1 files changed, 28 insertions, 0 deletions
diff --git a/src/test/ui/coherence/const-generics-orphan-check-ok.rs b/src/test/ui/coherence/const-generics-orphan-check-ok.rs
new file mode 100644
index 000000000..217e8aed2
--- /dev/null
+++ b/src/test/ui/coherence/const-generics-orphan-check-ok.rs
@@ -0,0 +1,28 @@
+// check-pass
+// aux-build:trait-with-const-param.rs
+extern crate trait_with_const_param;
+use trait_with_const_param::*;
+
+// Trivial case, const param after local type.
+struct Local1;
+impl<const N: usize, T> Trait<N, T> for Local1 {}
+
+// Concrete consts behave the same as foreign types,
+// so this also trivially works.
+impl Trait<3, Local1> for i32 {}
+
+// This case isn't as trivial as we would forbid type
+// parameters here, we do allow const parameters though.
+//
+// The reason that type parameters are forbidden for
+// `impl<T> Trait<T, LocalInA> for i32 {}` is that another
+// downstream crate can add `impl<T> Trait<LocalInB, T> for i32`.
+// As these two impls would overlap we forbid any impls which
+// have a type parameter in front of a local type.
+//
+// With const parameters this issue does not exist as there are no
+// constants local to another downstream crate.
+struct Local2;
+impl<const N: usize> Trait<N, Local2> for i32 {}
+
+fn main() {}