chore: release v0.20.1

[github-actions]

🤖 New release

• deku_derive: 0.20.0 -> 0.20.1
• deku: 0.20.0 -> 0.20.1 (✓ API compatible changes)

Changelog

deku

0.20.1 - 2025-11-13

Other

• Add DekuSize impl (#618)
• Improved documentation on how endian etc. interacts with ctx (#623)
• Lift alloc requirement for bits feature (#614)
• Update stable trybuild (#619)
• add thumbv6m-none-eabi target to ensure_no_std step (#616)
• update release-plz.toml
• release v0.20.0 (#610)

---

This PR was generated with release-plz.

[sharksforarms]

@amboar @wcampbell0x2a technically #614 doesn't break old code/compatibility right? would you agree in a patch bump or should we do a 0.21 release

[amboar]

@sharksforarms nothing should break, no. The test suite changes were mainly to accommodate changes to reported formatted strings in errors, and the reduction in allocation count.

[wcampbell0x2a]

@amboar @wcampbell0x2a technically #614 doesn't break old code/compatibility right? would you agree in a patch bump or should we do a 0.21 release

Should be semver compatible.

[amboar]

I think there might be an unintended change in behaviour between v0.20.0 and master for bit_order = "lsb" on some structs. Glimpsed it when testing some other things, and it's clearly not caught by the current test suite, so needs some further investigation.

[amboar]

This fails after #614 but passes if it's reverted:

#[test]
fn test_misaligned_pad_bits_aaelf32_flags() {
    #[derive(Debug, DekuRead, DekuWrite, PartialEq)]
    #[deku(endian = "little", bit_order = "lsb")]
    pub struct AaElf32Flags {
        #[deku(bits = "1", pad_bits_before = "9")]
        ef_arm_abi_float_soft: bool,
        #[deku(bits = "1")]
        ef_arm_abi_float_hard: bool,
        #[deku(bits = "1", pad_bits_before = "11")]
        ef_arm_gccmask: bool,
        #[deku(bits = "1")]
        ef_arm_be8: bool,
        ef_arm_abimask: u8,
    }

    let word = 83886592u32;
    let bytes = word.to_le_bytes();
    let (_, flags) = AaElf32Flags::from_bytes((&bytes, 0)).unwrap();
    assert_eq!(
        AaElf32Flags {
            ef_arm_abi_float_soft: true,
            ef_arm_abi_float_hard: false,
            ef_arm_gccmask: false,
            ef_arm_be8: false,
            ef_arm_abimask: 5,
        },
        flags
    );
}

Looks like I missed specifying some invariants when using seek:

> RUST_LOG=trace cargo test --no-default-features --features=alloc,bits,logging --test test_lsb_le -- test_misaligned_pad_bits_aaelf32_flags
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.03s
     Running tests/test_lsb_le.rs (target/debug/deps/test_lsb_le-f72cea0c554eeb76)

running 1 test
[2025-11-24T01:58:46Z TRACE deku::reader] skip_bits: 9
[2025-11-24T01:58:46Z TRACE deku::reader] seek: Current(1)
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 1
[2025-11-24T01:58:46Z TRACE test_lsb_le] Reading: AaElf32Flags.ef_arm_abi_float_soft
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 1
[2025-11-24T01:58:46Z TRACE test_lsb_le] Reading: AaElf32Flags.ef_arm_abi_float_hard
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 1
[2025-11-24T01:58:46Z TRACE deku::reader] skip_bits: 11
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 3
[2025-11-24T01:58:46Z TRACE deku::reader] seek: Current(1)
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 0
[2025-11-24T01:58:46Z TRACE test_lsb_le] Reading: AaElf32Flags.ef_arm_gccmask
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 1
[2025-11-24T01:58:46Z TRACE test_lsb_le] Reading: AaElf32Flags.ef_arm_be8
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 1
[2025-11-24T01:58:46Z TRACE test_lsb_le] Reading: AaElf32Flags.ef_arm_abimask
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 8
test test_misaligned_pad_bits_aaelf32_flags ... FAILED

After

[2025-11-24T01:58:46Z TRACE deku::reader] skip_bits: 11
[2025-11-24T01:58:46Z TRACE deku::reader] read_bits_into: Lsb0, 3

the current position is not byte-aligned - we've only read 14 bits, so it's incorrect to seek at that point. The requested padding is 11 bits and is incorrectly split into 3 and 8; it should rather be 5 (to become byte-aligned with respect to the already-consumed bits) and then 6, which cannot be seeked, however a read is needed to satisfy the request.

[amboar]

[I] 1 andrew@heihei ~/s/g/s/deku (bit-order-lsb) [101]> git diff
diff --git a/src/reader.rs b/src/reader.rs
index 22b212fb8e1d..bbe0ebc4784e 100644
--- a/src/reader.rs
+++ b/src/reader.rs
@@ -207,6 +207,7 @@ impl<R: Read + Seek> Reader<R> {
 
             // first, seek with bytes
             if bytes_amt != 0 {
+                debug_assert_eq!(self.bits_read % 8, 0);
                 self.seek(SeekFrom::Current(
                     i64::try_from(bytes_amt).expect("could not convert seek usize into i64"),
                 ))

[I] 1 andrew@heihei ~/s/g/s/deku (bit-order-lsb)> cargo test --no-default-features --features=alloc,bits,logging --test test_lsb_le -- test_misaligned_pad_bits_aaelf32_flags
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.03s
     Running tests/test_lsb_le.rs (target/debug/deps/test_lsb_le-f72cea0c554eeb76)

running 1 test
test test_misaligned_pad_bits_aaelf32_flags ... FAILED

failures:

---- test_misaligned_pad_bits_aaelf32_flags stdout ----

thread 'test_misaligned_pad_bits_aaelf32_flags' (131091) panicked at /home/andrew/src/github.com/sharksforarms/deku/src/reader.rs:210:17:
assertion `left == right` failed
  left: 6
 right: 0
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    test_misaligned_pad_bits_aaelf32_flags

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 8 filtered out; finished in 0.00s

error: test failed, to rerun pass `--test test_lsb_le`