From a388b3be843783297b04171b05ba33faa85eb687 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sun, 8 Dec 2024 09:38:49 -0300
Subject: [PATCH] cgen: fixed for in loop with generic fixed array (fix #23075)
 (#23101)

---
 vlib/v/gen/c/for.v                             | 11 ++++++++++-
 vlib/v/tests/arrays_closure_fixed_array_test.v | 17 +++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/tests/arrays_closure_fixed_array_test.v

diff --git a/vlib/v/gen/c/for.v b/vlib/v/gen/c/for.v
index 31a8bfe3a..b5fd5a026 100644
--- a/vlib/v/gen/c/for.v
+++ b/vlib/v/gen/c/for.v
@@ -267,6 +267,8 @@ fn (mut g Gen) for_in_stmt(node_ ast.ForInStmt) {
 				g.writeln('\t${styp} ${c_name(node.val_var)};')
 				g.writeln('\tmemcpy(*(${styp}*)${c_name(node.val_var)}, (byte*)${right}, sizeof(${styp}));')
 			} else {
+				needs_memcpy := !node.val_type.is_ptr()
+					&& g.table.final_sym(node.val_type).kind == .array_fixed
 				// If val is mutable (pointer behind the scenes), we need to generate
 				// `int* val = ((int*)arr.data) + i;`
 				// instead of
@@ -276,10 +278,17 @@ fn (mut g Gen) for_in_stmt(node_ ast.ForInStmt) {
 					'((${styp}*)${opt_expr}${op_field}data)[${i}]'
 				} else if node.val_is_mut || node.val_is_ref {
 					'((${styp})${cond_var}${op_field}data) + ${i}'
+				} else if val_sym.kind == .array_fixed {
+					'((${styp}*)${cond_var}${op_field}data)[${i}]'
 				} else {
 					'((${styp}*)${cond_var}${op_field}data)[${i}]'
 				}
-				g.writeln('\t${styp} ${c_name(node.val_var)} = ${right};')
+				if !needs_memcpy {
+					g.writeln('\t${styp} ${c_name(node.val_var)} = ${right};')
+				} else {
+					g.writeln('\t${styp} ${c_name(node.val_var)} = {0};')
+					g.writeln('\tmemcpy(${c_name(node.val_var)}, ${right}, sizeof(${styp}));')
+				}
 			}
 		}
 	} else if node.kind == .array_fixed {
diff --git a/vlib/v/tests/arrays_closure_fixed_array_test.v b/vlib/v/tests/arrays_closure_fixed_array_test.v
new file mode 100644
index 000000000..6496086d6
--- /dev/null
+++ b/vlib/v/tests/arrays_closure_fixed_array_test.v
@@ -0,0 +1,17 @@
+import arrays
+
+fn test_main() {
+	mut rules := [][2]int{}
+	rules << [1, 2]!
+	rules << [2, 3]!
+
+	common_rule := [1, 2]!
+	assert arrays.index_of_first(rules, fn [common_rule] (idx int, rule [2]int) bool {
+		return rule == common_rule
+	}) == 0
+
+	common_rule2 := [2, 3]!
+	assert arrays.index_of_first(rules, fn [common_rule2] (idx int, rule [2]int) bool {
+		return rule == common_rule2
+	}) == 1
+}
-- 
2.39.5