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Check assoc consts and tys later like assoc fns #143519

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54 changes: 39 additions & 15 deletions compiler/rustc_passes/src/dead.rs
Original file line number Diff line number Diff line change
Expand Up @@ -115,7 +115,10 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {

fn handle_res(&mut self, res: Res) {
match res {
Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::TyAlias, def_id) => {
Res::Def(
DefKind::Const | DefKind::AssocConst | DefKind::AssocTy | DefKind::TyAlias,
def_id,
) => {
self.check_def_id(def_id);
}
_ if self.in_pat => {}
Expand Down Expand Up @@ -482,7 +485,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
) -> bool {
let trait_def_id = match self.tcx.def_kind(local_def_id) {
// assoc impl items of traits are live if the corresponding trait items are live
DefKind::AssocFn => self
DefKind::AssocConst | DefKind::AssocTy | DefKind::AssocFn => self
.tcx
.associated_item(local_def_id)
.trait_item_def_id
Expand Down Expand Up @@ -647,6 +650,29 @@ impl<'tcx> Visitor<'tcx> for MarkSymbolVisitor<'tcx> {

self.in_pat = in_pat;
}

fn visit_poly_trait_ref(&mut self, t: &'tcx hir::PolyTraitRef<'tcx>) {
// Mark the assoc const appears in poly-trait-ref live
if let Some(pathsegment) = t.trait_ref.path.segments.last()
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In theory, constraints can appear in non-last segments, and outside of poly trait refs too.
So, a safer choice here would probably be using visit_assoc_item_constraint.

&& let Some(args) = pathsegment.args
{
for constraint in args.constraints {
if let Some(item) = self
.tcx
.associated_items(pathsegment.res.def_id())
.filter_by_name_unhygienic(constraint.ident.name)
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I'm sufficiently sure that this name resolution is already performed somewhere else, and the result is stored in some table.
So here we need to obtain it from that table by id, instead of doing resolution by name again.

.find(|i| {
matches!(i.kind, ty::AssocKind::Const { .. })
&& i.ident(self.tcx).normalize_to_macros_2_0() == constraint.ident
})
&& let Some(local_def_id) = item.def_id.as_local()
{
self.worklist.push((local_def_id, ComesFromAllowExpect::No));
}
}
}
intravisit::walk_poly_trait_ref(self, t);
}
}

fn has_allow_dead_code_or_lang_attr(
Expand Down Expand Up @@ -744,18 +770,12 @@ fn check_item<'tcx>(
{
worklist.push((local_def_id, comes_from_allow));
} else if of_trait {
// FIXME: This condition can be removed
// if we support dead check for assoc consts and tys.
if !matches!(tcx.def_kind(local_def_id), DefKind::AssocFn) {
worklist.push((local_def_id, ComesFromAllowExpect::No));
} else {
// We only care about associated items of traits,
// because they cannot be visited directly,
// so we later mark them as live if their corresponding traits
// or trait items and self types are both live,
// but inherent associated items can be visited and marked directly.
unsolved_items.push((id, local_def_id));
}
// We only care about associated items of traits,
// because they cannot be visited directly,
// so we later mark them as live if their corresponding traits
// or trait items and self types are both live,
// but inherent associated items can be visited and marked directly.
unsolved_items.push((id, local_def_id));
}
}
}
Expand Down Expand Up @@ -792,7 +812,10 @@ fn check_trait_item(
id: hir::TraitItemId,
) {
use hir::TraitItemKind::{Const, Fn};
if matches!(tcx.def_kind(id.owner_id), DefKind::AssocConst | DefKind::AssocFn) {
if matches!(
tcx.def_kind(id.owner_id),
DefKind::AssocConst | DefKind::AssocTy | DefKind::AssocFn
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This condition is redundant, no?
Trait items cannot have any other DefKind than these.

