Tests for closure spans

10 files changed, 666 insertions, 0 deletions

diff --git a/src/test/ui/nll/closure-access-spans.rs b/src/test/ui/nll/closure-access-spans.rs
new file mode 100644
index 00000000000..b49436fabcf
--- /dev/null
+++ b/src/test/ui/nll/closure-access-spans.rs
@@ -0,0 +1,68 @@
+// 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.
+
+// check that accesses due to a closure capture give a special note
+
+#![feature(nll)]
+
+fn closure_imm_capture_conflict(mut x: i32) {
+    let r = &mut x;
+    || x; //~ ERROR
+    r.use_mut();
+}
+
+fn closure_mut_capture_conflict(mut x: i32) {
+    let r = &mut x;
+    || x = 2; //~ ERROR
+    r.use_mut();
+}
+
+fn closure_unique_capture_conflict(mut x: &mut i32) {
+    let r = &mut x;
+    || *x = 2; //~ ERROR
+    r.use_mut();
+}
+
+fn closure_copy_capture_conflict(mut x: i32) {
+    let r = &mut x;
+    move || x; //~ ERROR
+    r.use_ref();
+}
+
+fn closure_move_capture_conflict(mut x: String) {
+    let r = &x;
+    || x; //~ ERROR
+    r.use_ref();
+}
+
+fn closure_imm_capture_moved(mut x: String) {
+    let r = x;
+    || x.len(); //~ ERROR
+}
+
+fn closure_mut_capture_moved(mut x: String) {
+    let r = x;
+    || x = String::new(); //~ ERROR
+}
+
+fn closure_unique_capture_moved(x: &mut String) {
+    let r = x;
+    || *x = String::new(); //~ ERROR
+}
+
+fn closure_move_capture_moved(x: &mut String) {
+    let r = x;
+    || x; //~ ERROR
+}
+
+fn main() {}
+
+trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { }  }
+impl<T> Fake for T { }
diff --git a/src/test/ui/nll/closure-access-spans.stderr b/src/test/ui/nll/closure-access-spans.stderr
new file mode 100644
index 00000000000..0042b5d7d52
--- /dev/null
+++ b/src/test/ui/nll/closure-access-spans.stderr
@@ -0,0 +1,110 @@
+error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
+  --> $DIR/closure-access-spans.rs:17:5
+   |
+LL |     let r = &mut x;
+   |             ------ mutable borrow occurs here
+LL |     || x; //~ ERROR
+   |     ^^ - second borrow occurs due to use of `x` in closure
+   |     |
+   |     immutable borrow occurs here
+LL |     r.use_mut();
+   |     - borrow later used here
+
+error[E0499]: cannot borrow `x` as mutable more than once at a time
+  --> $DIR/closure-access-spans.rs:23:5
+   |
+LL |     let r = &mut x;
+   |             ------ first mutable borrow occurs here
+LL |     || x = 2; //~ ERROR
+   |     ^^ - second borrow occurs due to use of `x` in closure
+   |     |
+   |     second mutable borrow occurs here
+LL |     r.use_mut();
+   |     - borrow later used here
+
+error[E0500]: closure requires unique access to `x` but it is already borrowed
+  --> $DIR/closure-access-spans.rs:29:5
+   |
+LL |     let r = &mut x;
+   |             ------ borrow occurs here
+LL |     || *x = 2; //~ ERROR
+   |     ^^  - second borrow occurs due to use of `x` in closure
+   |     |
+   |     closure construction occurs here
+LL |     r.use_mut();
+   |     - borrow later used here
+
+error[E0503]: cannot use `x` because it was mutably borrowed
+  --> $DIR/closure-access-spans.rs:35:13
+   |
+LL |     let r = &mut x;
+   |             ------ borrow of `x` occurs here
+LL |     move || x; //~ ERROR
+   |             ^ use of borrowed `x`
+LL |     r.use_ref();
+   |     - borrow later used here
+
+error[E0505]: cannot move out of `x` because it is borrowed
+  --> $DIR/closure-access-spans.rs:41:5
+   |
+LL |     let r = &x;
+   |             -- borrow of `x` occurs here
+LL |     || x; //~ ERROR
+   |     ^^ - move occurs due to use in closure
+   |     |
+   |     move out of `x` occurs here
+LL |     r.use_ref();
+   |     - borrow later used here
+
+error[E0382]: borrow of moved value: `x`
+  --> $DIR/closure-access-spans.rs:47:5
+   |
+LL |     let r = x;
+   |             - value moved here
+LL |     || x.len(); //~ ERROR
+   |     ^^ - borrow occurs due to use in closure
+   |     |
+   |     value borrowed here after move
+   |
