Merging upstream version 1.73.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

13 files changed, 334 insertions, 293 deletions

diff --git a/compiler/rustc_errors/Cargo.toml b/compiler/rustc_errors/Cargo.toml
index e8bcd7c11..faab9f09d 100644
--- a/compiler/rustc_errors/Cargo.toml
+++ b/compiler/rustc_errors/Cargo.toml
@@ -25,6 +25,7 @@ annotate-snippets = "0.9"
 termize = "0.1.1"
 serde = { version = "1.0.125", features = [ "derive" ] }
 serde_json = "1.0.59"
+derive_setters = "0.1.6"
 
 [target.'cfg(windows)'.dependencies.windows]
 version = "0.48.0"
diff --git a/compiler/rustc_errors/messages.ftl b/compiler/rustc_errors/messages.ftl
index 8e8223c3c..d68dba0be 100644
--- a/compiler/rustc_errors/messages.ftl
+++ b/compiler/rustc_errors/messages.ftl
@@ -1,3 +1,25 @@
+errors_delayed_at_with_newline =
+    delayed at {$emitted_at}
+    {$note}
+
+errors_delayed_at_without_newline =
+    delayed at {$emitted_at} - {$note}
+
+errors_expected_lifetime_parameter =
+    expected lifetime {$count ->
+        [1] parameter
+        *[other] parameters
+    }
+
+errors_indicate_anonymous_lifetime =
+    indicate the anonymous {$count ->
+        [1] lifetime
+        *[other] lifetimes
+    }
+
+errors_invalid_flushed_delayed_diagnostic_level =
+    `flushed_delayed` got diagnostic with level {$level}, instead of the expected `DelayedBug`
+
 errors_target_inconsistent_architecture =
     inconsistent target specification: "data-layout" claims architecture is {$dl}-endian, while "target-endian" is `{$target}`
 
diff --git a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
index 9872b3bda..a88fba6da 100644
--- a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
+++ b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
@@ -157,10 +157,8 @@ impl AnnotateSnippetEmitterWriter {
             {
                 annotated_files.swap(0, pos);
             }
-            // owned: line source, line index, annotations
-            type Owned = (String, usize, Vec<crate::snippet::Annotation>);
-            let filename = source_map.filename_for_diagnostics(&primary_lo.file.name);
-            let origin = filename.to_string_lossy();
+            // owned: file name, line source, line index, annotations
+            type Owned = (String, String, usize, Vec<crate::snippet::Annotation>);
             let annotated_files: Vec<Owned> = annotated_files
                 .into_iter()
                 .flat_map(|annotated_file| {
@@ -169,7 +167,15 @@ impl AnnotateSnippetEmitterWriter {
                         .lines
                         .into_iter()
                         .map(|line| {
-                            (source_string(file.clone(), &line), line.line_index, line.annotations)
+                            // Ensure the source file is present before we try
+                            // to load a string from it.
+                            source_map.ensure_source_file_source_present(file.clone());
+                            (
+                                format!("{}", source_map.filename_for_diagnostics(&file.name)),
+                                source_string(file.clone(), &line),
+                                line.line_index,
+                                line.annotations,
+                            )
                         })
                         .collect::<Vec<Owned>>()
                 })
@@ -192,11 +198,11 @@ impl AnnotateSnippetEmitterWriter {
                 },
                 slices: annotated_files
                     .iter()
-                    .map(|(source, line_index, annotations)| {
+                    .map(|(file_name, source, line_index, annotations)| {
                         Slice {
                             source,
                             line_start: *line_index,
-                            origin: Some(&origin),
+                            origin: Some(&file_name),
                             // FIXME(#59346): Not really sure when `fold` should be true or false
                             fold: false,
                             annotations: annotations
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index ed0d06ed0..a96e317df 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -420,13 +420,13 @@ impl Diagnostic {
         let expected_label = if expected_label.is_empty() {
             "expected".to_string()
         } else {
-            format!("expected {}", expected_label)
+            format!("expected {expected_label}")
         };
         let found_label = found_label.to_string();
         let found_label = if found_label.is_empty() {
             "found".to_string()
         } else {
-            format!("found {}", found_label)
+            format!("found {found_label}")
         };
         let (found_padding, expected_padding) = if expected_label.len() > found_label.len() {
             (expected_label.len() - found_label.len(), 0)
@@ -439,13 +439,13 @@ impl Diagnostic {
             StringPart::Normal(ref s) => (s.to_owned(), Style::NoStyle),
             StringPart::Highlighted(ref s) => (s.to_owned(), Style::Highlight),
         }));
-        msg.push((format!("`{}\n", expected_extra), Style::NoStyle));
+        msg.push((format!("`{expected_extra}\n"), Style::NoStyle));
         msg.push((format!("{}{} `", " ".repeat(found_padding), found_label), Style::NoStyle));
         msg.extend(found.0.iter().map(|x| match *x {
             StringPart::Normal(ref s) => (s.to_owned(), Style::NoStyle),
             StringPart::Highlighted(ref s) => (s.to_owned(), Style::Highlight),
         }));
-        msg.push((format!("`{}", found_extra), Style::NoStyle));
+        msg.push((format!("`{found_extra}"), Style::NoStyle));
 
