vfmt: support `x chan Name` in fn args

vlib/v/fmt/fmt.v

@@ -725,12 +725,20 @@ pub fn (mut f Fmt) prefix_expr_cast_expr(fexpr ast.Expr) {
 
 pub fn (f &Fmt) type_to_str(t table.Type) string {
 	mut res := f.table.type_to_str(t)
-	map_prefix := 'map[string]'
 	cur_mod := f.cur_mod + '.'
+	//
+	map_prefix := 'map[string]'
 	has_map_prefix := res.starts_with(map_prefix)
 	if has_map_prefix {
 		res = res.replace(map_prefix, '')
 	}
+	//
+	chan_prefix := 'chan '
+	has_chan_prefix := res.starts_with(chan_prefix)
+	if has_chan_prefix {
+		res = res.replace(chan_prefix, '')
+	}
+	//
 	no_symbols := res.trim_left('&[]')
 	should_shorten := no_symbols.starts_with(cur_mod)
 	//
@@ -752,6 +760,9 @@ pub fn (f &Fmt) type_to_str(t table.Type) string {
 	if should_shorten {
 		res = res.replace_once(cur_mod, '')
 	}
+	if has_chan_prefix {
+		res = chan_prefix + res
+	}
 	if has_map_prefix {
 		res = map_prefix + res
 	}

vlib/v/fmt/tests/chan_init_keep.vv

@@ -4,6 +4,18 @@ struct FSMEvent {
 	x int
 }
 
+fn abc(n FSMEvent) {
+}
+
+fn (e FSMEvent) abc(n FSMEvent) {
+}
+
+fn (e FSMEvent) x(ch chan FSMEvent) {
+}
+
+fn produce_events(ch chan FSMEvent) {
+}
+
 fn main() {
 	ch_fsm_events := chan FSMEvent{cap: 1000}
 	eprintln('ch_fsm_events.len: $ch_fsm_events.len')

vlib/v/table/atypes.v

@@ -810,6 +810,9 @@ pub fn (table &Table) type_to_str(t Type) string {
 		res = res.replace('map_string_', 'map[string]')
 		map_start = 'map[string]'
 	}
+	if sym.kind == .chan || 'chan_' in res {
+		res = res.replace('chan_', '')
+	}
 	// mod.submod.submod2.Type => submod2.Type
 	if res.contains('.') {
 		vals := res.split('.')
@@ -826,6 +829,9 @@ pub fn (table &Table) type_to_str(t Type) string {
 		if sym.kind == .map && !res.starts_with('map') {
 			res = map_start + res
 		}
+		if sym.kind == .chan && !res.starts_with('chan') {
+			res = 'chan ' + res
+		}
 	}
 	nr_muls := t.nr_muls()
 	if nr_muls > 0 {
@@ -838,11 +844,6 @@ pub fn (table &Table) type_to_str(t Type) string {
 			res = '?' + res
 		}
 	}
-	/*
-	if res.starts_with(cur_mod +'.') {
-	res = res[cur_mod.len+1.. ]
-	}
-	*/
 	return res
 }