rust/clippy_lints/src/partial_pub_fields.rs

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use clippy_utils::diagnostics::span_lint_and_help;
use rustc_ast::ast::{Item, ItemKind};
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::declare_lint_pass;
declare_clippy_lint! {
/// ### What it does
/// Checks whether partial fields of a struct are public.
///
/// Either make all fields of a type public, or make none of them public
///
/// ### Why is this bad?
/// Most types should either be:
/// * Abstract data types: complex objects with opaque implementation which guard
/// interior invariants and expose intentionally limited API to the outside world.
/// * Data:relatively simple objects which group a bunch of related attributes together.
///
/// ### Example
/// ```no_run
/// pub struct Color {
/// pub r: u8,
/// pub g: u8,
/// b: u8,
/// }
/// ```
/// Use instead:
/// ```no_run
/// pub struct Color {
/// pub r: u8,
/// pub g: u8,
/// pub b: u8,
/// }
/// ```
#[clippy::version = "1.66.0"]
pub PARTIAL_PUB_FIELDS,
restriction,
"partial fields of a struct are public"
}
declare_lint_pass!(PartialPubFields => [PARTIAL_PUB_FIELDS]);
impl EarlyLintPass for PartialPubFields {
fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
let ItemKind::Struct(ref st, _) = item.kind else {
return;
};
let mut fields = st.fields().iter();
let Some(first_field) = fields.next() else {
// Empty struct.
return;
};
let all_pub = first_field.vis.kind.is_pub();
let all_priv = !all_pub;
let msg = "mixed usage of pub and non-pub fields";
for field in fields {
if all_priv && field.vis.kind.is_pub() {
span_lint_and_help(
cx,
PARTIAL_PUB_FIELDS,
field.vis.span,
msg,
None,
"consider using private field here",
);
return;
} else if all_pub && !field.vis.kind.is_pub() {
span_lint_and_help(
cx,
PARTIAL_PUB_FIELDS,
field.vis.span,
msg,
None,
"consider using public field here",
);
return;
}
}
}
}