         // For now, just attach these as notes.
         self.highlighted_note(msg);
@@ -454,7 +454,7 @@ impl Diagnostic {
 
     pub fn note_trait_signature(&mut self, name: Symbol, signature: String) -> &mut Self {
         self.highlighted_note(vec![
-            (format!("`{}` from trait: `", name), Style::NoStyle),
+            (format!("`{name}` from trait: `"), Style::NoStyle),
             (signature, Style::Highlight),
             ("`".to_string(), Style::NoStyle),
         ]);
diff --git a/compiler/rustc_errors/src/diagnostic_builder.rs b/compiler/rustc_errors/src/diagnostic_builder.rs
index 08ff2cfba..5e23ae655 100644
--- a/compiler/rustc_errors/src/diagnostic_builder.rs
+++ b/compiler/rustc_errors/src/diagnostic_builder.rs
@@ -536,7 +536,9 @@ impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
             }
         };
 
-        if handler.flags.dont_buffer_diagnostics || handler.flags.treat_err_as_bug.is_some() {
+        if handler.inner.lock().flags.dont_buffer_diagnostics
+            || handler.inner.lock().flags.treat_err_as_bug.is_some()
+        {
             self.emit();
             return None;
         }
diff --git a/compiler/rustc_errors/src/diagnostic_impls.rs b/compiler/rustc_errors/src/diagnostic_impls.rs
index 10fe7fc74..a170e3a89 100644
--- a/compiler/rustc_errors/src/diagnostic_impls.rs
+++ b/compiler/rustc_errors/src/diagnostic_impls.rs
@@ -1,3 +1,4 @@
+use crate::diagnostic::DiagnosticLocation;
 use crate::{fluent_generated as fluent, AddToDiagnostic};
 use crate::{DiagnosticArgValue, DiagnosticBuilder, Handler, IntoDiagnostic, IntoDiagnosticArg};
 use rustc_ast as ast;
@@ -10,6 +11,7 @@ use rustc_span::Span;
 use rustc_target::abi::TargetDataLayoutErrors;
 use rustc_target::spec::{PanicStrategy, SplitDebuginfo, StackProtector, TargetTriple};
 use rustc_type_ir as type_ir;
+use std::backtrace::Backtrace;
 use std::borrow::Cow;
 use std::fmt;
 use std::num::ParseIntError;
@@ -102,7 +104,7 @@ impl IntoDiagnosticArg for bool {
 
 impl IntoDiagnosticArg for char {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
-        DiagnosticArgValue::Str(Cow::Owned(format!("{:?}", self)))
+        DiagnosticArgValue::Str(Cow::Owned(format!("{self:?}")))
     }
 }
 
