Auto merge of #143879 - fee1-dead-contrib:push-lrlpoouyqqry, r=fmease

parse `const trait Trait`

r? oli-obk or anyone from project-const-traits

cc `@rust-lang/project-const-traits`

src/doc/rustc-dev-guide/src/effects.md

@@ -67,10 +67,8 @@ in [`wfcheck::check_impl`].
 Here's an example:
 
 ```rust
-#[const_trait]
-trait Bar {}
-#[const_trait]
-trait Foo: ~const Bar {}
+const trait Bar {}
+const trait Foo: ~const Bar {}
 // `const_conditions` contains `HostEffect(Self: Bar, maybe)`
 
 impl const Bar for () {}
@@ -85,8 +83,7 @@ predicates of the trait method, and we attempt to prove the predicates of the
 impl method. We do the same for `const_conditions`:
 
 ```rust
-#[const_trait]
-trait Foo {
+const trait Foo {
     fn hi<T: ~const Default>();
 }
 

src/librustdoc/clean/mod.rs

@@ -2865,7 +2865,7 @@ fn get_name(
             ItemKind::Fn { ref sig, generics, body: body_id, .. } => {
                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
             }
-            ItemKind::Trait(_, _, _, generics, bounds, item_ids) => {
+            ItemKind::Trait(_, _, _, _, generics, bounds, item_ids) => {
                 let items = item_ids
                     .iter()
                     .map(|&ti| clean_trait_item(cx.tcx.hir_trait_item(ti), cx))

src/librustdoc/clean/types.rs

@@ -648,7 +648,7 @@ fn build_fn_header(
             let sig = tcx.fn_sig(def_id).skip_binder();
             let constness = if tcx.is_const_fn(def_id) {
                 // rustc's `is_const_fn` returns `true` for associated functions that have an `impl const` parent
-                // or that have a `#[const_trait]` parent. Do not display those as `const` in rustdoc because we
+                // or that have a `const trait` parent. Do not display those as `const` in rustdoc because we
                 // won't be printing correct syntax plus the syntax is unstable.
                 match tcx.opt_associated_item(def_id) {
                     Some(ty::AssocItem {

src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs

@@ -306,7 +306,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
                     cur_f = Some(field);
                 }
             },
-            ItemKind::Trait(is_auto, _safety, _ident, _generics, _generic_bounds, item_ref)
+            ItemKind::Trait(_constness, is_auto, _safety, _ident, _generics, _generic_bounds, item_ref)
                 if self.enable_ordering_for_trait && *is_auto == IsAuto::No =>
             {
                 let mut cur_t: Option<(TraitItemId, Ident)> = None;

src/tools/clippy/clippy_lints/src/doc/mod.rs

@@ -740,7 +740,7 @@ fn check_attributes(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute])
                             );
                         }
                     },
-                    ItemKind::Trait(_, unsafety, ..) => match (headers.safety, unsafety) {
+                    ItemKind::Trait(_, _, unsafety, ..) => match (headers.safety, unsafety) {
                         (false, Safety::Unsafe) => span_lint(
                             cx,
                             MISSING_SAFETY_DOC,

src/tools/clippy/clippy_lints/src/len_zero.rs

@@ -125,7 +125,7 @@
 
 impl<'tcx> LateLintPass<'tcx> for LenZero {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
-        if let ItemKind::Trait(_, _, ident, _, _, trait_items) = item.kind
+        if let ItemKind::Trait(_, _, _, ident, _, _, trait_items) = item.kind
             && !item.span.from_expansion()
         {
             check_trait_items(cx, item, ident, trait_items);

src/tools/clippy/clippy_lints/src/missing_inline.rs

@@ -101,7 +101,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, it: &'tcx hir::Item<'_>) {
                 let attrs = cx.tcx.hir_attrs(it.hir_id());
                 check_missing_inline_attrs(cx, attrs, it.span, desc);
             },
-            hir::ItemKind::Trait(ref _is_auto, ref _unsafe, _ident, _generics, _bounds, trait_items) => {
+            hir::ItemKind::Trait(ref _constness, ref _is_auto, ref _unsafe, _ident, _generics, _bounds, trait_items) => {
                 // note: we need to check if the trait is exported so we can't use
                 // `LateLintPass::check_trait_item` here.
                 for &tit in trait_items {