) {
let trait_item = tcx.hir_trait_item(id);
if matches!(trait_item.kind, Const(_, Some(_)) | Fn(..))
&& let Some(comes_from_allow) =
Expand Down Expand Up @@ -1163,6 +1186,7 @@ impl<'tcx> DeadVisitor<'tcx> {
}
match self.tcx.def_kind(def_id) {
DefKind::AssocConst
| DefKind::AssocTy
| DefKind::AssocFn
| DefKind::Fn
| DefKind::Static { .. }
Expand Down
44 changes: 44 additions & 0 deletions tests/ui/associated-consts/equality-unused-issue-126729.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
//@ check-pass

#![feature(associated_const_equality)]
#![deny(dead_code)]

trait Tr {
const I: i32;
}

impl Tr for () {
const I: i32 = 1;
}

fn foo() -> impl Tr<I = 1> {}

trait Tr2 {
const J: i32;
const K: i32;
}

impl Tr2 for () {
const J: i32 = 1;
const K: i32 = 1;
}

fn foo2() -> impl Tr2<J = 1, K = 1> {}

mod t {
pub trait Tr3 {
const L: i32;
}

impl Tr3 for () {
const L: i32 = 1;
}
}

fn foo3() -> impl t::Tr3<L = 1> {}

fn main() {
foo();
foo2();
foo3();
}
1 change: 1 addition & 0 deletions tests/ui/const-generics/cross_crate_complex.rs
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ async fn foo() {
async_in_foo(async_out_foo::<4>().await).await;
}

#[allow(dead_code)]
struct Faz<const N: usize>;

impl<const N: usize> Foo<N> for Faz<N> {}
Expand Down
2 changes: 2 additions & 0 deletions tests/ui/generic-associated-types/missing-bounds.fixed
Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
//@ run-rustfix

#![allow(dead_code)]

use std::ops::Add;

struct A<B>(B);
Expand Down
2 changes: 2 additions & 0 deletions tests/ui/generic-associated-types/missing-bounds.rs
Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
//@ run-rustfix

#![allow(dead_code)]

use std::ops::Add;

struct A<B>(B);
Expand Down
18 changes: 9 additions & 9 deletions tests/ui/generic-associated-types/missing-bounds.stderr
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: equality constraints are not yet supported in `where` clauses
--> $DIR/missing-bounds.rs:37:33
--> $DIR/missing-bounds.rs:39:33
|
LL | impl<B: Add> Add for E<B> where <B as Add>::Output = B {
| ^^^^^^^^^^^^^^^^^^^^^^ not supported
Expand All @@ -12,7 +12,7 @@ LL + impl<B: Add> Add for E<B> where B: Add<Output = B> {
|

error[E0308]: mismatched types
--> $DIR/missing-bounds.rs:11:11
--> $DIR/missing-bounds.rs:13:11
|
LL | impl<B> Add for A<B> where B: Add {
| - expected this type parameter
Expand All @@ -25,14 +25,14 @@ LL | A(self.0 + rhs.0)
= note: expected type parameter `B`
found associated type `<B as Add>::Output`
help: the type constructed contains `<B as Add>::Output` due to the type of the argument passed
--> $DIR/missing-bounds.rs:11:9
--> $DIR/missing-bounds.rs:13:9
|
LL | A(self.0 + rhs.0)
| ^^--------------^
| |
| this argument influences the type of `A`
note: tuple struct defined here
--> $DIR/missing-bounds.rs:5:8
--> $DIR/missing-bounds.rs:7:8
|
LL | struct A<B>(B);
| ^
Expand All @@ -42,7 +42,7 @@ LL | impl<B> Add for A<B> where B: Add<Output = B> {
| ++++++++++++

