From c8c3579bffaeb29b1feae286e06d792293e10287 Mon Sep 17 00:00:00 2001
From: Austin Hicks <camlorn@camlorn.net>
Date: Wed, 23 Nov 2016 14:48:31 -0500
Subject: [PATCH] Fix closure arguments which are immediate because of field
 reordering.

While building immediates goes through type_of::type_of, extracting them must account for field reorderings.
---
 src/librustc_trans/mir/block.rs        | 10 ++++++++--
 src/test/run-pass/closure-immediate.rs | 22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 src/test/run-pass/closure-immediate.rs

diff --git a/src/librustc_trans/mir/block.rs b/src/librustc_trans/mir/block.rs
index 76f5f32b5dc..fe087bc4951 100644
--- a/src/librustc_trans/mir/block.rs
+++ b/src/librustc_trans/mir/block.rs
@@ -11,7 +11,7 @@
 use llvm::{self, ValueRef};
 use rustc_const_eval::{ErrKind, ConstEvalErr, note_const_eval_err};
 use rustc::middle::lang_items;
-use rustc::ty;
+use rustc::ty::{self, layout};
 use rustc::mir;
 use abi::{Abi, FnType, ArgType};
 use adt;
@@ -722,8 +722,14 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
 
             }
             Immediate(llval) => {
+                let l = bcx.ccx().layout_of(tuple.ty);
+                let v = if let layout::Univariant { ref variant, .. } = *l {
+                    variant
+                } else {
+                    bug!("Not a tuple.");
+                };
                 for (n, &ty) in arg_types.iter().enumerate() {
-                    let mut elem = bcx.extract_value(llval, n);
+                    let mut elem = bcx.extract_value(llval, v.memory_index[n] as usize);
                     // Truncate bools to i1, if needed
                     if ty.is_bool() && common::val_ty(elem) != Type::i1(bcx.ccx()) {
                         elem = bcx.trunc(elem, Type::i1(bcx.ccx()));
diff --git a/src/test/run-pass/closure-immediate.rs b/src/test/run-pass/closure-immediate.rs
new file mode 100644
index 00000000000..69aa16c3fb5
--- /dev/null
+++ b/src/test/run-pass/closure-immediate.rs
@@ -0,0 +1,22 @@
+// Copyright 2012 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.
+
+
+// After the work to reoptimize structs, it became possible for immediate logic to fail.
+// This test verifies that it actually works.
+
+fn main() {
+    let c = |a: u8, b: u16, c: u8| {
+        assert_eq!(a, 1);
+        assert_eq!(b, 2);
+        assert_eq!(c, 3);
+    };
+    c(1, 2, 3);
+}
\ No newline at end of file