update base64 to 0.23

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Install nightly toolchain for cargo-sync-rdme
         uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: nightly-2026-04-30
+          toolchain: nightly-2026-09-30
       - name: Regenerate readmes
         run: just generate-readmes
       - name: Check for differences
@@ -69,6 +69,23 @@ jobs:
       - name: Doctests
         run: just powerset test --doc
 
+  no-std:
+    name: Build for no_std
+    runs-on: ubuntu-latest
+    env:
+      RUSTFLAGS: -D warnings
+    steps:
+      - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: thumbv7em-none-eabi
+      - uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
+      - uses: taiki-e/install-action@cargo-hack
+      - uses: taiki-e/install-action@just
+      # schemars 0.8 requires std, so exclude it here.
+      - name: Build for a no_std target
+        run: just powerset --exclude-features schemars08 check --target thumbv7em-none-eabi
+
   docs:
     name: Deploy docs to GitHub Pages
     # Only deploy on pushes to main.

CHANGELOG.md

@@ -3,6 +3,15 @@
 <!-- next-header -->
 ## Unreleased - ReleaseDate
 
+### Changed
+
+- Updated the `base64` dependency to 0.23.
+
+### Fixed
+
+- The `base64` feature now builds on `no_std` targets. Previously, the `base64`
+  dependency was built with its `std` feature.
+
 ## [0.1.0] - 2026-03-05
 
 Initial release, with support for fixed-length hex arrays and variable-length base64 vectors.

Cargo.toml

@@ -49,7 +49,7 @@ schemars08 = ["alloc", "dep:schemars08", "dep:serde_json"]
 serde = ["dep:serde_core"]
 
 [dependencies]
-base64 = { version = "0.22", optional = true }
+base64 = { version = "0.23", default-features = false, features = ["alloc"], optional = true }
 hex = { version = "0.4", default-features = false, optional = true }
 schemars08 = { package = "schemars", version = "0.8", optional = true }
 serde_core = { version = "1", default-features = false, optional = true }

Justfile

@@ -16,7 +16,7 @@ rustdoc *args:
 
 # Generate README.md using `cargo-sync-rdme`.
 generate-readmes:
-    cargo sync-rdme --toolchain nightly-2026-04-30 --all-features
+    cargo +stable sync-rdme --toolchain nightly-2026-09-30 --all-features
 
 # Run cargo release in CI.
 ci-cargo-release:

README.md

@@ -79,7 +79,7 @@ Several crates solve parts of this problem, often using slightly
 different approaches from `byte-wrapper`.
 
 |feature|`byte-wrapper`|[`serde-human-bytes`] 0.1.2|[`serde-encoded-bytes`] 0.2.1|[`serde_with`] 3.17.0|[`hex-buffer-serde`] 0.4.0|[`hexutil`] 0.1.0|[`serde-bytes-repr`] 0.3.0|
-|-------|--------------|-------------------------|---------------------------|-------------------|------------------------|---------------|------------------------|
+|-------|--------------|------|------|-------|------|------|------|
 |newtype wrappers|yes|yes (hex only)|no|no|no|no|no|
 |[`is_human_readable()`] switch|yes|yes|yes|no|yes|yes|no|
 |[`Display`] / [`FromStr`] / [`Deref`]|yes|[`Deref`] only|no|no|no|[`Display`] / [`FromStr`] via macro|no|
@@ -113,7 +113,9 @@ The closest alternatives are:
 * **`serde`**: implements `Serialize` and `Deserialize` for
   enabled types. *Not enabled by default.*
 * **`schemars08`**: derives `JsonSchema` for enabled types.
-  *Not enabled by default.*
+  Requires `std`. *Not enabled by default.*
+
+All features other than `schemars08` are compatible with `no_std`.
 
