Auto merge of #124849 - matthiaskrgr:rollup-68humsk, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #124738 (rustdoc: dedup search form HTML)
 - #124827 (generalize hr alias: avoid unconstrainable infer vars)
 - #124832 (narrow down visibilities in `rustc_parse::lexer`)
 - #124842 (replace another Option<Span> by DUMMY_SP)
 - #124846 (Don't ICE when we cannot eval a const to a valtree in the new solver)

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

8 files changed, 132 insertions, 4 deletions

diff --git a/tests/rustdoc-gui/javascript-disabled.goml b/tests/rustdoc-gui/javascript-disabled.goml
index a7579ef7ec1..c6a7ad94b3f 100644
--- a/tests/rustdoc-gui/javascript-disabled.goml
+++ b/tests/rustdoc-gui/javascript-disabled.goml
@@ -4,7 +4,7 @@ javascript: false
 
 go-to: "file://" + |DOC_PATH| + "/test_docs/struct.Foo.html"
 show-text: true
-assert-css: (".sub", {"display": "none"})
+assert-false: ".sub"
 
 // Even though JS is disabled, we should still have themes applied. Links are never black-colored
 // if styles are applied so we check that they are not.
diff --git a/tests/rustdoc-gui/sidebar-source-code-display.goml b/tests/rustdoc-gui/sidebar-source-code-display.goml
index 3bfbe820b8d..7ce3be8a5b3 100644
--- a/tests/rustdoc-gui/sidebar-source-code-display.goml
+++ b/tests/rustdoc-gui/sidebar-source-code-display.goml
@@ -4,7 +4,7 @@ javascript: false
 go-to: "file://" + |DOC_PATH| + "/src/test_docs/lib.rs.html"
 // Since the javascript is disabled, there shouldn't be a toggle.
 wait-for-css: (".sidebar", {"display": "none"})
-assert-css: ("#sidebar-button", {"display": "none"})
+assert-false: "#sidebar-button"
 
 // Let's retry with javascript enabled.
 javascript: true
diff --git a/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.rs b/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.rs
index 33a6d7aa783..26d63fdde99 100644
--- a/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.rs
+++ b/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.rs
@@ -1,8 +1,9 @@
-//@ compile-flags: -Znext-solver=coherence
+//@ compile-flags: -Znext-solver
 
 #[derive(Debug)]
 struct X<const FN: fn() = { || {} }>;
 //~^ ERROR using function pointers as const generic parameters is forbidden
 //~| ERROR using function pointers as const generic parameters is forbidden
+//~| ERROR type annotations needed
 