+   = note: move occurs because `x` has type `std::string::String`, which does not implement the `Copy` trait
+
+error[E0382]: borrow of moved value: `x`
+  --> $DIR/closure-access-spans.rs:52:5
+   |
+LL |     let r = x;
+   |             - value moved here
+LL |     || x = String::new(); //~ ERROR
+   |     ^^ - borrow occurs due to use in closure
+   |     |
+   |     value borrowed here after move
+   |
+   = note: move occurs because `x` has type `std::string::String`, which does not implement the `Copy` trait
+
+error[E0382]: borrow of moved value: `x`
+  --> $DIR/closure-access-spans.rs:57:5
+   |
+LL |     let r = x;
+   |             - value moved here
+LL |     || *x = String::new(); //~ ERROR
+   |     ^^  - borrow occurs due to use in closure
+   |     |
+   |     value borrowed here after move
+   |
+   = note: move occurs because `x` has type `&mut std::string::String`, which does not implement the `Copy` trait
+
+error[E0382]: use of moved value: `x`
+  --> $DIR/closure-access-spans.rs:62:5
+   |
+LL |     let r = x;
+   |             - value moved here
+LL |     || x; //~ ERROR
+   |     ^^ - use occurs due to use in closure
+   |     |
+   |     value used here after move
+   |
+   = note: move occurs because `x` has type `&mut std::string::String`, which does not implement the `Copy` trait
+
+error: aborting due to 9 previous errors
+
+Some errors occurred: E0382, E0499, E0500, E0502, E0503, E0505.
+For more information about an error, try `rustc --explain E0382`.
diff --git a/src/test/ui/nll/closure-borrow-spans.rs b/src/test/ui/nll/closure-borrow-spans.rs
new file mode 100644
index 00000000000..d62dc27dade
--- /dev/null
+++ b/src/test/ui/nll/closure-borrow-spans.rs
@@ -0,0 +1,112 @@
+// 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.
+
+// check that existing borrows due to a closure capture give a special note
+
+#![feature(nll)]
+
+fn move_while_borrowed(x: String) {
+    let f = || x.len();
+    let y = x; //~ ERROR
+    f.use_ref();
+}
+
+fn borrow_mut_while_borrowed(mut x: i32) {
+    let f = || x;
+    let y = &mut x; //~ ERROR
+    f.use_ref();
+}
+
+fn drop_while_borrowed() {
+    let f;
+    {
+        let x = 1;
+        f = || x; //~ ERROR
+    }
+    f.use_ref();
+}
+
+fn assign_while_borrowed(mut x: i32) {
+    let f = || x;
+    x = 1; //~ ERROR
+    f.use_ref();
+}
+
+fn copy_while_borrowed_mut(mut x: i32) {
+    let f = || x = 0;
+    let y = x; //~ ERROR
+    f.use_ref();
+}
+
+fn borrow_while_borrowed_mut(mut x: i32) {
+    let f = || x = 0;
+    let y = &x; //~ ERROR
+    f.use_ref();
+}
+
+fn borrow_mut_while_borrowed_mut(mut x: i32) {
+    let f = || x = 0;
+    let y = &mut x; //~ ERROR
+    f.use_ref();
+}
+
+fn drop_while_borrowed_mut() {
+    let f;
+    {
+        let mut x = 1;
+        f = || x = 0; //~ ERROR
+    }
+    f.use_ref();
+}
+
+fn assign_while_borrowed_mut(mut x: i32) {
+    let f = || x = 0;
+    x = 1; //~ ERROR
+    f.use_ref();
+}
+
+fn copy_while_borrowed_unique(x: &mut i32) {
+    let f = || *x = 0;
+    let y = x; //~ ERROR
+    f.use_ref();
+}
+
+fn borrow_while_borrowed_unique(x: &mut i32) {
+    let f = || *x = 0;
+    let y = &x; //~ ERROR
+    f.use_ref();
+}
+
+fn borrow_mut_while_borrowed_unique(mut x: &mut i32) {
+    let f = || *x = 0;
+    let y = &mut x; //~ ERROR
+    f.use_ref();
+}
+
+fn drop_while_borrowed_unique() {
+    let mut z = 1;
+    let f;
+    {
+        let x = &mut z;
+        f = || *x = 0; //~ ERROR
+    }
+    f.use_ref();
+}
+
+fn assign_while_borrowed_unique(x: &mut i32) {
+    let f = || *x = 0;
+    *x = 1; //~ ERROR
+    f.use_ref();
+}
+
+fn main() {}
+
+trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { }  }
+impl<T> Fake for T { }
diff --git a/src/test/ui/nll/closure-borrow-spans.stderr b/src/test/ui/nll/closure-borrow-spans.stderr
new file mode 100644
index 00000000000..1b9420b3c0b
--- /dev/null
+++ b/src/test/ui/nll/closure-borrow-spans.stderr
@@ -0,0 +1,172 @@
+error[E0505]: cannot move out of `x` because it is borrowed
