From 4f532c0830d05faaee01e5cb71777f3693ddf9a8 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Tue, 4 Apr 2023 00:32:55 +0800
Subject: [PATCH] checker: fix fn returning alias of pointer (fix #17861)
 (#17864)

---
 vlib/v/checker/return.v                    |  5 +++--
 vlib/v/tests/fn_return_alias_of_ptr_test.v | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/tests/fn_return_alias_of_ptr_test.v

diff --git a/vlib/v/checker/return.v b/vlib/v/checker/return.v
index 21ccbd1d4c..f3544cddec 100644
--- a/vlib/v/checker/return.v
+++ b/vlib/v/checker/return.v
@@ -229,8 +229,9 @@ fn (mut c Checker) return_stmt(mut node ast.Return) {
 			c.error('fn `${c.table.cur_fn.name}` expects you to return a non reference type `${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 != ast.int_literal_type
+		unaliased_got_typ := c.table.unaliased_type(got_typ)
+		if (exp_type.is_ptr() || exp_type.is_pointer()) && !got_typ.is_real_pointer()
+			&& !unaliased_got_typ.is_real_pointer() && got_typ != ast.int_literal_type
 			&& !c.pref.translated && !c.file.is_translated {
 			pos := node.exprs[expr_idxs[i]].pos()
 			if node.exprs[expr_idxs[i]].is_auto_deref_var() {
diff --git a/vlib/v/tests/fn_return_alias_of_ptr_test.v b/vlib/v/tests/fn_return_alias_of_ptr_test.v
new file mode 100644
index 0000000000..0516cc785f
--- /dev/null
+++ b/vlib/v/tests/fn_return_alias_of_ptr_test.v
@@ -0,0 +1,16 @@
+type HANDLE = voidptr
+
+struct ExampleStruct {
+	handle HANDLE
+}
+
+fn get_ptr(arg ExampleStruct) voidptr {
+	return arg.handle
+}
+
+fn test_fn_return_alias_of_ptr() {
+	h := ExampleStruct{}
+	r := get_ptr(h)
+	println(r)
+	assert r == unsafe { nil }
+}