src/tools/clippy/clippy_lints/src/trait_bounds.rs

@@ -112,7 +112,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
         // special handling for self trait bounds as these are not considered generics
         // ie. trait Foo: Display {}
         if let Item {
-            kind: ItemKind::Trait(_, _, _, _, bounds, ..),
+            kind: ItemKind::Trait(_, _, _, _, _, bounds, ..),
             ..
         } = item
         {
@@ -133,7 +133,7 @@ fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'tc
                     ..
                 }) = segments.first()
                 && let Some(Node::Item(Item {
-                    kind: ItemKind::Trait(_, _, _, _, self_bounds, _),
+                    kind: ItemKind::Trait(_, _, _, _, _, self_bounds, _),
                     ..
                 })) = cx.tcx.hir_get_if_local(*def_id)
             {

src/tools/clippy/clippy_lints/src/upper_case_acronyms.rs

@@ -131,7 +131,7 @@ fn check_item(&mut self, cx: &LateContext<'_>, it: &Item<'_>) {
             return;
         }
         match it.kind {
-            ItemKind::TyAlias(ident, ..) | ItemKind::Struct(ident, ..) | ItemKind::Trait(_, _, ident, ..) => {
+            ItemKind::TyAlias(ident, ..) | ItemKind::Struct(ident, ..) | ItemKind::Trait(_, _, _, ident, ..) => {
                 check_ident(cx, &ident, it.hir_id(), self.upper_case_acronyms_aggressive);
             },
             ItemKind::Enum(ident, _, ref enumdef) => {

src/tools/clippy/clippy_utils/src/ast_utils/mod.rs

@@ -444,6 +444,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
         },
         (
             Trait(box ast::Trait {
+                constness: lc,
                 is_auto: la,
                 safety: lu,
                 ident: li,
@@ -452,6 +453,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 items: lis,
             }),
             Trait(box ast::Trait {
+                constness: rc,
                 is_auto: ra,
                 safety: ru,
                 ident: ri,
@@ -460,7 +462,8 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 items: ris,
             }),
         ) => {
-            la == ra
+            matches!(lc, ast::Const::No) == matches!(rc, ast::Const::No)
+                && la == ra
                 && matches!(lu, Safety::Default) == matches!(ru, Safety::Default)
                 && eq_id(*li, *ri)
                 && eq_generics(lg, rg)

src/tools/clippy/clippy_utils/src/check_proc_macro.rs

@@ -252,11 +252,11 @@ fn item_search_pat(item: &Item<'_>) -> (Pat, Pat) {
         ItemKind::Struct(_, _, VariantData::Struct { .. }) => (Pat::Str("struct"), Pat::Str("}")),
         ItemKind::Struct(..) => (Pat::Str("struct"), Pat::Str(";")),
         ItemKind::Union(..) => (Pat::Str("union"), Pat::Str("}")),
-        ItemKind::Trait(_, Safety::Unsafe, ..)
+        ItemKind::Trait(_, _, Safety::Unsafe, ..)
         | ItemKind::Impl(Impl {
             safety: Safety::Unsafe, ..
         }) => (Pat::Str("unsafe"), Pat::Str("}")),
-        ItemKind::Trait(IsAuto::Yes, ..) => (Pat::Str("auto"), Pat::Str("}")),
+        ItemKind::Trait(_, IsAuto::Yes, ..) => (Pat::Str("auto"), Pat::Str("}")),
         ItemKind::Trait(..) => (Pat::Str("trait"), Pat::Str("}")),
         ItemKind::Impl(_) => (Pat::Str("impl"), Pat::Str("}")),
         _ => return (Pat::Str(""), Pat::Str("")),

src/tools/clippy/tests/ui/assign_ops.fixed

@@ -84,8 +84,7 @@ mod issue14871 {
         const ONE: Self;
     }
 
-    #[const_trait]
-    pub trait NumberConstants {
+    pub const trait NumberConstants {
         fn constant(value: usize) -> Self;
     }
 

src/tools/clippy/tests/ui/assign_ops.rs

@@ -84,8 +84,7 @@ pub trait Number: Copy + Add<Self, Output = Self> + AddAssign {
         const ONE: Self;
     }
 
