Cargo dignostic for misplaced `cargo-features = ["edition2021"]` could be better

[Craig-Macomber]

I followed the process at https://blog.rust-lang.org/2021/07/21/Rust-2021-public-testing.html#public-testing-period and wish to report a quality issue with a diagnostic from Cargo. The issue template linked didn't have one for cargo diagnostics, so I'm using the rustc diagnostic template.

Given the following code:

[package]
name = "x"
version = "0.1.0"
authors = ["..."]
edition = "2021"
cargo-features = ["edition2021"]

The current output is:

$ cargo +nightly check
error: failed to parse manifest at `/home/craig/Scratch/rusty-flame/Cargo.toml`

Caused by:
  cargo-features = ["edition2021"] was found in the wrong location, it should be set at the top of Cargo.toml before any tables

Ideally the output should look like:

$ cargo +nightly check
error: failed to parse manifest at `/home/craig/Scratch/rusty-flame/Cargo.toml`

Caused by:
  cargo-features = ["edition2021"] was found in the wrong location: it should be set at the top of Cargo.toml before any sections.

The error is message is grammatically two sentences, which are comma spliced. They should have a period or a colon instead. Additionally the trailing period is missing, and https://doc.rust-lang.org/cargo/reference/manifest.html refers to the units within a toml file as "sections" not tables.

$ rustc +nightly --version --verbose
rustc 1.55.0-nightly (027187094 2021-07-22)
binary: rustc
commit-hash: 027187094ee05011d6602f5742f550851ccc7fd6
commit-date: 2021-07-22
host: x86_64-unknown-linux-gnu
release: 1.55.0-nightly
LLVM version: 12.0.1

[Craig-Macomber]

On a related note, I was very impressed that there is a diagnostic at all for this which is so helpful: I immediately knew what to do, despite the minor issues above!

[ehuss]

Thanks for the report! Transferred to rust-lang/cargo.

[0xPoe]

@rustbot claim

[navillanueva]

How did you solve this issue? This is my original Cargo.toml:

`[package]
name = "combiner"
version = "0.1.0"
edition = "2018"
cargo-features = ["edition2021"]

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

[dependencies]
image = "0.23.14"`

And I'm getting the same error as you:

error: failed to parse manifest at /home/runner/Rust-Template/combiner/Cargo.toml`

Caused by:
cargo-features = ["edition2021"] was found in the wrong location, it should be set at the top of Cargo.toml before any tables`

No matter where I add the cargo-features = ["edition2021"] I get the same error, and if I add it on top how it states, I get:

error: failed to download rayon-core v1.11.0`

Caused by:
unable to get packages from source

Caused by:
failed to parse manifest at /home/runner/.cargo/registry/src/gitproxy.zycloud.tk-1ecc6299db9ec823/rayon-core-1.11.0/Cargo.toml

Caused by:
feature edition2021 is required

consider adding cargo-features = ["edition2021"] to the manifest`