Auto merge of #105775 - matthiaskrgr:rollup-2o8qn7e, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #105725 (Allow `impl ~const Trait` opaque types)
 - #105744 (Rewrite `E0158` error-code docs for clarity)
 - #105747 (Fix ICE calling method on auto trait)
 - #105748 (doc: Fix a few small issues)
 - #105756 (rustdoc: simplify CSS for codeblock tooltips)
 - #105757 (rustdoc: remove unused CSS `.sub-settings`)
 - #105764 (rustdoc: name the source page sidebar-toggle `#src-sidebar-toggle`)
 - #105774 (Remove unused stderr files)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -42,7 +42,6 @@ enum SelfSemantic {
 /// What is the context that prevents using `~const`?
 enum DisallowTildeConstContext<'a> {
     TraitObject,
-    ImplTrait,
     Fn(FnKind<'a>),
 }
 
@@ -187,11 +186,7 @@ impl<'a> AstValidator<'a> {
 
     fn with_impl_trait(&mut self, outer: Option<Span>, f: impl FnOnce(&mut Self)) {
         let old = mem::replace(&mut self.outer_impl_trait, outer);
-        if outer.is_some() {
-            self.with_banned_tilde_const(DisallowTildeConstContext::ImplTrait, f);
-        } else {
-            f(self);
-        }
+        f(self);
         self.outer_impl_trait = old;
     }
 
@@ -1384,7 +1379,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     let mut err = self.err_handler().struct_span_err(bound.span(), "`~const` is not allowed here");
                     match reason {
                         DisallowTildeConstContext::TraitObject => err.note("trait objects cannot have `~const` trait bounds"),
-                        DisallowTildeConstContext::ImplTrait => err.note("`impl Trait`s cannot have `~const` trait bounds"),
                         DisallowTildeConstContext::Fn(FnKind::Closure(..)) => err.note("closures cannot have `~const` trait bounds"),
                         DisallowTildeConstContext::Fn(FnKind::Fn(_, ident, ..)) => err.span_note(ident.span, "this function is not `const`, so it cannot have `~const` trait bounds"),
                     };

compiler/rustc_error_codes/src/error_codes/E0158.md

@@ -1,38 +1,53 @@
-An associated const has been referenced in a pattern.
+An associated `const`, `const` parameter or `static` has been referenced
+in a pattern.
 
 Erroneous code example:
 
 ```compile_fail,E0158
-enum EFoo { A, B, C, D }
-
-trait Foo {
-    const X: EFoo;
+enum Foo {
+    One,
+    Two
 }
 
-fn test<A: Foo>(arg: EFoo) {
+trait Bar {
+    const X: Foo;
+}
+
+fn test<A: Bar>(arg: Foo) {
     match arg {
-        A::X => { // error!
-            println!("A::X");
-        }
+        A::X => println!("A::X"), // error: E0158: associated consts cannot be
+                                  //        referenced in patterns
+        Foo::Two => println!("Two")
     }
 }
 ```
 
-`const` and `static` mean different things. A `const` is a compile-time
-constant, an alias for a literal value. This property means you can match it
-directly within a pattern.
+Associated `const`s cannot be referenced in patterns because it is impossible
+for the compiler to prove exhaustiveness (that some pattern will always match).
+Take the above example, because Rust does type checking in the *generic*
+method, not the *monomorphized* specific instance. So because `Bar` could have
+theoretically infinite implementations, there's no way to always be sure that
+`A::X` is `Foo::One`. So this code must be rejected. Even if code can be
+proven exhaustive by a programmer, the compiler cannot currently prove this.
 
-The `static` keyword, on the other hand, guarantees a fixed location in memory.
-This does not always mean that the value is constant. For example, a global
-mutex can be declared `static` as well.
+The same holds true of `const` parameters and `static`s.
 
