export fn a() void {
const S = struct { x: i32, y: i32 };
var s: S = undefined;
s[0] = 10;
}
// error
// backend=stage2
// target=native
//
// :4:6: error: type 'tmp.a.S' does not support indexing
// :4:6: note: operand must be an array, slice, tuple, or vector