### What does this PR try to resolve?
This PR fixes a bug where `cargo add` breaks symlinks to Cargo.toml
files. Currently, when Cargo.toml is a symlink and `cargo add` is used
to add a dependency, the symlink is replaced with a regular file,
breaking the link to the original target file.
This issue was reported in #15241 where a user who relies on symlinked
Cargo.toml files found that `cargo add` breaks their workflow.
Fixes#15241
### How should we test and review this PR?
I've modified `LocalManifest::write()` to check if the path is a
symlink, and if so, follow it to get the actual target path. This
ensures we write to the actual file rather than replacing the symlink.
I've also added a test in `tests/testsuite/cargo_add/symlink.rs` that:
1. Creates a symlinked Cargo.toml file
2. Runs `cargo add` to add a dependency
3. Verifies the symlink is preserved and the dependency is added to the
target file
I've manually tested this fix and confirmed it works correctly.
- Preserve symlinks when writing files atomically in write_atomic()
- Update test to verify correct symlink preservation behavior
- Apply rustfmt formatting
This fixes the issue where cargo add would replace symlinked Cargo.toml
files with regular files, breaking the symlink to the original target.
Fixes#15241
This was mostly done by clippy via `clippy::doc_markdown`.
I then reviewed it to fix words that shouldn't have it or where `--fix`
put the backtick in the wrong location.
This is to bring us into conformance with the [Rust crate ownership
policy](https://forge.rust-lang.org/policies/crate-ownership.html).
Items of note
- `cargo-credential-1password` is declared as Experimental as it is
intended for the community but I was unsure if we wanted to commit to
full support for it. In my mind, the ideal thing to do would be to
expatriate this to 1password.
- `home` is declared as Internal despite its wide use within the
ecosystem.
- `cargo-credential` is declared as Intentional as its an API intended
for the wider ecosystem and I didn't see a reason to declare it
experimental.
- `cargo-platform`, `cargo-util-schemas`, and `crates-io` are declared
as Intentional as they are both used internally and intended for
others to use for logic that integrates with cargo/registries.
I wondered about these being Experimental or Internal instead.
Falling back to hard_link when that happens, retrying can lead to very
long wait before copying works (up to 4secs in my tests) while
hard_linking works straight away.
Looks related to https://github.com/openzfsonosx/zfs/issues/809Closes#13838
