From d3e88a58b9fad8c68e19c7603ec2725ee26bac29 Mon Sep 17 00:00:00 2001
From: flip1995 <hello@philkrones.com>
Date: Wed, 6 Nov 2019 18:14:47 +0100
Subject: [PATCH 1/2] Fix ICE #4775

---
 clippy_lints/src/loops.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index 731dd92c82a..805e609cea6 100644
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -1993,7 +1993,13 @@ fn is_ref_iterable_type(cx: &LateContext<'_, '_>, e: &Expr) -> bool {
 fn is_iterable_array<'tcx>(ty: Ty<'tcx>, cx: &LateContext<'_, 'tcx>) -> bool {
     // IntoIterator is currently only implemented for array sizes <= 32 in rustc
     match ty.kind {
-        ty::Array(_, n) => (0..=32).contains(&n.eval_usize(cx.tcx, cx.param_env)),
+        ty::Array(_, n) => {
+            if let Some(val) = n.try_eval_usize(cx.tcx, cx.param_env) {
+                (0..=32).contains(&val)
+            } else {
+                false
+            }
+        },
         _ => false,
     }
 }

From 073dbd42182febdf35f5193e891c4e24722dbca9 Mon Sep 17 00:00:00 2001
From: flip1995 <hello@philkrones.com>
Date: Wed, 6 Nov 2019 18:15:04 +0100
Subject: [PATCH 2/2] Add regression test for ICE #4775

---
 tests/ui/ice-4775.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 tests/ui/ice-4775.rs

diff --git a/tests/ui/ice-4775.rs b/tests/ui/ice-4775.rs
new file mode 100644
index 00000000000..31e53e846d5
--- /dev/null
+++ b/tests/ui/ice-4775.rs
@@ -0,0 +1,14 @@
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+
+pub struct ArrayWrapper<const N: usize>([usize; N]);
+
+impl<const N: usize> ArrayWrapper<{ N }> {
+    pub fn ice(&self) {
+        for i in self.0.iter() {
+            println!("{}", i);
+        }
+    }
+}
+
+fn main() {}