Auto merge of #55502 - kennytm:rollup, r=kennytm

Rollup of 12 pull requests

Successful merges:

 - #54885 (Don't lint 'unused_parens` on `if (break _) { .. }`)
 - #55205 (Improve a few cases of collecting to an FxHash(Map/Set))
 - #55450 (msp430: remove the whole Atomic* API)
 - #55459 (Add UI test for #49296)
 - #55472 (Use opt.take() instead of mem::replace(opt, None))
 - #55473 (Take advantage of impl Iterator in (transitive/elaborate)_bounds)
 - #55474 (Fix validation false positive)
 - #55476 (Change a flat_map with 0/1-element vecs to a filter_map)
 - #55487 (Adjust Ids of path segments in visibility modifiers)
 - #55493 (Doc fixes)
 - #55494 (borrowck=migrate must look at parents of closures)
 - #55496 (Update clippy)

Failed merges:

r? @ghost

16 files changed, 329 insertions, 65 deletions

diff --git a/src/test/run-pass/issue-55376.rs b/src/test/run-pass/issue-55376.rs
new file mode 100644
index 00000000000..9c7256fd26f
--- /dev/null
+++ b/src/test/run-pass/issue-55376.rs
@@ -0,0 +1,25 @@
+// 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.
+
+// Tests that paths in `pub(...)` don't fail HIR verification.
+
+#![allow(unused_imports)]
+#![allow(dead_code)]
+
+pub(self) use self::my_mod::Foo;
+
+mod my_mod {
+    pub(super) use self::Foo as Bar;
+    pub(in super::my_mod) use self::Foo as Baz;
+
+    pub struct Foo;
+}
+
+fn main() {}
diff --git a/src/test/ui/borrowck/borrowck-closures-unique.nll.stderr b/src/test/ui/borrowck/borrowck-closures-unique.nll.stderr
index 771ef88a662..231ae53fe82 100644
--- a/src/test/ui/borrowck/borrowck-closures-unique.nll.stderr
+++ b/src/test/ui/borrowck/borrowck-closures-unique.nll.stderr
@@ -40,19 +40,15 @@ LL |     let c2 = || set(x); //~ ERROR two closures require unique access to `x`
 LL |     c1;
    |     -- first borrow later used here
 
-warning[E0594]: cannot assign to `x`, as it is not declared as mutable
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
   --> $DIR/borrowck-closures-unique.rs:57:38
    |
 LL | fn e(x: &'static mut isize) {
    |      - help: consider changing this to be mutable: `mut x`
 LL |     let c1 = |y: &'static mut isize| x = y; //~ ERROR closure cannot assign to immutable argument
    |                                      ^^^^^ cannot assign
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 Some errors occurred: E0500, E0524, E0594.
 For more information about an error, try `rustc --explain E0500`.
diff --git a/src/test/ui/borrowck/borrowck-describe-lvalue.ast.nll.stderr b/src/test/ui/borrowck/borrowck-describe-lvalue.ast.nll.stderr
index 88ae73b6368..c3aba793f19 100644
--- a/src/test/ui/borrowck/borrowck-describe-lvalue.ast.nll.stderr
+++ b/src/test/ui/borrowck/borrowck-describe-lvalue.ast.nll.stderr
@@ -20,7 +20,7 @@ LL |                    //[mir]~^ ERROR cannot borrow `x` as mutable more than o
 LL |                    *y = 1;
    |                    ------ first borrow later used here
 
-warning: captured variable cannot escape `FnMut` closure body
+error: captured variable cannot escape `FnMut` closure body
   --> $DIR/borrowck-describe-lvalue.rs:305:16
    |
 LL |              || {
@@ -36,9 +36,6 @@ LL | |                 }
    |
    = note: `FnMut` closures only have access to their captured variables while they are executing...
    = note: ...therefore, they cannot allow references to captured variables to escape
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
 error[E0503]: cannot use `f.x` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:53:9
@@ -382,7 +379,7 @@ LL |                 drop(x); //[ast]~ ERROR use of moved value: `x`
    |
    = note: move occurs because `x` has type `std::vec::Vec<i32>`, which does not implement the `Copy` trait
 
-error: aborting due to 29 previous errors
+error: aborting due to 30 previous errors
 