@@ -164,6 +166,12 @@ impl IntoDiagnosticArg for hir::ConstContext {
     }
 }
 
+impl IntoDiagnosticArg for ast::Expr {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::Owned(pprust::expr_to_string(&self)))
+    }
+}
+
 impl IntoDiagnosticArg for ast::Path {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
         DiagnosticArgValue::Str(Cow::Owned(pprust::path_to_string(&self)))
@@ -311,3 +319,62 @@ pub enum LabelKind {
     Label,
     Help,
 }
+
+#[derive(Subdiagnostic)]
+#[label(errors_expected_lifetime_parameter)]
+pub struct ExpectedLifetimeParameter {
+    #[primary_span]
+    pub span: Span,
+    pub count: usize,
+}
+
+#[derive(Subdiagnostic)]
+#[note(errors_delayed_at_with_newline)]
+pub struct DelayedAtWithNewline {
+    #[primary_span]
+    pub span: Span,
+    pub emitted_at: DiagnosticLocation,
+    pub note: Backtrace,
+}
+#[derive(Subdiagnostic)]
+#[note(errors_delayed_at_without_newline)]
+pub struct DelayedAtWithoutNewline {
+    #[primary_span]
+    pub span: Span,
+    pub emitted_at: DiagnosticLocation,
+    pub note: Backtrace,
+}
+
+impl IntoDiagnosticArg for DiagnosticLocation {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::from(self.to_string()))
+    }
+}
+
+impl IntoDiagnosticArg for Backtrace {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::from(self.to_string()))
+    }
+}
+
+#[derive(Subdiagnostic)]
+#[note(errors_invalid_flushed_delayed_diagnostic_level)]
+pub struct InvalidFlushedDelayedDiagnosticLevel {
+    #[primary_span]
+    pub span: Span,
+    pub level: rustc_errors::Level,
+}
+impl IntoDiagnosticArg for rustc_errors::Level {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::from(self.to_string()))
+    }
+}
+
+#[derive(Subdiagnostic)]
+#[suggestion(errors_indicate_anonymous_lifetime, code = "{suggestion}", style = "verbose")]
+pub struct IndicateAnonymousLifetime {
+    #[primary_span]
+    pub span: Span,
+    pub count: usize,
+    pub suggestion: String,
+}
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 9d4d159fd..0cae06881 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -7,8 +7,6 @@
 //!
 //! The output types are defined in `rustc_session::config::ErrorOutputType`.
 
-use Destination::*;
-
 use rustc_span::source_map::SourceMap;
 use rustc_span::{FileLines, SourceFile, Span};
 
@@ -24,6 +22,7 @@ use crate::{
 };
 use rustc_lint_defs::pluralize;
 
+use derive_setters::Setters;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::sync::Lrc;
 use rustc_error_messages::{FluentArgs, SpanLabel};
@@ -35,8 +34,8 @@ use std::io::prelude::*;
 use std::io::{self, IsTerminal};
 use std::iter;
 use std::path::Path;
-use termcolor::{Ansi, BufferWriter, ColorChoice, ColorSpec, StandardStream};
-use termcolor::{Buffer, Color, WriteColor};
+use termcolor::{Ansi, Buffer, BufferWriter, ColorChoice, ColorSpec, StandardStream};
+use termcolor::{Color, WriteColor};
 
 /// Default column width, used in tests and when terminal dimensions cannot be determined.
 const DEFAULT_COLUMN_WIDTH: usize = 140;
@@ -60,31 +59,15 @@ impl HumanReadableErrorType {
     }
     pub fn new_emitter(
         self,
-        dst: Box<dyn Write + Send>,
-        source_map: Option<Lrc<SourceMap>>,
-        bundle: Option<Lrc<FluentBundle>>,
+        mut dst: Box<dyn WriteColor + Send>,
         fallback_bundle: LazyFallbackBundle,
-        teach: bool,
-        diagnostic_width: Option<usize>,
-        macro_backtrace: bool,
-        track_diagnostics: bool,
-        terminal_url: TerminalUrl,
     ) -> EmitterWriter {
         let (short, color_config) = self.unzip();
         let color = color_config.suggests_using_colors();
-        EmitterWriter::new(
-            dst,
-            source_map,
-            bundle,
-            fallback_bundle,
-            short,
-            teach,
-            color,
-            diagnostic_width,
-            macro_backtrace,
-            track_diagnostics,
-            terminal_url,
-        )
+        if !dst.supports_color() && color {
+            dst = Box::new(Ansi::new(dst));
+        }
+        EmitterWriter::new(dst, fallback_bundle).short_message(short)
     }
 }
 
@@ -279,12 +262,12 @@ pub trait Emitter: Translate {
                 let msg = if substitution.is_empty() || sugg.style.hide_inline() {
                     // This substitution is only removal OR we explicitly don't want to show the
                     // code inline (`hide_inline`). Therefore, we don't show the substitution.
-                    format!("help: {}", &msg)
+                    format!("help: {msg}")
                 } else {
                     // Show the default suggestion text with the substitution
                     format!(
                         "help: {}{}: `{}`",
-                        &msg,
+                        msg,
                         if self.source_map().is_some_and(|sm| is_case_difference(
                             sm,
                             substitution,
@@ -639,10 +622,13 @@ impl ColorConfig {
 }
 
