Auto merge of #128761 - matthiaskrgr:rollup-5p1mlqq, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #124944 (On trait bound mismatch, detect multiple crate versions in dep tree)
 - #125048 (PinCoerceUnsized trait into core)
 - #128406 (implement BufReader::peek)
 - #128539 (Forbid unused unsafe in vxworks-specific std modules)
 - #128687 (interpret: refactor function call handling to be better-abstracted)
 - #128692 (Add a triagebot mention for `library/Cargo.lock`)
 - #128710 (Don't ICE when getting an input file name's stem fails)
 - #128718 (Consider `cfg_attr` checked by `CheckAttrVisitor`)
 - #128751 (std::thread: set_name implementation proposal for vxWorks.)

r? `@ghost`
`@rustbot` modify labels: rollup

2 files changed, 34 insertions, 2 deletions

diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index e1dcbf5b280..67ca6d50cca 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -741,6 +741,16 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     }
 
+    #[rustc_lint_diagnostics]
+    pub fn highlighted_span_note(
+        &mut self,
+        span: impl Into<MultiSpan>,
+        msg: Vec<StringPart>,
+    ) -> &mut Self {
+        self.sub_with_highlights(Level::Note, msg, span.into());
+        self
+    }
+
     /// This is like [`Diag::note()`], but it's only printed once.
     #[rustc_lint_diagnostics]
     pub fn note_once(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
@@ -815,6 +825,17 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     }
 
+    /// Add a help message attached to this diagnostic with a customizable highlighted message.
+    #[rustc_lint_diagnostics]
+    pub fn highlighted_span_help(
+        &mut self,
+        span: impl Into<MultiSpan>,
+        msg: Vec<StringPart>,
+    ) -> &mut Self {
+        self.sub_with_highlights(Level::Help, msg, span.into());
+        self
+    }
+
     /// Prints the span with some help above it.
     /// This is like [`Diag::help()`], but it gets its own span.
     #[rustc_lint_diagnostics]
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 483b757f20c..88ed3128164 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -1347,7 +1347,7 @@ impl HumanEmitter {
                 label_width += 2;
             }
             let mut line = 0;
-            for (text, _) in msgs.iter() {
+            for (text, style) in msgs.iter() {
                 let text = self.translate_message(text, args).map_err(Report::new).unwrap();
                 // Account for newlines to align output to its label.
                 for text in normalize_whitespace(&text).lines() {
@@ -1358,10 +1358,21 @@ impl HumanEmitter {
                             if line == 0 { String::new() } else { " ".repeat(label_width) },
                             text
                         ),
-                        header_style,
+                        match style {
+                            Style::Highlight => *style,
+                            _ => header_style,
+                        },
                     );
                     line += 1;
                 }
+                // We add lines above, but if the last line has no explicit newline (which would
+                // yield an empty line), then we revert one line up to continue with the next
+                // styled text chunk on the same line as the last one from the prior one. Otherwise
+                // every `text` would appear on their own line (because even though they didn't end
+                // in '\n', they advanced `line` by one).
+                if line > 0 {
+                    line -= 1;
+                }
             }
             if self.short_message {
                 let labels = msp