verification does not respect workspace members with a virtual workspace

[wookietreiber]

top-level Cargo.toml:

[workspace]
members = [
    "a",
    "b",
]

running cargo msrv verify in top-level dir:

$ cargo msrv verify
Fetching index
Unable to find key 'package.rust-version' (or 'package.metadata.msrv') in '/path/to/top-level/Cargo.toml'

I can certainly do this as a workaround:

cargo msrv --path a verify
cargo msrv --path b verify

... or cd/pushd my way into the workspace members, but this gets annoying, especially considering:

• this example only has 2 workspace members, consider having a lot more members
• the expectation that all cargo commands respect workspace members, at the least with a --workspace or the deprecated --all flag
• verification in CI, it's not possible to have a simple cargo msrv verify snippet that can be copy-pasted to other projects, because you'd have to manually edit the snippet and explicitly use --path member for all you want to check

[wookietreiber]

My recommendation / ideal solution is:

• by default, check all workspace members, not only when there is a virtual workspace
• add a short -p variant to --path to mimic other cargo commands, likely even rename --path to --package (for full mimicry) and add --path as an alias for compatibility
• add --workspace to force/override -p|--package|--path, these should override each other as they do in other cargo commands

[foresterre]

add a short -p variant to --path to mimic other cargo commands, likely even rename --path to --package (for full mimicry) and add --path as an alias for compatibility

While -p would be better indeed, a cargo like alternative to --path exists: --manifest-path <Cargo.toml>

[foresterre]

See also: #295 and #590

[wookietreiber]

--manifest-path doesn't appear in cargo msrv --help nor in cargo msrv verify --help, is that not released yet / only in the 0.16 betas?