 /// Handles the writing of `HumanReadableErrorType::Default` and `HumanReadableErrorType::Short`
+#[derive(Setters)]
 pub struct EmitterWriter {
+    #[setters(skip)]
     dst: Destination,
     sm: Option<Lrc<SourceMap>>,
     fluent_bundle: Option<Lrc<FluentBundle>>,
+    #[setters(skip)]
     fallback_bundle: LazyFallbackBundle,
     short_message: bool,
     teach: bool,
@@ -662,65 +648,32 @@ pub struct FileWithAnnotatedLines {
 }
 
 impl EmitterWriter {
-    pub fn stderr(
-        color_config: ColorConfig,
-        source_map: Option<Lrc<SourceMap>>,
-        fluent_bundle: Option<Lrc<FluentBundle>>,
-        fallback_bundle: LazyFallbackBundle,
-        short_message: bool,
-        teach: bool,
-        diagnostic_width: Option<usize>,
-        macro_backtrace: bool,
-        track_diagnostics: bool,
-        terminal_url: TerminalUrl,
-    ) -> EmitterWriter {
-        let dst = Destination::from_stderr(color_config);
+    pub fn stderr(color_config: ColorConfig, fallback_bundle: LazyFallbackBundle) -> EmitterWriter {
+        let dst = from_stderr(color_config);
+        Self::create(dst, fallback_bundle)
+    }
+
+    fn create(dst: Destination, fallback_bundle: LazyFallbackBundle) -> EmitterWriter {
         EmitterWriter {
             dst,
-            sm: source_map,
-            fluent_bundle,
+            sm: None,
+            fluent_bundle: None,
             fallback_bundle,
-            short_message,
-            teach,
+            short_message: false,
+            teach: false,
             ui_testing: false,
-            diagnostic_width,
-            macro_backtrace,
-            track_diagnostics,
-            terminal_url,
+            diagnostic_width: None,
+            macro_backtrace: false,
+            track_diagnostics: false,
+            terminal_url: TerminalUrl::No,
         }
     }
 
     pub fn new(
-        dst: Box<dyn Write + Send>,
-        source_map: Option<Lrc<SourceMap>>,
-        fluent_bundle: Option<Lrc<FluentBundle>>,
+        dst: Box<dyn WriteColor + Send>,
         fallback_bundle: LazyFallbackBundle,
-        short_message: bool,
-        teach: bool,
-        colored: bool,
-        diagnostic_width: Option<usize>,
-        macro_backtrace: bool,
-        track_diagnostics: bool,
-        terminal_url: TerminalUrl,
     ) -> EmitterWriter {
-        EmitterWriter {
-            dst: Raw(dst, colored),
-            sm: source_map,
-            fluent_bundle,
-            fallback_bundle,
-            short_message,
-            teach,
-            ui_testing: false,
-            diagnostic_width,
-            macro_backtrace,
-            track_diagnostics,
-            terminal_url,
-        }
-    }
-
-    pub fn ui_testing(mut self, ui_testing: bool) -> Self {
-        self.ui_testing = ui_testing;
-        self
+        Self::create(dst, fallback_bundle)
     }
 
     fn maybe_anonymized(&self, line_num: usize) -> Cow<'static, str> {
@@ -1982,7 +1935,7 @@ impl EmitterWriter {
                 // We special case `#[derive(_)]\n` and other attribute suggestions, because those
                 // are the ones where context is most useful.
                 let file_lines = sm
-                    .span_to_lines(span.primary_span().unwrap().shrink_to_hi())
+                    .span_to_lines(parts[0].span.shrink_to_hi())
                     .expect("span_to_lines failed when emitting suggestion");
                 let line_num = sm.lookup_char_pos(parts[0].span.lo()).line;
                 if let Some(line) = file_lines.file.get_line(line_num - 1) {
@@ -2145,7 +2098,7 @@ impl EmitterWriter {
                         &mut self.dst,
                         self.short_message,
                     ) {
-                        panic!("failed to emit error: {}", e)
+                        panic!("failed to emit error: {e}")
                     }
                 }
                 if !self.short_message {
@@ -2161,7 +2114,7 @@ impl EmitterWriter {
                             true,
                             None,
                         ) {
-                            panic!("failed to emit error: {}", err);
+                            panic!("failed to emit error: {err}");
                         }
                     }
                     for sugg in suggestions {
@@ -2180,7 +2133,7 @@ impl EmitterWriter {
                                     true,
                                     None,
                                 ) {
-                                    panic!("failed to emit error: {}", e);
+                                    panic!("failed to emit error: {e}");
                                 }
                             }
                             SuggestionStyle::HideCodeInline
@@ -2193,22 +2146,21 @@ impl EmitterWriter {
                                     &Level::Help,
                                     max_line_num_len,
                                 ) {
-                                    panic!("failed to emit error: {}", e);
+                                    panic!("failed to emit error: {e}");
                                 }
                             }
                         }
                     }
                 }
             }
-            Err(e) => panic!("failed to emit error: {}", e),
+            Err(e) => panic!("failed to emit error: {e}"),
         }
 