 Some errors occurred: E0382, E0499, E0502, E0503.
 For more information about an error, try `rustc --explain E0382`.
diff --git a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.ast.stderr b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.ast.stderr
new file mode 100644
index 00000000000..3180823f643
--- /dev/null
+++ b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.ast.stderr
@@ -0,0 +1,55 @@
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:21:22
+   |
+LL |         let mut c1 = |y: &'static mut isize| x = y;
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow mutably
+help: consider removing the `&mut`, as it is an immutable binding to a mutable reference
+   |
+LL |         x
+   |
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:29:22
+   |
+LL |         let mut c1 = |z: &'static mut isize| {
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow mutably
+help: consider removing the `&mut`, as it is an immutable binding to a mutable reference
+   |
+LL |         x
+   |
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:40:9
+   |
+LL |     pub fn capture_assign_whole(x: (i32,)) {
+   |                                 - help: make this binding mutable: `mut x`
+LL |         || { x = (1,); };
+   |         ^^ cannot borrow mutably
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:43:9
+   |
+LL |     pub fn capture_assign_part(x: (i32,)) {
+   |                                - help: make this binding mutable: `mut x`
+LL |         || { x.0 = 1; };
+   |         ^^ cannot borrow mutably
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:46:9
+   |
+LL |     pub fn capture_reborrow_whole(x: (i32,)) {
+   |                                   - help: make this binding mutable: `mut x`
+LL |         || { &mut x; };
+   |         ^^ cannot borrow mutably
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:49:9
+   |
+LL |     pub fn capture_reborrow_part(x: (i32,)) {
+   |                                  - help: make this binding mutable: `mut x`
+LL |         || { &mut x.0; };
+   |         ^^ cannot borrow mutably
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0595`.
diff --git a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr
new file mode 100644
index 00000000000..0ccddf0a67d
--- /dev/null
+++ b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr
@@ -0,0 +1,54 @@
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:21:46
+   |
+LL |     pub fn e(x: &'static mut isize) {
+   |              - help: consider changing this to be mutable: `mut x`
+LL |         static mut Y: isize = 3;
+LL |         let mut c1 = |y: &'static mut isize| x = y;
+   |                                              ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:30:50
+   |
+LL |     pub fn ee(x: &'static mut isize) {
+   |               - help: consider changing this to be mutable: `mut x`
+...
+LL |             let mut c2 = |y: &'static mut isize| x = y;
+   |                                                  ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:40:14
+   |
+LL |     pub fn capture_assign_whole(x: (i32,)) {
+   |                                 - help: consider changing this to be mutable: `mut x`
+LL |         || { x = (1,); };
+   |              ^^^^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x.0`, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:43:14
+   |
+LL |     pub fn capture_assign_part(x: (i32,)) {
+   |                                - help: consider changing this to be mutable: `mut x`
+LL |         || { x.0 = 1; };
+   |              ^^^^^^^ cannot assign
+
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:46:14
+   |
+LL |     pub fn capture_reborrow_whole(x: (i32,)) {
+   |                                   - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x; };
+   |              ^^^^^^ cannot borrow as mutable
+
+error[E0596]: cannot borrow `x.0` as mutable, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:49:14
+   |
+LL |     pub fn capture_reborrow_part(x: (i32,)) {
+   |                                  - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x.0; };
+   |              ^^^^^^^^ cannot borrow as mutable
+
+error: aborting due to 6 previous errors
+
+Some errors occurred: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr
new file mode 100644
index 00000000000..0ccddf0a67d
--- /dev/null
+++ b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr
@@ -0,0 +1,54 @@
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:21:46
+   |
+LL |     pub fn e(x: &'static mut isize) {
+   |              - help: consider changing this to be mutable: `mut x`
+LL |         static mut Y: isize = 3;
+LL |         let mut c1 = |y: &'static mut isize| x = y;
+   |                                              ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:30:50
+   |
+LL |     pub fn ee(x: &'static mut isize) {
+   |               - help: consider changing this to be mutable: `mut x`
+...
+LL |             let mut c2 = |y: &'static mut isize| x = y;
+   |                                                  ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:40:14
+   |
+LL |     pub fn capture_assign_whole(x: (i32,)) {
+   |                                 - help: consider changing this to be mutable: `mut x`
+LL |         || { x = (1,); };
+   |              ^^^^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x.0`, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:43:14
+   |
+LL |     pub fn capture_assign_part(x: (i32,)) {
+   |                                - help: consider changing this to be mutable: `mut x`
+LL |         || { x.0 = 1; };
+   |              ^^^^^^^ cannot assign
+
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:46:14
+   |
+LL |     pub fn capture_reborrow_whole(x: (i32,)) {
+   |                                   - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x; };
+   |              ^^^^^^ cannot borrow as mutable
+
+error[E0596]: cannot borrow `x.0` as mutable, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:49:14
+   |
+LL |     pub fn capture_reborrow_part(x: (i32,)) {
+   |                                  - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x.0; };
+   |              ^^^^^^^^ cannot borrow as mutable
+
+error: aborting due to 6 previous errors
+
+Some errors occurred: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.rs b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.rs
new file mode 100644
index 00000000000..25ad66a5d9b
--- /dev/null
+++ b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.rs
@@ -0,0 +1,61 @@
+// rust-lang/rust#55492: errors detected during MIR-borrowck's
+// analysis of a closure body may only be caught when AST-borrowck
+// looks at some parent.
+
+// revisions: ast migrate nll
+
+// Since we are testing nll (and migration) explicitly as a separate
+// revisions, don't worry about the --compare-mode=nll on this test.
+
+// ignore-compare-mode-nll
+
+//[ast]compile-flags: -Z borrowck=ast
+//[migrate]compile-flags: -Z borrowck=migrate -Z two-phase-borrows
+//[nll]compile-flags: -Z borrowck=mir -Z two-phase-borrows
+
+
+// transcribed from borrowck-closures-unique.rs
+mod borrowck_closures_unique {
+    pub fn e(x: &'static mut isize) {
+        static mut Y: isize = 3;
+        let mut c1 = |y: &'static mut isize| x = y;
+        unsafe { c1(&mut Y); }
+    }
+}
+
+mod borrowck_closures_unique_grandparent {
+    pub fn ee(x: &'static mut isize) {
+        static mut Z: isize = 3;
+        let mut c1 = |z: &'static mut isize| {
+            let mut c2 = |y: &'static mut isize| x = y;
+            c2(z);
+        };
+        unsafe { c1(&mut Z); }
+    }
+}
+
+// adapted from mutability_errors.rs
+mod mutability_errors {
+    pub fn capture_assign_whole(x: (i32,)) {
+        || { x = (1,); };
+    }
+    pub fn capture_assign_part(x: (i32,)) {
+        || { x.0 = 1; };
+    }
+    pub fn capture_reborrow_whole(x: (i32,)) {
+        || { &mut x; };
+    }
+    pub fn capture_reborrow_part(x: (i32,)) {
+        || { &mut x.0; };
+    }
+}
+
+fn main() {
+    static mut X: isize = 2;
+    unsafe { borrowck_closures_unique::e(&mut X); }
+
+    mutability_errors::capture_assign_whole((1000,));
+    mutability_errors::capture_assign_part((2000,));
+    mutability_errors::capture_reborrow_whole((3000,));
+    mutability_errors::capture_reborrow_part((4000,));
+}
diff --git a/src/test/ui/borrowck/mutability-errors.nll.stderr b/src/test/ui/borrowck/mutability-errors.nll.stderr
index bb45fe2da81..14c41bb81b2 100644
--- a/src/test/ui/borrowck/mutability-errors.nll.stderr
+++ b/src/test/ui/borrowck/mutability-errors.nll.stderr
@@ -277,7 +277,7 @@ LL |     &mut x; //~ ERROR
 LL |     &mut x.0; //~ ERROR
    |     ^^^^^^^^ cannot borrow as mutable
 
