From a6026fd505b300447f7e9273fb5ccbc9365710b6 Mon Sep 17 00:00:00 2001
From: StunxFS <56417208+StunxFS@users.noreply.github.com>
Date: Mon, 8 Aug 2022 10:35:24 -0400
Subject: [PATCH] checker: disallow method calls with invalid expressions
 (#15337)

---
 vlib/v/checker/fn.v                       | 4 ++++
 vlib/v/checker/tests/void_method_call.out | 6 ++++++
 vlib/v/checker/tests/void_method_call.vv  | 6 ++++++
 3 files changed, 16 insertions(+)
 create mode 100644 vlib/v/checker/tests/void_method_call.out
 create mode 100644 vlib/v/checker/tests/void_method_call.vv

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 50f91be479..03d59b627f 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -1113,6 +1113,10 @@ pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool)
 
 pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 	left_type := c.expr(node.left)
+	if left_type == ast.void_type {
+		c.error('cannot call a method using an invalid expression', node.pos)
+		return ast.void_type
+	}
 	c.expected_type = left_type
 	mut is_generic := left_type.has_flag(.generic)
 	node.left_type = left_type
diff --git a/vlib/v/checker/tests/void_method_call.out b/vlib/v/checker/tests/void_method_call.out
new file mode 100644
index 0000000000..1df2dae421
--- /dev/null
+++ b/vlib/v/checker/tests/void_method_call.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/void_method_call.vv:5:17: error: cannot call a method using an invalid expression
+    3 |
+    4 | fn main() {
+    5 |     simple_fn().method()
+      |                 ~~~~~~~~
+    6 | }
diff --git a/vlib/v/checker/tests/void_method_call.vv b/vlib/v/checker/tests/void_method_call.vv
new file mode 100644
index 0000000000..87e5962ae9
--- /dev/null
+++ b/vlib/v/checker/tests/void_method_call.vv
@@ -0,0 +1,6 @@
+fn simple_fn() {
+}
+
+fn main() {
+    simple_fn().method()
+}