From 846042161c17bcc696715b3dfe2e6c4970da0b34 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Tue, 2 Jan 2018 15:25:53 -0800
Subject: [PATCH 1/6] Custom error when moving arg outside of its closure

When given the following code:

```rust
fn give_any<F: for<'r> FnOnce(&'r ())>(f: F) {
    f(&());
}

fn main() {
    let mut x = None;
    give_any(|y| x = Some(y));
}
```

provide a custom error:

```
error: borrowed data cannot be moved outside of its closure
 --> file.rs:7:27
  |
6 |     let mut x = None;
  |         ----- binding declared outside of closure
7 |     give_any(|y| x = Some(y));
  |              ---          ^ cannot be assigned to binding outside of its closure
  |              |
  |              closure you can't escape
```

instead of the generic lifetime error:

```
error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
 --> file.rs:7:27
  |
7 |     give_any(|y| x = Some(y));
  |                           ^
  |
note: first, the lifetime cannot outlive the anonymous lifetime #2 defined on the body at 7:14...
 --> file.rs:7:14
  |
7 |     give_any(|y| x = Some(y));
  |              ^^^^^^^^^^^^^^^
note: ...so that expression is assignable (expected &(), found &())
 --> file.rs:7:27
  |
7 |     give_any(|y| x = Some(y));
  |                           ^
note: but, the lifetime must be valid for the block suffix following statement 0 at 6:5...
 --> file.rs:6:5
  |
6 | /     let mut x = None;
7 | |     give_any(|y| x = Some(y));
8 | | }
  | |_^
note: ...so that variable is valid at time of its declaration
 --> file.rs:6:9
  |
6 |     let mut x = None;
  |         ^^^^^
```
---
 src/librustc/infer/error_reporting/mod.rs     | 36 ++++++++++++++++++-
 .../compile-fail/regions-escape-bound-fn-2.rs |  2 +-
 src/test/ui/borrowck/issue-45983.rs           | 19 ++++++++++
 src/test/ui/borrowck/issue-45983.stderr       | 12 +++++++
 4 files changed, 67 insertions(+), 2 deletions(-)
 create mode 100644 src/test/ui/borrowck/issue-45983.rs
 create mode 100644 src/test/ui/borrowck/issue-45983.stderr

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index c477a0d383e21..3cd7c5e0af3ee 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -66,7 +66,7 @@ use hir::map as hir_map;
 use hir::def_id::DefId;
 use middle::region;
 use traits::{ObligationCause, ObligationCauseCode};
-use ty::{self, Region, Ty, TyCtxt, TypeFoldable, TypeVariants};
+use ty::{self, Region, RegionKind, Ty, TyCtxt, TypeFoldable, TypeVariants};
 use ty::error::TypeError;
 use syntax::ast::DUMMY_NODE_ID;
 use syntax_pos::{Pos, Span};
@@ -1067,6 +1067,40 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                                sub_region: Region<'tcx>,
                                sup_origin: SubregionOrigin<'tcx>,
                                sup_region: Region<'tcx>) {
+
+        // #45983: when trying to assign the contents of an argument to a binding outside of a
+        // closure, provide a specific message pointing this out.
+        if let (&SubregionOrigin::BindingTypeIsNotValidAtDecl(ref external_span),
+                &SubregionOrigin::Subtype(TypeTrace { ref cause, .. }),
+                &RegionKind::ReFree(ref free_region)) = (&sub_origin, &sup_origin, sup_region) {
+            let hir = &self.tcx.hir;
+            if let Some(node_id) = hir.as_local_node_id(free_region.scope) {
+                match hir.get(node_id) {
+                    hir_map::NodeExpr(hir::Expr {
+                        node: hir::ExprClosure(_, _, _, closure_span, false),
+                        ..
+                    }) => {
+                        let sp = var_origin.span();
+                        let mut err = self.tcx.sess.struct_span_err(
+                            sp,
+                            "borrowed data cannot be moved outside of its closure");
+                        let label = match cause.code {
+                            ObligationCauseCode::ExprAssignable => {
+                                "cannot be assigned to binding outside of its closure"
+                            }
+                            _ => "cannot be moved outside of its closure",
+                        };
+                        err.span_label(sp, label);
+                        err.span_label(*closure_span, "closure you can't escape");
+                        err.span_label(*external_span, "binding declared outside of closure");
+                        err.emit();
+                        return;
+                    }
+                    _ => {}
+                }
+            }
+        }
+
         let mut err = self.report_inference_failure(var_origin);
 
         self.tcx.note_and_explain_region(region_scope_tree, &mut err,
diff --git a/src/test/compile-fail/regions-escape-bound-fn-2.rs b/src/test/compile-fail/regions-escape-bound-fn-2.rs
index 1329d05a0f690..042c55eed866e 100644
--- a/src/test/compile-fail/regions-escape-bound-fn-2.rs
+++ b/src/test/compile-fail/regions-escape-bound-fn-2.rs
@@ -16,5 +16,5 @@ fn with_int<F>(f: F) where F: FnOnce(&isize) {
 fn main() {
     let mut x = None;
     with_int(|y| x = Some(y));
-         //~^ ERROR cannot infer
+         //~^ ERROR borrowed data cannot be moved outside of its closure
 }
diff --git a/src/test/ui/borrowck/issue-45983.rs b/src/test/ui/borrowck/issue-45983.rs
new file mode 100644
index 0000000000000..b2316a6b61c81
--- /dev/null
+++ b/src/test/ui/borrowck/issue-45983.rs
@@ -0,0 +1,19 @@
+// 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 give_any<F: for<'r> FnOnce(&'r ())>(f: F) {
+    f(&());
+}
+
+fn main() {
+    let x = None;
+    give_any(|y| x = Some(y));
+    //~^ ERROR borrowed data cannot be moved outside of its closure
+}
diff --git a/src/test/ui/borrowck/issue-45983.stderr b/src/test/ui/borrowck/issue-45983.stderr
new file mode 100644
index 0000000000000..689fe6053c9a9
--- /dev/null
+++ b/src/test/ui/borrowck/issue-45983.stderr
@@ -0,0 +1,12 @@
+error: borrowed data cannot be moved outside of its closure
+  --> $DIR/issue-45983.rs:17:27
+   |
+16 |     let x = None;
+   |         - binding declared outside of closure
+17 |     give_any(|y| x = Some(y));
+   |              ---          ^ cannot be assigned to binding outside of its closure
+   |              |
+   |              closure you can't escape
+
+error: aborting due to previous error
+

From c31c60cbb9ceb75402240bfe1adc9c2b48a29aa0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Wed, 3 Jan 2018 14:22:38 -0800
Subject: [PATCH 2/6] Reword diagnostic