-        let mut dst = self.dst.writable();
-        match writeln!(dst) {
-            Err(e) => panic!("failed to emit error: {}", e),
+        match writeln!(self.dst) {
+            Err(e) => panic!("failed to emit error: {e}"),
             _ => {
-                if let Err(e) = dst.flush() {
-                    panic!("failed to emit error: {}", e)
+                if let Err(e) = self.dst.flush() {
+                    panic!("failed to emit error: {e}")
                 }
             }
         }
@@ -2618,8 +2570,6 @@ fn emit_to_destination(
 ) -> io::Result<()> {
     use crate::lock;
 
-    let mut dst = dst.writable();
-
     // In order to prevent error message interleaving, where multiple error lines get intermixed
     // when multiple compiler processes error simultaneously, we emit errors with additional
     // steps.
@@ -2635,7 +2585,8 @@ fn emit_to_destination(
     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
     for (pos, line) in rendered_buffer.iter().enumerate() {
         for part in line {
-            dst.apply_style(*lvl, part.style)?;
+            let style = part.style.color_spec(*lvl);
+            dst.set_color(&style)?;
             write!(dst, "{}", part.text)?;
             dst.reset()?;
         }
@@ -2647,61 +2598,69 @@ fn emit_to_destination(
     Ok(())
 }
 
-pub enum Destination {
-    Terminal(StandardStream),
-    Buffered(BufferWriter),
-    // The bool denotes whether we should be emitting ansi color codes or not
-    Raw(Box<(dyn Write + Send)>, bool),
-}
+pub type Destination = Box<(dyn WriteColor + Send)>;
 
-pub enum WritableDst<'a> {
-    Terminal(&'a mut StandardStream),
-    Buffered(&'a mut BufferWriter, Buffer),
-    Raw(&'a mut (dyn Write + Send)),
-    ColoredRaw(Ansi<&'a mut (dyn Write + Send)>),
+struct Buffy {
+    buffer_writer: BufferWriter,
+    buffer: Buffer,
 }
 
-impl Destination {
-    fn from_stderr(color: ColorConfig) -> Destination {
-        let choice = color.to_color_choice();
-        // On Windows we'll be performing global synchronization on the entire
-        // system for emitting rustc errors, so there's no need to buffer
-        // anything.
-        //
-        // On non-Windows we rely on the atomicity of `write` to ensure errors
-        // don't get all jumbled up.
-        if cfg!(windows) {
-            Terminal(StandardStream::stderr(choice))
-        } else {
-            Buffered(BufferWriter::stderr(choice))
-        }
+impl Write for Buffy {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.buffer.write(buf)
     }
 
-    fn writable(&mut self) -> WritableDst<'_> {
-        match *self {
-            Destination::Terminal(ref mut t) => WritableDst::Terminal(t),
-            Destination::Buffered(ref mut t) => {
-                let buf = t.buffer();
-                WritableDst::Buffered(t, buf)
-            }
-            Destination::Raw(ref mut t, false) => WritableDst::Raw(t),
-            Destination::Raw(ref mut t, true) => WritableDst::ColoredRaw(Ansi::new(t)),
+    fn flush(&mut self) -> io::Result<()> {
+        self.buffer_writer.print(&self.buffer)?;
+        self.buffer.clear();
+        Ok(())
+    }
+}
+
+impl Drop for Buffy {
+    fn drop(&mut self) {
+        if !self.buffer.is_empty() {
+            self.flush().unwrap();
+            panic!("buffers need to be flushed in order to print their contents");
         }
     }
+}
 