+  --> $DIR/closure-borrow-spans.rs:17:13
+   |
+LL |     let f = || x.len();
+   |             -- - borrow occurs due to use in closure
+   |             |
+   |             borrow of `x` occurs here
+LL |     let y = x; //~ ERROR
+   |             ^ move out of `x` occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
+  --> $DIR/closure-borrow-spans.rs:23:13
+   |
+LL |     let f = || x;
+   |             -- - first borrow occurs due to use of `x` in closure
+   |             |
+   |             immutable borrow occurs here
+LL |     let y = &mut x; //~ ERROR
+   |             ^^^^^^ mutable borrow occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0597]: `x` does not live long enough
+  --> $DIR/closure-borrow-spans.rs:31:16
+   |
+LL |         f = || x; //~ ERROR
+   |             -- ^ borrowed value does not live long enough
+   |             |
+   |             value captured here
+LL |     }
+   |     - `x` dropped here while still borrowed
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0506]: cannot assign to `x` because it is borrowed
+  --> $DIR/closure-borrow-spans.rs:38:5
+   |
+LL |     let f = || x;
+   |             -- - borrow occurs due to use in closure
+   |             |
+   |             borrow of `x` occurs here
+LL |     x = 1; //~ ERROR
+   |     ^^^^^ assignment to borrowed `x` occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0503]: cannot use `x` because it was mutably borrowed
+  --> $DIR/closure-borrow-spans.rs:44:13
+   |
+LL |     let f = || x = 0;
+   |             -- - borrow occurs due to use of `x` in closure
+   |             |
+   |             borrow of `x` occurs here
+LL |     let y = x; //~ ERROR
+   |             ^ use of borrowed `x`
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
+  --> $DIR/closure-borrow-spans.rs:50:13
+   |
+LL |     let f = || x = 0;
+   |             -- - first borrow occurs due to use of `x` in closure
+   |             |
+   |             mutable borrow occurs here
+LL |     let y = &x; //~ ERROR
+   |             ^^ immutable borrow occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0499]: cannot borrow `x` as mutable more than once at a time
+  --> $DIR/closure-borrow-spans.rs:56:13
+   |
+LL |     let f = || x = 0;
+   |             -- - first borrow occurs due to use of `x` in closure
+   |             |
+   |             first mutable borrow occurs here
+LL |     let y = &mut x; //~ ERROR
+   |             ^^^^^^ second mutable borrow occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0597]: `x` does not live long enough
+  --> $DIR/closure-borrow-spans.rs:64:16
+   |
+LL |         f = || x = 0; //~ ERROR
+   |             -- ^ borrowed value does not live long enough
+   |             |
+   |             value captured here
+LL |     }
+   |     - `x` dropped here while still borrowed
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0506]: cannot assign to `x` because it is borrowed
+  --> $DIR/closure-borrow-spans.rs:71:5
+   |
+LL |     let f = || x = 0;
+   |             -- - borrow occurs due to use in closure
+   |             |
+   |             borrow of `x` occurs here
+LL |     x = 1; //~ ERROR
+   |     ^^^^^ assignment to borrowed `x` occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0505]: cannot move out of `x` because it is borrowed
+  --> $DIR/closure-borrow-spans.rs:77:13
+   |
+LL |     let f = || *x = 0;
+   |             --  - borrow occurs due to use in closure
+   |             |
+   |             borrow of `x` occurs here
+LL |     let y = x; //~ ERROR
+   |             ^ move out of `x` occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0501]: cannot borrow `x` as immutable because previous closure requires unique access
+  --> $DIR/closure-borrow-spans.rs:83:13
+   |
+LL |     let f = || *x = 0;
+   |             --  - first borrow occurs due to use of `x` in closure
+   |             |
+   |             closure construction occurs here