---
 src/librustc/infer/error_reporting/mod.rs | 16 ++++++----------
 src/test/ui/borrowck/issue-45983.stderr   |  6 +++---
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index 3cd7c5e0af3ee..cdb90c7ba7e96 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -1071,7 +1071,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         // #45983: when trying to assign the contents of an argument to a binding outside of a
         // closure, provide a specific message pointing this out.
         if let (&SubregionOrigin::BindingTypeIsNotValidAtDecl(ref external_span),
-                &SubregionOrigin::Subtype(TypeTrace { ref cause, .. }),
+                &SubregionOrigin::Subtype(_),
                 &RegionKind::ReFree(ref free_region)) = (&sub_origin, &sup_origin, sup_region) {
             let hir = &self.tcx.hir;
             if let Some(node_id) = hir.as_local_node_id(free_region.scope) {
@@ -1084,15 +1084,11 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         let mut err = self.tcx.sess.struct_span_err(
                             sp,
                             "borrowed data cannot be moved outside of its closure");
-                        let label = match cause.code {
-                            ObligationCauseCode::ExprAssignable => {
-                                "cannot be assigned to binding outside of its closure"
-                            }
-                            _ => "cannot be moved outside of its closure",
-                        };
-                        err.span_label(sp, label);
-                        err.span_label(*closure_span, "closure you can't escape");
-                        err.span_label(*external_span, "binding declared outside of closure");
+                        err.span_label(sp, "cannot be moved outside of its closure");
+                        err.span_label(*external_span,
+                                       "borrowed data cannot be moved into here...");
+                        err.span_label(*closure_span,
+                                       "...because it cannot outlive this closure");
                         err.emit();
                         return;
                     }
diff --git a/src/test/ui/borrowck/issue-45983.stderr b/src/test/ui/borrowck/issue-45983.stderr
index 689fe6053c9a9..cbc4a557be9ef 100644
--- a/src/test/ui/borrowck/issue-45983.stderr
+++ b/src/test/ui/borrowck/issue-45983.stderr
@@ -2,11 +2,11 @@ error: borrowed data cannot be moved outside of its closure
   --> $DIR/issue-45983.rs:17:27
    |
 16 |     let x = None;
-   |         - binding declared outside of closure
+   |         - borrowed data cannot be moved into here...
 17 |     give_any(|y| x = Some(y));
-   |              ---          ^ cannot be assigned to binding outside of its closure
+   |              ---          ^ cannot be moved outside of its closure
    |              |
-   |              closure you can't escape
+   |              ...because it cannot outlive this closure
 
 error: aborting due to previous error
 

From 2c5f2df201c65bbea0c0d3abe1190049093eb7b6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Wed, 3 Jan 2018 15:54:33 -0800
Subject: [PATCH 3/6] Generalize cases where specific move error ocurrs

Trigger new diagnostic in `compile-fail/regions-escape-bound-fn.rs`
test, and not only in `compile-fail/regions-escape-bound-fn-2.rs`.
---
 src/librustc/infer/error_reporting/mod.rs                   | 3 +--
 .../closure-expected-type/expect-region-supply-region.rs    | 6 +++---
 src/test/compile-fail/issue-7573.rs                         | 3 ++-
 src/test/compile-fail/regions-escape-bound-fn-2.rs          | 2 +-
 src/test/compile-fail/regions-escape-bound-fn.rs            | 3 ++-
 src/test/compile-fail/regions-escape-unboxed-closure.rs     | 3 ++-
 6 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index cdb90c7ba7e96..645c8403b8e44 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -1071,8 +1071,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         // #45983: when trying to assign the contents of an argument to a binding outside of a
         // closure, provide a specific message pointing this out.
         if let (&SubregionOrigin::BindingTypeIsNotValidAtDecl(ref external_span),
-                &SubregionOrigin::Subtype(_),
-                &RegionKind::ReFree(ref free_region)) = (&sub_origin, &sup_origin, sup_region) {
+                &RegionKind::ReFree(ref free_region)) = (&sub_origin, sup_region) {
             let hir = &self.tcx.hir;
             if let Some(node_id) = hir.as_local_node_id(free_region.scope) {
                 match hir.get(node_id) {
diff --git a/src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs b/src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs
index 9da12dc901fba..678647ff28da5 100644
--- a/src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs
+++ b/src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs
@@ -25,7 +25,7 @@ fn expect_bound_supply_nothing() {
     // it to escape into `f`:
     let mut f: Option<&u32> = None;
     closure_expecting_bound(|x| {
-        f = Some(x); //~ ERROR E0495
+        f = Some(x); //~ ERROR borrowed data cannot be moved outside of its closure
     });
 }
 
@@ -35,7 +35,7 @@ fn expect_bound_supply_bound() {
     // closure:
     let mut f: Option<&u32> = None;
     closure_expecting_bound(|x: &u32| {
-        f = Some(x); //~ ERROR E0495
+        f = Some(x); //~ ERROR borrowed data cannot be moved outside of its closure
     });
 }
 
@@ -50,7 +50,7 @@ fn expect_bound_supply_named<'x>() {
 
         // And we still cannot let `x` escape into `f`.
         f = Some(x);
-        //~^ ERROR cannot infer
+        //~^ ERROR borrowed data cannot be moved outside of its closure
     });
 }
 
diff --git a/src/test/compile-fail/issue-7573.rs b/src/test/compile-fail/issue-7573.rs
index d13da1d9fd948..7445501c4ebe6 100644
--- a/src/test/compile-fail/issue-7573.rs
+++ b/src/test/compile-fail/issue-7573.rs
@@ -24,7 +24,8 @@ impl CrateId {
 }
 
 pub fn remove_package_from_database() {
-    let mut lines_to_use: Vec<&CrateId> = Vec::new(); //~ ERROR E0495
+    let mut lines_to_use: Vec<&CrateId> = Vec::new();
+    //~^ ERROR borrowed data cannot be moved outside of its closure
     let push_id = |installed_id: &CrateId| {
         lines_to_use.push(installed_id);
     };
diff --git a/src/test/compile-fail/regions-escape-bound-fn-2.rs b/src/test/compile-fail/regions-escape-bound-fn-2.rs
index 042c55eed866e..df07aec998a3b 100644
--- a/src/test/compile-fail/regions-escape-bound-fn-2.rs
+++ b/src/test/compile-fail/regions-escape-bound-fn-2.rs
@@ -16,5 +16,5 @@ fn with_int<F>(f: F) where F: FnOnce(&isize) {
 fn main() {
     let mut x = None;
     with_int(|y| x = Some(y));
-         //~^ ERROR borrowed data cannot be moved outside of its closure
+    //~^ ERROR borrowed data cannot be moved outside of its closure
 }
diff --git a/src/test/compile-fail/regions-escape-bound-fn.rs b/src/test/compile-fail/regions-escape-bound-fn.rs
index 02e62ffddfd50..86d91f530627b 100644
--- a/src/test/compile-fail/regions-escape-bound-fn.rs
+++ b/src/test/compile-fail/regions-escape-bound-fn.rs
@@ -15,5 +15,6 @@ fn with_int<F>(f: F) where F: FnOnce(&isize) {
 
