atomic

vlib/v/scanner/scanner.v

@@ -450,7 +450,7 @@ fn (mut s Scanner) end_of_file() token.Token {
 	s.eofs++
 	if s.eofs > 50 {
 		s.line_nr--
-		s.error('the end of file `$s.file_path` has been reached 50 times already, the v parser is probably stuck.\n' +
+		panic('the end of file `$s.file_path` has been reached 50 times already, the v parser is probably stuck.\n' +
 			'This should not happen. Please report the bug here, and include the last 2-3 lines of your source code:\n' +
 			'https://github.com/vlang/v/issues/new?labels=Bug&template=bug_report.md')
 	}