-If you want to match against a `static`, consider using a guard instead:
+If you want to match against an associated `const`, `const` parameter or
+`static` consider using a guard instead:
 
 ```
-static FORTY_TWO: i32 = 42;
+trait Trait {
+    const X: char;
+}
 
-match Some(42) {
-    Some(x) if x == FORTY_TWO => {}
-    _ => {}
+static FOO: char = 'j';
+
+fn test<A: Trait, const Y: char>(arg: char) {
+    match arg {
+        c if c == A::X => println!("A::X"),
+        c if c == Y => println!("Y"),
+        c if c == FOO => println!("FOO"),
+        _ => ()
+    }
 }
 ```

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -689,6 +689,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 let entry = spanned_predicates.entry(spans);
                                 entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p);
                             }
+                            Some(Node::Item(hir::Item {
+                                kind: hir::ItemKind::Trait(rustc_ast::ast::IsAuto::Yes, ..),
+                                span: item_span,
+                                ..
+                            })) => {
+                                tcx.sess.delay_span_bug(
+                                        *item_span,
+                                        "auto trait is invoked with no method error, but no error reported?",
+                                    );
+                            }
                             Some(_) => unreachable!(),
                             None => (),
                         }

library/alloc/src/collections/vec_deque/mod.rs

@@ -2541,7 +2541,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// The deque is assumed to be partitioned according to the given predicate.
     /// This means that all elements for which the predicate returns true are at the start of the deque
     /// and all elements for which the predicate returns false are at the end.
-    /// For example, [7, 15, 3, 5, 4, 12, 6] is a partitioned under the predicate x % 2 != 0
+    /// For example, `[7, 15, 3, 5, 4, 12, 6]` is partitioned under the predicate `x % 2 != 0`
     /// (all odd numbers are at the start, all even at the end).
     ///
     /// If the deque is not partitioned, the returned result is unspecified and meaningless,

library/core/src/array/mod.rs

@@ -69,7 +69,7 @@ where
 /// if any element creation was unsuccessful.
 ///
 /// The return type of this function depends on the return type of the closure.
-/// If you return `Result<T, E>` from the closure, you'll get a `Result<[T; N]; E>`.
+/// If you return `Result<T, E>` from the closure, you'll get a `Result<[T; N], E>`.
 /// If you return `Option<T>` from the closure, you'll get an `Option<[T; N]>`.
 ///
 /// # Arguments
@@ -522,7 +522,7 @@ impl<T, const N: usize> [T; N] {
     /// return an array the same size as `self` or the first error encountered.
     ///
     /// The return type of this function depends on the return type of the closure.
-    /// If you return `Result<T, E>` from the closure, you'll get a `Result<[T; N]; E>`.
+    /// If you return `Result<T, E>` from the closure, you'll get a `Result<[T; N], E>`.
     /// If you return `Option<T>` from the closure, you'll get an `Option<[T; N]>`.
     ///
     /// # Examples

library/core/src/iter/traits/iterator.rs

@@ -2734,7 +2734,7 @@ pub trait Iterator {
     /// the first true result or the first error.
     ///
     /// The return type of this method depends on the return type of the closure.
-    /// If you return `Result<bool, E>` from the closure, you'll get a `Result<Option<Self::Item>; E>`.
+    /// If you return `Result<bool, E>` from the closure, you'll get a `Result<Option<Self::Item>, E>`.
     /// If you return `Option<bool>` from the closure, you'll get an `Option<Option<Self::Item>>`.
     ///
     /// # Examples

library/core/src/slice/mod.rs

@@ -3795,7 +3795,7 @@ impl<T> [T] {
     /// The slice is assumed to be partitioned according to the given predicate.
     /// This means that all elements for which the predicate returns true are at the start of the slice
     /// and all elements for which the predicate returns false are at the end.
-    /// For example, [7, 15, 3, 5, 4, 12, 6] is a partitioned under the predicate x % 2 != 0
+    /// For example, `[7, 15, 3, 5, 4, 12, 6]` is partitioned under the predicate `x % 2 != 0`
     /// (all odd numbers are at the start, all even at the end).
     ///
     /// If this slice is not partitioned, the returned result is unspecified and meaningless,

src/librustdoc/html/static/css/rustdoc.css

@@ -396,15 +396,15 @@ img {
 	overflow-y: hidden;
 }
 
-.source .sidebar, #sidebar-toggle, #source-sidebar {
+.source .sidebar, #src-sidebar-toggle, #source-sidebar {
 	background-color: var(--sidebar-background-color);
 }
 
