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, 6 insertions, 3 deletions

diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs
index f29cc75664d..b22098408a3 100644
--- a/src/libsyntax_ext/format.rs
+++ b/src/libsyntax_ext/format.rs
@@ -767,9 +767,12 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt,
     }
 
     if !parser.errors.is_empty() {
-        let (err, note) = parser.errors.remove(0);
-        let mut e = cx.ecx.struct_span_err(cx.fmtsp, &format!("invalid format string: {}", err));
-        if let Some(note) = note {
+        let err = parser.errors.remove(0);
+        let sp = cx.fmtsp.from_inner_byte_pos(err.start, err.end);
+        let mut e = cx.ecx.struct_span_err(sp, &format!("invalid format string: {}",
+                                                        err.description));
+        e.span_label(sp, err.label + " in format string");
+        if let Some(note) = err.note {
             e.note(&note);
         }
         e.emit();