Workaround #49855 by forcing rustc_error in any mode, including NLL.

NOTE: I was careful to make each change in a manner that preserves the
existing diagnostic output (usually by ensuring that no lines were
added or removed). This means that the resulting source files are not
as nice to read as they were at the start. But we will have to review
these cases by hand anyway as follow-up work, so cleanup could
reasonably happen then (or not at all).

src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.rs

@@ -7,9 +7,9 @@
 // <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.
-
+#![feature(rustc_attrs)]
 #![allow(dead_code)]
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     // Original borrow ends at end of function
     let mut x = 1;
     let y = &mut x;

src/test/ui/borrowck/mut-borrow-outside-loop.rs

@@ -9,8 +9,8 @@
 // except according to those terms.
 
 // ensure borrowck messages are correct outside special case
-
-fn main() {
+#![feature(rustc_attrs)]
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut void = ();
 
     let first = &mut void;

src/test/ui/codemap_tests/issue-11715.rs

@@ -93,8 +93,8 @@
 
 
 
-
-fn main() {
+#![feature(rustc_attrs)]
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut x = "foo";
     let y = &mut x;
     let z = &mut x; //~ ERROR cannot borrow

src/test/ui/dropck/dropck-eyepatch-extern-crate.rs

@@ -19,12 +19,12 @@
 //
 // See also dropck-eyepatch.rs for more information about the general
 // structure of the test.
-
+#![feature(rustc_attrs)]
 extern crate dropck_eyepatch_extern_crate as other;
 
 use other::{Dt,Dr,Pt,Pr,St,Sr};
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     use std::cell::Cell;
     let c_long;
     let (c, mut dt, mut dr, mut pt, mut pr, st, sr)

src/test/ui/dropck/dropck-eyepatch-reorder.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(dropck_eyepatch)]
+#![feature(dropck_eyepatch, rustc_attrs)]
 
 // The point of this test is to test uses of `#[may_dangle]` attribute
 // where the formal declaration order (in the impl generics) does not
@@ -41,7 +41,7 @@ unsafe impl<'b, #[may_dangle] 'a, B: fmt::Debug> Drop for Pr<'a, 'b, B> {
     fn drop(&mut self) { println!("drop {} {:?}", self.0, self.2); }
 }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     use std::cell::Cell;
     let c_long;
     let (c, mut dt, mut dr, mut pt, mut pr, st, sr)

src/test/ui/dropck/dropck-eyepatch.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(dropck_eyepatch)]
+#![feature(dropck_eyepatch, rustc_attrs)]
 
 // The point of this test is to illustrate that the `#[may_dangle]`
 // attribute specifically allows, in the context of a type
@@ -64,7 +64,7 @@ unsafe impl<#[may_dangle] 'a, 'b, B: fmt::Debug> Drop for Pr<'a, 'b, B> {
     fn drop(&mut self) { println!("drop {} {:?}", self.0, self.2); }
 }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     use std::cell::Cell;
     let c_long;
     let (c, mut dt, mut dr, mut pt, mut pr, st, sr)

src/test/ui/error-codes/E0499.rs

@@ -7,8 +7,8 @@
 // <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 main() {
+#![feature(rustc_attrs)]
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut i = 0;
     let mut x = &mut i;
     let mut a = &mut i; //~ ERROR E0499

src/test/ui/error-codes/E0502.rs

@@ -7,12 +7,12 @@
 // <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.
-
+#![feature(rustc_attrs)]
 fn bar(x: &mut i32) {}
 fn foo(a: &mut i32) {
     let ref y = a;
     bar(a); //~ ERROR E0502
 }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
 }

src/test/ui/error-codes/E0503.rs

@@ -7,8 +7,8 @@
 // <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 main() {
+#![feature(rustc_attrs)]
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut value = 3;
     let _borrow = &mut value;
     let _sum = value + 1; //~ ERROR E0503

src/test/ui/error-codes/E0505.rs

@@ -7,12 +7,12 @@
 // <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.
-
+#![feature(rustc_attrs)]
 struct Value {}
 
 fn eat(val: Value) {}
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let x = Value{};
     {
         let _ref_to_val: &Value = &x;

src/test/ui/error-codes/E0597.rs

@@ -7,12 +7,12 @@
 // <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.
-
+#![feature(rustc_attrs)]
 struct Foo<'a> {
     x: Option<&'a u32>,
 }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut x = Foo { x: None };
     let y = 0;
     x.x = Some(&y);

src/test/ui/feature-gate-nll.rs

@@ -7,10 +7,10 @@
 // <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.
-
+#![feature(rustc_attrs)]
 #![allow(dead_code)]
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut x = 33;
 
     let p = &x;

src/test/ui/generator/borrowing.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(generators, generator_trait)]
+#![feature(generators, generator_trait, rustc_attrs)]
 
 use std::ops::Generator;
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let _b = {
         let a = 3;
         unsafe { (|| yield &a).resume() }

