Auto merge of #113188 - matthiaskrgr:rollup-j3abaks, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #107624 (Stabilize `const_cstr_methods`)
 - #111403 (suggest `slice::swap` for `mem::swap(&mut x[0], &mut x[1])` borrowck error)
 - #113071 (Account for late-bound vars from parent arg-position impl trait)
 - #113165 (Encode item bounds for `DefKind::ImplTraitPlaceholder`)
 - #113171 (Properly implement variances_of for RPITIT GAT)
 - #113177 (Use structured suggestion when telling user about `for<'a>`)

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

23 files changed, 205 insertions, 70 deletions

diff --git a/tests/ui/error-codes/E0637.stderr b/tests/ui/error-codes/E0637.stderr
index 78341735e19..d9db89ddb0c 100644
--- a/tests/ui/error-codes/E0637.stderr
+++ b/tests/ui/error-codes/E0637.stderr
@@ -22,11 +22,10 @@ error[E0637]: `&` without an explicit lifetime name cannot be used here
 LL |     T: Into<&u32>,
    |             ^ explicit lifetime name needed here
    |
-help: consider introducing a higher-ranked lifetime here with `for<'a>`
-  --> $DIR/E0637.rs:13:8
+help: consider introducing a higher-ranked lifetime here
    |
-LL |     T: Into<&u32>,
-   |        ^
+LL |     T: for<'a> Into<&'a u32>,
+   |        +++++++       ++
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/generics/issue-65285-incorrect-explicit-lifetime-name-needed.stderr b/tests/ui/generics/issue-65285-incorrect-explicit-lifetime-name-needed.stderr
index faf4c9eb872..bcd1fbc55ed 100644
--- a/tests/ui/generics/issue-65285-incorrect-explicit-lifetime-name-needed.stderr
+++ b/tests/ui/generics/issue-65285-incorrect-explicit-lifetime-name-needed.stderr
@@ -4,11 +4,10 @@ error[E0637]: `&` without an explicit lifetime name cannot be used here
 LL | fn should_error<T>() where T : Into<&u32> {}
    |                                     ^ explicit lifetime name needed here
    |
-help: consider introducing a higher-ranked lifetime here with `for<'a>`
-  --> $DIR/issue-65285-incorrect-explicit-lifetime-name-needed.rs:5:32
+help: consider introducing a higher-ranked lifetime here
    |
-LL | fn should_error<T>() where T : Into<&u32> {}
-   |                                ^
+LL | fn should_error<T>() where T : for<'a> Into<&'a u32> {}
+   |                                +++++++       ++
 
 error[E0106]: missing lifetime specifier
   --> $DIR/issue-65285-incorrect-explicit-lifetime-name-needed.rs:9:20
diff --git a/tests/ui/impl-trait/in-trait/foreign.rs b/tests/ui/impl-trait/in-trait/foreign.rs
index 98417b343a1..b0fbe3a3d4a 100644
--- a/tests/ui/impl-trait/in-trait/foreign.rs
+++ b/tests/ui/impl-trait/in-trait/foreign.rs
@@ -14,6 +14,10 @@ impl Foo for Local {
     fn bar(self) -> Arc<String> { Arc::new(String::new()) }
 }
 
+fn generic(f: impl Foo) {
+    let x = &*f.bar();
+}
+
 fn main() {
     // Witness an RPITIT from another crate.
     let &() = Foreign.bar();
diff --git a/tests/ui/impl-trait/in-trait/variances-of-gat.rs b/tests/ui/impl-trait/in-trait/variances-of-gat.rs
new file mode 100644
index 00000000000..4008ece94da
--- /dev/null
+++ b/tests/ui/impl-trait/in-trait/variances-of-gat.rs
@@ -0,0 +1,19 @@
+// check-pass
+// [next] compile-flags: -Zlower-impl-trait-in-trait-to-assoc-ty
+// revisions: current next
+
+#![feature(return_position_impl_trait_in_trait)]
+
+trait Foo {}
+
+impl Foo for () {}
+
+trait ThreeCellFragment {
+    fn ext_cells<'a>(&'a self) -> impl Foo + 'a {
+        self.ext_adjacent_cells()
+    }
+
+    fn ext_adjacent_cells<'a>(&'a self) -> impl Foo + 'a;
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/universal_wrong_hrtb.rs b/tests/ui/impl-trait/universal_wrong_hrtb.rs
index b9551c2ceb0..48561710143 100644
--- a/tests/ui/impl-trait/universal_wrong_hrtb.rs
+++ b/tests/ui/impl-trait/universal_wrong_hrtb.rs
@@ -3,6 +3,6 @@ trait Trait<'a> {
 }
 