 fn main() {
     let mut x: Option<&isize> = None;
-    with_int(|y| x = Some(y));   //~ ERROR cannot infer
+    with_int(|y| x = Some(y));
+    //~^ ERROR borrowed data cannot be moved outside of its closure
 }
diff --git a/src/test/compile-fail/regions-escape-unboxed-closure.rs b/src/test/compile-fail/regions-escape-unboxed-closure.rs
index cf41fad270839..e422dd02f06fa 100644
--- a/src/test/compile-fail/regions-escape-unboxed-closure.rs
+++ b/src/test/compile-fail/regions-escape-unboxed-closure.rs
@@ -13,5 +13,6 @@ fn with_int(f: &mut FnMut(&isize)) {
 
 fn main() {
     let mut x: Option<&isize> = None;
-    with_int(&mut |y| x = Some(y));   //~ ERROR cannot infer
+    with_int(&mut |y| x = Some(y));
+    //~^ ERROR borrowed data cannot be moved outside of its closure
 }

From 1a1afd74a643cead4794094e286adc9cf5ae2009 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Thu, 4 Jan 2018 09:55:15 -0800
Subject: [PATCH 4/6] Handle case of moving into vec with uninferred lifetime

---
 src/librustc/infer/error_reporting/mod.rs | 22 +++++++++++++++-------
 src/test/compile-fail/issue-7573.rs       |  5 ++++-
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index 645c8403b8e44..630a2d857a014 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -1079,15 +1079,23 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         node: hir::ExprClosure(_, _, _, closure_span, false),
                         ..
                     }) => {
-                        let sp = var_origin.span();
+                        let sup_sp = sup_origin.span();
+                        let origin_sp = var_origin.span();
                         let mut err = self.tcx.sess.struct_span_err(
-                            sp,
+                            sup_sp,
                             "borrowed data cannot be moved outside of its closure");
-                        err.span_label(sp, "cannot be moved outside of its closure");
-                        err.span_label(*external_span,
-                                       "borrowed data cannot be moved into here...");
-                        err.span_label(*closure_span,
-                                       "...because it cannot outlive this closure");
+                        err.span_label(sup_sp, "cannot be moved outside of its closure");
+                        if sup_sp == origin_sp {
+                            err.span_label(*external_span,
+                                           "borrowed data cannot be moved into here...");
+                            err.span_label(*closure_span,
+                                           "...because it cannot outlive this closure");
+                        } else {
+                            err.span_label(*closure_span,
+                                           "borrowed data cannot outlive this closure");
+                            err.span_label(origin_sp,
+                                           "cannot infer an appropriate lifetime");
+                        }
                         err.emit();
                         return;
                     }
diff --git a/src/test/compile-fail/issue-7573.rs b/src/test/compile-fail/issue-7573.rs
index 7445501c4ebe6..e41d25c17ead2 100644
--- a/src/test/compile-fail/issue-7573.rs
+++ b/src/test/compile-fail/issue-7573.rs
@@ -25,9 +25,12 @@ impl CrateId {
 
 pub fn remove_package_from_database() {
     let mut lines_to_use: Vec<&CrateId> = Vec::new();
-    //~^ ERROR borrowed data cannot be moved outside of its closure
+        //~^ NOTE cannot infer an appropriate lifetime
     let push_id = |installed_id: &CrateId| {
+        //~^ NOTE borrowed data cannot outlive this closure
         lines_to_use.push(installed_id);
+        //~^ ERROR borrowed data cannot be moved outside of its closure
+        //~| NOTE cannot be moved outside of its closure
     };
     list_database(push_id);
 

From 1820da52110cc5cfb40436225c939067049ccf32 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Mon, 15 Jan 2018 10:55:10 -0800
Subject: [PATCH 5/6] Move diagnostic logic to its own module

- Move specialized borrow checker diagnostic for bindings escaping its
  closure to its own module.
- Move affected tests to `ui`.
---
 src/librustc/infer/error_reporting/mod.rs     |  38 +------
 .../nice_region_error/different_lifetimes.rs  |   2 +-
 .../error_reporting/nice_region_error/mod.rs  |  40 +++++--
 .../nice_region_error/named_anon_conflict.rs  |   2 +-
 .../nice_region_error/outlives_closure.rs     |  94 ++++++++++++++++
 .../borrow_check/nll/region_infer/mod.rs      |   2 +-
 src/test/ui/borrowck/issue-45983.rs           |   2 +-
 src/test/ui/borrowck/issue-45983.stderr       |   6 +-
 .../borrowck}/issue-7573.rs                   |   4 +-
 src/test/ui/borrowck/issue-7573.stderr        |  14 +++
 .../borrowck}/regions-escape-bound-fn-2.rs    |   2 +-
 .../borrowck/regions-escape-bound-fn-2.stderr |  12 +++
 .../borrowck}/regions-escape-bound-fn.rs      |   2 +-
 .../borrowck/regions-escape-bound-fn.stderr   |  12 +++
 .../regions-escape-unboxed-closure.rs         |   2 +-
 .../regions-escape-unboxed-closure.stderr     |  12 +++
 .../expect-region-supply-region.rs            |   6 +-
 .../expect-region-supply-region.stderr        | 100 ++++++++++++++++++
 18 files changed, 289 insertions(+), 63 deletions(-)
 create mode 100644 src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs
 rename src/test/{compile-fail => ui/borrowck}/issue-7573.rs (90%)
 create mode 100644 src/test/ui/borrowck/issue-7573.stderr
 rename src/test/{compile-fail => ui/borrowck}/regions-escape-bound-fn-2.rs (89%)
 create mode 100644 src/test/ui/borrowck/regions-escape-bound-fn-2.stderr
 rename src/test/{compile-fail => ui/borrowck}/regions-escape-bound-fn.rs (90%)
 create mode 100644 src/test/ui/borrowck/regions-escape-bound-fn.stderr
 rename src/test/{compile-fail => ui/borrowck}/regions-escape-unboxed-closure.rs (89%)
 create mode 100644 src/test/ui/borrowck/regions-escape-unboxed-closure.stderr
 rename src/test/{compile-fail => ui}/closure-expected-type/expect-region-supply-region.rs (90%)
 create mode 100644 src/test/ui/closure-expected-type/expect-region-supply-region.stderr