-#sidebar-toggle > button:hover, #sidebar-toggle > button:focus {
+#src-sidebar-toggle > button:hover, #src-sidebar-toggle > button:focus {
 	background-color: var(--sidebar-background-color-hover);
 }
 
-.source .sidebar > *:not(#sidebar-toggle) {
+.source .sidebar > *:not(#src-sidebar-toggle) {
 	visibility: hidden;
 }
 
@@ -413,7 +413,7 @@ img {
 	flex-basis: 300px;
 }
 
-.source-sidebar-expanded .source .sidebar > *:not(#sidebar-toggle) {
+.source-sidebar-expanded .source .sidebar > *:not(#src-sidebar-toggle) {
 	visibility: visible;
 }
 
@@ -1118,8 +1118,7 @@ pre.rust .doccomment {
 	top: 5px;
 }
 
-.example-wrap .tooltip::after {
-	display: none;
+.example-wrap .tooltip:hover::after {
 	text-align: center;
 	padding: 5px 3px 3px 3px;
 	border-radius: 6px;
@@ -1134,35 +1133,30 @@ pre.rust .doccomment {
 	color: var(--tooltip-color);
 }
 
-.example-wrap .tooltip::before {
+.example-wrap .tooltip:hover::before {
 	content: " ";
 	position: absolute;
 	top: 50%;
 	left: 16px;
 	margin-top: -5px;
-	display: none;
 	z-index: 1;
 	border: 5px solid transparent;
 	border-right-color: var(--tooltip-background-color);
 }
 
-.example-wrap.ignore .tooltip::after {
+.example-wrap.ignore .tooltip:hover::after {
 	content: "This example is not tested";
 }
-.example-wrap.compile_fail .tooltip::after {
+.example-wrap.compile_fail .tooltip:hover::after {
 	content: "This example deliberately fails to compile";
 }
-.example-wrap.should_panic .tooltip::after {
+.example-wrap.should_panic .tooltip:hover::after {
 	content: "This example panics";
 }
-.example-wrap.edition .tooltip::after {
+.example-wrap.edition .tooltip:hover::after {
 	content: "This code runs with edition " attr(data-edition);
 }
 
-.example-wrap .tooltip:hover::before, .example-wrap .tooltip:hover::after {
-	display: inline;
-}
-
 .example-wrap.compile_fail .tooltip,
 .example-wrap.should_panic .tooltip,
 .example-wrap.ignore .tooltip {
@@ -1295,7 +1289,7 @@ a.test-arrow:hover {
 	font-size: 1rem;
 }
 
-#sidebar-toggle {
+#src-sidebar-toggle {
 	position: sticky;
 	top: 0;
 	left: 0;
@@ -1324,7 +1318,7 @@ a.test-arrow:hover {
 #source-sidebar div.files > a.selected {
 	background-color: var(--source-sidebar-background-selected);
 }
-#sidebar-toggle > button {
+#src-sidebar-toggle > button {
 	font-size: inherit;
 	font-weight: bold;
 	background: none;
@@ -1726,7 +1720,7 @@ in storage.js
 		left: -11px;
 	}
 
-	#sidebar-toggle {
+	#src-sidebar-toggle {
 		position: fixed;
 		left: 1px;
 		top: 100px;
@@ -1740,7 +1734,7 @@ in storage.js
 		border-left: 0;
 	}
 
-	.source-sidebar-expanded #sidebar-toggle {
+	.source-sidebar-expanded #src-sidebar-toggle {
 		left: unset;
 		top: unset;
 		width: unset;
@@ -1851,10 +1845,10 @@ in storage.js
 		width: 35px;
 	}
 
