From 8289bf2994cc0522616275594cd2bd1a8d10d4b4 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Thu, 21 Jun 2018 14:32:52 -0400
Subject: [PATCH] use `pat_ty_adjusted` from `expr_use_visitor` to type of
 arguments

---
 src/librustc/middle/expr_use_visitor.rs     |  3 ++-
 src/librustc/middle/mem_categorization.rs   |  2 +-
 src/test/ui/borrowck/issue-51415.nll.stderr |  9 +++++++++
 src/test/ui/borrowck/issue-51415.rs         | 21 +++++++++++++++++++++
 src/test/ui/borrowck/issue-51415.stderr     | 12 ++++++++++++
 5 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 src/test/ui/borrowck/issue-51415.nll.stderr
 create mode 100644 src/test/ui/borrowck/issue-51415.rs
 create mode 100644 src/test/ui/borrowck/issue-51415.stderr

diff --git a/src/librustc/middle/expr_use_visitor.rs b/src/librustc/middle/expr_use_visitor.rs
index 9fb7d31ed6f75..8ef45a966da85 100644
--- a/src/librustc/middle/expr_use_visitor.rs
+++ b/src/librustc/middle/expr_use_visitor.rs
@@ -313,7 +313,8 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
         debug!("consume_body(body={:?})", body);
 
         for arg in &body.arguments {
-            let arg_ty = return_if_err!(self.mc.node_ty(arg.pat.hir_id));
+            let arg_ty = return_if_err!(self.mc.pat_ty_adjusted(&arg.pat));
+            debug!("consume_body: arg_ty = {:?}", arg_ty);
 
             let fn_body_scope_r =
                 self.tcx().mk_region(ty::ReScope(region::Scope::Node(body.value.hir_id.local_id)));
diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs
index 2d3140a943b1c..597872ef45de0 100644
--- a/src/librustc/middle/mem_categorization.rs
+++ b/src/librustc/middle/mem_categorization.rs
@@ -517,7 +517,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
     ///   implicit deref patterns attached (e.g., it is really
     ///   `&Some(x)`). In that case, we return the "outermost" type
     ///   (e.g., `&Option<T>).
-    fn pat_ty_adjusted(&self, pat: &hir::Pat) -> McResult<Ty<'tcx>> {
+    pub fn pat_ty_adjusted(&self, pat: &hir::Pat) -> McResult<Ty<'tcx>> {
         // Check for implicit `&` types wrapping the pattern; note
         // that these are never attached to binding patterns, so
         // actually this is somewhat "disjoint" from the code below
diff --git a/src/test/ui/borrowck/issue-51415.nll.stderr b/src/test/ui/borrowck/issue-51415.nll.stderr
new file mode 100644
index 0000000000000..79454b635263c
--- /dev/null
+++ b/src/test/ui/borrowck/issue-51415.nll.stderr
@@ -0,0 +1,9 @@
+error[E0507]: cannot move out of borrowed content
+  --> $DIR/issue-51415.rs:16:47
+   |
+LL |     let opt = a.iter().enumerate().find(|(_, &s)| {
+   |                                               ^ cannot move out of borrowed content
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0507`.
diff --git a/src/test/ui/borrowck/issue-51415.rs b/src/test/ui/borrowck/issue-51415.rs
new file mode 100644
index 0000000000000..9067a50a8476d
--- /dev/null
+++ b/src/test/ui/borrowck/issue-51415.rs
@@ -0,0 +1,21 @@
+// Copyright 2014 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.
+
+// Regression test for #51415: match default bindings were failing to
+// see the "move out" implied by `&s` below.
+
+fn main() {
+    let a = vec![String::from("a")];
+    let opt = a.iter().enumerate().find(|(_, &s)| {
+        //~^ ERROR cannot move out
+        *s == String::from("d")
+    }).map(|(i, _)| i);
+    println!("{:?}", opt);
+}
diff --git a/src/test/ui/borrowck/issue-51415.stderr b/src/test/ui/borrowck/issue-51415.stderr
new file mode 100644
index 0000000000000..b4b0bc7594305
--- /dev/null
+++ b/src/test/ui/borrowck/issue-51415.stderr
@@ -0,0 +1,12 @@
+error[E0507]: cannot move out of borrowed content
+  --> $DIR/issue-51415.rs:16:46
+   |
+LL |     let opt = a.iter().enumerate().find(|(_, &s)| {
+   |                                              ^-
+   |                                              ||
+   |                                              |hint: to prevent move, use `ref s` or `ref mut s`
+   |                                              cannot move out of borrowed content
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0507`.