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:

1 files changed, 12 insertions, 0 deletions

diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index 5315a3028ff..90dd5d819b0 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -59,6 +59,8 @@ pub enum Subcommand {
     },
     Test {
         paths: Vec<PathBuf>,
+        /// Whether to automatically update stderr/stdout files
+        bless: bool,
         test_args: Vec<String>,
         rustc_args: Vec<String>,
         fail_fast: bool,
@@ -173,6 +175,7 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`");
                 );
                 opts.optflag("", "no-doc", "do not run doc tests");
                 opts.optflag("", "doc", "only run doc tests");
+                opts.optflag("", "bless", "update all stderr/stdout files of failing ui tests");
             },
             "bench" => { opts.optmulti("", "test-args", "extra arguments", "ARGS"); },
             "clean" => { opts.optflag("", "all", "clean all build artifacts"); },
@@ -258,6 +261,7 @@ Arguments:
         ./x.py test src/test/run-pass
         ./x.py test src/libstd --test-args hash_map
         ./x.py test src/libstd --stage 0
+        ./x.py test src/test/ui --bless
 
     If no arguments are passed then the complete artifacts for that stage are
     compiled and tested.
@@ -322,6 +326,7 @@ Arguments:
             "test" => {
                 Subcommand::Test {
                     paths,
+                    bless: matches.opt_present("bless"),
                     test_args: matches.opt_strs("test-args"),
                     rustc_args: matches.opt_strs("rustc-args"),
                     fail_fast: !matches.opt_present("no-fail-fast"),
@@ -424,6 +429,13 @@ impl Subcommand {
             _ => DocTests::Yes,
         }
     }
+
+    pub fn bless(&self) -> bool {
+        match *self {
+            Subcommand::Test { bless, .. } => bless,
+            _ => false,
+        }
+    }
 }
 
 fn split(s: Vec<String>) -> Vec<String> {