From ee9cfb6df4806de732d8d053fc599fedb4ef3ebf Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Thu, 27 Apr 2023 10:50:09 -0300
Subject: [PATCH] checker: add check for mixing multi-return results with other
 types in return statements (fix #17501) (#18067)

---
 vlib/v/checker/return.v                      | 3 +++
 vlib/v/checker/tests/multireturn_mix_err.out | 6 ++++++
 vlib/v/checker/tests/multireturn_mix_err.vv  | 7 +++++++
 3 files changed, 16 insertions(+)
 create mode 100644 vlib/v/checker/tests/multireturn_mix_err.out
 create mode 100644 vlib/v/checker/tests/multireturn_mix_err.vv

diff --git a/vlib/v/checker/return.v b/vlib/v/checker/return.v
index ac95dfd0f..ce2f1c174 100644
--- a/vlib/v/checker/return.v
+++ b/vlib/v/checker/return.v
@@ -82,6 +82,9 @@ fn (mut c Checker) return_stmt(mut node ast.Return) {
 		// Unpack multi return types
 		sym := c.table.sym(typ)
 		if sym.kind == .multi_return {
+			if i > 0 || i != node.exprs.len - 1 {
+				c.error('cannot use multi-return with other return types', expr.pos())
+			}
 			for t in sym.mr_info().types {
 				got_types << t
 				expr_idxs << i
diff --git a/vlib/v/checker/tests/multireturn_mix_err.out b/vlib/v/checker/tests/multireturn_mix_err.out
new file mode 100644
index 000000000..c0c5dd87d
--- /dev/null
+++ b/vlib/v/checker/tests/multireturn_mix_err.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/multireturn_mix_err.vv:6:9: error: cannot use multi-return with other return types
+    4 | 
+    5 | fn foo() (string, int, bool) {
+    6 |     return goo(), true
+      |            ~~~~~
+    7 | }
diff --git a/vlib/v/checker/tests/multireturn_mix_err.vv b/vlib/v/checker/tests/multireturn_mix_err.vv
new file mode 100644
index 000000000..2c4ef615a
--- /dev/null
+++ b/vlib/v/checker/tests/multireturn_mix_err.vv
@@ -0,0 +1,7 @@
+fn goo() (string, int) {
+	return '', 100
+}
+
+fn foo() (string, int, bool) {
+	return goo(), true
+}
-- 
2.39.5