Auto merge of #2107 - RalfJung:err, r=RalfJung

test for "erroneous constant used" post-monomorphization error

Fixes #2106

Author: bors

src/diagnostics.rs

@@ -182,7 +182,11 @@ pub fn report_error<'tcx, 'mir>(
                     "Undefined Behavior",
                 ResourceExhaustion(_) =>
                     "resource exhaustion",
-                InvalidProgram(InvalidProgramInfo::AlreadyReported(_) | InvalidProgramInfo::Layout(..)) =>
+                InvalidProgram(
+                    InvalidProgramInfo::AlreadyReported(_) |
+                    InvalidProgramInfo::Layout(..) |
+                    InvalidProgramInfo::ReferencedConstant
+                ) =>
                     "post-monomorphization error",
                 kind =>
                     bug!("This error should be impossible in Miri: {:?}", kind),

tests/compile-fail/erroneous_const2.rs

@@ -0,0 +1,12 @@
+const X: u32 = 5;
+const Y: u32 = 6;
+const FOO: u32 = [X - Y, Y - X][(X < Y) as usize];
+//~^ERROR any use of this value
+//~|WARN previously accepted
+
+fn main() {
+    println!("{}", FOO); //~ERROR post-monomorphization error
+    //~|ERROR evaluation of constant value failed
+    //~|ERROR erroneous constant used
+    //~|WARN previously accepted
+}