-	#sidebar-toggle {
+	#src-sidebar-toggle {
 		top: 10px;
 	}
-	.source-sidebar-expanded #sidebar-toggle {
+	.source-sidebar-expanded #src-sidebar-toggle {
 		top: unset;
 	}
 }

src/librustdoc/html/static/css/settings.css

@@ -59,12 +59,6 @@
 	cursor: pointer;
 }
 
-.setting-line > .sub-settings {
-	padding-left: 42px;
-	width: 100%;
-	display: block;
-}
-
 #settings .setting-line {
 	margin: 1.2em 0.6em;
 }

src/librustdoc/html/static/js/source-script.js

@@ -83,7 +83,7 @@ function toggleSidebar() {
 
 function createSidebarToggle() {
     const sidebarToggle = document.createElement("div");
-    sidebarToggle.id = "sidebar-toggle";
+    sidebarToggle.id = "src-sidebar-toggle";
 
     const inner = document.createElement("button");
 

src/test/rustdoc-gui/code-sidebar-toggle.goml

@@ -1,7 +1,7 @@
 // This test checks that the source code pages sidebar toggle is working as expected.
 goto: "file://" + |DOC_PATH| + "/test_docs/index.html"
 click: ".srclink"
-wait-for: "#sidebar-toggle"
-click: "#sidebar-toggle"
+wait-for: "#src-sidebar-toggle"
+click: "#src-sidebar-toggle"
 fail: true
 assert-css: ("#source-sidebar", { "left": "-300px" })

src/test/rustdoc-gui/codeblock-tooltip.goml

@@ -20,7 +20,7 @@ define-function: (
             {"border-left": "2px solid rgba(255, 0, 0, 0.5)"},
         )),
 
-        ("move-cursor-to", ".docblock .example-wrap.compile_fail"),
+        ("move-cursor-to", ".docblock .example-wrap.compile_fail .tooltip"),
 
         ("assert-css", (
             ".docblock .example-wrap.compile_fail .tooltip",
@@ -60,7 +60,7 @@ define-function: (
             {"border-left": "2px solid rgba(255, 0, 0, 0.5)"},
         )),
 
-        ("move-cursor-to", ".docblock .example-wrap.should_panic"),
+        ("move-cursor-to", ".docblock .example-wrap.should_panic .tooltip"),
 
         ("assert-css", (
             ".docblock .example-wrap.should_panic .tooltip",
@@ -100,7 +100,7 @@ define-function: (
             {"border-left": "2px solid rgba(255, 142, 0, 0.6)"},
         )),
 
-        ("move-cursor-to", ".docblock .example-wrap.ignore"),
+        ("move-cursor-to", ".docblock .example-wrap.ignore .tooltip"),
 
         ("assert-css", (
             ".docblock .example-wrap.ignore .tooltip",

src/test/rustdoc-gui/cursor.goml

@@ -21,4 +21,4 @@ assert-css: (".sidebar-menu-toggle", {"cursor": "pointer"})
 
 // the sidebar toggle button on the source code pages
 goto: "file://" + |DOC_PATH| + "/src/lib2/lib.rs.html"
-assert-css: ("#sidebar-toggle > button", {"cursor": "pointer"})
+assert-css: ("#src-sidebar-toggle > button", {"cursor": "pointer"})

src/test/rustdoc-gui/sidebar-source-code-display.goml

@@ -2,18 +2,18 @@
 javascript: false
 goto: "file://" + |DOC_PATH| + "/src/test_docs/lib.rs.html"
 // Since the javascript is disabled, there shouldn't be a toggle.
-assert-false: "#sidebar-toggle"
+assert-false: "#src-sidebar-toggle"
 wait-for-css: (".sidebar", {"display": "none"})
 
 // Let's retry with javascript enabled.
 javascript: true
 reload:
-wait-for: "#sidebar-toggle"
-assert-css: ("#sidebar-toggle", {"visibility": "visible"})
-assert-css: (".sidebar > *:not(#sidebar-toggle)", {"visibility": "hidden"})
+wait-for: "#src-sidebar-toggle"
+assert-css: ("#src-sidebar-toggle", {"visibility": "visible"})
+assert-css: (".sidebar > *:not(#src-sidebar-toggle)", {"visibility": "hidden"})
 // Let's expand the sidebar now.
-click: "#sidebar-toggle"
-wait-for-css: ("#sidebar-toggle", {"visibility": "visible"})
+click: "#src-sidebar-toggle"
+wait-for-css: ("#src-sidebar-toggle", {"visibility": "visible"})
 