error[E0308]: mismatched types
--> $DIR/missing-bounds.rs:21:14
--> $DIR/missing-bounds.rs:23:14
|
LL | impl<B: Add> Add for C<B> {
| - expected this type parameter
Expand All @@ -55,7 +55,7 @@ LL | Self(self.0 + rhs.0)
= note: expected type parameter `B`
found associated type `<B as Add>::Output`
note: tuple struct defined here
--> $DIR/missing-bounds.rs:15:8
--> $DIR/missing-bounds.rs:17:8
|
LL | struct C<B>(B);
| ^
Expand All @@ -65,7 +65,7 @@ LL | impl<B: Add<Output = B>> Add for C<B> {
| ++++++++++++

error[E0369]: cannot add `B` to `B`
--> $DIR/missing-bounds.rs:31:21
--> $DIR/missing-bounds.rs:33:21
|
LL | Self(self.0 + rhs.0)
| ------ ^ ----- B
Expand All @@ -78,7 +78,7 @@ LL | impl<B: std::ops::Add<Output = B>> Add for D<B> {
| +++++++++++++++++++++++++++

error[E0308]: mismatched types
--> $DIR/missing-bounds.rs:42:14
--> $DIR/missing-bounds.rs:44:14
|
LL | impl<B: Add> Add for E<B> where <B as Add>::Output = B {
| - expected this type parameter
Expand All @@ -91,7 +91,7 @@ LL | Self(self.0 + rhs.0)
= note: expected type parameter `B`
found associated type `<B as Add>::Output`
note: tuple struct defined here
--> $DIR/missing-bounds.rs:35:8
--> $DIR/missing-bounds.rs:37:8
|
LL | struct E<B>(B);
| ^
Expand Down
13 changes: 13 additions & 0 deletions tests/ui/lint/dead-code/unused-trait-with-assoc-const.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
#![deny(dead_code)]

trait Tr { //~ ERROR trait `Tr` is never used
const I: Self;
}

struct Foo; //~ ERROR struct `Foo` is never constructed

impl Tr for Foo {
const I: Self = Foo;
}

fn main() {}
20 changes: 20 additions & 0 deletions tests/ui/lint/dead-code/unused-trait-with-assoc-const.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
error: trait `Tr` is never used
--> $DIR/unused-trait-with-assoc-const.rs:3:7
|
LL | trait Tr {
| ^^
|
note: the lint level is defined here
--> $DIR/unused-trait-with-assoc-const.rs:1:9
|
LL | #![deny(dead_code)]
| ^^^^^^^^^

error: struct `Foo` is never constructed
--> $DIR/unused-trait-with-assoc-const.rs:7:8
|
LL | struct Foo;
| ^^^

error: aborting due to 2 previous errors

11 changes: 11 additions & 0 deletions tests/ui/lint/dead-code/unused-trait-with-assoc-ty.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
#![deny(dead_code)]

struct T1; //~ ERROR struct `T1` is never constructed

trait Foo { type Unused; } //~ ERROR trait `Foo` is never used
impl Foo for T1 { type Unused = Self; }

pub trait Bar { type Used; }
impl Bar for T1 { type Used = Self; }

fn main() {}
20 changes: 20 additions & 0 deletions tests/ui/lint/dead-code/unused-trait-with-assoc-ty.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
error: struct `T1` is never constructed
--> $DIR/unused-trait-with-assoc-ty.rs:3:8
|
LL | struct T1;
| ^^
|
note: the lint level is defined here
--> $DIR/unused-trait-with-assoc-ty.rs:1:9
|
LL | #![deny(dead_code)]
| ^^^^^^^^^

error: trait `Foo` is never used
--> $DIR/unused-trait-with-assoc-ty.rs:5:7
|
LL | trait Foo { type Unused; }
| ^^^

error: aborting due to 2 previous errors

2 changes: 1 addition & 1 deletion tests/ui/pattern/issue-22546.rs
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ impl<T: std::fmt::Display> Foo<T> {
}
}

trait Tr { //~ WARN trait `Tr` is never used
trait Tr {
type U;
}

Expand Down
10 changes: 0 additions & 10 deletions tests/ui/pattern/issue-22546.stderr

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