-warning[E0594]: cannot assign to `x`, as it is not declared as mutable
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
   --> $DIR/mutability-errors.rs:70:9
    |
 LL | fn imm_capture(x: (i32,)) {
@@ -285,12 +285,8 @@ LL | fn imm_capture(x: (i32,)) {
 LL |     || { //~ ERROR
 LL |         x = (1,);
    |         ^^^^^^^^ cannot assign
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-warning[E0594]: cannot assign to `x.0`, as `x` is not declared as mutable
+error[E0594]: cannot assign to `x.0`, as `x` is not declared as mutable
   --> $DIR/mutability-errors.rs:71:9
    |
 LL | fn imm_capture(x: (i32,)) {
@@ -298,12 +294,8 @@ LL | fn imm_capture(x: (i32,)) {
 ...
 LL |         x.0 = 1;
    |         ^^^^^^^ cannot assign
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-warning[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
   --> $DIR/mutability-errors.rs:72:9
    |
 LL | fn imm_capture(x: (i32,)) {
@@ -311,12 +303,8 @@ LL | fn imm_capture(x: (i32,)) {
 ...
 LL |         &mut x;
    |         ^^^^^^ cannot borrow as mutable
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-warning[E0596]: cannot borrow `x.0` as mutable, as `x` is not declared as mutable
+error[E0596]: cannot borrow `x.0` as mutable, as `x` is not declared as mutable
   --> $DIR/mutability-errors.rs:73:9
    |
 LL | fn imm_capture(x: (i32,)) {
@@ -324,10 +312,6 @@ LL | fn imm_capture(x: (i32,)) {
 ...
 LL |         &mut x.0;
    |         ^^^^^^^^ cannot borrow as mutable
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
 error[E0594]: cannot assign to `x`, as it is not declared as mutable
   --> $DIR/mutability-errors.rs:76:9
@@ -389,7 +373,7 @@ error[E0596]: cannot borrow `X.0` as mutable, as `X` is an immutable static item
 LL |     &mut X.0; //~ ERROR
    |     ^^^^^^^^ cannot borrow as mutable
 