 fn test_argument_position(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {}
-//~^ ERROR `impl Trait` can only mention lifetimes bound at the fn or impl level
+//~^ ERROR `impl Trait` can only mention lifetimes from an fn or impl
 
 fn main() {}
diff --git a/tests/ui/impl-trait/universal_wrong_hrtb.stderr b/tests/ui/impl-trait/universal_wrong_hrtb.stderr
index 37eb8dfa1a1..b5a091b61fa 100644
--- a/tests/ui/impl-trait/universal_wrong_hrtb.stderr
+++ b/tests/ui/impl-trait/universal_wrong_hrtb.stderr
@@ -1,14 +1,8 @@
-error: `impl Trait` can only mention lifetimes bound at the fn or impl level
+error: `impl Trait` can only mention lifetimes from an fn or impl
   --> $DIR/universal_wrong_hrtb.rs:5:73
    |
 LL | fn test_argument_position(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {}
-   |                                                                         ^^
-   |
-note: lifetime declared here
-  --> $DIR/universal_wrong_hrtb.rs:5:39
-   |
-LL | fn test_argument_position(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {}
-   |                                       ^^
+   |                                       -- lifetime declared here         ^^
 
 error: aborting due to previous error
 
diff --git a/tests/ui/suggestions/suggest-split-at-mut.stderr b/tests/ui/suggestions/suggest-split-at-mut.stderr
index 330f012b2a9..bb185138383 100644
--- a/tests/ui/suggestions/suggest-split-at-mut.stderr
+++ b/tests/ui/suggestions/suggest-split-at-mut.stderr
@@ -9,6 +9,7 @@ LL |     *a = 5;
    |     ------ first borrow later used here
    |
    = help: consider using `.split_at_mut(position)` or similar method to obtain two mutable non-overlapping sub-slices
+   = help: consider using `.swap(index_1, index_2)` to swap elements at the specified indices
 