src/test/ui/generator/dropck.rs

@@ -8,12 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(generators, generator_trait, box_leak)]
+#![feature(generators, generator_trait, box_leak, rustc_attrs)]
 
 use std::cell::RefCell;
 use std::ops::Generator;
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let (cell, mut gen);
     cell = Box::new(RefCell::new(0));
     let ref_ = Box::leak(Box::new(Some(cell.borrow_mut())));

src/test/ui/generator/pattern-borrow.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(generators)]
+#![feature(generators, rustc_attrs)]
 
 enum Test { A(i32), B, }
 
-fn main() { }
+fn main() { #![rustc_error] } // rust-lang/rust#49855
 
 fn fun(test: Test) {
     move || {

src/test/ui/issue-17263.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(box_syntax)]
+#![feature(box_syntax, rustc_attrs)]
 
 struct Foo { a: isize, b: isize }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut x: Box<_> = box Foo { a: 1, b: 2 };
     let (a, b) = (&mut x.a, &mut x.b);
     //~^ ERROR cannot borrow `x` (via `x.b`) as mutable more than once at a time

src/test/ui/issue-25793.rs

@@ -7,7 +7,7 @@
 // <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.
-
+#![feature(rustc_attrs)]
 macro_rules! width(
     ($this:expr) => {
         $this.width.unwrap()
@@ -29,4 +29,4 @@ impl HasInfo {
     }
 }
 
-fn main() {}
+fn main() { #![rustc_error] } // rust-lang/rust#49855

src/test/ui/issue-42106.rs

@@ -7,10 +7,10 @@
 // <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.
-
+#![feature(rustc_attrs)]
 fn do_something<T>(collection: &mut Vec<T>) {
     let _a = &collection;
     collection.swap(1, 2); //~ ERROR also borrowed as immutable
 }
 
-fn main() {}
+fn main() { #![rustc_error] } // rust-lang/rust#49855

src/test/ui/lifetimes/borrowck-let-suggestion.rs

@@ -7,11 +7,11 @@
 // <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.
-
+#![feature(rustc_attrs)]
 fn f() {
     let x = vec![1].iter();
 }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     f();
 }

src/test/ui/span/borrowck-let-suggestion-suffixes.rs

@@ -7,7 +7,7 @@
 // <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.
-
+#![feature(rustc_attrs)]
 fn id<T>(x: T) -> T { x }
 
 fn f() {
@@ -58,6 +58,6 @@ fn f() {
 //~| NOTE temporary value needs to live until here
 //~| NOTE temporary value needs to live until here
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     f();
 }

src/test/ui/span/issue-36537.rs

@@ -7,8 +7,8 @@
 // <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 main() {
+#![feature(rustc_attrs)]
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let p;
     let a = 42;
     p = &a;

src/test/ui/span/mut-ptr-cant-outlive-ref.rs

@@ -7,10 +7,10 @@
 // <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.
-
+#![feature(rustc_attrs)]
 use std::cell::RefCell;
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let m = RefCell::new(0);
     let p;
     {

src/test/ui/span/range-2.rs

@@ -9,8 +9,8 @@
 // except according to those terms.
 
 // Test range syntax - borrow errors.
-
-pub fn main() {
+#![feature(rustc_attrs)]
+pub fn main() { #![rustc_error] // rust-lang/rust#49855
     let r = {
         let a = 42;
         let b = 42;

src/test/ui/span/regionck-unboxed-closure-lifetimes.rs

@@ -7,10 +7,10 @@
 // <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.
-
+#![feature(rustc_attrs)]
 use std::ops::FnMut;
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut f;
     {
         let c = 1;

src/test/ui/span/slice-borrow.rs

@@ -7,10 +7,10 @@
 // <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.
-
+#![feature(rustc_attrs)]
 // Test slicing expressions doesn't defeat the borrow checker.
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let y;
     {
         let x: &[isize] = &vec![1, 2, 3, 4, 5];

src/test/ui/span/vec_refs_data_with_early_death.rs

@@ -17,8 +17,8 @@
 //  element it owns; thus, for data like this, it seems like we could
 //  loosen the restrictions here if we wanted. But it also is not
 //  clear whether such loosening is terribly important.)
-
-fn main() {
+#![feature(rustc_attrs)]
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let mut v = Vec::new();
 
     let x: i8 = 3;

src/test/ui/span/wf-method-late-bound-regions.rs

@@ -11,7 +11,7 @@
 // A method's receiver must be well-formed, even if it has late-bound regions.
 // Because of this, a method's substs being well-formed does not imply that
 // the method's implied bounds are met.
-
+#![feature(rustc_attrs)]
 struct Foo<'b>(Option<&'b ()>);
 
 trait Bar<'b> {
@@ -22,7 +22,7 @@ impl<'b> Bar<'b> for Foo<'b> {
     fn xmute<'a>(&'a self, u: &'b u32) -> &'a u32 { u }
 }
 
-fn main() {
+fn main() { #![rustc_error] // rust-lang/rust#49855
     let f = Foo(None);
     let f2 = f;
     let dangling = {