harec

commit 371d85f2a8fc8085aeb54403b8d39305ee60aa11
parent 0397b5f11741d0be92e5ba04c155c416b914ffd0
Author: Eyal Sawady <ecs@d2evs.net>
Date:   Fri, 13 Aug 2021 10:40:06 +0000

gen: fix type assertions to tagged unions

Minimal reproduction:

type a = (int | void);
type b = (a | void);

fn test() void = {
    let x: b = void;
    x as a;
};

Signed-off-by: Eyal Sawady <ecs@d2evs.net>

Diffstat:
M
src/gen.c
 | 
7
++++++-

1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/src/gen.c b/src/gen.c
@@ -1094,6 +1094,11 @@ cast_prefers_at(const struct expression *expr)
 	if (expr->cast.kind == C_TEST) {
 		return false;
 	}
+	// tagged => *; subtype compatible
+	if (type_dealias(from)->storage == STORAGE_TAGGED
+			&& tagged_select_subtype(from, to)) {
+		return false;
+	}
 	// * => tagged
 	if (type_dealias(to)->storage == STORAGE_TAGGED) {
 		return true;
@@ -1139,7 +1144,7 @@ gen_expr_cast(struct gen_context *ctx, const struct expression *expr)
 		return gen_expr_type_test(ctx, expr);
 	case C_ASSERTION:
 		assert(type_dealias(from)->storage == STORAGE_TAGGED);
-		assert(type_dealias(to)->storage != STORAGE_TAGGED);
+		assert(tagged_select_subtype(from, to));
 		// Fallthrough
 	case C_CAST:
 		break;