Confusing error message when feature depends on an optional dependency and its feature

[divergentdave]

Problem

I wrote a feature specification that depended on both an optional dependency, and a feature of that optional dependency, and I got a confusing error message. Deleting the dep:... item from the list fixed the issue, and got things working the way I wanted, but this fix wasn't apparent from the error message. Here's a minimal reproducing Cargo.toml file, and the resulting error message.

[package]
name = "cargo-feature-error-message"
version = "0.1.0"
edition = "2021"

[dependencies]
keccak = { version = "0.1.4", optional = true }

[features]
my_feature = ["dep:keccak", "keccak/asm"]

error: Package `cargo-feature-error-message v0.1.0 (/home/david/scratch/cargo-feature-error-message)` does not have feature `keccak`. It has an optional dependency with that name, but that dependency uses the "dep:" syntax in the features table, so it does not have an implicit feature with that name.

Does keccak/asm implicitly enable a keccak feature, and is that why I'm getting this message, or is this just an error handling edge case?

Steps

No response

Possible Solution(s)

No response

Notes

No response

Version

cargo 1.69.0 (6e9a83356 2023-04-12)
release: 1.69.0
commit-hash: 6e9a83356b70586d4b77613a6b33f9ea067b9cdf
commit-date: 2023-04-12
host: x86_64-unknown-linux-gnu
libgit2: 1.5.0 (sys:0.16.0 vendored)
libcurl: 7.86.0-DEV (sys:0.4.59+curl-7.86.0 vendored ssl:OpenSSL/1.1.1q)
os: Ubuntu 22.04 (jammy) [64-bit]

[Eh2406]

Does keccak/asm implicitly enable a keccak feature?

Yes, it does.

[ehuss]

Thanks fore the report! This is a duplicate of #10788, so closing in favor of that. This is supposed to work, it was just an oversight.