cgen: fix codegen for returning option reference from indexexpr (fix #23133) (#23139)

Author: felipensp

vlib/v/gen/c/index.v

@@ -325,7 +325,11 @@ fn (mut g Gen) index_of_array(node ast.IndexExpr, sym ast.TypeSymbol) {
 			if !node.is_option {
 				g.or_block(tmp_opt, node.or_expr, elem_type)
 			}
-			g.write('\n${cur_line}(*(${elem_type_str}*)${tmp_opt}.data)')
+			if !g.is_amp {
+				g.write('\n${cur_line}(*(${elem_type_str}*)${tmp_opt}.data)')
+			} else {
+				g.write('\n${cur_line}*${tmp_opt_ptr}')
+			}
 		}
 	}
 }

vlib/v/tests/options/option_index_amp_test.v

@@ -0,0 +1,28 @@
+module main
+
+struct Bar {
+	name string
+}
+
+struct Foo {
+	bars []Bar
+}
+
+fn (f Foo) find() ?&Bar {
+	return &f.bars[1] or { return none }
+}
+
+fn test_main() {
+	foo := Foo{
+		bars: [Bar{
+			name: '123'
+		}, Bar{
+			name: 'aaa'
+		}, Bar{
+			name: 's34'
+		}]
+	}
+	bar := foo.find() or { panic('not found') }
+	println(bar.name)
+	assert bar.name == 'aaa'
+}