v fmt: fix extra space for lock/rlock without expressions (#16103)

vlib/v/fmt/fmt.v

@@ -2238,6 +2238,9 @@ pub fn (mut f Fmt) lock_expr(node ast.LockExpr) {
 	}
 	if num_locked > 0 || num_rlocked == 0 {
 		f.write('lock')
+		if num_locked > 0 {
+			f.write(' ')
+		}
 		mut n := 0
 		for i, v in node.lockeds {
 			if !node.is_rlock[i] {

vlib/v/fmt/tests/lock_expected.vv

@@ -0,0 +1,50 @@
+fn simple_lock() {
+	a := 100
+	b := 100
+
+	lock {
+	}
+
+	lock {
+	}
+
+	lock a {
+	}
+
+	lock a, b {
+	}
+}
+
+fn lock_with_statements() {
+	shared a := []int{}
+	lock {
+		a << 1
+		a << 2
+	}
+
+	lock a {
+		a << 1
+		a << 2
+	}
+}
+
+fn simple_rlock() {
+	a := 100
+
+	lock {
+	}
+
+	rlock a {
+	}
+}
+
+fn rlock_with_statements() {
+	shared a := [1]
+	lock {
+		println(a[0])
+	}
+
+	rlock a {
+		println(a[0])
+	}
+}

vlib/v/fmt/tests/lock_input.vv

@@ -0,0 +1,52 @@
+fn simple_lock() {
+	a := 100
+	b := 100
+
+	lock  {
+	}
+
+	lock       {         }
+
+	lock    a     {
+
+	}
+
+	lock    a  , b    {
+
+	}
+}
+
+fn lock_with_statements() {
+	shared a := []int{}
+	lock  {
+		a << 1
+		a << 2
+	}
+
+	lock   a   {
+		a << 1
+		a << 2
+	}
+}
+
+fn simple_rlock() {
+	a := 100
+
+	rlock  {
+	}
+
+	rlock    a     {
+
+	}
+}
+
+fn rlock_with_statements() {
+	shared a := [1]
+	rlock  {
+		println(a[0])
+	}
+
+	rlock  a     {
+		println(a[0])
+	}
+}