 error: aborting due to previous error
 
diff --git a/tests/ui/traits/non_lifetime_binders/nested-apit-mentioning-outer-bound-var.rs b/tests/ui/traits/non_lifetime_binders/nested-apit-mentioning-outer-bound-var.rs
new file mode 100644
index 00000000000..e9ae00df7a0
--- /dev/null
+++ b/tests/ui/traits/non_lifetime_binders/nested-apit-mentioning-outer-bound-var.rs
@@ -0,0 +1,11 @@
+#![feature(non_lifetime_binders)]
+//~^ WARN the feature `non_lifetime_binders` is incomplete
+
+trait Trait<Input> {
+    type Assoc;
+}
+
+fn uwu(_: impl for<T> Trait<(), Assoc = impl Trait<T>>) {}
+//~^ ERROR `impl Trait` can only mention type parameters from an fn or impl
+
+fn main() {}
diff --git a/tests/ui/traits/non_lifetime_binders/nested-apit-mentioning-outer-bound-var.stderr b/tests/ui/traits/non_lifetime_binders/nested-apit-mentioning-outer-bound-var.stderr
new file mode 100644
index 00000000000..1124076c23c
--- /dev/null
+++ b/tests/ui/traits/non_lifetime_binders/nested-apit-mentioning-outer-bound-var.stderr
@@ -0,0 +1,17 @@
+warning: the feature `non_lifetime_binders` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/nested-apit-mentioning-outer-bound-var.rs:1:12
+   |
+LL | #![feature(non_lifetime_binders)]
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error: `impl Trait` can only mention type parameters from an fn or impl
+  --> $DIR/nested-apit-mentioning-outer-bound-var.rs:8:52
+   |
+LL | fn uwu(_: impl for<T> Trait<(), Assoc = impl Trait<T>>) {}
+   |                    - type parameter declared here  ^
+
+error: aborting due to previous error; 1 warning emitted
+
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.fixed b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.fixed
new file mode 100644
index 00000000000..5be6ff8e7e1
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.fixed
@@ -0,0 +1,17 @@
+// run-rustfix
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+#[allow(dead_code)]
+struct Foo<T> {
+    t: T
+}
+
+impl<T> Foo<T>
+where
+    T: for<'a> WithType<&'a u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.rs b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.rs
new file mode 100644
index 00000000000..d7072aa1181
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.rs
@@ -0,0 +1,17 @@
+// run-rustfix
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+#[allow(dead_code)]
+struct Foo<T> {
+    t: T
+}
+
+impl<T> Foo<T>
+where
+    T: WithType<&u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rust2015.stderr b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.stderr
index 63fc1a19b93..3e197dc9a9d 100644
--- a/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rust2015.stderr
+++ b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2015.stderr
@@ -1,14 +1,13 @@
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/where-clause-trait-impl-region.rs:11:17
+  --> $DIR/where-clause-inherent-impl-ampersand-rust2015.rs:13:17
    |
 LL |     T: WithType<&u32>
    |                 ^ explicit lifetime name needed here
    |
-help: consider introducing a higher-ranked lifetime here with `for<'a>`
-  --> $DIR/where-clause-trait-impl-region.rs:11:8
+help: consider introducing a higher-ranked lifetime here
    |
-LL |     T: WithType<&u32>
-   |        ^
+LL |     T: for<'a> WithType<&'a u32>
+   |        +++++++           ++
 
 error: aborting due to previous error
 
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.fixed b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.fixed
new file mode 100644
index 00000000000..0f1be586589
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.fixed
@@ -0,0 +1,18 @@
+// edition:2018
+// run-rustfix
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+#[allow(dead_code)]
+struct Foo<T> {
+    t: T
+}
+
+impl<T> Foo<T>
+where
+    T: for<'a> WithType<&'a u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.rs b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.rs
new file mode 100644
index 00000000000..59f7e472e2d
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.rs
@@ -0,0 +1,18 @@
+// edition:2018
+// run-rustfix
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+#[allow(dead_code)]
+struct Foo<T> {
+    t: T
+}
+
+impl<T> Foo<T>
+where
+    T: WithType<&u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rust2018.stderr b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.stderr
index 63fc1a19b93..08b4268e5d2 100644
--- a/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rust2018.stderr
+++ b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand-rust2018.stderr
@@ -1,14 +1,13 @@
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/where-clause-trait-impl-region.rs:11:17
+  --> $DIR/where-clause-inherent-impl-ampersand-rust2018.rs:14:17
    |
 LL |     T: WithType<&u32>
    |                 ^ explicit lifetime name needed here
    |
-help: consider introducing a higher-ranked lifetime here with `for<'a>`
-  --> $DIR/where-clause-trait-impl-region.rs:11:8
+help: consider introducing a higher-ranked lifetime here
    |
-LL |     T: WithType<&u32>
-   |        ^
+LL |     T: for<'a> WithType<&'a u32>
+   |        +++++++           ++
 