 [`HexArray<N>`]: https://docs.rs/byte-wrapper/0.1.0/byte_wrapper/hex_array/struct.HexArray.html "struct byte_wrapper::hex_array::HexArray"
 [`Base64Vec`]: https://docs.rs/byte-wrapper/0.1.0/byte_wrapper/base64_vec/struct.Base64Vec.html "struct byte_wrapper::base64_vec::Base64Vec"
@@ -126,9 +128,9 @@ The closest alternatives are:
 [`hexutil`]: https://docs.rs/hexutil
 [`serde-bytes-repr`]: https://docs.rs/serde-bytes-repr
 [`is_human_readable()`]: https://docs.rs/serde/latest/serde/trait.Serializer.html#method.is_human_readable
-[`Display`]: https://doc.rust-lang.org/nightly/core/fmt/trait.Display.html "trait core::fmt::Display"
-[`FromStr`]: https://doc.rust-lang.org/nightly/core/str/traits/trait.FromStr.html "trait core::str::traits::FromStr"
-[`Deref`]: https://doc.rust-lang.org/nightly/core/ops/deref/trait.Deref.html "trait core::ops::deref::Deref"
+[`Display`]: https://doc.rust-lang.org/stable/core/fmt/trait.Display.html "trait core::fmt::Display"
+[`FromStr`]: https://doc.rust-lang.org/stable/core/str/traits/trait.FromStr.html "trait core::str::traits::FromStr"
+[`Deref`]: https://doc.rust-lang.org/stable/core/ops/deref/trait.Deref.html "trait core::ops::deref::Deref"
 [`HexArray`]: https://docs.rs/byte-wrapper/0.1.0/byte_wrapper/hex_array/struct.HexArray.html "struct byte_wrapper::hex_array::HexArray"
 <!-- cargo-sync-rdme ]] -->
 

src/base64_vec.rs

@@ -107,9 +107,11 @@ fn from_decode_error(e: base64::DecodeError) -> ParseBase64Error {
         base64::DecodeError::InvalidLength(length) => {
             ParseBase64Error::InvalidLength { length }
         }
-        base64::DecodeError::InvalidLastSymbol(offset, byte) => {
-            ParseBase64Error::InvalidLastSymbol { offset, byte }
-        }
+        base64::DecodeError::InvalidLastSymbol {
+            offset,
+            symbol,
+            symbol_value: _,
+        } => ParseBase64Error::InvalidLastSymbol { offset, byte: symbol },
         base64::DecodeError::InvalidPadding => ParseBase64Error::InvalidPadding,
     }
 }

src/lib.rs

@@ -126,7 +126,9 @@
 //! - **`serde`**: implements `Serialize` and `Deserialize` for
 //!   enabled types. *Not enabled by default.*
 //! - **`schemars08`**: derives `JsonSchema` for enabled types.
-//!   *Not enabled by default.*
+//!   Requires `std`. *Not enabled by default.*
+//!
+//! All features other than `schemars08` are compatible with `no_std`.
 
 #![deny(missing_docs)]
 #![no_std]

tests/integration/base64.rs

@@ -37,6 +37,25 @@ fn base64_from_str_invalid_length() {
     assert_eq!(err, ParseBase64Error::InvalidLength { length: 1 });
 }
 
+#[test]
+fn base64_from_str_invalid_last_symbol() {
+    // "QQ==" is an encoding of [0x41]. "QR==" sets trailing bits.
+    let err = "QR==".parse::<Base64Vec>().expect_err("invalid last symbol");
+    assert_eq!(
+        err,
+        ParseBase64Error::InvalidLastSymbol { offset: 1, byte: b'R' },
+        "got: {err}",
+    );
+    assert!(err.to_string().contains("offset 1"), "got: {err}");
+}
+
+#[test]
+fn base64_from_str_invalid_padding() {
+    // The standard engine requires canonical padding.
+    let err = "QQ".parse::<Base64Vec>().expect_err("missing padding");
+    assert_eq!(err, ParseBase64Error::InvalidPadding);
+}
+
 // -- Display and Debug formatting tests --
 
 #[test]