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index 630a2d857a014..541c1356dd4ab 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -66,7 +66,7 @@ use hir::map as hir_map;
 use hir::def_id::DefId;
 use middle::region;
 use traits::{ObligationCause, ObligationCauseCode};
-use ty::{self, Region, RegionKind, Ty, TyCtxt, TypeFoldable, TypeVariants};
+use ty::{self, Region, Ty, TyCtxt, TypeFoldable, TypeVariants};
 use ty::error::TypeError;
 use syntax::ast::DUMMY_NODE_ID;
 use syntax_pos::{Pos, Span};
@@ -1068,42 +1068,6 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                                sup_origin: SubregionOrigin<'tcx>,
                                sup_region: Region<'tcx>) {
 
-        // #45983: when trying to assign the contents of an argument to a binding outside of a
-        // closure, provide a specific message pointing this out.
-        if let (&SubregionOrigin::BindingTypeIsNotValidAtDecl(ref external_span),
-                &RegionKind::ReFree(ref free_region)) = (&sub_origin, sup_region) {
-            let hir = &self.tcx.hir;
-            if let Some(node_id) = hir.as_local_node_id(free_region.scope) {
-                match hir.get(node_id) {
-                    hir_map::NodeExpr(hir::Expr {
-                        node: hir::ExprClosure(_, _, _, closure_span, false),
-                        ..
-                    }) => {
-                        let sup_sp = sup_origin.span();
-                        let origin_sp = var_origin.span();
-                        let mut err = self.tcx.sess.struct_span_err(
-                            sup_sp,
-                            "borrowed data cannot be moved outside of its closure");
-                        err.span_label(sup_sp, "cannot be moved outside of its closure");
-                        if sup_sp == origin_sp {
-                            err.span_label(*external_span,
-                                           "borrowed data cannot be moved into here...");
-                            err.span_label(*closure_span,
-                                           "...because it cannot outlive this closure");
-                        } else {
-                            err.span_label(*closure_span,
-                                           "borrowed data cannot outlive this closure");
-                            err.span_label(origin_sp,
-                                           "cannot infer an appropriate lifetime");
-                        }
-                        err.emit();
-                        return;
-                    }
-                    _ => {}
-                }
-            }
-        }
-
         let mut err = self.report_inference_failure(var_origin);
 
         self.tcx.note_and_explain_region(region_scope_tree, &mut err,
diff --git a/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs b/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs
index d4ea899dc747f..7b0f2933580b3 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/different_lifetimes.rs
@@ -53,7 +53,7 @@ impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
     ///
     /// It will later be extended to trait objects.
     pub(super) fn try_report_anon_anon_conflict(&self) -> Option<ErrorReported> {
-        let NiceRegionError { span, sub, sup, .. } = *self;
+        let (span, sub, sup) = self.get_regions();
 
         // Determine whether the sub and sup consist of both anonymous (elided) regions.
         let anon_reg_sup = self.is_suitable_region(sup)?;
diff --git a/src/librustc/infer/error_reporting/nice_region_error/mod.rs b/src/librustc/infer/error_reporting/nice_region_error/mod.rs
index edc38b6bb14ee..59b36a50a2b09 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/mod.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/mod.rs
@@ -18,46 +18,64 @@ use util::common::ErrorReported;
 mod different_lifetimes;
 mod find_anon_type;
 mod named_anon_conflict;
+mod outlives_closure;
 mod util;
 
 impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
     pub fn try_report_nice_region_error(&self, error: &RegionResolutionError<'tcx>) -> bool {
-        let (span, sub, sup) = match *error {
-            ConcreteFailure(ref origin, sub, sup) => (origin.span(), sub, sup),
-            SubSupConflict(_, ref origin, sub, _, sup) => (origin.span(), sub, sup),
-            _ => return false, // inapplicable
-        };
+        match *error {
+            ConcreteFailure(..) | SubSupConflict(..) => {}
+            _ => return false,  // inapplicable
+        }
 
         if let Some(tables) = self.in_progress_tables {
             let tables = tables.borrow();
-            NiceRegionError::new(self.tcx, span, sub, sup, Some(&tables)).try_report().is_some()
+            NiceRegionError::new(self.tcx, error.clone(), Some(&tables)).try_report().is_some()
         } else {
-            NiceRegionError::new(self.tcx, span, sub, sup, None).try_report().is_some()
+            NiceRegionError::new(self.tcx, error.clone(), None).try_report().is_some()
         }
     }
 }
 
 pub struct NiceRegionError<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
     tcx: TyCtxt<'cx, 'gcx, 'tcx>,
-    span: Span,
-    sub: ty::Region<'tcx>,
-    sup: ty::Region<'tcx>,
+    error: Option<RegionResolutionError<'tcx>>,
+    regions: Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)>,
     tables: Option<&'cx ty::TypeckTables<'tcx>>,
 }
 
 impl<'cx, 'gcx, 'tcx> NiceRegionError<'cx, 'gcx, 'tcx> {
     pub fn new(
+        tcx: TyCtxt<'cx, 'gcx, 'tcx>,
+        error: RegionResolutionError<'tcx>,
+        tables: Option<&'cx ty::TypeckTables<'tcx>>,
+    ) -> Self {
+        Self { tcx, error: Some(error), regions: None, tables }
+    }
+
+    pub fn new_from_span(
         tcx: TyCtxt<'cx, 'gcx, 'tcx>,
         span: Span,
         sub: ty::Region<'tcx>,
         sup: ty::Region<'tcx>,
         tables: Option<&'cx ty::TypeckTables<'tcx>>,
     ) -> Self {
-        Self { tcx, span, sub, sup, tables }
+        Self { tcx, error: None, regions: Some((span, sub, sup)), tables }
     }
 
     pub fn try_report(&self) -> Option<ErrorReported> {
         self.try_report_named_anon_conflict()
             .or_else(|| self.try_report_anon_anon_conflict())
+            .or_else(|| self.try_report_outlives_closure())
+    }
+
+    pub fn get_regions(&self) -> (Span, ty::Region<'tcx>, ty::Region<'tcx>) {
+        match (&self.error, self.regions) {
+            (&Some(ConcreteFailure(ref origin, sub, sup)), None) => (origin.span(), sub, sup),
+            (&Some(SubSupConflict(_, ref origin, sub, _, sup)), None) => (origin.span(), sub, sup),
+            (None, Some((span, sub, sup))) => (span, sub, sup),
+            (Some(_), Some(_)) => panic!("incorrectly built NiceRegionError"),
+            _ => panic!("trying to report on an incorrect lifetime failure"),
+        }
     }
 }
diff --git a/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs b/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs
index 9d0ddfd4be04b..657480c486c87 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/named_anon_conflict.rs
@@ -18,7 +18,7 @@ impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
     /// When given a `ConcreteFailure` for a function with arguments containing a named region and
     /// an anonymous region, emit an descriptive diagnostic error.
     pub(super) fn try_report_named_anon_conflict(&self) -> Option<ErrorReported> {
-        let NiceRegionError { span, sub, sup, .. } = *self;
+        let (span, sub, sup) = self.get_regions();
 
