hex-literal: remove support for comments inside literals and migrate to CTFE (#816)

Author: newpavlov

.github/workflows/hex-literal.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.45.0 # MSRV
+          - 1.57.0 # MSRV
           - stable
         target:
           - thumbv7em-none-eabi
@@ -48,7 +48,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.45.0 # MSRV
+          - 1.57.0 # MSRV
           - stable
     steps:
       - uses: actions/checkout@v3

hex-literal/CHANGELOG.md

@@ -4,6 +4,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## UNRELEASED
+### Changed
+- Disallow comments inside hex strings ([#816])
+- Migrate to 2021 edition and bump MSRV to 1.57 ([#816])
+- Use CTFE instead of proc macro ([#816])
+
+[#816]: https://github.com/RustCrypto/utils/pull/816
+
 ## 0.3.4 (2021-11-11)
 ### Changed
 - Provide more info in `panic!` messages ([#664])

hex-literal/Cargo.toml

@@ -3,11 +3,9 @@ name = "hex-literal"
 version = "0.3.4"
 authors = ["RustCrypto Developers"]
 license = "MIT OR Apache-2.0"
-description = "Procedural macro for converting hexadecimal string to byte array at compile time."
+description = "Macro for converting hexadecimal string to a byte array at compile time"
 documentation = "https://docs.rs/hex-literal"
 repository = "https://github.com/RustCrypto/utils"
-keywords = ["hex", "proc-macro", "literals"]
-edition = "2018"
-
-[lib]
-proc-macro = true
+keywords = ["hex", "literals"]
+edition = "2021"
+rust-version = "1.57"

hex-literal/README.md

@@ -0,0 +1,84 @@
+# [RustCrypto]: hex-literal
+
+[![Crate][crate-image]][crate-link]
+[![Docs][docs-image]][docs-link]
+![Apache 2.0/MIT Licensed][license-image]
+![MSRV][rustc-image]
+[![Build Status][build-image]][build-link]
+
+This crate provides the `hex!` macro for converting hexadecimal string literals to a byte array at compile time.
+
+It accepts the following characters in the input string:
+
+- `'0'...'9'`, `'a'...'f'`, `'A'...'F'` — hex characters which will be used in construction of the output byte array
+- `' '`, `'\r'`, `'\n'`, `'\t'` — formatting characters which will be ignored
+
+# Examples
+```rust
+use hex_literal::hex;
+
+// The macro can be used in const contexts
+const DATA: [u8; 4] = hex!("01020304");
+assert_eq!(DATA, [1, 2, 3, 4]);
+
+// Both upper and lower hex values are supported
+assert_eq!(hex!("a1 b2 c3 d4"), [0xA1, 0xB2, 0xC3, 0xD4]);
+assert_eq!(hex!("E5 E6 90 92"), [0xE5, 0xE6, 0x90, 0x92]);
+assert_eq!(hex!("0a0B 0C0d"), [10, 11, 12, 13]);
+
+// Multi-line literals
+let bytes1 = hex!("
+    00010203 04050607
+    08090a0b 0c0d0e0f
+");
+assert_eq!(bytes1, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
+
+// It's possible to use several literals (results will be concatenated)
+let bytes2 = hex!(
+    "00010203 04050607" // first half
+    "08090a0b" /* block comment */ "0c0d0e0f" // second half
+);
+assert_eq!(bytes1, bytes2);
+```
+
+Using an unsupported character inside literals will result in a compilation error:
+```rust,compile_fail
+# use hex_literal::hex;
+hex!("АА"); // Cyrillic "А"
+hex!("11　22"); // Japanese space
+hex!("0123 // Сomments inside literals are not supported");
+```
+
+## Minimum Supported Rust Version
+
+Rust **1.57** or newer.
+
+In the future, we reserve the right to change MSRV (i.e. MSRV is out-of-scope for this crate's SemVer guarantees), however when we do it will be accompanied by a minor version bump.
+
+## License
+
+Licensed under either of:
+
+* [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
+* [MIT license](http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
+
+[//]: # (badges)
+
+[crate-image]: https://img.shields.io/crates/v/hex-literal.svg
+[crate-link]: https://crates.io/crates/hex-literal
+[docs-image]: https://docs.rs/hex-literal/badge.svg
+[docs-link]: https://docs.rs/hex-literal/
+[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.57+-blue.svg
+[build-image]: https://github.com/RustCrypto/utils/actions/workflows/hex-literal.yml/badge.svg
+[build-link]: https://github.com/RustCrypto/utils/actions/workflows/hex-literal.yml
+
+[//]: # (general links)
+
+[RustCrypto]: https://github.com/RustCrypto