Auto merge of #50847 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 10 pull requests

Successful merges:

 - #50387 (Remove leftover tab in libtest outputs)
 - #50553 (Add Option::xor method)
 - #50610 (Improve format string errors)
 - #50649 (Tweak `nearest_common_ancestor()`.)
 - #50790 (Fix grammar documentation wrt Unicode identifiers)
 - #50791 (Fix null exclusions in grammar docs)
 - #50806 (Add `bless` x.py subcommand for easy ui test replacement)
 - #50818 (Speed up `opt_normalize_projection_type`)
 - #50837 (Revert #49767)
 - #50839 (Make sure people know the book is free oline)

Failed merges:

src/test/COMPILER_TESTS.md

@@ -140,13 +140,9 @@ check that the test compiles successfully.
 ### Editing and updating the reference files
 
 If you have changed the compiler's output intentionally, or you are
-making a new test, you can use the script `ui/update-references.sh` to
-update the references. When you run the test framework, it will report
-various errors: in those errors is a command you can use to run the
-`ui/update-references.sh` script, which will then copy over the files
-from the build directory and use them as the new reference. You can
-also just run `ui/update-all-references.sh`. In both cases, you can run
-the script with `--help` to get a help message.
+making a new test, you can pass `--bless` to the command you used to
+run the tests. This will then copy over the files
+from the build directory and use them as the new reference.
 
 ### Normalization
 

src/test/ui/E0508.ast.nll.stderr

@@ -0,0 +1,9 @@
+error[E0508]: cannot move out of type `[NonCopy; 1]`, a non-copy array
+  --> $DIR/E0508.rs:18:18
+   |
+LL |     let _value = array[0];  //[ast]~ ERROR [E0508]
+   |                  ^^^^^^^^ cannot move out of here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0508`.

src/test/ui/E0508.ast.stderr

@@ -0,0 +1,12 @@
+error[E0508]: cannot move out of type `[NonCopy; 1]`, a non-copy array
+  --> $DIR/E0508.rs:18:18
+   |
+LL |     let _value = array[0];  //[ast]~ ERROR [E0508]
+   |                  ^^^^^^^^
+   |                  |
+   |                  cannot move out of here
+   |                  help: consider using a reference instead: `&array[0]`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0508`.

src/test/ui/E0508.mir.stderr

@@ -0,0 +1,9 @@
+error[E0508]: cannot move out of type `[NonCopy; 1]`, a non-copy array
+  --> $DIR/E0508.rs:18:18
+   |
+LL |     let _value = array[0];  //[ast]~ ERROR [E0508]
+   |                  ^^^^^^^^ cannot move out of here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0508`.

src/test/ui/E0508.rs

@@ -0,0 +1,20 @@
+// Copyright 2016 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.
+
+// revisions: ast mir
+//[mir]compile-flags: -Z borrowck=mir
+
+struct NonCopy;
+
+fn main() {
+    let array = [NonCopy; 1];
+    let _value = array[0];  //[ast]~ ERROR [E0508]
+                            //[mir]~^ ERROR [E0508]
+}

src/test/ui/fmt/format-string-error.rs

@@ -12,5 +12,14 @@ fn main() {
     println!("{");
     println!("{{}}");
     println!("}");
+    let _ = format!("{_foo}", _foo = 6usize);
+    //~^ ERROR invalid format string: invalid argument name `_foo`
+    let _ = format!("{_}", _ = 6usize);
+    //~^ ERROR invalid format string: invalid argument name `_`
+    let _ = format!("{");
+    //~^ ERROR invalid format string: expected `'}'` but string was terminated
+    let _ = format!("}");
+    //~^ ERROR invalid format string: unmatched `}` found
+    let _ = format!("{\\}");
+    //~^ ERROR invalid format string: expected `'}'`, found `'\\'`
 }
-

src/test/ui/fmt/format-string-error.stderr

@@ -2,7 +2,7 @@ error: invalid format string: expected `'}'` but string was terminated
   --> $DIR/format-string-error.rs:12:5
    |
 LL |     println!("{");
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^ expected `'}'` in format string
    |
    = note: if you intended to print `{`, you can escape it using `{{`
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
@@ -11,10 +11,48 @@ error: invalid format string: unmatched `}` found
   --> $DIR/format-string-error.rs:14:5
    |
 LL |     println!("}");
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^ unmatched `}` in format string
    |
    = note: if you intended to print `}`, you can escape it using `}}`
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
-error: aborting due to 2 previous errors
+error: invalid format string: invalid argument name `_foo`
+  --> $DIR/format-string-error.rs:15:23
+   |
+LL |     let _ = format!("{_foo}", _foo = 6usize);
+   |                       ^^^^ invalid argument name in format string
+   |
+   = note: argument names cannot start with an underscore
+
+error: invalid format string: invalid argument name `_`
+  --> $DIR/format-string-error.rs:17:23
+   |
+LL |     let _ = format!("{_}", _ = 6usize);
+   |                       ^ invalid argument name in format string
+   |
+   = note: argument names cannot start with an underscore
+
+error: invalid format string: expected `'}'` but string was terminated
+  --> $DIR/format-string-error.rs:19:23
+   |
+LL |     let _ = format!("{");
+   |                       ^ expected `'}'` in format string
+   |
+   = note: if you intended to print `{`, you can escape it using `{{`
+
+error: invalid format string: unmatched `}` found
+  --> $DIR/format-string-error.rs:21:22
+   |
+LL |     let _ = format!("}");
+   |                      ^ unmatched `}` in format string
+   |
+   = note: if you intended to print `}`, you can escape it using `}}`
+
+error: invalid format string: expected `'}'`, found `'/'`
+  --> $DIR/format-string-error.rs:23:23
+   |
+LL |     let _ = format!("{/}");
+   |                       ^ expected `}` in format string
+
+error: aborting due to 7 previous errors