 // We now check that opening the sidebar and clicking a link will leave it open.
 // The behavior here on desktop is different than the behavior on mobile,
@@ -38,25 +38,25 @@ define-function: (
     [
         ("local-storage", {"rustdoc-theme": |theme|, "rustdoc-use-system-theme": "false"}),
         ("reload"),
-        ("wait-for-css", ("#sidebar-toggle", {"visibility": "visible"})),
+        ("wait-for-css", ("#src-sidebar-toggle", {"visibility": "visible"})),
         ("assert-css", (
             "#source-sidebar details[open] > .files a.selected",
             {"color": |color_hover|, "background-color": |background|},
         )),
 
         // Without hover or focus.
-        ("assert-css", ("#sidebar-toggle > button", {"background-color": |background_toggle|})),
+        ("assert-css", ("#src-sidebar-toggle > button", {"background-color": |background_toggle|})),
         // With focus.
-        ("focus", "#sidebar-toggle > button"),
+        ("focus", "#src-sidebar-toggle > button"),
         ("assert-css", (
-            "#sidebar-toggle > button:focus",
+            "#src-sidebar-toggle > button:focus",
             {"background-color": |background_toggle_hover|},
         )),
         ("focus", ".search-input"),
         // With hover.
-        ("move-cursor-to", "#sidebar-toggle > button"),
+        ("move-cursor-to", "#src-sidebar-toggle > button"),
         ("assert-css", (
-            "#sidebar-toggle > button:hover",
+            "#src-sidebar-toggle > button:hover",
             {"background-color": |background_toggle_hover|},
         )),
 
@@ -151,16 +151,16 @@ call-function: ("check-colors", {
 size: (500, 700)
 reload:
 // Waiting for the sidebar to be displayed...
-wait-for-css: ("#sidebar-toggle", {"visibility": "visible"})
+wait-for-css: ("#src-sidebar-toggle", {"visibility": "visible"})
 
 // We now check it takes the full size of the display.
 assert-property: ("body", {"clientWidth": "500", "clientHeight": "700"})
 assert-property: (".sidebar", {"clientWidth": "500", "clientHeight": "700"})
 
 // We now check the display of the toggle once the sidebar is expanded.
-assert-property: ("#sidebar-toggle", {"clientWidth": "500", "clientHeight": "39"})
+assert-property: ("#src-sidebar-toggle", {"clientWidth": "500", "clientHeight": "39"})
 assert-css: (
-    "#sidebar-toggle",
+    "#src-sidebar-toggle",
     {
         "border-top-width": "0px",
         "border-right-width": "0px",
@@ -170,28 +170,28 @@ assert-css: (
 )
 
 // We now check that the scroll position is kept when opening the sidebar.
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: (".sidebar", {"width": "0px"})
 // We scroll to line 117 to change the scroll position.
 scroll-to: '//*[@id="117"]'
 assert-window-property: {"pageYOffset": "2542"}
 // Expanding the sidebar...
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: (".sidebar", {"width": "500px"})
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: (".sidebar", {"width": "0px"})
 // The "scrollTop" property should be the same.
 assert-window-property: {"pageYOffset": "2542"}
 
 // We now check that the scroll position is restored if the window is resized.
 size: (500, 700)
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: ("#source-sidebar", {"visibility": "visible"})
 assert-window-property: {"pageYOffset": "0"}
 size: (900, 900)
 assert-window-property: {"pageYOffset": "2542"}
 size: (500, 700)
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: ("#source-sidebar", {"visibility": "hidden"})
 