         debug!(
             "try_report_named_anon_conflict(sub={:?}, sup={:?})",
diff --git a/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs b/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs
new file mode 100644
index 0000000000000..f6a99579598ca
--- /dev/null
+++ b/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs
@@ -0,0 +1,94 @@
+// 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.
+
+//! Error Reporting for Anonymous Region Lifetime Errors
+//! where both the regions are anonymous.
+
+use infer::error_reporting::nice_region_error::NiceRegionError;
+use infer::SubregionOrigin;
+use ty::RegionKind;
+use hir::{Expr, ExprClosure};
+use hir::map::NodeExpr;
+use util::common::ErrorReported;
+use infer::lexical_region_resolve::RegionResolutionError::SubSupConflict;
+
+impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
+    /// Print the error message for lifetime errors when binding excapes a closure.
+    ///
+    /// Consider a case where we have
+    ///
+    /// ```no_run
+    /// fn with_int<F>(f: F) where F: FnOnce(&isize) {
+    ///     let x = 3;
+    ///     f(&x);
+    /// }
+    /// fn main() {
+    ///     let mut x = None;
+    ///     with_int(|y| x = Some(y));
+    /// }
+    /// ```
+    ///
+    /// the output will be
+    ///
+    /// ```text
+    ///     let mut x = None;
+    ///         ----- borrowed data cannot be stored into here...
+    ///     with_int(|y| x = Some(y));
+    ///              ---          ^ cannot be stored outside of its closure
+    ///              |
+    ///              ...because it cannot outlive this closure
+    /// ```
+    pub(super) fn try_report_outlives_closure(&self) -> Option<ErrorReported> {
+        if let Some(SubSupConflict(origin,
+                                   ref sub_origin,
+                                   _,
+                                   ref sup_origin,
+                                   sup_region)) = self.error {
+
+            // #45983: when trying to assign the contents of an argument to a binding outside of a
+            // closure, provide a specific message pointing this out.
+            if let (&SubregionOrigin::BindingTypeIsNotValidAtDecl(ref external_span),
+                    &RegionKind::ReFree(ref free_region)) = (&sub_origin, sup_region) {
+                let hir = &self.tcx.hir;
+                if let Some(node_id) = hir.as_local_node_id(free_region.scope) {
+                    match hir.get(node_id) {
+                        NodeExpr(Expr {
+                            node: ExprClosure(_, _, _, closure_span, false),
+                            ..
+                        }) => {
+                            let sup_sp = sup_origin.span();
+                            let origin_sp = origin.span();
+                            let mut err = self.tcx.sess.struct_span_err(
+                                sup_sp,
+                                "borrowed data cannot be stored outside of its closure");
+                            err.span_label(sup_sp, "cannot be stored outside of its closure");
+                            if sup_sp == origin_sp {
+                                err.span_label(*external_span,
+                                               "borrowed data cannot be stored into here...");
+                                err.span_label(*closure_span,
+                                               "...because it cannot outlive this closure");
+                            } else {
+                                err.span_label(*closure_span,
+                                               "borrowed data cannot outlive this closure");
+                                err.span_label(origin_sp,
+                                               "cannot infer an appropriate lifetime");
+                            }
+                            err.emit();
+                            return Some(ErrorReported);
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+        None
+    }
+}
+
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
index da136a34b9971..9a2f98d4622f7 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
@@ -989,7 +989,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         if let (Some(f), Some(o)) = (fr_name, outlived_fr_name) {
             let tables = infcx.tcx.typeck_tables_of(mir_def_id);
-            let nice = NiceRegionError::new(infcx.tcx, blame_span, o, f, Some(tables));
+            let nice = NiceRegionError::new_from_span(infcx.tcx, blame_span, o, f, Some(tables));
             if let Some(ErrorReported) = nice.try_report() {
                 return;
             }
diff --git a/src/test/ui/borrowck/issue-45983.rs b/src/test/ui/borrowck/issue-45983.rs
index b2316a6b61c81..a6e5067195f47 100644
--- a/src/test/ui/borrowck/issue-45983.rs
+++ b/src/test/ui/borrowck/issue-45983.rs
@@ -15,5 +15,5 @@ fn give_any<F: for<'r> FnOnce(&'r ())>(f: F) {
 fn main() {
     let x = None;
     give_any(|y| x = Some(y));
-    //~^ ERROR borrowed data cannot be moved outside of its closure
+    //~^ ERROR borrowed data cannot be stored outside of its closure
 }
diff --git a/src/test/ui/borrowck/issue-45983.stderr b/src/test/ui/borrowck/issue-45983.stderr
index cbc4a557be9ef..496f15c289c17 100644
--- a/src/test/ui/borrowck/issue-45983.stderr
+++ b/src/test/ui/borrowck/issue-45983.stderr
@@ -1,10 +1,10 @@
-error: borrowed data cannot be moved outside of its closure
+error: borrowed data cannot be stored outside of its closure
   --> $DIR/issue-45983.rs:17:27
    |
 16 |     let x = None;
-   |         - borrowed data cannot be moved into here...
+   |         - borrowed data cannot be stored into here...
 17 |     give_any(|y| x = Some(y));
-   |              ---          ^ cannot be moved outside of its closure
+   |              ---          ^ cannot be stored outside of its closure
    |              |
    |              ...because it cannot outlive this closure
 
diff --git a/src/test/compile-fail/issue-7573.rs b/src/test/ui/borrowck/issue-7573.rs
similarity index 90%
rename from src/test/compile-fail/issue-7573.rs
rename to src/test/ui/borrowck/issue-7573.rs
index e41d25c17ead2..b318bd70cf2d2 100644
--- a/src/test/compile-fail/issue-7573.rs
+++ b/src/test/ui/borrowck/issue-7573.rs
@@ -29,8 +29,8 @@ pub fn remove_package_from_database() {
     let push_id = |installed_id: &CrateId| {
         //~^ NOTE borrowed data cannot outlive this closure
         lines_to_use.push(installed_id);
-        //~^ ERROR borrowed data cannot be moved outside of its closure
-        //~| NOTE cannot be moved outside of its closure
+        //~^ ERROR borrowed data cannot be stored outside of its closure
+        //~| NOTE cannot be stored outside of its closure
     };
     list_database(push_id);
 
