Add new lint partial_pub_fields

Signed-off-by: TennyZhuang <zty0826@gmail.com>

clippy_lints/src/lib.register_lints.rs

@@ -479,6 +479,7 @@ store.register_lints(&[
     panic_unimplemented::TODO,
     panic_unimplemented::UNIMPLEMENTED,
     panic_unimplemented::UNREACHABLE,
+    partial_pub_fields::PARTIAL_PUB_FIELDS,
     partialeq_ne_impl::PARTIALEQ_NE_IMPL,
     partialeq_to_none::PARTIALEQ_TO_NONE,
     pass_by_ref_or_value::LARGE_TYPES_PASSED_BY_VALUE,

clippy_lints/src/lib.register_restriction.rs

@@ -61,6 +61,7 @@ store.register_group(true, "clippy::restriction", Some("clippy_restriction"), ve
     LintId::of(panic_unimplemented::TODO),
     LintId::of(panic_unimplemented::UNIMPLEMENTED),
     LintId::of(panic_unimplemented::UNREACHABLE),
+    LintId::of(partial_pub_fields::PARTIAL_PUB_FIELDS),
     LintId::of(pattern_type_mismatch::PATTERN_TYPE_MISMATCH),
     LintId::of(pub_use::PUB_USE),
     LintId::of(redundant_slicing::DEREF_BY_SLICING),

clippy_lints/src/lib.rs

@@ -324,6 +324,7 @@ mod option_if_let_else;
 mod overflow_check_conditional;
 mod panic_in_result_fn;
 mod panic_unimplemented;
+mod partial_pub_fields;
 mod partialeq_ne_impl;
 mod partialeq_to_none;
 mod pass_by_ref_or_value;
@@ -908,6 +909,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|_| Box::new(bool_to_int_with_if::BoolToIntWithIf));
     store.register_late_pass(|_| Box::new(box_default::BoxDefault));
     store.register_late_pass(|_| Box::new(implicit_saturating_add::ImplicitSaturatingAdd));
+    store.register_early_pass(|| Box::new(partial_pub_fields::PartialPubFields));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }
 

clippy_lints/src/partial_pub_fields.rs

@@ -0,0 +1,81 @@
+use clippy_utils::diagnostics::span_lint_and_help;
+use rustc_ast::ast::*;
+use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+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
+    /// ```rust
+    /// pub struct Color {
+    ///     pub r,
+    ///     pub g,
+    ///     b,
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// pub struct Color {
+    ///     pub r,
+    ///     pub g,
+    ///     pub b,
+    /// }
+    /// ```
+    #[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;
+            }
+        }
+    }
+}