From b1f64a32e386cbd7cd88f86e47e062186e9eadd9 Mon Sep 17 00:00:00 2001
From: Swastik Baranwal <swstkbaranwal@gmail.com>
Date: Mon, 1 Jan 2024 16:57:12 +0530
Subject: [PATCH]  checker: give an error for `.free()` method calls, when used
 on fixed arrays  (#20320)

---
 vlib/v/checker/fn.v                                        | 3 +++
 .../checker/tests/array_fixed_no_free_method_call_err.out  | 7 +++++++
 .../v/checker/tests/array_fixed_no_free_method_call_err.vv | 7 +++++++
 3 files changed, 17 insertions(+)
 create mode 100644 vlib/v/checker/tests/array_fixed_no_free_method_call_err.out
 create mode 100644 vlib/v/checker/tests/array_fixed_no_free_method_call_err.vv

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 499ddde81..42dbf9c62 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -1902,6 +1902,9 @@ fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 				c.warn('manual memory management with `free()` is only allowed in unsafe code',
 					node.pos)
 			}
+			if left_sym.kind == .array_fixed {
+				c.error('unknown method or field: ${left_sym.name}.free()', node.pos)
+			}
 			return ast.void_type
 		}
 		// call struct field fn type
diff --git a/vlib/v/checker/tests/array_fixed_no_free_method_call_err.out b/vlib/v/checker/tests/array_fixed_no_free_method_call_err.out
new file mode 100644
index 000000000..9b47a5e5a
--- /dev/null
+++ b/vlib/v/checker/tests/array_fixed_no_free_method_call_err.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/array_fixed_no_free_method_call_err.vv:5:19: error: unknown method or field: [24]u8.free()
+    3 |         `0`, `:`, `0`, `0`, `.`, `0`, `0`, `0`, `Z`]!
+    4 |     defer {
+    5 |         unsafe { buffer.free() }
+      |                         ~~~~~~
+    6 |     }
+    7 | }
diff --git a/vlib/v/checker/tests/array_fixed_no_free_method_call_err.vv b/vlib/v/checker/tests/array_fixed_no_free_method_call_err.vv
new file mode 100644
index 000000000..53c07ead4
--- /dev/null
+++ b/vlib/v/checker/tests/array_fixed_no_free_method_call_err.vv
@@ -0,0 +1,7 @@
+fn main() {
+	mut buffer := [u8(`0`), `0`, `0`, `0`, `-`, `0`, `0`, `-`, `0`, `0`, `T`, `0`, `0`, `:`, `0`,
+		`0`, `:`, `0`, `0`, `.`, `0`, `0`, `0`, `Z`]!
+	defer {
+		unsafe { buffer.free() }
+	}
+}
-- 
2.39.5