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Rollup merge of rust-lang#126040 - Urgau:unreachable_pub-fields-less,…
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… r=petrochenkov

Don't warn on fields in the `unreachable_pub` lint

This PR restrict the `unreachable_pub` lint by not linting on `pub` fields of `pub(restricted)` structs and unions. This is done because that can quickly clutter the code for an uncertain value, in particular since the "real" visibility is defined by the parent (the struct it-self).

This is meant to address one of the last concern of the `unreachable_pub` lint.

r? `@petrochenkov`
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@workingjubilee
workingjubilee authored Jun 7, 2024
2 parents ee664a5 + 89d86ae commit cfb9479
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Showing 3 changed files with 34 additions and 29 deletions.
21 changes: 15 additions & 6 deletions compiler/rustc_lint/src/builtin.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
use rustc_hir::intravisit::FnKind as HirFnKind;
use rustc_hir::{Body, FnDecl, GenericParamKind, Node, PatKind, PredicateOrigin};
use rustc_hir::{Body, FnDecl, GenericParamKind, PatKind, PredicateOrigin};
use rustc_middle::bug;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::layout::LayoutOf;
Expand Down Expand Up @@ -1423,11 +1423,20 @@ impl<'tcx> LateLintPass<'tcx> for UnreachablePub {
self.perform_lint(cx, "item", foreign_item.owner_id.def_id, foreign_item.vis_span, true);
}

fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
if matches!(cx.tcx.parent_hir_node(field.hir_id), Node::Variant(_)) {
return;
}
self.perform_lint(cx, "field", field.def_id, field.vis_span, false);
fn check_field_def(&mut self, _cx: &LateContext<'_>, _field: &hir::FieldDef<'_>) {
// - If an ADT definition is reported then we don't need to check fields
// (as it would add unnecessary complexity to the source code, the struct
// definition is in the immediate proximity to give the "real" visibility).
// - If an ADT is not reported because it's not `pub` - we don't need to
// check fields.
// - If an ADT is not reported because it's reachable - we also don't need
// to check fields because then they are reachable by construction if they
// are pub.
//
// Therefore in no case we check the fields.
//
// cf. https://github.com/rust-lang/rust/pull/126013#issuecomment-2152839205
// cf. https://github.com/rust-lang/rust/pull/126040#issuecomment-2152944506
}

fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
Expand Down
10 changes: 7 additions & 3 deletions tests/ui/lint/unreachable_pub.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,12 +9,16 @@ mod private_mod {
pub use std::env::{Args}; // braced-use has different item spans than unbraced
//~^ WARNING unreachable_pub

// we lint on struct definition
pub struct Hydrogen { //~ WARNING unreachable_pub
// `pub` struct fields, too
pub neutrons: usize, //~ WARNING unreachable_pub
// (... but not more-restricted fields)
// but not on fields, even if they are `pub` as putting `pub(crate)`
// it would clutter the source code for little value
pub neutrons: usize,
pub(crate) electrons: usize
}
pub(crate) struct Calcium {
pub neutrons: usize,
}
impl Hydrogen {
// impls, too
pub fn count_neutrons(&self) -> usize { self.neutrons } //~ WARNING unreachable_pub
Expand Down
32 changes: 12 additions & 20 deletions tests/ui/lint/unreachable_pub.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ LL | pub use std::env::{Args}; // braced-use has different item spans than u
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:12:5
--> $DIR/unreachable_pub.rs:13:5
|
LL | pub struct Hydrogen {
| ---^^^^^^^^^^^^^^^^
Expand All @@ -33,24 +33,16 @@ LL | pub struct Hydrogen {
|
= help: or consider exporting it for use by other crates

warning: unreachable `pub` field
--> $DIR/unreachable_pub.rs:14:9
|
LL | pub neutrons: usize,
| ---^^^^^^^^^^^^^^^^
| |
| help: consider restricting its visibility: `pub(crate)`

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:20:9
--> $DIR/unreachable_pub.rs:24:9
|
LL | pub fn count_neutrons(&self) -> usize { self.neutrons }
| ---^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| help: consider restricting its visibility: `pub(crate)`

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:29:5
--> $DIR/unreachable_pub.rs:33:5
|
LL | pub enum Helium {}
| ---^^^^^^^^^^^^
Expand All @@ -60,7 +52,7 @@ LL | pub enum Helium {}
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:30:5
--> $DIR/unreachable_pub.rs:34:5
|
LL | pub union Lithium { c1: usize, c2: u8 }
| ---^^^^^^^^^^^^^^
Expand All @@ -70,7 +62,7 @@ LL | pub union Lithium { c1: usize, c2: u8 }
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:31:5
--> $DIR/unreachable_pub.rs:35:5
|
LL | pub fn beryllium() {}
| ---^^^^^^^^^^^^^^^
Expand All @@ -80,7 +72,7 @@ LL | pub fn beryllium() {}
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:32:5
--> $DIR/unreachable_pub.rs:36:5
|
LL | pub trait Boron {}
| ---^^^^^^^^^^^^
Expand All @@ -90,7 +82,7 @@ LL | pub trait Boron {}
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:33:5
--> $DIR/unreachable_pub.rs:37:5
|
LL | pub const CARBON: usize = 1;
| ---^^^^^^^^^^^^^^^^^^^^
Expand All @@ -100,7 +92,7 @@ LL | pub const CARBON: usize = 1;
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:34:5
--> $DIR/unreachable_pub.rs:38:5
|
LL | pub static NITROGEN: usize = 2;
| ---^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -110,7 +102,7 @@ LL | pub static NITROGEN: usize = 2;
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:35:5
--> $DIR/unreachable_pub.rs:39:5
|
LL | pub type Oxygen = bool;
| ---^^^^^^^^^^^^
Expand All @@ -120,7 +112,7 @@ LL | pub type Oxygen = bool;
= help: or consider exporting it for use by other crates

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:38:47
--> $DIR/unreachable_pub.rs:42:47
|
LL | ($visibility: vis, $name: ident) => { $visibility struct $name {} }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -135,7 +127,7 @@ LL | define_empty_struct_with_visibility!(pub, Fluorine);
= note: this warning originates in the macro `define_empty_struct_with_visibility` (in Nightly builds, run with -Z macro-backtrace for more info)

warning: unreachable `pub` item
--> $DIR/unreachable_pub.rs:44:9
--> $DIR/unreachable_pub.rs:48:9
|
LL | pub fn catalyze() -> bool;
| ---^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -144,5 +136,5 @@ LL | pub fn catalyze() -> bool;
|
= help: or consider exporting it for use by other crates

warning: 14 warnings emitted
warning: 13 warnings emitted

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