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Unreachable code fault at config-0.14.0/src/file/format/yaml.rs:53:26 #547

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mjaakkol opened this issue Mar 15, 2024 · 2 comments
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@mjaakkol
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I'm getting above error as

thread 'XXX' panicked at /home/username/.cargo/registry/src/index.crates.io-6f17d22bba15001f/config-0.14.0/src/file/format/yaml.rs:53:26:
internal error: entered unreachable code

Yaml file looks like

link:
  null:
    name: "null"
  tcp:
    address: "localhost:1234"

My structure definitions for the section are:

#[derive(serde::Deserialize, Clone)]
pub struct LinkSettings {
    pub serial: Option<SerialSettings>,
    pub unix: Option<UnixSettings>,
    pub null: Option<NullSettings>,
    pub tcp: Option<TcpSettings>,
}

#[derive(serde::Deserialize, Clone)]
pub struct NullSettings {
    pub name: String,
}

#[derive(serde::Deserialize, Clone)]
pub struct UnixSettings {
    pub name: String,
}

#[derive(serde::Deserialize, Clone)]
pub struct TcpSettings {
    pub address: String,
}

I believe above is valid yaml (not the best looking yaml but I'll add more things to the hashtable later so the structure is needed. This worked with 0.13.x

@goingforbrooke
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Confirmed. Thanks for the Issue @mjaakkol! 🙏🏻

Seems like the mixture of string and integer in `"localhost:1234" is unexpected.

Backtrace:

   3: config::file::format::yaml::from_yaml_value
             at ./src/file/format/yaml.rs:53:26

Assumed SerialSettings is:

#[derive(serde::Deserialize, Clone)]
pub struct SerialSettings {
    pub name: String,
}

@goingforbrooke
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goingforbrooke commented Mar 18, 2024

Nevermind-- the underlying YAML library is "guessing" that localhost:1234 is a hash. I'll look into making ours "guess" better.

    match *value {
...
yaml::Yaml::Integer(value) => Ok(Value::new(uri, ValueKind::I64(value))),
        yaml::Yaml::Boolean(value) => Ok(Value::new(uri, ValueKind::Boolean(value))),
        yaml::Yaml::Hash(ref table) => {
            let mut m = Map::new();
            for (key, value) in table {
                match key {
                    yaml::Yaml::String(k) => m.insert(k.to_owned(), from_yaml_value(uri, value)?),
                    yaml::Yaml::Integer(k) => m.insert(k.to_string(), from_yaml_value(uri, value)?),
                    _ => {
                        println!("yaml::Yaml::{:?}", key);
                        unreachable!()

@mjaakkol if you want a quick fix, then separate localhost and 1234. 🩹

epage added a commit that referenced this issue Mar 12, 2025
The `unreachable!` code at
https://github.com/rust-cli/config-rs/blob/main/src/file/format/yaml.rs#L53
is reachable, and this PR fixes it for two simple types: reals and
booleans.

Prior to this change you'd get this error trying to parse the following:
```
thread '...' panicked at .../config-0.15.9/src/file/format/yaml.rs:53:26:
internal error: entered unreachable code
```

The problematic case for me turned out to be float keys:
```yaml
inner_float:
    0.1: "float 0.1"
    0.2: "float 0.2"
```

The change in this PR follows the same pattern as already exists for
Strings and Integers - just parse them as strings and leave it up to the
user to work out what to do with that.

Personally I only need the Real support, so happy to remove the Boolean
case if that's at all contentious.

I decided not to look into whether you can craft a hash with the other
Yaml types (below) because it's such an odd use case it didn't seam
realistic! That said, #547
suggests that just treating Hash as string would have avoided that
users' problem. However, converting from these types back into the exact
string format they were parsed in would be difficult, so it's not clear
what the right implementation would be. So getting the simpler case
(reals, booleans) done feels like the right sized change to make.
```
    Array(Array),
    Hash(Hash),
    Alias(usize),
    Null,
    BadValue,
 ```

Let me know what you think! And thanks for maintaining this useful crate :)
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