Rollup merge of #93175 - spastorino:negative-traits-coherence-new, r=nikomatsakis

Implement stable overlap check considering negative traits

This PR implement the new disjointness rules for overlap check described in https://rust-lang.github.io/negative-impls-initiative/explainer/coherence-check.html#new-disjointness-rules

r? ``@nikomatsakis``

2 files changed, 26 insertions, 0 deletions

diff --git a/src/test/ui/coherence/auxiliary/option_future.rs b/src/test/ui/coherence/auxiliary/option_future.rs
new file mode 100644
index 00000000000..f71df1b87fc
--- /dev/null
+++ b/src/test/ui/coherence/auxiliary/option_future.rs
@@ -0,0 +1,8 @@
+#![crate_type = "lib"]
+#![feature(negative_impls)]
+#![feature(rustc_attrs)]
+
+pub trait Future {}
+
+#[rustc_with_negative_coherence]
+impl<E> !Future for Option<E> where E: Sized {}
diff --git a/src/test/ui/coherence/coherence-overlap-negative-trait2.rs b/src/test/ui/coherence/coherence-overlap-negative-trait2.rs
new file mode 100644
index 00000000000..1f47b5ba46e
--- /dev/null
+++ b/src/test/ui/coherence/coherence-overlap-negative-trait2.rs
@@ -0,0 +1,18 @@
+// check-pass
+// aux-build:option_future.rs
+//
+// Check that if we promise to not impl what would overlap it doesn't actually overlap
+
+#![feature(rustc_attrs)]
+
+extern crate option_future as lib;
+use lib::Future;
+
+trait Termination {}
+
+#[rustc_with_negative_coherence]
+impl<E> Termination for Option<E> where E: Sized {}
+#[rustc_with_negative_coherence]
+impl<F> Termination for F where F: Future + Sized {}
+
+fn main() {}