 error: aborting due to previous error
 
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rs b/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rs
deleted file mode 100644
index 43de30944ca..00000000000
--- a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rs
+++ /dev/null
@@ -1,18 +0,0 @@
-// revisions: rust2015 rust2018
-//[rust2018] edition:2018
-
-trait WithType<T> {}
-trait WithRegion<'a> { }
-
-struct Foo<T> {
-    t: T
-}
-
-impl<T> Foo<T>
-where
-    T: WithType<&u32>
-//[rust2015]~^ ERROR `&` without an explicit lifetime name cannot be used here
-//[rust2018]~^^ ERROR `&` without an explicit lifetime name cannot be used here
-{ }
-
-fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.fixed b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.fixed
new file mode 100644
index 00000000000..55c7470960e
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.fixed
@@ -0,0 +1,14 @@
+// run-rustfix
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+trait Foo { }
+
+impl<T> Foo for Vec<T>
+where
+    T: for<'a> WithType<&'a u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.rs b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.rs
new file mode 100644
index 00000000000..42a35b02161
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.rs
@@ -0,0 +1,14 @@
+// run-rustfix
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+trait Foo { }
+
+impl<T> Foo for Vec<T>
+where
+    T: WithType<&u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rust2015.stderr b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.stderr
index f4d14b5f87b..8c5bbb631b4 100644
--- a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rust2015.stderr
+++ b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2015.stderr
@@ -1,14 +1,13 @@
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/where-clause-inherent-impl-ampersand.rs:13:17
+  --> $DIR/where-clause-trait-impl-region-2015.rs:10:17
    |
 LL |     T: WithType<&u32>
    |                 ^ explicit lifetime name needed here
    |
-help: consider introducing a higher-ranked lifetime here with `for<'a>`
-  --> $DIR/where-clause-inherent-impl-ampersand.rs:13:8
+help: consider introducing a higher-ranked lifetime here
    |
-LL |     T: WithType<&u32>
-   |        ^
+LL |     T: for<'a> WithType<&'a u32>
+   |        +++++++           ++
 
 error: aborting due to previous error
 
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.fixed b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.fixed
new file mode 100644
index 00000000000..09b96fe5ea4
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.fixed
@@ -0,0 +1,15 @@
+// run-rustfix
+// edition:2018
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+trait Foo { }
+
+impl<T> Foo for Vec<T>
+where
+    T: for<'a> WithType<&'a u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.rs b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.rs
new file mode 100644
index 00000000000..445f38cbee1
--- /dev/null
+++ b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.rs
@@ -0,0 +1,15 @@
+// run-rustfix
+// edition:2018
+
+trait WithType<T> {}
+trait WithRegion<'a> { }
+
+trait Foo { }
+
+impl<T> Foo for Vec<T>
+where
+    T: WithType<&u32>
+//~^ ERROR `&` without an explicit lifetime name cannot be used here
+{ }
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rust2018.stderr b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.stderr
index f4d14b5f87b..0268c59fa4a 100644
--- a/tests/ui/underscore-lifetime/where-clause-inherent-impl-ampersand.rust2018.stderr
+++ b/tests/ui/underscore-lifetime/where-clause-trait-impl-region-2018.stderr
@@ -1,14 +1,13 @@
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/where-clause-inherent-impl-ampersand.rs:13:17
+  --> $DIR/where-clause-trait-impl-region-2018.rs:11:17
    |
 LL |     T: WithType<&u32>
    |                 ^ explicit lifetime name needed here
    |
-help: consider introducing a higher-ranked lifetime here with `for<'a>`
-  --> $DIR/where-clause-inherent-impl-ampersand.rs:13:8
+help: consider introducing a higher-ranked lifetime here
    |
-LL |     T: WithType<&u32>
-   |        ^
+LL |     T: for<'a> WithType<&'a u32>
+   |        +++++++           ++
 
 error: aborting due to previous error
 
diff --git a/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rs b/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rs
deleted file mode 100644
index 09e5bbd846d..00000000000
--- a/tests/ui/underscore-lifetime/where-clause-trait-impl-region.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-// revisions: rust2015 rust2018
-//[rust2018] edition:2018
-
-trait WithType<T> {}
-trait WithRegion<'a> { }
-
-trait Foo { }
-
-impl<T> Foo for Vec<T>
-where
-    T: WithType<&u32>
-//[rust2015,rust2018]~^ ERROR `&` without an explicit lifetime name cannot be used here
-{ }
-
-fn main() {}