rust-cli / rust-cli/config-rs

serde flatten does not work for type in flattened structs that are not strings

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Rust
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Description

Using the flatten attribute from serde almost works but breaks in the case of non string values in flattened structs. In this case config always parses size as a string. However, if I put the size attribute directly in Config then everything works.

#[derive(Deserialize)]
struct Config {
   #[serde(flatten)]
   pub subconfig: Subconfig
}

#[derive(Deserialize)]
struct Subconfig {
   pub size: usize
}

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Research direction

Start by reproducing the Config/Subconfig example with serde flatten and a non-string size value, then inspect the config-rs deserialization path. Done means flattened numeric fields such as size: usize parse as numeric values, as they do when declared directly on Config, with a regression test.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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