From 64430f9471d9a660f1b1c356f1c4c069bef3c053 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Mon, 15 Jul 2024 17:13:21 +0800
Subject: [PATCH] checker: check mismatch of fn call mut argument (fix #21857)
 (#21873)

---
 vlib/v/checker/check_types.v                     |  6 ++++++
 .../tests/fn_call_mut_arg_mismatch_err.out       |  6 ++++++
 .../tests/fn_call_mut_arg_mismatch_err.vv        | 16 ++++++++++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.out
 create mode 100644 vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.vv

diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
index 26f5f7a5ed14c2..9bb20fca08e15f 100644
--- a/vlib/v/checker/check_types.v
+++ b/vlib/v/checker/check_types.v
@@ -249,6 +249,12 @@ fn (mut c Checker) check_expected_call_arg(got ast.Type, expected_ ast.Type, lan
 			}
 		}
 
+		// `fn foo(mut p &Expr); mut expr := Expr{}; foo(mut expr)`
+		if arg.is_mut && expected.nr_muls() > 1 && !got.is_ptr() {
+			got_typ_str, expected_typ_str := c.get_string_names_of(got, expected)
+			return error('cannot use `${got_typ_str}` as `${expected_typ_str}`')
+		}
+
 		exp_sym_idx := c.table.sym(expected).idx
 		got_sym_idx := c.table.sym(got).idx
 
diff --git a/vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.out b/vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.out
new file mode 100644
index 00000000000000..27a1d47e0f28ca
--- /dev/null
+++ b/vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.vv:15:10: error: cannot use `Expr1` as `&&Expr1` in argument 1 to `foo`
+   13 |         name: '123'
+   14 |     }
+   15 |     foo(mut expr)
+      |             ~~~~
+   16 | }
diff --git a/vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.vv b/vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.vv
new file mode 100644
index 00000000000000..75d05986b6d947
--- /dev/null
+++ b/vlib/v/checker/tests/fn_call_mut_arg_mismatch_err.vv
@@ -0,0 +1,16 @@
+module main
+
+pub struct Expr1 {
+	name string
+}
+
+fn foo(mut expr &Expr1) { // <---- &
+	println(expr.name)
+}
+
+fn main() {
+	mut expr := Expr1{
+		name: '123'
+	}
+	foo(mut expr)
+}