From 80477e3acfd13f169d1ed130190eb23c4b2b188f Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Fri, 28 Feb 2025 17:15:06 -0300
Subject: [PATCH] cgen: fix array fixed assignment for `@[keep_args_alive]`
 (partial fix for #23804) (#23805)

---
 vlib/v/gen/c/fn.v                     | 14 +++++++++++---
 vlib/v/tests/c_function/code.c        |  3 +++
 vlib/v/tests/c_function/code_test.c.v | 10 ++++++++++
 vlib/v/tests/c_function/v.mod         |  7 +++++++
 4 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/tests/c_function/code.c
 create mode 100644 vlib/v/tests/c_function/code_test.c.v
 create mode 100644 vlib/v/tests/c_function/v.mod

diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 506576916..f7461b319 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -2579,9 +2579,17 @@ fn (mut g Gen) keep_alive_call_pregen(node ast.CallExpr) int {
 		// save all arguments in temp vars (not only pointers) to make sure the
 		// evaluation order is preserved
 		expected_type := node.expected_arg_types[i]
-		typ := g.table.sym(expected_type).cname
-		g.write('${typ} __tmp_arg_${tmp_cnt_save + i} = ')
-		g.ref_or_deref_arg(arg, expected_type, node.language, false)
+		typ_sym := g.table.sym(expected_type)
+		typ := typ_sym.cname
+		if typ_sym.kind != .array_fixed {
+			g.write('${typ} __tmp_arg_${tmp_cnt_save + i} = ')
+			g.ref_or_deref_arg(arg, expected_type, node.language, false)
+		} else {
+			g.writeln('${typ} __tmp_arg_${tmp_cnt_save + i} = {0};')
+			g.write('memcpy(&__tmp_arg_${tmp_cnt_save + i}, ')
+			g.ref_or_deref_arg(arg, expected_type, node.language, false)
+			g.writeln(', sizeof(${typ}));')
+		}
 		g.writeln(';')
 	}
 	g.empty_line = false
diff --git a/vlib/v/tests/c_function/code.c b/vlib/v/tests/c_function/code.c
new file mode 100644
index 000000000..72cad6343
--- /dev/null
+++ b/vlib/v/tests/c_function/code.c
@@ -0,0 +1,3 @@
+void foo(int arg[1]) {
+
+}
\ No newline at end of file
diff --git a/vlib/v/tests/c_function/code_test.c.v b/vlib/v/tests/c_function/code_test.c.v
new file mode 100644
index 000000000..6aa1606a0
--- /dev/null
+++ b/vlib/v/tests/c_function/code_test.c.v
@@ -0,0 +1,10 @@
+module main
+
+#include "@VMODROOT/code.c"
+
+@[keep_args_alive]
+fn C.foo(arg [1]int)
+
+fn test_main() {
+	C.foo([1]!)
+}
diff --git a/vlib/v/tests/c_function/v.mod b/vlib/v/tests/c_function/v.mod
new file mode 100644
index 000000000..dc270208c
--- /dev/null
+++ b/vlib/v/tests/c_function/v.mod
@@ -0,0 +1,7 @@
+Module {
+	name: 'c_function'
+	description: ''
+	version: ''
+	license: ''
+	dependencies: []
+}
-- 
2.39.5