Merging upstream version 1.74.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 86 insertions, 10 deletions

diff --git a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr b/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
index 7d3535e1f..a86115671 100644
--- a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
+++ b/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
@@ -5,10 +5,10 @@ LL |     impls::<W<_>>();
    |     ^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `impls`
 
 error[E0275]: overflow evaluating the requirement `W<_>: Trait`
-  --> $DIR/fixpoint-exponential-growth.rs:29:5
+  --> $DIR/fixpoint-exponential-growth.rs:29:13
    |
 LL |     impls::<W<_>>();
-   |     ^^^^^^^^^^^^^
+   |             ^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`fixpoint_exponential_growth`)
 note: required by a bound in `impls`
diff --git a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr b/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
index 4b8846da5..a3404da51 100644
--- a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
+++ b/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
@@ -1,8 +1,8 @@
 error[E0275]: overflow evaluating the requirement `(): Trait`
-  --> $DIR/double-cycle-inductive-coinductive.rs:32:5
+  --> $DIR/double-cycle-inductive-coinductive.rs:32:19
    |
 LL |     impls_trait::<()>();
-   |     ^^^^^^^^^^^^^^^^^
+   |                   ^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`double_cycle_inductive_coinductive`)
 note: required by a bound in `impls_trait`
@@ -12,10 +12,10 @@ LL | fn impls_trait<T: Trait>() {}
    |                   ^^^^^ required by this bound in `impls_trait`
 
 error[E0275]: overflow evaluating the requirement `(): TraitRev`
-  --> $DIR/double-cycle-inductive-coinductive.rs:35:5
+  --> $DIR/double-cycle-inductive-coinductive.rs:35:23
    |
 LL |     impls_trait_rev::<()>();
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |                       ^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`double_cycle_inductive_coinductive`)
 note: required by a bound in `impls_trait_rev`
diff --git a/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.rs b/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
new file mode 100644
index 000000000..279063923
--- /dev/null
+++ b/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.rs
@@ -0,0 +1,53 @@
+// compile-flags: -Ztrait-solver=next
+#![feature(rustc_attrs)]
+
+// Check that we correctly rerun the trait solver for heads of cycles,
+// even if they are not the root.
+
+struct A<T: ?Sized>(*const T);
+struct B<T: ?Sized>(*const T);
+struct C<T: ?Sized>(*const T);
+
+#[rustc_coinductive]
+trait Trait<'a, 'b> {}
+trait NotImplemented {}
+
+impl<'a, 'b, T: ?Sized> Trait<'a, 'b> for A<T> where B<T>: Trait<'a, 'b> {}
+
+// With this the root of `B<T>` is `A<T>`, even if the other impl does
+// not have a cycle with `A<T>`. This candidate never applies because of
+// the `A<T>: NotImplemented` bound.
+impl<'a, 'b, T: ?Sized> Trait<'a, 'b> for B<T>
+where
+    A<T>: Trait<'a, 'b>,
+    A<T>: NotImplemented,
+{
+}
+
+// This impl directly requires 'b to be equal to 'static.
+//
+// Because of the coinductive cycle through `C<T>` it also requires
+// 'a to be 'static.
+impl<'a, T: ?Sized> Trait<'a, 'static> for B<T>
+where
+    C<T>: Trait<'a, 'a>,
+{}
+
+// In the first iteration of `B<T>: Trait<'a, 'b>` we don't add any
+// constraints here, only after setting the provisional result to require
+// `'b == 'static` do we also add that constraint for `'a`.
+impl<'a, 'b, T: ?Sized> Trait<'a, 'b> for C<T>
+where
+    B<T>: Trait<'a, 'b>,
+{}
+
+fn impls_trait<'a, 'b, T: Trait<'a, 'b> + ?Sized>() {}
+
+fn check<'a, T: ?Sized>() {
+    impls_trait::<'a, 'static, A<T>>();
+    //~^ ERROR lifetime may not live long enough
+}
+
+fn main() {
+    check::<()>();
+}
diff --git a/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr b/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr
new file mode 100644
index 000000000..4cbd08981
--- /dev/null
+++ b/tests/ui/traits/new-solver/cycles/fixpoint-rerun-all-cycle-heads.stderr
@@ -0,0 +1,10 @@
+error: lifetime may not live long enough
+  --> $DIR/fixpoint-rerun-all-cycle-heads.rs:47:5
+   |
+LL | fn check<'a, T: ?Sized>() {
+   |          -- lifetime `'a` defined here
+LL |     impls_trait::<'a, 'static, A<T>>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ requires that `'a` must outlive `'static`
+
+error: aborting due to previous error
+
diff --git a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs
index 3cfe7ab87..f06b98a79 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs
+++ b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs
@@ -39,7 +39,7 @@ fn impls_ar<T: AR>() {}
 
 fn main() {
     impls_a::<()>();
-    // FIXME(-Ztrait-solver=next): This is broken and should error.
+    //~^ ERROR overflow evaluating the requirement `(): A`
 
     impls_ar::<()>();
     //~^ ERROR overflow evaluating the requirement `(): AR`
diff --git a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
index 0e1c86c1b..859b3f3f1 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
+++ b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
@@ -1,8 +1,21 @@
+error[E0275]: overflow evaluating the requirement `(): A`
+  --> $DIR/inductive-not-on-stack.rs:41:15
+   |
+LL |     impls_a::<()>();
+   |               ^^
+   |
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`inductive_not_on_stack`)
+note: required by a bound in `impls_a`
+  --> $DIR/inductive-not-on-stack.rs:25:15
+   |
+LL | fn impls_a<T: A>() {}
+   |               ^ required by this bound in `impls_a`
+
 error[E0275]: overflow evaluating the requirement `(): AR`
-  --> $DIR/inductive-not-on-stack.rs:44:5
+  --> $DIR/inductive-not-on-stack.rs:44:16
    |
 LL |     impls_ar::<()>();
-   |     ^^^^^^^^^^^^^^
+   |                ^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`inductive_not_on_stack`)
 note: required by a bound in `impls_ar`
@@ -11,6 +24,6 @@ note: required by a bound in `impls_ar`
 LL | fn impls_ar<T: AR>() {}
    |                ^^ required by this bound in `impls_ar`
 
-error: aborting due to previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0275`.