 // We now check that opening the sidebar and clicking a link will close it.
@@ -199,7 +199,7 @@ wait-for-css: ("#source-sidebar", {"visibility": "hidden"})
 // but common sense dictates that if you have a list of files that fills the entire screen, and
 // you click one of them, you probably want to actually see the file's contents, and not just
 // make it the current selection.
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: ("#source-sidebar", {"visibility": "visible"})
 assert-local-storage: {"rustdoc-source-sidebar-show": "true"}
 click: ".sidebar a.selected"
@@ -210,6 +210,6 @@ assert-local-storage: {"rustdoc-source-sidebar-show": "false"}
 size: (1000, 1000)
 wait-for-css: ("#source-sidebar", {"visibility": "hidden"})
 assert-local-storage: {"rustdoc-source-sidebar-show": "false"}
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 wait-for-css: ("#source-sidebar", {"visibility": "visible"})
 assert-local-storage: {"rustdoc-source-sidebar-show": "true"}

src/test/rustdoc-gui/source-code-page.goml

@@ -97,7 +97,7 @@ assert-document-property: ({"URL": "/lib.rs.html"}, ENDS_WITH)
 // Checking the source code sidebar.
 
 // First we "open" it.
-click: "#sidebar-toggle"
+click: "#src-sidebar-toggle"
 assert: ".source-sidebar-expanded"
 
 // We check that the first entry of the sidebar is collapsed

src/test/ui/const-generics/defaults/complex-unord-param.min.stderr

@@ -1,8 +0,0 @@
-error: type parameters must be declared prior to const parameters
-  --> $DIR/complex-unord-param.rs:8:41
-   |
-LL | struct NestedArrays<'a, const N: usize, A: 'a, const M: usize, T:'a =u32> {
-   |                    ---------------------^----------------------^--------- help: reorder the parameters: lifetimes, then types, then consts: `<'a, A: 'a, T: 'a = u32, const N: usize, const M: usize>`
-
-error: aborting due to previous error
-

src/test/ui/const-generics/type-after-const-ok.min.stderr

@@ -1,8 +0,0 @@
-error: type parameters must be declared prior to const parameters
-  --> $DIR/type-after-const-ok.rs:8:26
-   |
-LL | struct A<const N: usize, T>(T);
-   |         -----------------^- help: reorder the parameters: lifetimes, then types, then consts: `<T, const N: usize>`
-
-error: aborting due to previous error
-

src/test/ui/methods/issues/issue-105732.rs

@@ -0,0 +1,13 @@
+#![feature(auto_traits)]
+
+auto trait Foo {
+    fn g(&self); //~ ERROR auto traits cannot have associated items
+}
+
+trait Bar {
+    fn f(&self) {
+        self.g(); //~ ERROR the method `g` exists for reference `&Self`, but its trait bounds were not satisfied
+    }
+}
+
+fn main() {}

src/test/ui/methods/issues/issue-105732.stderr

@@ -0,0 +1,28 @@
+error[E0380]: auto traits cannot have associated items
+  --> $DIR/issue-105732.rs:4:8
+   |
+LL | auto trait Foo {
+   |            --- auto trait cannot have associated items
+LL |     fn g(&self);
+   |     ---^-------- help: remove these associated items
+
+error[E0599]: the method `g` exists for reference `&Self`, but its trait bounds were not satisfied
+  --> $DIR/issue-105732.rs:9:14
+   |
+LL |         self.g();
+   |              ^
+   |
+   = note: the following trait bounds were not satisfied:
+           `Self: Foo`
+           which is required by `&Self: Foo`
+           `&Self: Foo`
+   = help: items from traits can only be used if the type parameter is bounded by the trait
+help: the following trait defines an item `g`, perhaps you need to add a supertrait for it:
+   |
+LL | trait Bar: Foo {
+   |          +++++
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0380, E0599.
+For more information about an error, try `rustc --explain E0380`.

