From 973756d715f9caaeee44e9387f5c60458ae5c4fc Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <edy.burt@gmail.com>
Date: Wed, 31 Jan 2018 00:23:25 +0200
Subject: [PATCH] rustc_trans: keep LLVM types for trait objects anonymous.

---
 src/librustc_trans/type_of.rs          |  4 +++-
 src/test/codegen/function-arguments.rs |  4 ++--
 src/test/run-pass/issue-47638.rs       | 18 ++++++++++++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 src/test/run-pass/issue-47638.rs

diff --git a/src/librustc_trans/type_of.rs b/src/librustc_trans/type_of.rs
index b1533cfad19..af957500f70 100644
--- a/src/librustc_trans/type_of.rs
+++ b/src/librustc_trans/type_of.rs
@@ -57,7 +57,9 @@ fn uncached_llvm_type<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
         ty::TyClosure(..) |
         ty::TyGenerator(..) |
         ty::TyAdt(..) |
-        ty::TyDynamic(..) |
+        // FIXME(eddyb) producing readable type names for trait objects can result
+        // in problematically distinct types due to HRTB and subtyping (see #47638).
+        // ty::TyDynamic(..) |
         ty::TyForeign(..) |
         ty::TyStr => {
             let mut name = String::with_capacity(32);
diff --git a/src/test/codegen/function-arguments.rs b/src/test/codegen/function-arguments.rs
index f8945a6ee8d..0e98d3f9050 100644
--- a/src/test/codegen/function-arguments.rs
+++ b/src/test/codegen/function-arguments.rs
@@ -122,13 +122,13 @@ pub fn unsafe_slice(_: &[UnsafeInner]) {
 pub fn str(_: &[u8]) {
 }
 
-// CHECK: @trait_borrow(%"core::ops::drop::Drop"* nonnull %arg0.0, {}* noalias nonnull readonly %arg0.1)
+// CHECK: @trait_borrow({}* nonnull %arg0.0, {}* noalias nonnull readonly %arg0.1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn trait_borrow(_: &Drop) {
 }
 
-// CHECK: @trait_box(%"core::ops::drop::Drop"* noalias nonnull, {}* noalias nonnull readonly)
+// CHECK: @trait_box({}* noalias nonnull, {}* noalias nonnull readonly)
 #[no_mangle]
 pub fn trait_box(_: Box<Drop>) {
 }
diff --git a/src/test/run-pass/issue-47638.rs b/src/test/run-pass/issue-47638.rs
new file mode 100644
index 00000000000..6f627b2a3c1
--- /dev/null
+++ b/src/test/run-pass/issue-47638.rs
@@ -0,0 +1,18 @@
+// Copyright 2018 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.
+
+fn id<'c, 'b>(f: &'c &'b Fn(&i32)) -> &'c &'b Fn(&'static i32) {
+    f
+}
+
+fn main() {
+    let f: &Fn(&i32) = &|x| {};
+    id(&f);
+}