//ww:run
// probe: after io.close flushes the encoder, encode_closer calls
// clear(e) = bytes.zero(e.ibuf); bytes.zero(e.obuf). Under a correct
// build, ibuf/obuf are all zero afterwards. Under the wwstage
// miscompile the zeroing slice has len 0 -> stale bytes survive.
package main;
import encoding.base64;
import io;
import memio;
export fn main() int = {
	let out: memio.stream = memio.dynamic();
	let e: base64.encoder = base64.newencoder(&base64.std_encoding, &out.vt);
	let raw: [5]u8 = ['f', 'o', 'o', 'b', 'a'];
	match (io.write(&e.vt, raw)) {
	case let n: size => void;
	case let er: io.error => return 2;
	};
	match (io.close(&e.vt)) {
	case void => void;
	case let er: io.error => return 3;
	};
	// 5 = 3+2: the trailing 2-byte group went through the closer's
	// pad path, so both ibuf and obuf held nonzero bytes before
	// clear(). All must now read zero.
	let i: i32 = 0;
	for (i < 3) {
		if (e.ibuf[i] != 0u8) { return (10 + i): int; };
		i += 1;
	};
	i = 0;
	for (i < 4) {
		if (e.obuf[i] != 0u8) { return (20 + i): int; };
		i += 1;
	};
	return 0;
};