Add broken MIR regression tests

src/test/ui/const-generics/broken-mir-1.rs

@@ -0,0 +1,17 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+pub trait Foo {
+    fn foo(&self);
+}
+
+
+impl<T, const N: usize> Foo for [T; N] {
+    fn foo(&self) {
+        let _ = &self;
+    }
+}
+
+fn main() {}

src/test/ui/const-generics/broken-mir-1.stderr

@@ -0,0 +1,6 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/broken-mir-1.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+

src/test/ui/const-generics/broken-mir-2.rs

@@ -0,0 +1,9 @@
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+use std::fmt::Debug;
+
+#[derive(Debug)]
+struct S<T: Debug, const N: usize>([T; N]); //~ ERROR `[T; N]` doesn't implement `std::fmt::Debug`
+
+fn main() {}

src/test/ui/const-generics/broken-mir-2.stderr

@@ -0,0 +1,19 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/broken-mir-2.rs:1:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+
+error[E0277]: `[T; N]` doesn't implement `std::fmt::Debug`
+  --> $DIR/broken-mir-2.rs:7:36
+   |
+LL | struct S<T: Debug, const N: usize>([T; N]);
+   |                                    ^^^^^^ `[T; N]` cannot be formatted using `{:?}` because it doesn't implement `std::fmt::Debug`
+   |
+   = help: the trait `std::fmt::Debug` is not implemented for `[T; N]`
+   = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[T; N]`
+   = note: required for the cast to the object type `dyn std::fmt::Debug`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.