src/test/ui/rfc-2632-const-trait-impl/const-impl-trait.rs

@@ -0,0 +1,55 @@
+// check-pass
+#![allow(incomplete_features)]
+#![feature(
+    associated_type_bounds,
+    const_trait_impl,
+    const_cmp,
+    return_position_impl_trait_in_trait,
+)]
+
+use std::marker::Destruct;
+
+const fn cmp(a: &impl ~const PartialEq) -> bool {
+    a == a
+}
+
+const fn wrap(x: impl ~const PartialEq + ~const Destruct)
+    -> impl ~const PartialEq + ~const Destruct
+{
+    x
+}
+
+#[const_trait]
+trait Foo {
+    fn huh() -> impl ~const PartialEq + ~const Destruct + Copy;
+}
+
+impl const Foo for () {
+    fn huh() -> impl ~const PartialEq + ~const Destruct + Copy {
+        123
+    }
+}
+
+const _: () = {
+    assert!(cmp(&0xDEADBEEFu32));
+    assert!(cmp(&()));
+    assert!(wrap(123) == wrap(123));
+    assert!(wrap(123) != wrap(456));
+    let x = <() as Foo>::huh();
+    assert!(x == x);
+};
+
+#[const_trait]
+trait T {}
+struct S;
+impl const T for S {}
+
+const fn rpit() -> impl ~const T { S }
+
+const fn apit(_: impl ~const T + ~const Destruct) {}
+
+const fn rpit_assoc_bound() -> impl IntoIterator<Item: ~const T> { Some(S) }
+
+const fn apit_assoc_bound(_: impl IntoIterator<Item: ~const T> + ~const Destruct) {}
+
+fn main() {}

src/test/ui/rfc-2632-const-trait-impl/tilde-const-invalid-places.rs

@@ -1,23 +1,6 @@
 #![feature(const_trait_impl)]
 #![feature(associated_type_bounds)]
 
-#[const_trait]
-trait T {}
-struct S;
-impl T for S {}
-
-fn rpit() -> impl ~const T { S }
-//~^ ERROR `~const` is not allowed
-
-fn apit(_: impl ~const T) {}
-//~^ ERROR `~const` is not allowed
-
-fn rpit_assoc_bound() -> impl IntoIterator<Item: ~const T> { Some(S) }
-//~^ ERROR `~const` is not allowed
-
-fn apit_assoc_bound(_: impl IntoIterator<Item: ~const T>) {}
-//~^ ERROR `~const` is not allowed
-
 struct TildeQuestion<T: ~const ?Sized>(std::marker::PhantomData<T>);
 //~^ ERROR `~const` and `?` are mutually exclusive
 

src/test/ui/rfc-2632-const-trait-impl/tilde-const-invalid-places.stderr

@@ -1,40 +1,8 @@
-error: `~const` is not allowed here
-  --> $DIR/tilde-const-invalid-places.rs:9:19
-   |
-LL | fn rpit() -> impl ~const T { S }
-   |                   ^^^^^^^^
-   |
-   = note: `impl Trait`s cannot have `~const` trait bounds
-
-error: `~const` is not allowed here
-  --> $DIR/tilde-const-invalid-places.rs:12:17
-   |
-LL | fn apit(_: impl ~const T) {}
-   |                 ^^^^^^^^
-   |
-   = note: `impl Trait`s cannot have `~const` trait bounds
-
-error: `~const` is not allowed here
-  --> $DIR/tilde-const-invalid-places.rs:15:50
-   |
-LL | fn rpit_assoc_bound() -> impl IntoIterator<Item: ~const T> { Some(S) }
-   |                                                  ^^^^^^^^
-   |
-   = note: `impl Trait`s cannot have `~const` trait bounds
-
-error: `~const` is not allowed here
-  --> $DIR/tilde-const-invalid-places.rs:18:48
-   |
-LL | fn apit_assoc_bound(_: impl IntoIterator<Item: ~const T>) {}
-   |                                                ^^^^^^^^
-   |
-   = note: `impl Trait`s cannot have `~const` trait bounds
-
 error: `~const` and `?` are mutually exclusive
-  --> $DIR/tilde-const-invalid-places.rs:21:25
+  --> $DIR/tilde-const-invalid-places.rs:4:25
    |
 LL | struct TildeQuestion<T: ~const ?Sized>(std::marker::PhantomData<T>);
    |                         ^^^^^^^^^^^^^
 
-error: aborting due to 5 previous errors
+error: aborting due to previous error