diff --git a/src/test/ui/borrowck/issue-7573.stderr b/src/test/ui/borrowck/issue-7573.stderr
new file mode 100644
index 0000000000000..6c549a029b602
--- /dev/null
+++ b/src/test/ui/borrowck/issue-7573.stderr
@@ -0,0 +1,14 @@
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/issue-7573.rs:31:27
+   |
+27 |     let mut lines_to_use: Vec<&CrateId> = Vec::new();
+   |                               - cannot infer an appropriate lifetime
+28 |         //~^ NOTE cannot infer an appropriate lifetime
+29 |     let push_id = |installed_id: &CrateId| {
+   |                   ------------------------ borrowed data cannot outlive this closure
+30 |         //~^ NOTE borrowed data cannot outlive this closure
+31 |         lines_to_use.push(installed_id);
+   |                           ^^^^^^^^^^^^ cannot be stored outside of its closure
+
+error: aborting due to previous error
+
diff --git a/src/test/compile-fail/regions-escape-bound-fn-2.rs b/src/test/ui/borrowck/regions-escape-bound-fn-2.rs
similarity index 89%
rename from src/test/compile-fail/regions-escape-bound-fn-2.rs
rename to src/test/ui/borrowck/regions-escape-bound-fn-2.rs
index df07aec998a3b..1c38dee99a7b0 100644
--- a/src/test/compile-fail/regions-escape-bound-fn-2.rs
+++ b/src/test/ui/borrowck/regions-escape-bound-fn-2.rs
@@ -16,5 +16,5 @@ fn with_int<F>(f: F) where F: FnOnce(&isize) {
 fn main() {
     let mut x = None;
     with_int(|y| x = Some(y));
-    //~^ ERROR borrowed data cannot be moved outside of its closure
+    //~^ ERROR borrowed data cannot be stored outside of its closure
 }
diff --git a/src/test/ui/borrowck/regions-escape-bound-fn-2.stderr b/src/test/ui/borrowck/regions-escape-bound-fn-2.stderr
new file mode 100644
index 0000000000000..3d88f4fd52e2e
--- /dev/null
+++ b/src/test/ui/borrowck/regions-escape-bound-fn-2.stderr
@@ -0,0 +1,12 @@
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/regions-escape-bound-fn-2.rs:18:27
+   |
+17 |     let mut x = None;
+   |         ----- borrowed data cannot be stored into here...
+18 |     with_int(|y| x = Some(y));
+   |              ---          ^ cannot be stored outside of its closure
+   |              |
+   |              ...because it cannot outlive this closure
+
+error: aborting due to previous error
+
diff --git a/src/test/compile-fail/regions-escape-bound-fn.rs b/src/test/ui/borrowck/regions-escape-bound-fn.rs
similarity index 90%
rename from src/test/compile-fail/regions-escape-bound-fn.rs
rename to src/test/ui/borrowck/regions-escape-bound-fn.rs
index 86d91f530627b..c22742371acbc 100644
--- a/src/test/compile-fail/regions-escape-bound-fn.rs
+++ b/src/test/ui/borrowck/regions-escape-bound-fn.rs
@@ -16,5 +16,5 @@ fn with_int<F>(f: F) where F: FnOnce(&isize) {
 fn main() {
     let mut x: Option<&isize> = None;
     with_int(|y| x = Some(y));
-    //~^ ERROR borrowed data cannot be moved outside of its closure
+    //~^ ERROR borrowed data cannot be stored outside of its closure
 }
diff --git a/src/test/ui/borrowck/regions-escape-bound-fn.stderr b/src/test/ui/borrowck/regions-escape-bound-fn.stderr
new file mode 100644
index 0000000000000..306da8b54e4f7
--- /dev/null
+++ b/src/test/ui/borrowck/regions-escape-bound-fn.stderr
@@ -0,0 +1,12 @@
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/regions-escape-bound-fn.rs:18:27
+   |
+18 |     with_int(|y| x = Some(y));
+   |              ---     -----^-
+   |              |       |    |
+   |              |       |    cannot be stored outside of its closure
+   |              |       cannot infer an appropriate lifetime
+   |              borrowed data cannot outlive this closure
+
+error: aborting due to previous error
+
diff --git a/src/test/compile-fail/regions-escape-unboxed-closure.rs b/src/test/ui/borrowck/regions-escape-unboxed-closure.rs
similarity index 89%
rename from src/test/compile-fail/regions-escape-unboxed-closure.rs
rename to src/test/ui/borrowck/regions-escape-unboxed-closure.rs
index e422dd02f06fa..5a214504df4c1 100644
--- a/src/test/compile-fail/regions-escape-unboxed-closure.rs
+++ b/src/test/ui/borrowck/regions-escape-unboxed-closure.rs
@@ -14,5 +14,5 @@ fn with_int(f: &mut FnMut(&isize)) {
 fn main() {
     let mut x: Option<&isize> = None;
     with_int(&mut |y| x = Some(y));
-    //~^ ERROR borrowed data cannot be moved outside of its closure
+    //~^ ERROR borrowed data cannot be stored outside of its closure
 }
diff --git a/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr b/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr
new file mode 100644
index 0000000000000..5e51be4629539
--- /dev/null
+++ b/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr
@@ -0,0 +1,12 @@
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/regions-escape-unboxed-closure.rs:16:32
+   |
+16 |     with_int(&mut |y| x = Some(y));
+   |                   ---     -----^-
+   |                   |       |    |
+   |                   |       |    cannot be stored outside of its closure
+   |                   |       cannot infer an appropriate lifetime
+   |                   borrowed data cannot outlive this closure
+
+error: aborting due to previous error
+
diff --git a/src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs b/src/test/ui/closure-expected-type/expect-region-supply-region.rs
similarity index 90%
rename from src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs
rename to src/test/ui/closure-expected-type/expect-region-supply-region.rs
index 678647ff28da5..a464c5853e1c1 100644
--- a/src/test/compile-fail/closure-expected-type/expect-region-supply-region.rs
+++ b/src/test/ui/closure-expected-type/expect-region-supply-region.rs
@@ -25,7 +25,7 @@ fn expect_bound_supply_nothing() {
     // it to escape into `f`:
     let mut f: Option<&u32> = None;
     closure_expecting_bound(|x| {
-        f = Some(x); //~ ERROR borrowed data cannot be moved outside of its closure
+        f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
     });
 }
 
@@ -35,7 +35,7 @@ fn expect_bound_supply_bound() {
     // closure:
     let mut f: Option<&u32> = None;
     closure_expecting_bound(|x: &u32| {
-        f = Some(x); //~ ERROR borrowed data cannot be moved outside of its closure
+        f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
     });
 }
 
