From f7ceb1a8862495b343acc26260eb314ed088b49f Mon Sep 17 00:00:00 2001
From: Mark Rousskov <mark.simulacrum@gmail.com>
Date: Tue, 21 Apr 2020 13:37:18 -0400
Subject: [PATCH] Error on casting floats to integers

This is intended for a crater run to know the total (worst case) extent of
slowdowns introduced by changing the behavior here.
---
 src/librustc_typeck/check/cast.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/librustc_typeck/check/cast.rs b/src/librustc_typeck/check/cast.rs
index 981e6d2c47eef..fed9755bc3b24 100644
--- a/src/librustc_typeck/check/cast.rs
+++ b/src/librustc_typeck/check/cast.rs
@@ -613,6 +613,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
             (Int(CEnum), Int(_)) => Ok(CastKind::EnumCast),
             (Int(Char) | Int(Bool), Int(_)) => Ok(CastKind::PrimIntCast),
 
+            (Float, Int(_)) if std::env::var_os("RUSTC_BOOTSTRAP").is_none() => Err(CastError::IllegalCast),
             (Int(_) | Float, Int(_) | Float) => Ok(CastKind::NumericCast),
         }
     }