+LL |     let y = &x; //~ ERROR
+   |             ^^ borrow occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0501]: cannot borrow `x` as mutable because previous closure requires unique access
+  --> $DIR/closure-borrow-spans.rs:89:13
+   |
+LL |     let f = || *x = 0;
+   |             --  - first borrow occurs due to use of `x` in closure
+   |             |
+   |             closure construction occurs here
+LL |     let y = &mut x; //~ ERROR
+   |             ^^^^^^ borrow occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0597]: `x` does not live long enough
+  --> $DIR/closure-borrow-spans.rs:98:17
+   |
+LL |         f = || *x = 0; //~ ERROR
+   |             --  ^ borrowed value does not live long enough
+   |             |
+   |             value captured here
+LL |     }
+   |     - `x` dropped here while still borrowed
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error[E0506]: cannot assign to `*x` because it is borrowed
+  --> $DIR/closure-borrow-spans.rs:105:5
+   |
+LL |     let f = || *x = 0;
+   |             --  - borrow occurs due to use in closure
+   |             |
+   |             borrow of `*x` occurs here
+LL |     *x = 1; //~ ERROR
+   |     ^^^^^^ assignment to borrowed `*x` occurs here
+LL |     f.use_ref();
+   |     - borrow later used here
+
+error: aborting due to 14 previous errors
+
+Some errors occurred: E0499, E0501, E0502, E0503, E0505, E0506, E0597.
+For more information about an error, try `rustc --explain E0499`.
diff --git a/src/test/ui/nll/closure-move-spans.rs b/src/test/ui/nll/closure-move-spans.rs
new file mode 100644
index 00000000000..7e836275c8b
--- /dev/null
+++ b/src/test/ui/nll/closure-move-spans.rs
@@ -0,0 +1,33 @@
+// 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.
+
+// check that moves due to a closure capture give a special note
+
+#![feature(nll)]
+
+fn move_after_move(x: String) {
+    || x;
+    let y = x; //~ ERROR
+}
+
+fn borrow_after_move(x: String) {
+    || x;
+    let y = &x; //~ ERROR
+}
+
+fn borrow_mut_after_move(mut x: String) {
+    || x;
+    let y = &mut x; //~ ERROR
+}
+
+fn fn_ref<F: Fn()>(f: F) -> F { f }
+fn fn_mut<F: FnMut()>(f: F) -> F { f }
+
+fn main() {}
diff --git a/src/test/ui/nll/closure-move-spans.stderr b/src/test/ui/nll/closure-move-spans.stderr
new file mode 100644
index 00000000000..80b7b4246a7
--- /dev/null
+++ b/src/test/ui/nll/closure-move-spans.stderr
@@ -0,0 +1,39 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/closure-move-spans.rs:17:13
+   |
+LL |     || x;
+   |     -- - variable moved due to use in closure
+   |     |
+   |     value moved into closure here
+LL |     let y = x; //~ ERROR
+   |             ^ value used here after move
+   |
+   = note: move occurs because `x` has type `std::string::String`, which does not implement the `Copy` trait
+
+error[E0382]: borrow of moved value: `x`
+  --> $DIR/closure-move-spans.rs:22:13
+   |
+LL |     || x;
+   |     -- - variable moved due to use in closure
+   |     |
+   |     value moved into closure here
+LL |     let y = &x; //~ ERROR
+   |             ^^ value borrowed here after move
+   |
+   = note: move occurs because `x` has type `std::string::String`, which does not implement the `Copy` trait
+
+error[E0382]: borrow of moved value: `x`
+  --> $DIR/closure-move-spans.rs:27:13
+   |
+LL |     || x;
+   |     -- - variable moved due to use in closure
+   |     |
+   |     value moved into closure here
+LL |     let y = &mut x; //~ ERROR
+   |             ^^^^^^ value borrowed here after move
+   |
+   = note: move occurs because `x` has type `std::string::String`, which does not implement the `Copy` trait
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0382`.
diff --git a/src/test/ui/nll/closure-use-spans.rs b/src/test/ui/nll/closure-use-spans.rs
new file mode 100644
index 00000000000..7ab382a96bb
--- /dev/null
+++ b/src/test/ui/nll/closure-use-spans.rs
@@ -0,0 +1,33 @@
+// 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.
