Add rustc_strict_coherence attribute and use it to check overlap

3 files changed, 49 insertions, 0 deletions

diff --git a/src/test/ui/coherence/coherence-overlap-negate-alias-strict.rs b/src/test/ui/coherence/coherence-overlap-negate-alias-strict.rs
new file mode 100644
index 00000000000..16ace450b06
--- /dev/null
+++ b/src/test/ui/coherence/coherence-overlap-negate-alias-strict.rs
@@ -0,0 +1,19 @@
+#![feature(negative_impls)]
+#![feature(rustc_attrs)]
+#![feature(trait_alias)]
+
+trait A {}
+trait B {}
+trait AB = A + B;
+
+impl !A for u32 {}
+
+trait C {}
+#[rustc_strict_coherence]
+impl<T: AB> C for T {}
+#[rustc_strict_coherence]
+impl C for u32 {}
+//~^ ERROR: conflicting implementations of trait `C` for type `u32` [E0119]
+// FIXME this should work, we should implement an `assemble_neg_candidates` fn
+
+fn main() {}
diff --git a/src/test/ui/coherence/coherence-overlap-negate-alias-strict.stderr b/src/test/ui/coherence/coherence-overlap-negate-alias-strict.stderr
new file mode 100644
index 00000000000..5e436223119
--- /dev/null
+++ b/src/test/ui/coherence/coherence-overlap-negate-alias-strict.stderr
@@ -0,0 +1,12 @@
+error[E0119]: conflicting implementations of trait `C` for type `u32`
+  --> $DIR/coherence-overlap-negate-alias-strict.rs:15:1
+   |
+LL | impl<T: AB> C for T {}
+   | ------------------- first implementation here
+LL | #[rustc_strict_coherence]
+LL | impl C for u32 {}
+   | ^^^^^^^^^^^^^^ conflicting implementation for `u32`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0119`.
diff --git a/src/test/ui/coherence/coherence-overlap-negate-strict.rs b/src/test/ui/coherence/coherence-overlap-negate-strict.rs
new file mode 100644
index 00000000000..b3ae9a7bf78
--- /dev/null
+++ b/src/test/ui/coherence/coherence-overlap-negate-strict.rs
@@ -0,0 +1,18 @@
+// check-pass
+
+#![feature(negative_impls)]
+#![feature(rustc_attrs)]
+#![feature(trait_alias)]
+
+trait A {}
+trait B {}
+
+impl !A for u32 {}
+
+trait C {}
+#[rustc_strict_coherence]
+impl<T: A + B> C for T {}
+#[rustc_strict_coherence]
+impl C for u32 {}
+
+fn main() {}