为何编译器无法识别该`From` trait实现？

近期尝试使用format_serde_error（用于格式化serde错误信息的Rust crate），发现官方提供的示例代码无法编译。

示例代码 #

use format_serde_error::SerdeError;
use serde::Deserialize;

#[derive(Debug, Deserialize)]
struct Foo {
    x: u64,
}

fn main() {
    let content = "x: 3";
    let foo = serde_yaml::from_str(content)
        .map_err(|err| SerdeError::new(content.to_string(), err))
        .unwrap();
    println!("Read in {:?}", foo);
}

Cargo.toml配置 #

[package]
name = "ser-test"
version = "0.1.0"
edition = "2021"

[dependencies]
format_serde_error = { version = "0.3.0", features = ["serde_yaml"] }
serde = { version = "1.0.183", features = ["derive"] }
serde_yaml = "0.9.25"

编译错误信息 #

error[E0277]: the trait bound `ErrorTypes: From<serde_yaml::Error>` is not satisfied
   --> src/main.rs:12:61
    |
12  |         .map_err(|err| SerdeError::new(content.to_string(), err))
    |                        ---------------                      ^^^ the trait `From<serde_yaml::Error>` is not implemented for `ErrorTypes`
    |                        |
    |                        required by a bound introduced by this call
    |
= help: the following other types implement trait `From<T>`:
          <ErrorTypes as From<serde_json::error::Error>>
          <ErrorTypes as From<serde_yaml::error::Error>>
          <ErrorTypes as From<(Box<(dyn StdError + 'static)>, std::option::Option<usize>, std::option::Option<usize>)>>
= note: required for `serde_yaml::Error` to implement `Into<ErrorTypes>`
note: required by a bound in `SerdeError::new`
   --> /home/c/.cargo/registry/src/index.crates.io-6f17d22bba15001f/format_serde_error-0.3.0/src/lib.rs:278:41
    |
278 |     pub fn new(input: String, err: impl Into<ErrorTypes>) -> SerdeError {
    |                                         ^^^^^^^^^^^^^^^^ required by this bound in `SerdeError::new`

问题疑惑 #

编译器提示ErrorTypes未实现From<serde_yaml::Error>，但无论是format_serde_error的仓库代码，还是编译器输出中指向的lib.rs文件，都已定义了该实现：

#[cfg(feature = "serde_yaml")]
impl From<serde_yaml::Error> for ErrorTypes {
    fn from(err: serde_yaml::Error) -> Self {
        Self::Yaml(err)
    }
}

已尝试将Rust更新至1.73.0-nightly (f3623871c 2023-08-06)，执行cargo clean，无论使用默认特性还是显式指定serde_yaml特性，问题均存在。且代码完全复制自format_serde_error的官方示例。

复现步骤 #

cargo new ser-test
cd ser-test
cargo add serde --features derive
cargo add serde_yaml
cargo add format_serde_error
# 将上述示例代码复制到src/main.rs中
cargo run

内容的提问来源于stack exchange，提问作者Carson