-    #[const_trait]
-    pub trait NumberConstants {
+    pub const trait NumberConstants {
         fn constant(value: usize) -> Self;
     }
 

src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.fixed

@@ -3,8 +3,7 @@
 
 // Reduced test case from https://github.com/rust-lang/rust-clippy/issues/14658
 
-#[const_trait]
-trait ConstTrait {
+const trait ConstTrait {
     fn method(self);
 }
 

src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.rs

@@ -3,8 +3,7 @@
 
 // Reduced test case from https://github.com/rust-lang/rust-clippy/issues/14658
 
-#[const_trait]
-trait ConstTrait {
+const trait ConstTrait {
     fn method(self);
 }
 

src/tools/clippy/tests/ui/missing_const_for_fn/const_trait.stderr

@@ -1,5 +1,5 @@
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/const_trait.rs:24:1
+  --> tests/ui/missing_const_for_fn/const_trait.rs:23:1
    |
 LL | / fn can_be_const() {
 LL | |     0u64.method();

src/tools/clippy/tests/ui/trait_duplication_in_bounds.fixed

@@ -167,8 +167,7 @@ where
 }
 
 // #13476
-#[const_trait]
-trait ConstTrait {}
+const trait ConstTrait {}
 const fn const_trait_bounds_good<T: ConstTrait + [const] ConstTrait>() {}
 
 const fn const_trait_bounds_bad<T: [const] ConstTrait>() {}

src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs

@@ -167,8 +167,7 @@ fn assoc_tys_generics<'a, 'b, T, U>()
 }
 
 // #13476
-#[const_trait]
-trait ConstTrait {}
+const trait ConstTrait {}
 const fn const_trait_bounds_good<T: ConstTrait + [const] ConstTrait>() {}
 
 const fn const_trait_bounds_bad<T: [const] ConstTrait + [const] ConstTrait>() {}

src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr

@@ -59,19 +59,19 @@ LL | fn bad_trait_object(arg0: &(dyn Any + Send + Send)) {
    |                                 ^^^^^^^^^^^^^^^^^ help: try: `Any + Send`
 
 error: these bounds contain repeated elements
-  --> tests/ui/trait_duplication_in_bounds.rs:174:36
+  --> tests/ui/trait_duplication_in_bounds.rs:173:36
    |
 LL | const fn const_trait_bounds_bad<T: [const] ConstTrait + [const] ConstTrait>() {}
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `[const] ConstTrait`
 
 error: these where clauses contain repeated elements
-  --> tests/ui/trait_duplication_in_bounds.rs:181:8
+  --> tests/ui/trait_duplication_in_bounds.rs:180:8
    |
 LL |     T: IntoIterator<Item = U::Owned> + IntoIterator<Item = U::Owned>,
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `IntoIterator<Item = U::Owned>`
 
 error: these where clauses contain repeated elements
-  --> tests/ui/trait_duplication_in_bounds.rs:203:8
+  --> tests/ui/trait_duplication_in_bounds.rs:202:8
    |
 LL |     T: AssocConstTrait<ASSOC = 0> + AssocConstTrait<ASSOC = 0>,
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `AssocConstTrait<ASSOC = 0>`

src/tools/rust-analyzer/crates/test-utils/src/minicore.rs

@@ -1011,8 +1011,7 @@ pub trait Add<Rhs = Self> {
     }
 
     #[lang = "add_assign"]
-    #[const_trait]
-    pub trait AddAssign<Rhs = Self> {
+    pub const trait AddAssign<Rhs = Self> {
         fn add_assign(&mut self, rhs: Rhs);
     }
 

src/tools/rustfmt/src/items.rs

@@ -1172,6 +1172,7 @@ pub(crate) fn format_trait(
         unreachable!();
     };
     let ast::Trait {
+        constness,
         is_auto,
         safety,
         ident,
@@ -1182,7 +1183,8 @@ pub(crate) fn format_trait(
 
     let mut result = String::with_capacity(128);
     let header = format!(
-        "{}{}{}trait ",
+        "{}{}{}{}trait ",
+        format_constness(constness),
         format_visibility(context, &item.vis),
         format_safety(safety),
         format_auto(is_auto),