-error: aborting due to 34 previous errors
+error: aborting due to 38 previous errors
 
 Some errors occurred: E0594, E0596.
 For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/consts/const-eval/issue-49296.rs b/src/test/ui/consts/const-eval/issue-49296.rs
new file mode 100644
index 00000000000..a7c3c5318d4
--- /dev/null
+++ b/src/test/ui/consts/const-eval/issue-49296.rs
@@ -0,0 +1,23 @@
+// issue-49296: Unsafe shenigans in constants can result in missing errors
+
+#![feature(const_fn)]
+#![feature(const_fn_union)]
+
+const unsafe fn transmute<T: Copy, U: Copy>(t: T) -> U {
+    union Transmute<T: Copy, U: Copy> {
+        from: T,
+        to: U,
+    }
+
+    Transmute { from: t }.to
+}
+
+const fn wat(x: u64) -> &'static u64 {
+    unsafe { transmute(&x) }
+}
+const X: u64 = *wat(42);
+//~^ ERROR any use of this value will cause an error
+
+fn main() {
+    println!("{}", X);
+}
diff --git a/src/test/ui/consts/const-eval/issue-49296.stderr b/src/test/ui/consts/const-eval/issue-49296.stderr
new file mode 100644
index 00000000000..37462db4c96
--- /dev/null
+++ b/src/test/ui/consts/const-eval/issue-49296.stderr
@@ -0,0 +1,12 @@
+error: any use of this value will cause an error
+  --> $DIR/issue-49296.rs:18:1
+   |
+LL | const X: u64 = *wat(42);
+   | ^^^^^^^^^^^^^^^--------^
+   |                |
+   |                dangling pointer was dereferenced
+   |
+   = note: #[deny(const_err)] on by default
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/consts/const-validation-fail-55455.rs b/src/test/ui/consts/const-validation-fail-55455.rs
new file mode 100644
index 00000000000..def4062339f
--- /dev/null
+++ b/src/test/ui/consts/const-validation-fail-55455.rs
@@ -0,0 +1,9 @@
+// https://github.com/rust-lang/rust/issues/55454
+// compile-pass
+
+struct This<T>(T);
+
+const C: This<Option<&i32>> = This(Some(&1));
+
+fn main() {
+}
diff --git a/src/test/ui/consts/promoted-validation-55454.rs b/src/test/ui/consts/promoted-validation-55454.rs
new file mode 100644
index 00000000000..5e193b1b7de
--- /dev/null
+++ b/src/test/ui/consts/promoted-validation-55454.rs
@@ -0,0 +1,9 @@
+// https://github.com/rust-lang/rust/issues/55454
+// compile-pass
+
+#[derive(PartialEq)]
+struct This<T>(T);
+
+fn main() {
+    This(Some(&1)) == This(Some(&1));
+}
diff --git a/src/test/ui/lint/unused_parens_json_suggestion.rs b/src/test/ui/lint/unused_parens_json_suggestion.rs
index 187e7f31dfd..9eda59614f4 100644
--- a/src/test/ui/lint/unused_parens_json_suggestion.rs
+++ b/src/test/ui/lint/unused_parens_json_suggestion.rs
@@ -23,4 +23,13 @@ fn main() {
     // We want to suggest the properly-balanced expression `1 / (2 + 3)`, not
     // the malformed `1 / (2 + 3`
     let _a = (1 / (2 + 3));
+    f();
+}
+
+fn f() -> bool {
+    loop {
+        if (break { return true }) {
+        }
+    }
+    false
 }
diff --git a/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.nll.stderr b/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.nll.stderr
index ee91ea3b66f..084d7ff3bcd 100644
--- a/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.nll.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.nll.stderr
@@ -33,7 +33,7 @@ LL |     let x = 0;
 LL |     move || set(&mut x); //~ ERROR cannot borrow
    |                 ^^^^^^ cannot borrow as mutable
 
