From 93eb34863157e1cf58902d539b404eb8930bc5ea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Bernier?= <frankbernier@gmail.com>
Date: Tue, 19 Nov 2024 00:15:51 -0500
Subject: [PATCH] impl core::error::Error for errors

---
 Cargo.toml |  3 ++-
 src/lib.rs | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 10a182c..2489998 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,13 +1,14 @@
 [package]
 name = "base62"
 version = "2.0.3"
+rust-version = "1.81.0"
 authors = [
     "François Bernier <frankbernier@gmail.com>",
     "Chai T. Rex <ChaiTRex@users.noreply.github.com>",
     "Kevin Darlington <kevin@outroot.com>",
     "Christopher Tarquini <code@tarq.io>",
 ]
-edition = "2018"
+edition = "2021"
 description = "A Base62 encoding/decoding library"
 documentation = "https://docs.rs/base62/"
 homepage = "https://github.com/fbernier/base62"
diff --git a/src/lib.rs b/src/lib.rs
index f0b01a6..1823a1e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,7 @@ encoding to and decoding from [base62](https://en.wikipedia.org/wiki/Base62).
 
 #![no_std]
 extern crate alloc;
+
 use alloc::string::String;
 
 const BASE: u64 = 62;
@@ -67,6 +68,26 @@ impl core::fmt::Display for DecodeError {
     }
 }
 
+impl core::error::Error for DecodeError {
+    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
+        None
+    }
+}
+
+impl core::fmt::Display for EncodeError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            EncodeError::BufferTooSmall => f.write_str("Buffer too small to encode number"),
+        }
+    }
+}
+
+impl core::error::Error for EncodeError {
+    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
+        None
+    }
+}
+
 /// Indicates the cause of an encoding failure in [`encode`](crate::encode_bytes).
 #[derive(Copy, Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub enum EncodeError {
@@ -804,7 +825,10 @@ pub fn encode_alternative_buf<T: Into<u128>>(num: T, buf: &mut String) {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use alloc::boxed::Box;
+    use alloc::string::ToString;
     use alloc::vec::Vec;
+    extern crate std;
 
     // Don't run quickcheck tests under miri because that's infinitely slow
     #[cfg(not(miri))]
@@ -1315,4 +1339,24 @@ mod tests {
         assert_eq!(buf, "26Tf05FVsiGH0000000000");
         // buf.clear();
     }
+
+    #[test]
+    fn test_error_trait() {
+        fn assert_error<T: core::error::Error>(_: &T) {}
+
+        // Test that our errors implement Error
+        assert_error(&DecodeError::EmptyInput);
+        assert_error(&EncodeError::BufferTooSmall);
+    }
+
+    #[test]
+    fn test_std_error_compatibility() {
+        use std::error::Error;
+
+        let decode_err: Box<dyn Error> = Box::new(DecodeError::EmptyInput);
+        assert!(decode_err.to_string().contains("empty string"));
+
+        let encode_err: Box<dyn Error> = Box::new(EncodeError::BufferTooSmall);
+        assert!(encode_err.to_string().contains("Buffer too small"));
+    }
 }