8. Use Cases¶

Use Case: Installing rustfmt USE_RUSTFMT_INSTALL

Actor(s): User, tar (compression utility)
Input: A rustfmt release tarball.
Output: The rustfmt binary in the Ferrocene directory.
Environment constraints: tar is correctly installed.

Description:

The user downloads the rustfmt archive.
The user extracts the archive into the installation directory using tar:
```
tar -C path/to/installation -xf path/to/archive.tar.xz
```

Use Case: Format a file USE_RUSTFMT_FORMAT

causes: ERR_RUSTFMT_CHANGED_SEMANTICS

Actor(s): User, rustfmt.
Input: One or multiple Rust source files.
Output: Rust source files with the same paths, potentially modified.
Environment constraints: rustfmt is installed.

Description:

The user calls rustfmt with the following command line arguments:

<path>...
# where <path> is the path to a Rust source file.

rustfmt modifies Rust source files if they are not well-formatted.

Use Case: Check formatting of a file USE_RUSTFMT_CHECK

Actor(s): User, rustfmt.
Input: One or multiple Rust source files.
Output: A terminal exit code.
Output: A diff between current and well-formatted code (omitted if code is well-formatted).
Environment constraints: rustfmt is installed.

Description:

The user calls rustfmt with the following command line arguments:

--check
<path>...
# where <path> is the path to a Rust source file.

rustfmt outputs a terminal status code, indicating if the checked files are well-formatted.