Don't ICE on placeholder consts in deep reject

2 files changed, 37 insertions, 0 deletions

diff --git a/tests/ui/traits/new-solver/const-param-placeholder.fail.stderr b/tests/ui/traits/new-solver/const-param-placeholder.fail.stderr
new file mode 100644
index 00000000000..4db6e22e57f
--- /dev/null
+++ b/tests/ui/traits/new-solver/const-param-placeholder.fail.stderr
@@ -0,0 +1,16 @@
+error[E0277]: the trait bound `[T; N]: Foo` is not satisfied
+  --> $DIR/const-param-placeholder.rs:17:17
+   |
+LL |     needs_foo::<[T; N]>();
+   |                 ^^^^^^ the trait `Foo` is not implemented for `[T; N]`
+   |
+   = help: the trait `Foo` is implemented for `[T; 1]`
+note: required by a bound in `needs_foo`
+  --> $DIR/const-param-placeholder.rs:8:17
+   |
+LL | fn needs_foo<F: Foo>() {}
+   |                 ^^^ required by this bound in `needs_foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/traits/new-solver/const-param-placeholder.rs b/tests/ui/traits/new-solver/const-param-placeholder.rs
new file mode 100644
index 00000000000..a83102a4cdd
--- /dev/null
+++ b/tests/ui/traits/new-solver/const-param-placeholder.rs
@@ -0,0 +1,21 @@
+// compile-flags: -Ztrait-solver=next
+// revisions: pass fail
+//[pass] check-pass
+
+struct Wrapper<T, const N: usize>([T; N]);
+
+trait Foo {}
+fn needs_foo<F: Foo>() {}
+
+#[cfg(fail)]
+impl<T> Foo for [T; 1] {}
+
+#[cfg(pass)]
+impl<T, const N: usize> Foo for [T; N] {}
+
+fn test<T, const N: usize>() {
+    needs_foo::<[T; N]>();
+    //[fail]~^ ERROR the trait bound `[T; N]: Foo` is not satisfied
+}
+
+fn main() {}