From b717fbfb3f8aa111b77ed390700af3f872981a9a Mon Sep 17 00:00:00 2001
From: dishmaker <141624503+dishmaker@users.noreply.github.com>
Date: Thu, 16 Oct 2025 10:45:54 +0200
Subject: [PATCH 1/2] der: docs: add `DecodeValue` trait example

---
 der/src/decode.rs | 30 ++++++++++++++++++++++++++++++
 der/src/tag.rs    |  2 +-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/der/src/decode.rs b/der/src/decode.rs
index 58b6b4ba3..ab896e799 100644
--- a/der/src/decode.rs
+++ b/der/src/decode.rs
@@ -158,6 +158,36 @@ impl<T: DecodeOwned<Error = Error> + PemLabel> DecodePem for T {
 ///
 /// As opposed to [`Decode`], implementer is expected to read the inner content only,
 /// without the [`Header`], which was decoded beforehand.
+///
+/// ## Example
+/// ```
+/// use der::{Decode, DecodeValue, ErrorKind, FixedTag, Header, Length, Reader, Tag};
+///
+/// /// 4-digit year
+/// struct MyStringYear(u16);
+///
+/// impl<'a> DecodeValue<'a> for MyStringYear {
+///     type Error = der::Error;
+///
+///     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> der::Result<Self> {
+///         let slice = reader.read_slice(Length::new(4))?;
+///         let year = std::str::from_utf8(slice).ok().and_then(|s| s.parse::<u16>().ok());
+///         if let Some(year) = year {
+///             Ok(Self(year))
+///         } else {
+///             Err(reader.error(ErrorKind::DateTime))
+///         }
+///     }
+/// }
+///
+/// impl FixedTag for MyStringYear {
+///     const TAG: Tag = Tag::Utf8String;
+/// }
+///
+/// let year = MyStringYear::from_der(b"\x0C\x041670").expect("year to decode");
+///
+/// assert_eq!(year.0, 1670);
+/// ```
 pub trait DecodeValue<'a>: Sized {
     /// Type returned in the event of a decoding error.
     type Error: From<Error> + 'static;
diff --git a/der/src/tag.rs b/der/src/tag.rs
index b0c316b9b..34644892e 100644
--- a/der/src/tag.rs
+++ b/der/src/tag.rs
@@ -86,7 +86,7 @@ impl<T: FixedTag + ?Sized> Tagged for T {
 ///         if let Some(year) = year {
 ///             Ok(Self(year))
 ///         } else {
-///             Err(ErrorKind::DateTime.into())
+///             Err(reader.error(ErrorKind::DateTime))
 ///         }
 ///     }
 /// }

From f7bb64d7e3230e9025e7fc0a5f32a6fffdfa79db Mon Sep 17 00:00:00 2001
From: dishmaker <141624503+dishmaker@users.noreply.github.com>
Date: Thu, 16 Oct 2025 10:53:30 +0200
Subject: [PATCH 2/2] der: docs: MyByteMonth struct example

---
 der/src/decode.rs | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/der/src/decode.rs b/der/src/decode.rs
index ab896e799..700c3145a 100644
--- a/der/src/decode.rs
+++ b/der/src/decode.rs
@@ -161,32 +161,32 @@ impl<T: DecodeOwned<Error = Error> + PemLabel> DecodePem for T {
 ///
 /// ## Example
 /// ```
-/// use der::{Decode, DecodeValue, ErrorKind, FixedTag, Header, Length, Reader, Tag};
+/// use der::{Decode, DecodeValue, ErrorKind, FixedTag, Header, Reader, Tag};
 ///
-/// /// 4-digit year
-/// struct MyStringYear(u16);
+/// /// 1-byte month
+/// struct MyByteMonth(u8);
 ///
-/// impl<'a> DecodeValue<'a> for MyStringYear {
+/// impl<'a> DecodeValue<'a> for MyByteMonth {
 ///     type Error = der::Error;
 ///
 ///     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> der::Result<Self> {
-///         let slice = reader.read_slice(Length::new(4))?;
-///         let year = std::str::from_utf8(slice).ok().and_then(|s| s.parse::<u16>().ok());
-///         if let Some(year) = year {
-///             Ok(Self(year))
+///         let month = reader.read_byte()?;
+///         
+///         if (0..12).contains(&month) {
+///             Ok(Self(month))
 ///         } else {
 ///             Err(reader.error(ErrorKind::DateTime))
 ///         }
 ///     }
 /// }
 ///
-/// impl FixedTag for MyStringYear {
-///     const TAG: Tag = Tag::Utf8String;
+/// impl FixedTag for MyByteMonth {
+///     const TAG: Tag = Tag::OctetString;
 /// }
 ///
-/// let year = MyStringYear::from_der(b"\x0C\x041670").expect("year to decode");
+/// let month = MyByteMonth::from_der(b"\x04\x01\x09").expect("month to decode");
 ///
-/// assert_eq!(year.0, 1670);
+/// assert_eq!(month.0, 9);
 /// ```
 pub trait DecodeValue<'a>: Sized {
     /// Type returned in the event of a decoding error.