cgen: fix codegen for const fixed array initialization with another const as item

vlib/v/gen/c/cgen.v

@@ -6076,14 +6076,17 @@ fn (mut g Gen) check_expr_is_const(expr ast.Expr) bool {
 		ast.InfixExpr {
 			return g.check_expr_is_const(expr.left) && g.check_expr_is_const(expr.right)
 		}
-		ast.Ident, ast.StructInit, ast.EnumVal {
+		ast.Ident {
+			return expr.kind == .function || g.table.final_sym(expr.obj.typ).kind != .array_fixed
+		}
+		ast.StructInit, ast.EnumVal {
 			return true
 		}
 		ast.CastExpr {
 			return g.check_expr_is_const(expr.expr)
 		}
 		ast.PrefixExpr {
-			return g.check_expr_is_const(expr.right)
+			return expr.right is ast.Ident || g.check_expr_is_const(expr.right)
 		}
 		else {
 			return false

vlib/v/gen/c/consts_and_globals.v

@@ -367,6 +367,16 @@ fn (mut g Gen) const_decl_init_later_msvc_string_fixed_array(mod string, name st
 			elem_typ := g.styp(elem_expr.typ)
 			init.writeln(g.expr_string_surround('\tmemcpy(${cname}[${i}], (${elem_typ})',
 				elem_expr, ', sizeof(${elem_typ}));'))
+		} else if elem_expr is ast.Ident {
+			elem_typ := elem_expr.obj.typ
+			if g.table.final_sym(elem_typ).kind == .array_fixed {
+				elem_styp := g.styp(elem_expr.obj.typ)
+				init.writeln(g.expr_string_surround('\tmemcpy(${cname}[${i}], ', elem_expr,
+					', sizeof(${elem_styp}));'))
+			} else {
+				init.writeln(g.expr_string_surround('\t${cname}[${i}] = ', elem_expr,
+					';'))
+			}
 		} else {
 			init.writeln(g.expr_string_surround('\t${cname}[${i}] = ', elem_expr, ';'))
 		}

vlib/v/tests/consts/const_fixed_array_with_var_item_test.v

@@ -0,0 +1,7 @@
+const f = [u8(0), 1, 2]!
+
+const ff = [[u8(1), 2, 3]!, [u8(5), 4, 3]!, f]!
+
+fn test_main() {
+	assert ff == [[u8(1), 2, 3]!, [u8(5), 4, 3]!, [u8(0), 1, 2]!]!
+}