 fn main() {}
diff --git a/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.stderr b/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.stderr
index 4eef8c0ab6c..044c24fd2b2 100644
--- a/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.stderr
+++ b/tests/ui/traits/next-solver/canonical/const-region-infer-to-static-in-binder.stderr
@@ -1,3 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/const-region-infer-to-static-in-binder.rs:4:10
+   |
+LL | struct X<const FN: fn() = { || {} }>;
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of the constant `{ || {} }`
+
 error: using function pointers as const generic parameters is forbidden
   --> $DIR/const-region-infer-to-static-in-binder.rs:4:20
    |
@@ -15,5 +21,6 @@ LL | struct X<const FN: fn() = { || {} }>;
    = note: the only supported types are integers, `bool` and `char`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/traits/next-solver/generalize/hr-alias-non-hr-alias-self-ty-1.rs b/tests/ui/traits/next-solver/generalize/hr-alias-non-hr-alias-self-ty-1.rs
new file mode 100644
index 00000000000..3be118a5b39
--- /dev/null
+++ b/tests/ui/traits/next-solver/generalize/hr-alias-non-hr-alias-self-ty-1.rs
@@ -0,0 +1,36 @@
+//@ revisions: old next
+//@[next] compile-flags: -Znext-solver
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@ check-pass
+
+// Generalizing an alias referencing escaping bound variables
+// is hard. We previously didn't replace this alias with inference
+// variables but did replace nested alias which do not reference
+// any bound variables. This caused us to stall with the following
+// goal, which cannot make any progress:
+//
+// <<T as Id>::Refl as HigherRanked>::Output<'a>
+//    alias-relate
+// <?unconstrained as HigherRanked>::Output<'a>
+//
+//
+// cc trait-system-refactor-initiative#110
+
+#![allow(unused)]
+trait HigherRanked {
+    type Output<'a>;
+}
+trait Id {
+    type Refl: HigherRanked;
+}
+
+fn foo<T: Id>() -> for<'a> fn(<<T as Id>::Refl as HigherRanked>::Output<'a>) {
+    todo!()
+}
+
+fn bar<T: Id>() {
+    // we generalize here
+    let x = foo::<T>();
+}
+
+fn main() {}
diff --git a/tests/ui/traits/next-solver/generalize/hr-alias-non-hr-alias-self-ty-2.rs b/tests/ui/traits/next-solver/generalize/hr-alias-non-hr-alias-self-ty-2.rs
new file mode 100644
index 00000000000..560eb34a977
--- /dev/null
+++ b/tests/ui/traits/next-solver/generalize/hr-alias-non-hr-alias-self-ty-2.rs
@@ -0,0 +1,32 @@
+//@ revisions: old next
+//@[next] compile-flags: -Znext-solver
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@ check-pass
+
+// A minimization of an ambiguity error in `icu_provider`.
+//
+// cc trait-system-refactor-initiative#110
+
+trait Yokeable<'a> {
+    type Output;
+}
+trait Id {
+    type Refl;
+}
+
+fn into_deserialized<M: Id>() -> M
+where
+    M::Refl: for<'a> Yokeable<'a>,
+{
+    try_map_project::<M, _>(|_| todo!())
+}
+
+fn try_map_project<M: Id, F>(_f: F) -> M
+where
+    M::Refl: for<'a> Yokeable<'a>,
+    F: for<'a> FnOnce(&'a ()) -> <<M as Id>::Refl as Yokeable<'a>>::Output,
+{
+    todo!()
+}
+
+fn main() {}
diff --git a/tests/ui/traits/next-solver/generalize/hr-alias-universe-lowering-ambiguity.rs b/tests/ui/traits/next-solver/generalize/hr-alias-universe-lowering-ambiguity.rs
new file mode 100644
index 00000000000..1e2ba81129d
--- /dev/null
+++ b/tests/ui/traits/next-solver/generalize/hr-alias-universe-lowering-ambiguity.rs
@@ -0,0 +1,51 @@
+//@ compile-flags: -Znext-solver
+//@ check-pass
+
+// A regression test for a fairly subtle issue with how we
+// generalize aliases referencing higher-ranked regions
+// which previously caused unexpected ambiguity errors.
+//
+// The explanations in the test may end up being out of date
+// in the future as we may refine our approach to generalization
+// going forward.
+//
+// cc trait-system-refactor-initiative#108
+trait Trait<'a> {
+    type Assoc;
+}
+
+impl<'a> Trait<'a> for () {
+    type Assoc = ();
+}
+
+fn foo<T: for<'a> Trait<'a>>(x: T) -> for<'a> fn(<T as Trait<'a>>::Assoc) {
+    |_| ()
+}
+
+fn unconstrained<T>() -> T {
+    todo!()
+}
+
+fn main() {
+    // create `?x.0` in the root universe
+    let mut x = unconstrained();
+
+    // bump the current universe of the inference context
+    let bump: for<'a, 'b> fn(&'a (), &'b ()) = |_, _| ();
+    let _: for<'a> fn(&'a (), &'a ()) = bump;
+
+    // create `?y.1` in a higher universe
+    let mut y = Default::default();
+
+    // relate `?x.0` with `for<'a> fn(<?y.1 as Trait<'a>>::Assoc)`
+    // -> instantiate `?x.0` with `for<'a> fn(<?y_new.0 as Trait<'a>>::Assoc)`
+    x = foo(y);
+
+    // Constrain `?y.1` to `()`
+    let _: () = y;
+
+    // `AliasRelate(<?y_new.0 as Trait<'a>>::Assoc, <() as Trait<'a>>::Assoc)`
+    // remains ambiguous unless we somehow constrain `?y_new.0` during
+    // generalization to be equal to `?y.1`, which is exactly what we
+    // did to fix this issue.
+}
diff --git a/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.rs b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.rs
index 536e7e97c40..00dc7a9d337 100644
--- a/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.rs
+++ b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.rs
@@ -1,5 +1,6 @@
 //@ revisions: old next
 //@[next] compile-flags: -Znext-solver
+//@ ignore-compare-mode-next-solver (explicit revisions)
 //@ check-pass
 
 // case 3 of https://github.com/rust-lang/trait-system-refactor-initiative/issues/8.