From 1a6f07dda53311dc79d648eec880219cee839bc7 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Fri, 21 Nov 2025 00:57:55 -0300
Subject: [PATCH] checker: fix array fixed unresolved return check and resolver
 (fix #25774) (#25790)

---
 vlib/v/checker/checker.v                        |  6 ++++++
 vlib/v/checker/return.v                         |  5 +++++
 vlib/v/gen/c/cgen.v                             |  4 ++--
 .../tests/fns/array_fixed_unresolved_ret_test.v | 17 +++++++++++++++++
 4 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/tests/fns/array_fixed_unresolved_ret_test.v

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index a54212da7..525b0cc85 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -5913,7 +5913,13 @@ pub fn (mut c Checker) update_unresolved_fixed_sizes() {
 			ret_sym := c.table.sym(stmt.return_type)
 			if ret_sym.info is ast.ArrayFixed && c.array_fixed_has_unresolved_size(ret_sym.info) {
 				mut size_expr := ret_sym.info.size_expr
+				old_typ := c.cast_fixed_array_ret(stmt.return_type, c.table.final_sym(stmt.return_type))
 				stmt.return_type = c.eval_array_fixed_sizes(mut size_expr, 0, ret_sym.info.elem_type)
+				new_sym := c.table.sym(stmt.return_type)
+				mut typ_sym := c.table.type_symbols[old_typ.idx()]
+				typ_sym.name = new_sym.name
+				typ_sym.cname = new_sym.cname
+				typ_sym.info = new_sym.info
 			}
 		} else if mut stmt is ast.TypeDecl { // alias
 			mut alias_decl := stmt
diff --git a/vlib/v/checker/return.v b/vlib/v/checker/return.v
index e8b9614ab..463762277 100644
--- a/vlib/v/checker/return.v
+++ b/vlib/v/checker/return.v
@@ -278,6 +278,11 @@ fn (mut c Checker) return_stmt(mut node ast.Return) {
 				if c.inside_lambda && exp_type.has_flag(.generic) {
 					continue
 				}
+				if exp_final_sym.info is ast.ArrayFixed
+					&& c.array_fixed_has_unresolved_size(exp_final_sym.info) {
+					continue
+				}
+
 				c.error('cannot use `${got_type_name}` as ${c.error_type_name(exp_type)} in return argument',
 					exprv.pos())
 			}
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index f4e9a83b9..d462e58e5 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -7034,8 +7034,8 @@ fn (mut g Gen) write_types(symbols []&ast.TypeSymbol) {
 			ast.ArrayFixed {
 				elem_sym := g.table.sym(sym.info.elem_type)
 				if !elem_sym.is_builtin() && !sym.info.elem_type.has_flag(.generic)
-					&& (!g.pref.skip_unused || (!sym.info.is_fn_ret
-					&& sym.idx in g.table.used_features.used_syms)) {
+					&& !sym.info.is_fn_ret && (!g.pref.skip_unused
+					|| (!sym.info.is_fn_ret && sym.idx in g.table.used_features.used_syms)) {
 					// .array_fixed {
 					styp := sym.cname
 					// array_fixed_char_300 => char x[300]
diff --git a/vlib/v/tests/fns/array_fixed_unresolved_ret_test.v b/vlib/v/tests/fns/array_fixed_unresolved_ret_test.v
new file mode 100644
index 000000000..320f75938
--- /dev/null
+++ b/vlib/v/tests/fns/array_fixed_unresolved_ret_test.v
@@ -0,0 +1,17 @@
+enum Abc {
+	a = 1
+	b = 2
+	c = 3
+}
+
+const abc_len = int(Abc.c)
+
+fn build_arr() [abc_len]Abc {
+	return [abc_len]Abc{}
+}
+
+fn test_main() {
+	a := build_arr()
+	println(a)
+	assert a.len == 3
+}
-- 
2.39.5