From ecce274e56e1da80dff66f9d8886c7645f129244 Mon Sep 17 00:00:00 2001
From: cjkenn <cam.j.kennedy@gmail.com>
Date: Wed, 16 May 2018 20:02:01 -0700
Subject: [PATCH 1/2] use if let to avoid potential div by zero

remove semicolon -_-

Add rem_bytes to conditional to avoid error when performing mod by 0

Add test file to confirm compilation passes.

Ensure we don't divide or mod by zero in llvm_type. Include test file from issue.
---
 src/librustc_codegen_llvm/abi.rs |  8 ++++++--
 src/test/ui/issue-50761.rs       | 35 ++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 src/test/ui/issue-50761.rs

diff --git a/src/librustc_codegen_llvm/abi.rs b/src/librustc_codegen_llvm/abi.rs
index 25c598c532c..221012903d9 100644
--- a/src/librustc_codegen_llvm/abi.rs
+++ b/src/librustc_codegen_llvm/abi.rs
@@ -127,8 +127,12 @@ impl LlvmType for Reg {
 impl LlvmType for CastTarget {
     fn llvm_type(&self, cx: &CodegenCx) -> Type {
         let rest_ll_unit = self.rest.unit.llvm_type(cx);
-        let rest_count = self.rest.total.bytes() / self.rest.unit.size.bytes();
-        let rem_bytes = self.rest.total.bytes() % self.rest.unit.size.bytes();
+        let (rest_count, rem_bytes) = if self.rest.unit.size.bytes() == 0 {
+            (0, 0)
+        } else {
+            (self.rest.total.bytes() / self.rest.unit.size.bytes(),
+            self.rest.total.bytes() % self.rest.unit.size.bytes())
+        };
 
         if self.prefix.iter().all(|x| x.is_none()) {
             // Simplify to a single unit when there is no prefix and size <= unit size
diff --git a/src/test/ui/issue-50761.rs b/src/test/ui/issue-50761.rs
new file mode 100644
index 00000000000..534d483dc42
--- /dev/null
+++ b/src/test/ui/issue-50761.rs
@@ -0,0 +1,35 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Confirm that we don't accidently divide or mod by zero in llvm_type
+
+// compile-pass
+
+#![feature(test)]
+
+mod a {
+    pub trait A {}
+}
+
+mod b {
+    pub struct Builder {}
+
+    pub fn new() -> Builder {
+        Builder {}
+    }
+
+    impl Builder {
+        pub fn with_a(&mut self, _a: fn() -> ::a::A) {}
+    }
+}
+
+pub use self::b::new;
+
+fn main() {}

From 8d9a87c14d9c5abe433444a641282ae1afb0577d Mon Sep 17 00:00:00 2001
From: cjkenn <cam.j.kennedy@gmail.com>
Date: Sat, 19 May 2018 13:01:28 -0700
Subject: [PATCH 2/2] remove feature line from test

---
 src/test/ui/issue-50761.rs | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/test/ui/issue-50761.rs b/src/test/ui/issue-50761.rs
index 534d483dc42..b8a7a089c23 100644
--- a/src/test/ui/issue-50761.rs
+++ b/src/test/ui/issue-50761.rs
@@ -12,8 +12,6 @@
 
 // compile-pass
 
-#![feature(test)]
-
 mod a {
     pub trait A {}
 }