checker: check reference return to be really reference (#7739)

vlib/live/common.v

@@ -52,7 +52,7 @@ pub mut:
 // so that the user can set callbacks, read meta information, etc.
 pub fn info() &LiveReloadInfo {
 	if C.g_live_info != 0 {
-		return C.g_live_info
+		return &LiveReloadInfo(C.g_live_info)
 	}
 	// When the current program is not compiled with -live, simply
 	// return a new empty struct LiveReloadInfo in order to prevent

vlib/v/checker/checker.v

@@ -2047,6 +2047,12 @@ pub fn (mut c Checker) return_stmt(mut return_stmt ast.Return) {
 			c.error('fn `$c.cur_fn.name` expects you to return a non reference type `${c.table.type_to_str(exp_type)}`, but you are returning `${c.table.type_to_str(got_typ)}` instead',
 				pos)
 		}
+		if (exp_type.is_ptr() || exp_type.is_pointer()) &&
+			(!got_typ.is_ptr() && !got_typ.is_pointer()) && got_typ != table.any_int_type {
+			pos := return_stmt.exprs[i].position()
+			c.error('fn `$c.cur_fn.name` expects you to return a reference type `${c.table.type_to_str(exp_type)}`, but you are returning `${c.table.type_to_str(got_typ)}` instead',
+				pos)
+		}
 	}
 	if exp_is_optional && return_stmt.exprs.len > 0 {
 		expr0 := return_stmt.exprs[0]

vlib/v/checker/tests/reference_return.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/reference_return.vv:6:9: error: fn `f` expects you to return a reference type `&Aa`, but you are returning `Aa` instead
+    4 | 
+    5 | fn f() &Aa {
+    6 |     return Aa{
+      |            ~~~
+    7 |         a: 1
+    8 |     }

vlib/v/checker/tests/reference_return.vv

@@ -0,0 +1,14 @@
+struct Aa {
+	a int
+}
+
+fn f() &Aa {
+	return Aa{
+		a: 1
+	}
+}
+
+fn main() {
+	x := f()
+	println(x.a)
+}

vlib/v/tests/ref_return_test.v

@@ -0,0 +1,14 @@
+struct Aa {
+	a int
+}
+
+fn f() &Aa {
+	return &Aa{
+		a: 5
+	}
+}
+
+fn test_ref_return() {
+	x := f()
+	assert x.a == 5
+}