cargo add reformats the features lists

[lopopolo]

Problem

cargo add does not preserve formatting of TOML lists unrelated to the [dependencies] table

Steps

With the following Cargo.toml:

[package]
name = "xxx"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]

[features]
default = [
  "a",
  "b",
  "c",
]
a = []
b = []
c = []

Run:

$ cargo add directories
    Updating crates.io index
      Adding directories v4.0.1 to dependencies.

observe that the [features] table is reformatted:

diff --git i/Cargo.toml w/Cargo.toml
index ccae1b6..61c1383 100644
--- i/Cargo.toml
+++ w/Cargo.toml
@@ -6,13 +6,10 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

 [dependencies]
+directories = "4.0.1"

 [features]
-default = [
-  "a",
-  "b",
-  "c",
-]
+default = ["a", "b", "c"]
 a = []
 b = []
 c = []

Possible Solution(s)

Preserve formatting of all TOML contents outside of the newly added dependency.

Notes

No response

Version

cargo 1.67.1 (8ecd4f20a 2023-01-10)
release: 1.67.1
commit-hash: 8ecd4f20a9efb626975ac18a016d480dc7183d9b
commit-date: 2023-01-10
host: x86_64-apple-darwin
libgit2: 1.5.0 (sys:0.16.0 vendored)
libcurl: 7.86.0 (sys:0.4.59+curl-7.86.0 system ssl:(SecureTransport) LibreSSL/3.3.6)
os: Mac OS 13.2.1 [64-bit]

[weihanglo]

Just did a simple bisect. This regression started from 1.66.

On an unrelated note, cargo add appends the new dependency to the end of the [dependencies] table and does not attempt to respect existing alphabetization as npm install does.

This might be a bug as well 🥲. If you have a reproducible example, please file an issue. Thank you!

[epage]

I think this was broken in #11099, specifically 7c218b1. When cargo rm removes a feature, it needs to fix up the whitespace but the existing fix instead removes user formatting

[SummerGram]

Hi,

cargo add <a> should only append a to the dependencies only. Is it correct?

I would like to contribute this.

[epage]

#12191 reduced the chance we'll hit this. If the user makes a change that would remove an item from the feature list (more likely with cargo remove)., then we'll still hit this.