@@ -50,7 +50,7 @@ fn expect_bound_supply_named<'x>() {
 
         // And we still cannot let `x` escape into `f`.
         f = Some(x);
-        //~^ ERROR borrowed data cannot be moved outside of its closure
+        //~^ ERROR borrowed data cannot be stored outside of its closure
     });
 }
 
diff --git a/src/test/ui/closure-expected-type/expect-region-supply-region.stderr b/src/test/ui/closure-expected-type/expect-region-supply-region.stderr
new file mode 100644
index 0000000000000..d34b17bb25b5f
--- /dev/null
+++ b/src/test/ui/closure-expected-type/expect-region-supply-region.stderr
@@ -0,0 +1,100 @@
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/expect-region-supply-region.rs:28:18
+   |
+27 |     closure_expecting_bound(|x| {
+   |                             --- borrowed data cannot outlive this closure
+28 |         f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
+   |             -----^-
+   |             |    |
+   |             |    cannot be stored outside of its closure
+   |             cannot infer an appropriate lifetime
+
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/expect-region-supply-region.rs:38:18
+   |
+37 |     closure_expecting_bound(|x: &u32| {
+   |                             --------- borrowed data cannot outlive this closure
+38 |         f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
+   |             -----^-
+   |             |    |
+   |             |    cannot be stored outside of its closure
+   |             cannot infer an appropriate lifetime
+
+error[E0308]: mismatched types
+  --> $DIR/expect-region-supply-region.rs:47:33
+   |
+47 |     closure_expecting_bound(|x: &'x u32| {
+   |                                 ^^^^^^^ lifetime mismatch
+   |
+   = note: expected type `&u32`
+              found type `&'x u32`
+note: the anonymous lifetime #2 defined on the body at 47:29...
+  --> $DIR/expect-region-supply-region.rs:47:29
+   |
+47 |       closure_expecting_bound(|x: &'x u32| {
+   |  _____________________________^
+48 | |         //~^ ERROR mismatched types
+49 | |         //~| ERROR mismatched types
+50 | |
+...  |
+53 | |         //~^ ERROR borrowed data cannot be stored outside of its closure
+54 | |     });
+   | |_____^
+note: ...does not necessarily outlive the lifetime 'x as defined on the function body at 42:1
+  --> $DIR/expect-region-supply-region.rs:42:1
+   |
+42 | / fn expect_bound_supply_named<'x>() {
+43 | |     let mut f: Option<&u32> = None;
+44 | |
+45 | |     // Here we give a type annotation that `x` should be free. We get
+...  |
+54 | |     });
+55 | | }
+   | |_^
+
+error[E0308]: mismatched types
+  --> $DIR/expect-region-supply-region.rs:47:33
+   |
+47 |     closure_expecting_bound(|x: &'x u32| {
+   |                                 ^^^^^^^ lifetime mismatch
+   |
+   = note: expected type `&u32`
+              found type `&'x u32`
+note: the lifetime 'x as defined on the function body at 42:1...
+  --> $DIR/expect-region-supply-region.rs:42:1
+   |
+42 | / fn expect_bound_supply_named<'x>() {
+43 | |     let mut f: Option<&u32> = None;
+44 | |
+45 | |     // Here we give a type annotation that `x` should be free. We get
+...  |
+54 | |     });
+55 | | }
+   | |_^
+note: ...does not necessarily outlive the anonymous lifetime #2 defined on the body at 47:29
+  --> $DIR/expect-region-supply-region.rs:47:29
+   |
+47 |       closure_expecting_bound(|x: &'x u32| {
+   |  _____________________________^
+48 | |         //~^ ERROR mismatched types
+49 | |         //~| ERROR mismatched types
+50 | |
+...  |
+53 | |         //~^ ERROR borrowed data cannot be stored outside of its closure
+54 | |     });
+   | |_____^
+
+error: borrowed data cannot be stored outside of its closure
+  --> $DIR/expect-region-supply-region.rs:52:18
+   |
+47 |     closure_expecting_bound(|x: &'x u32| {
+   |                             ------------ borrowed data cannot outlive this closure
+...
+52 |         f = Some(x);
+   |             -----^-
+   |             |    |
+   |             |    cannot be stored outside of its closure
+   |             cannot infer an appropriate lifetime
+
+error: aborting due to 5 previous errors
+

From 6f9ecaa7cf0a15db46d13d72932acb2d678c29f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 19 Jan 2018 12:30:30 -0800
Subject: [PATCH 6/6] Tweak wording and spans of closure lifetime errors

---
 .../nice_region_error/outlives_closure.rs     | 36 +++++++++++++++++--
 src/test/ui/borrowck/issue-7573.rs            |  1 +
 src/test/ui/borrowck/issue-7573.stderr        | 12 ++++---
 .../borrowck/regions-escape-bound-fn.stderr   | 10 +++---
 .../regions-escape-unboxed-closure.stderr     | 10 +++---
 .../expect-region-supply-region.stderr        | 28 +++++++--------
 6 files changed, 64 insertions(+), 33 deletions(-)

