test post-monomorphization const errors

Author: RalfJung

src/diagnostics.rs

@@ -88,6 +88,8 @@ pub fn report_error<'tcx, 'mir>(
                     "Undefined Behavior",
                 ResourceExhaustion(_) =>
                     "resource exhaustion",
+                InvalidProgram(InvalidProgramInfo::ReferencedConstant) =>
+                    "post-monomorphization error",
                 _ =>
                     bug!("This error should be impossible in Miri: {}", e),
             };

tests/compile-fail/erroneous_const.rs

@@ -0,0 +1,18 @@
+// compile-flags: -Zmir-opt-level=3
+//! Make sure we detect erroneous constants post-monomorphization even when they are optimized away.
+//! (https://github.com/rust-lang/miri/issues/1382)
+#![feature(const_panic)]
+#![feature(never_type)]
+#![warn(const_err)]
+
+struct PrintName<T>(T);
+impl<T> PrintName<T> {
+    const VOID: ! = panic!(); //~WARN any use of this value will cause an error
+}
+
+fn no_codegen<T>() {
+    let _ = PrintName::<T>::VOID; //~ERROR referenced constant has errors
+}
+fn main() {
+    no_codegen::<i32>();
+}