fmt: enable `or` block for `ch <- x` (#7969)

vlib/sync/channel_opt_propagate_test.v

@@ -4,13 +4,13 @@ const (
 	num_iterations = 10000
 )
 
-fn get_val_from_chan(ch chan i64) ?i64 {
+fn get_val_from_chan(ch chan int) ?int {
 	r := <-ch ?
 	return r
 }
 
-// this function gets an array of channels for `i64`
-fn do_rec_calc_send(chs []chan i64, sem sync.Semaphore) {
+// this function gets an array of channels for `int`
+fn do_rec_calc_send(chs []chan int, sem sync.Semaphore) {
 	mut msg := ''
 	for {
 		mut s := get_val_from_chan(chs[0]) or {
@@ -25,10 +25,10 @@ fn do_rec_calc_send(chs []chan i64, sem sync.Semaphore) {
 }
 
 fn test_channel_array_mut() {
-	mut chs := [chan i64{}, chan i64{cap: 10}]
+	mut chs := [chan int{}, chan int{cap: 10}]
 	sem := sync.new_semaphore()
 	go do_rec_calc_send(chs, sem)
-	mut t := i64(100)
+	mut t := int(100)
 	for _ in 0 .. num_iterations {
 		chs[0] <- t
 		t = <-chs[1]

vlib/v/fmt/fmt.v

@@ -1564,6 +1564,7 @@ pub fn (mut f Fmt) infix_expr(node ast.InfixExpr) {
 		f.penalties = []int{}
 		f.precedences = []int{}
 	}
+	f.or_expr(node.or_block)
 }
 
 pub fn (mut f Fmt) if_expr(it ast.IfExpr) {

vlib/v/fmt/tests/chan_or_keep.vv

@@ -0,0 +1,33 @@
+const n = 1000
+
+fn f(ch chan int) {
+	mut s := 0
+	for _ in 0 .. n {
+		s += <-ch or {
+			println('Something went wrong:')
+			println('got $err')
+		}
+	}
+	assert s == n * (n + 1) / 2
+	ch.close()
+}
+
+fn do_send(ch chan int, val int) ?int {
+	ch <- val ?
+	return val + 1
+}
+
+fn do_send_2(ch chan int, val int) ?int {
+	ch <- val or { return error('could not send') }
+	return val + 1
+}
+
+fn main() {
+	ch := chan int{}
+	go f(ch)
+	mut s := 1
+	for {
+		s = do_send(ch, s) or { break }
+	}
+	assert s == n + 1
+}