+
+// check that liveness due to a closure capture gives a special note
+
+#![feature(nll)]
+
+fn use_as_borrow_capture(mut x: i32) {
+    let y = &x;
+    x = 0; //~ ERROR
+    || *y;
+}
+
+fn use_as_borrow_mut_capture(mut x: i32) {
+    let y = &mut x;
+    x = 0; //~ ERROR
+    || *y = 1;
+}
+
+fn use_as_move_capture(mut x: i32) {
+    let y = &x;
+    x = 0; //~ ERROR
+    move || *y;
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/closure-use-spans.stderr b/src/test/ui/nll/closure-use-spans.stderr
new file mode 100644
index 00000000000..7e5f9621d09
--- /dev/null
+++ b/src/test/ui/nll/closure-use-spans.stderr
@@ -0,0 +1,33 @@
+error[E0506]: cannot assign to `x` because it is borrowed
+  --> $DIR/closure-use-spans.rs:17:5
+   |
+LL |     let y = &x;
+   |             -- borrow of `x` occurs here
+LL |     x = 0; //~ ERROR
+   |     ^^^^^ assignment to borrowed `x` occurs here
+LL |     || *y;
+   |         - borrow later captured here by closure
+
+error[E0506]: cannot assign to `x` because it is borrowed
+  --> $DIR/closure-use-spans.rs:23:5
+   |
+LL |     let y = &mut x;
+   |             ------ borrow of `x` occurs here
+LL |     x = 0; //~ ERROR
+   |     ^^^^^ assignment to borrowed `x` occurs here
+LL |     || *y = 1;
+   |         - borrow later captured here by closure
+
+error[E0506]: cannot assign to `x` because it is borrowed
+  --> $DIR/closure-use-spans.rs:29:5
+   |
+LL |     let y = &x;
+   |             -- borrow of `x` occurs here
+LL |     x = 0; //~ ERROR
+   |     ^^^^^ assignment to borrowed `x` occurs here
+LL |     move || *y;
+   |              - borrow later captured here by closure
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0506`.
diff --git a/src/test/ui/nll/closures-in-loops.rs b/src/test/ui/nll/closures-in-loops.rs
new file mode 100644
index 00000000000..c6113f3a9c5
--- /dev/null
+++ b/src/test/ui/nll/closures-in-loops.rs
@@ -0,0 +1,36 @@
+// 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.
+
+// Test messages where a closure capture conflicts with itself because it's in
+// a loop.
+
+#![feature(nll)]
+
+fn repreated_move(x: String) {
+    for i in 0..10 {
+        || x; //~ ERROR
+    }
+}
+
+fn repreated_mut_borrow(mut x: String) {
+    let mut v = Vec::new();
+    for i in 0..10 {
+        v.push(|| x = String::new()); //~ ERROR
+    }
+}
+
+fn repreated_unique_borrow(x: &mut String) {
+    let mut v = Vec::new();
+    for i in 0..10 {
+        v.push(|| *x = String::new()); //~ ERROR
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/closures-in-loops.stderr b/src/test/ui/nll/closures-in-loops.stderr
new file mode 100644
index 00000000000..9758a803620
--- /dev/null
+++ b/src/test/ui/nll/closures-in-loops.stderr
@@ -0,0 +1,30 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/closures-in-loops.rs:18:9
+   |
+LL |         || x; //~ ERROR
+   |         ^^ - use occurs due to use in closure
+   |         |
+   |         value moved into closure here in previous iteration of loop
+   |
+   = note: move occurs because `x` has type `std::string::String`, which does not implement the `Copy` trait
+
+error[E0499]: cannot borrow `x` as mutable more than once at a time
+  --> $DIR/closures-in-loops.rs:25:16
+   |
+LL |         v.push(|| x = String::new()); //~ ERROR
+   |                ^^ - borrows occur due to use of `x` in closure
+   |                |
+   |                mutable borrow starts here in previous iteration of loop
+
+error[E0524]: two closures require unique access to `x` at the same time
+  --> $DIR/closures-in-loops.rs:32:16
+   |
+LL |         v.push(|| *x = String::new()); //~ ERROR
+   |                ^^  - borrows occur due to use of `x` in closure
+   |                |
+   |                closures are constructed here in different iterations of loop
+
+error: aborting due to 3 previous errors
+
+Some errors occurred: E0382, E0499, E0524.
+For more information about an error, try `rustc --explain E0382`.