clippy::disallowed_fields: Denies the configured fields in clippy.toml Note: Even though this lint is warn-by-default, it will only trigger if fields are defined in the clippy.toml file

use std::ops::Range;

let range = Range { start: 0, end: 1 };
println!("{}", range.start); // `start` is disallowed in the config.

use std::ops::Range;

let range = Range { start: 0, end: 1 };
println!("{}", range.end); // `end` is _not_ disallowed in the config.

#[allow(clippy::disallowed_fields)]
fn my_function() { /* ... */ }

[lints.clippy]
disallowed_fields = "allow"

cargo clippy -- -A clippy::disallowed-fields

Clippy's own documentation

What it does

Denies the configured fields in clippy.toml

Note: Even though this lint is warn-by-default, it will only trigger if fields are defined in the clippy.toml file.

Why is this bad?

Some fields are undesirable in certain contexts, and it’s beneficial to lint for them as needed.

Example

An example clippy.toml configuration:

disallowed-fields = [
    # Can use a string as the path of the disallowed field.
    "std::ops::Range::start",
    # Can also use an inline table with a `path` key.
    { path = "std::ops::Range::start" },
    # When using an inline table, can add a `reason` for why the field
    # is disallowed.
    { path = "std::ops::Range::start", reason = "The start of the range is not used" },
]

use std::ops::Range;

let range = Range { start: 0, end: 1 };
println!("{}", range.start); // `start` is disallowed in the config.

Use instead:

use std::ops::Range;

let range = Range { start: 0, end: 1 };
println!("{}", range.end); // `end` is _not_ disallowed in the config.

Configuration

• disallowed-fields: The list of disallowed fields, written as fully qualified paths.

Fields:

• path (required): the fully qualified path to the field that should be disallowed

• reason (optional): explanation why this field is disallowed

• replacement (optional): suggested alternative method

• allow-invalid (optional, false by default): when set to true, it will ignore this entry if the path doesn’t exist, instead of emitting an error

  (default: [])

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

Related lints

• needless_returnunneeded `return` statement
• new_without_defaultChecks for public types with a pub fn new() -> Self method and no implementation of Default
• len_zeroChecks for getting the length of something via .len() just to compare to zero, and suggests using .is_empty() where applicable
• collapsible_matchthis `match` can be collapsed into the outer `match`
• comparison_to_emptyChecks for comparing to an empty slice such as "" or [], and suggests using .is_empty() where applicable
• default_instead_of_iter_empty`std::iter::empty()` is the more idiomatic way
• disallowed_macrosDenies the configured macros in clippy.toml Note: Even though this lint is warn-by-default, it will only trigger if macros are defined in the clippy.toml file
• disallowed_methodsDenies the configured methods and functions in clippy.toml Note: Even though this lint is warn-by-default, it will only trigger if methods are defined in the clippy.toml file
• disallowed_namesuse of a disallowed/placeholder name `foo`

All 847 Clippy lints · Rust compiler errors · Cargo.toml checker