cgen: fix codegen for const of fixed array (fix #22357) (#22364)

vlib/v/gen/c/cgen.v

@@ -6248,7 +6248,13 @@ fn (mut g Gen) const_decl_init_later_msvc_string_fixed_array(mod string, name st
 	cname := g.c_const_name(name)
 	mut init := strings.new_builder(100)
 	for i, elem_expr in expr.exprs {
-		init.writeln(g.expr_string_surround('\t${cname}[${i}] = ', elem_expr, ';'))
+		if elem_expr is ast.ArrayInit && elem_expr.is_fixed {
+			elem_typ := g.typ(elem_expr.typ)
+			init.writeln(g.expr_string_surround('\tmemcpy(${cname}[${i}], (${elem_typ})',
+				elem_expr, ', sizeof(${elem_typ}));'))
+		} else {
+			init.writeln(g.expr_string_surround('\t${cname}[${i}] = ', elem_expr, ';'))
+		}
 	}
 	mut def := '${styp} ${cname}'
 	g.global_const_defs[util.no_dots(name)] = GlobalConstDef{

vlib/v/tests/consts/const_array_fixed_test.v

@@ -0,0 +1,32 @@
+@[has_globals]
+module main
+
+struct Foo {
+	bar int = 120
+}
+
+__global (
+	a Foo
+)
+
+const c = [[a.bar]!]!
+const d = [[a.bar]]!
+const e = [[a.bar]!]
+const f = [[[a.bar]!]!]!
+const g = [a.bar]
+
+fn test_selector() {
+	assert dump(c == [[a.bar]!]!)
+	assert dump(d == [[a.bar]]!)
+	assert dump(e == [[a.bar]!])
+	assert dump(f == [[[a.bar]!]!]!)
+	assert dump(g == [a.bar])
+}
+
+fn test_literal() {
+	assert dump(c == [[120]!]!)
+	assert dump(d == [[120]]!)
+	assert dump(e == [[120]!])
+	assert dump(f == [[[120]!]!]!)
+	assert dump(g == [120])
+}