From a6af3d514b07b08e14562fca3f61f5045ef05567 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sat, 28 Sep 2024 10:20:44 -0300
Subject: [PATCH] cgen: fix interface method call after smartcast (fix #17056)
 (#22335)

---
 vlib/v/ast/table.v                                   |  6 ++++++
 vlib/v/gen/c/fn.v                                    |  3 +++
 .../tests/interfaces/interface_smartcast_call_test.v | 12 ++++++++++++
 3 files changed, 21 insertions(+)
 create mode 100644 vlib/v/tests/interfaces/interface_smartcast_call_test.v

diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index 0cb6ac0db..f728acb6a 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -1389,6 +1389,12 @@ pub fn (t &Table) is_interface_var(var ScopeObject) bool {
 		&& t.sym(var.smartcasts.last()).kind != .interface_
 }
 
+@[inline]
+pub fn (t &Table) is_interface_smartcast(var ScopeObject) bool {
+	return var is Var && var.orig_type != 0 && t.sym(var.orig_type).kind == .interface_
+		&& var.smartcasts.len > 0
+}
+
 // only used for debugging V compiler type bugs
 pub fn (t &Table) known_type_names() []string {
 	mut res := []string{cap: t.type_idxs.len}
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 74cfb65ee..6c096166d 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -1748,6 +1748,9 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 			if !node.left.is_lvalue() {
 				g.write('ADDR(${rec_cc_type}, ')
 				cast_n++
+			} else if node.left is ast.Ident && g.table.is_interface_smartcast(node.left.obj) {
+				g.write('ADDR(${rec_cc_type}, ')
+				cast_n++
 			} else if !is_array_method_first_last_repeat && !(left_type.has_flag(.shared_f)
 				&& g.typ(left_type) == g.typ(node.receiver_type)) {
 				g.write('&')
diff --git a/vlib/v/tests/interfaces/interface_smartcast_call_test.v b/vlib/v/tests/interfaces/interface_smartcast_call_test.v
new file mode 100644
index 000000000..13d9ecf4c
--- /dev/null
+++ b/vlib/v/tests/interfaces/interface_smartcast_call_test.v
@@ -0,0 +1,12 @@
+interface Foo {}
+
+fn (f &Foo) func() {}
+
+struct Bar {}
+
+fn test_main() {
+	mut f := Foo(Bar{})
+	if mut f is Foo {
+		f.func()
+	}
+}
-- 
2.39.5