diff --git a/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs b/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs
index f6a99579598ca..95f44b813c5d2 100644
--- a/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs
+++ b/src/librustc/infer/error_reporting/nice_region_error/outlives_closure.rs
@@ -69,16 +69,46 @@ impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
                                 sup_sp,
                                 "borrowed data cannot be stored outside of its closure");
                             err.span_label(sup_sp, "cannot be stored outside of its closure");
-                            if sup_sp == origin_sp {
+                            if origin_sp == sup_sp || origin_sp.contains(sup_sp) {
+// // sup_sp == origin.span():
+//
+// let mut x = None;
+//     ----- borrowed data cannot be stored into here...
+// with_int(|y| x = Some(y));
+//          ---          ^ cannot be stored outside of its closure
+//          |
+//          ...because it cannot outlive this closure
+//
+// // origin.contains(&sup_sp):
+//
+// let mut f: Option<&u32> = None;
+//     ----- borrowed data cannot be stored into here...
+// closure_expecting_bound(|x: &'x u32| {
+//                         ------------ ... because it cannot outlive this closure
+//     f = Some(x);
+//              ^ cannot be stored outside of its closure
                                 err.span_label(*external_span,
                                                "borrowed data cannot be stored into here...");
                                 err.span_label(*closure_span,
                                                "...because it cannot outlive this closure");
                             } else {
+// FIXME: the wording for this case could be much improved
+//
+// let mut lines_to_use: Vec<&CrateId> = Vec::new();
+//                           - cannot infer an appropriate lifetime...
+// let push_id = |installed_id: &CrateId| {
+//     -------   ------------------------ borrowed data cannot outlive this closure
+//     |
+//     ...so that variable is valid at time of its declaration
+//     lines_to_use.push(installed_id);
+//                       ^^^^^^^^^^^^ cannot be stored outside of its closure
+                                err.span_label(origin_sp,
+                                               "cannot infer an appropriate lifetime...");
+                                err.span_label(*external_span,
+                                               "...so that variable is valid at time of its \
+                                                declaration");
                                 err.span_label(*closure_span,
                                                "borrowed data cannot outlive this closure");
-                                err.span_label(origin_sp,
-                                               "cannot infer an appropriate lifetime");
                             }
                             err.emit();
                             return Some(ErrorReported);
diff --git a/src/test/ui/borrowck/issue-7573.rs b/src/test/ui/borrowck/issue-7573.rs
index b318bd70cf2d2..8f1545fa00986 100644
--- a/src/test/ui/borrowck/issue-7573.rs
+++ b/src/test/ui/borrowck/issue-7573.rs
@@ -28,6 +28,7 @@ pub fn remove_package_from_database() {
         //~^ NOTE cannot infer an appropriate lifetime
     let push_id = |installed_id: &CrateId| {
         //~^ NOTE borrowed data cannot outlive this closure
+        //~| NOTE ...so that variable is valid at time of its declaration
         lines_to_use.push(installed_id);
         //~^ ERROR borrowed data cannot be stored outside of its closure
         //~| NOTE cannot be stored outside of its closure
diff --git a/src/test/ui/borrowck/issue-7573.stderr b/src/test/ui/borrowck/issue-7573.stderr
index 6c549a029b602..99b48d9276c06 100644
--- a/src/test/ui/borrowck/issue-7573.stderr
+++ b/src/test/ui/borrowck/issue-7573.stderr
@@ -1,13 +1,15 @@
 error: borrowed data cannot be stored outside of its closure
-  --> $DIR/issue-7573.rs:31:27
+  --> $DIR/issue-7573.rs:32:27
    |
 27 |     let mut lines_to_use: Vec<&CrateId> = Vec::new();
-   |                               - cannot infer an appropriate lifetime
+   |                               - cannot infer an appropriate lifetime...
 28 |         //~^ NOTE cannot infer an appropriate lifetime
 29 |     let push_id = |installed_id: &CrateId| {
-   |                   ------------------------ borrowed data cannot outlive this closure
-30 |         //~^ NOTE borrowed data cannot outlive this closure
-31 |         lines_to_use.push(installed_id);
+   |         -------   ------------------------ borrowed data cannot outlive this closure
+   |         |
+   |         ...so that variable is valid at time of its declaration
+...
+32 |         lines_to_use.push(installed_id);
    |                           ^^^^^^^^^^^^ cannot be stored outside of its closure
 
 error: aborting due to previous error
diff --git a/src/test/ui/borrowck/regions-escape-bound-fn.stderr b/src/test/ui/borrowck/regions-escape-bound-fn.stderr
index 306da8b54e4f7..a2ad7c3f768c6 100644
--- a/src/test/ui/borrowck/regions-escape-bound-fn.stderr
+++ b/src/test/ui/borrowck/regions-escape-bound-fn.stderr
@@ -1,12 +1,12 @@
 error: borrowed data cannot be stored outside of its closure
   --> $DIR/regions-escape-bound-fn.rs:18:27
    |
+17 |     let mut x: Option<&isize> = None;
+   |         ----- borrowed data cannot be stored into here...
 18 |     with_int(|y| x = Some(y));
-   |              ---     -----^-
-   |              |       |    |
-   |              |       |    cannot be stored outside of its closure
-   |              |       cannot infer an appropriate lifetime
-   |              borrowed data cannot outlive this closure
+   |              ---          ^ cannot be stored outside of its closure
+   |              |
+   |              ...because it cannot outlive this closure
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr b/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr
index 5e51be4629539..4b01e42fa67d0 100644
--- a/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr
+++ b/src/test/ui/borrowck/regions-escape-unboxed-closure.stderr
@@ -1,12 +1,12 @@
 error: borrowed data cannot be stored outside of its closure
   --> $DIR/regions-escape-unboxed-closure.rs:16:32
    |
+15 |     let mut x: Option<&isize> = None;
+   |         ----- borrowed data cannot be stored into here...
 16 |     with_int(&mut |y| x = Some(y));
-   |                   ---     -----^-
-   |                   |       |    |
-   |                   |       |    cannot be stored outside of its closure
-   |                   |       cannot infer an appropriate lifetime
-   |                   borrowed data cannot outlive this closure
+   |                   ---          ^ cannot be stored outside of its closure
+   |                   |
+   |                   ...because it cannot outlive this closure
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closure-expected-type/expect-region-supply-region.stderr b/src/test/ui/closure-expected-type/expect-region-supply-region.stderr
index d34b17bb25b5f..ebb1e561e57ab 100644
--- a/src/test/ui/closure-expected-type/expect-region-supply-region.stderr
+++ b/src/test/ui/closure-expected-type/expect-region-supply-region.stderr
@@ -1,24 +1,22 @@
 error: borrowed data cannot be stored outside of its closure
   --> $DIR/expect-region-supply-region.rs:28:18
    |
+26 |     let mut f: Option<&u32> = None;
+   |         ----- borrowed data cannot be stored into here...
 27 |     closure_expecting_bound(|x| {
-   |                             --- borrowed data cannot outlive this closure
+   |                             --- ...because it cannot outlive this closure
 28 |         f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
-   |             -----^-
-   |             |    |
-   |             |    cannot be stored outside of its closure
-   |             cannot infer an appropriate lifetime
+   |                  ^ cannot be stored outside of its closure
 
 error: borrowed data cannot be stored outside of its closure
   --> $DIR/expect-region-supply-region.rs:38:18
    |
+36 |     let mut f: Option<&u32> = None;
+   |         ----- borrowed data cannot be stored into here...
 37 |     closure_expecting_bound(|x: &u32| {
-   |                             --------- borrowed data cannot outlive this closure
+   |                             --------- ...because it cannot outlive this closure
 38 |         f = Some(x); //~ ERROR borrowed data cannot be stored outside of its closure
-   |             -----^-
-   |             |    |
-   |             |    cannot be stored outside of its closure
-   |             cannot infer an appropriate lifetime
+   |                  ^ cannot be stored outside of its closure
 
 error[E0308]: mismatched types
   --> $DIR/expect-region-supply-region.rs:47:33
@@ -87,14 +85,14 @@ note: ...does not necessarily outlive the anonymous lifetime #2 defined on the b
 error: borrowed data cannot be stored outside of its closure
   --> $DIR/expect-region-supply-region.rs:52:18
    |
+43 |     let mut f: Option<&u32> = None;
+   |         ----- borrowed data cannot be stored into here...
+...
 47 |     closure_expecting_bound(|x: &'x u32| {
-   |                             ------------ borrowed data cannot outlive this closure
+   |                             ------------ ...because it cannot outlive this closure
 ...
 52 |         f = Some(x);
-   |             -----^-
-   |             |    |
-   |             |    cannot be stored outside of its closure
-   |             cannot infer an appropriate lifetime
+   |                  ^ cannot be stored outside of its closure
 
 error: aborting due to 5 previous errors