-warning[E0594]: cannot assign to `x`, as it is not declared as mutable
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
   --> $DIR/unboxed-closure-immutable-capture.rs:23:8
    |
 LL |     let x = 0;
@@ -41,12 +41,8 @@ LL |     let x = 0;
 ...
 LL |     || x = 1; //~ ERROR cannot assign
    |        ^^^^^ cannot assign
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-warning[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
   --> $DIR/unboxed-closure-immutable-capture.rs:25:12
    |
 LL |     let x = 0;
@@ -54,12 +50,8 @@ LL |     let x = 0;
 ...
 LL |     || set(&mut x); //~ ERROR cannot assign
    |            ^^^^^^ cannot borrow as mutable
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-warning[E0594]: cannot assign to `x`, as it is not declared as mutable
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
   --> $DIR/unboxed-closure-immutable-capture.rs:26:8
    |
 LL |     let x = 0;
@@ -67,12 +59,8 @@ LL |     let x = 0;
 ...
 LL |     || x = 1; //~ ERROR cannot assign
    |        ^^^^^ cannot assign
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-warning[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
   --> $DIR/unboxed-closure-immutable-capture.rs:28:12
    |
 LL |     let x = 0;
@@ -80,12 +68,8 @@ LL |     let x = 0;
 ...
 LL |     || set(&mut x); //~ ERROR cannot assign
    |            ^^^^^^ cannot borrow as mutable
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
-error: aborting due to 4 previous errors
+error: aborting due to 8 previous errors
 
 Some errors occurred: E0594, E0596.
 For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.nll.stderr b/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.nll.stderr
index fa0aba96e18..718c3a19938 100644
--- a/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.nll.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.nll.stderr
@@ -1,4 +1,4 @@
-warning[E0596]: cannot borrow `tick1` as mutable, as it is not declared as mutable
+error[E0596]: cannot borrow `tick1` as mutable, as it is not declared as mutable
   --> $DIR/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.rs:27:9
    |
 LL |     let tick1 = || {
@@ -6,10 +6,6 @@ LL |     let tick1 = || {
 ...
 LL |         tick1();
    |         ^^^^^ cannot borrow as mutable
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
 error[E0596]: cannot borrow `tick2` as mutable, as it is not declared as mutable
   --> $DIR/unboxed-closures-infer-fnmut-calling-fnmut-no-mut.rs:30:5
@@ -20,6 +16,6 @@ LL |     let tick2 = || { //~ ERROR closure cannot assign to immutable local var
 LL |     tick2(); //~ ERROR cannot borrow
    |     ^^^^^ cannot borrow as mutable
 
-error: aborting due to previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0596`.
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.nll.stderr b/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.nll.stderr
index 9858b8db211..f765f207303 100644
--- a/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.nll.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.nll.stderr
@@ -1,4 +1,4 @@
-warning[E0594]: cannot assign to `n`, as it is not declared as mutable
+error[E0594]: cannot assign to `n`, as it is not declared as mutable
   --> $DIR/unboxed-closures-mutate-upvar.rs:25:9
    |
 LL |     let n = 0;
@@ -6,10 +6,6 @@ LL |     let n = 0;
 LL |     let mut f = to_fn_mut(|| { //~ ERROR closure cannot assign
 LL |         n += 1;
    |         ^^^^^^ cannot assign
-   |
-   = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
-           It represents potential unsoundness in your code.
-           This warning will become a hard error in the future.
 
 error[E0594]: cannot assign to `n`, as it is not declared as mutable
   --> $DIR/unboxed-closures-mutate-upvar.rs:42:9
@@ -44,6 +40,6 @@ LL | |         n += 1; //~ ERROR cannot assign
 LL | |     });
    | |_____^
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0594`.