value if/loop follow-ups

examples/programs/yield/main.bro

@@ -130,6 +130,50 @@ loop_while :: func() i32 {
 	return 2
 }
 
+# --- value if/loop follow-ups (milestone 20.6) -------------------------------
+
+# A branch may exit on every path (here `return`) instead of yielding; the slot
+# read after the `if` is only reached on the yielding path.
+vif_return :: func(sel i32) i32 {
+	r :: if (sel == 0) {
+		yield 10
+	} else {
+		return 55 # exits the function instead of yielding
+	}
+	return r + 1 # only when sel == 0: 10 + 1 = 11
+}
+
+# unwrap-`if` as a value source: present -> transform, absent -> default.
+vif_unwrap :: func(opt ?i32) i32 {
+	r :: if opt |v| {
+		yield v * 2
+	} else {
+		yield 99
+	}
+	return r
+}
+
+# The simple "unwrap or fallback" case is just `orelse` (already a plain expression).
+orelse_value :: func(opt ?i32) i32 {
+	r :: opt orelse 7
+	return r
+}
+
+# Untyped value loop where `none` is yielded (in a labeled yield) before any
+# concrete value: the element type still resolves to ?<i> from `yield :blk i`.
+loop_none_first :: func() i32 {
+	r :: for 0..10 |i| blk: {
+		if (i > 100) yield :blk none
+		if (i * i > 40) yield :blk i # first concrete yield: i == 7
+		yield none
+	}
+	if r |found| {
+		if (found == 7) return 0
+		return 1
+	}
+	return 2
+}
+
 main :: func() i32 {
 	if (basic() != 42) return 101
 	if (typed() != 100) return 102
@@ -149,5 +193,13 @@ main :: func() i32 {
 	if (loop_none() != 0) return 114
 	if (loop_while() != 0) return 115
 
+	if (vif_return(0) != 11) return 116
+	if (vif_return(1) != 55) return 117
+	if (vif_unwrap(21) != 42) return 118
+	if (vif_unwrap(none) != 99) return 119
+	if (orelse_value(5) != 5) return 120
+	if (orelse_value(none) != 7) return 121
+	if (loop_none_first() != 0) return 122
+
 	return 42
 }