+impl WriteColor for Buffy {
     fn supports_color(&self) -> bool {
-        match *self {
-            Self::Terminal(ref stream) => stream.supports_color(),
-            Self::Buffered(ref buffer) => buffer.buffer().supports_color(),
-            Self::Raw(_, supports_color) => supports_color,
-        }
+        self.buffer.supports_color()
+    }
+
+    fn set_color(&mut self, spec: &ColorSpec) -> io::Result<()> {
+        self.buffer.set_color(spec)
+    }
+
+    fn reset(&mut self) -> io::Result<()> {
+        self.buffer.reset()
+    }
+}
+
+fn from_stderr(color: ColorConfig) -> Destination {
+    let choice = color.to_color_choice();
+    // On Windows we'll be performing global synchronization on the entire
+    // system for emitting rustc errors, so there's no need to buffer
+    // anything.
+    //
+    // On non-Windows we rely on the atomicity of `write` to ensure errors
+    // don't get all jumbled up.
+    if cfg!(windows) {
+        Box::new(StandardStream::stderr(choice))
+    } else {
+        let buffer_writer = BufferWriter::stderr(choice);
+        let buffer = buffer_writer.buffer();
+        Box::new(Buffy { buffer_writer, buffer })
     }
 }
 
-impl<'a> WritableDst<'a> {
-    fn apply_style(&mut self, lvl: Level, style: Style) -> io::Result<()> {
+impl Style {
+    fn color_spec(&self, lvl: Level) -> ColorSpec {
         let mut spec = ColorSpec::new();
-        match style {
+        match self {
             Style::Addition => {
                 spec.set_fg(Some(Color::Green)).set_intense(true);
             }
@@ -2746,53 +2705,7 @@ impl<'a> WritableDst<'a> {
                 spec.set_bold(true);
             }
         }
-        self.set_color(&spec)
-    }
-
-    fn set_color(&mut self, color: &ColorSpec) -> io::Result<()> {
-        match *self {
-            WritableDst::Terminal(ref mut t) => t.set_color(color),
-            WritableDst::Buffered(_, ref mut t) => t.set_color(color),
-            WritableDst::ColoredRaw(ref mut t) => t.set_color(color),
-            WritableDst::Raw(_) => Ok(()),
-        }
-    }
-
-    fn reset(&mut self) -> io::Result<()> {
-        match *self {
-            WritableDst::Terminal(ref mut t) => t.reset(),
-            WritableDst::Buffered(_, ref mut t) => t.reset(),
-            WritableDst::ColoredRaw(ref mut t) => t.reset(),
-            WritableDst::Raw(_) => Ok(()),
-        }
-    }
-}
-
-impl<'a> Write for WritableDst<'a> {
-    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
-        match *self {
-            WritableDst::Terminal(ref mut t) => t.write(bytes),
-            WritableDst::Buffered(_, ref mut buf) => buf.write(bytes),
-            WritableDst::Raw(ref mut w) => w.write(bytes),
-            WritableDst::ColoredRaw(ref mut t) => t.write(bytes),
-        }
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        match *self {
-            WritableDst::Terminal(ref mut t) => t.flush(),
-            WritableDst::Buffered(_, ref mut buf) => buf.flush(),
-            WritableDst::Raw(ref mut w) => w.flush(),
-            WritableDst::ColoredRaw(ref mut w) => w.flush(),
-        }
-    }
-}
-
-impl<'a> Drop for WritableDst<'a> {
-    fn drop(&mut self) {
-        if let WritableDst::Buffered(ref mut dst, ref mut buf) = self {
-            drop(dst.print(buf));
-        }
+        spec
     }
 }
 
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index f32d6b96b..b8f58e305 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -10,6 +10,7 @@
 // FIXME: spec the JSON output properly.
 
 use rustc_span::source_map::{FilePathMapping, SourceMap};
+use termcolor::{ColorSpec, WriteColor};
 
 use crate::emitter::{Emitter, HumanReadableErrorType};
 use crate::registry::Registry;
@@ -159,7 +160,7 @@ impl Emitter for JsonEmitter {
         }
         .and_then(|_| self.dst.flush());
         if let Err(e) = result {
-            panic!("failed to print diagnostics: {:?}", e);
+            panic!("failed to print diagnostics: {e:?}");
         }
     }
 
@@ -172,7 +173,7 @@ impl Emitter for JsonEmitter {
         }
         .and_then(|_| self.dst.flush());
         if let Err(e) = result {
-            panic!("failed to print notification: {:?}", e);
+            panic!("failed to print notification: {e:?}");
         }
     }
 
@@ -194,7 +195,7 @@ impl Emitter for JsonEmitter {
         }
         .and_then(|_| self.dst.flush());
         if let Err(e) = result {
-            panic!("failed to print future breakage report: {:?}", e);
+            panic!("failed to print future breakage report: {e:?}");
         }
     }
 
@@ -208,7 +209,7 @@ impl Emitter for JsonEmitter {
         }
         .and_then(|_| self.dst.flush());
         if let Err(e) = result {
-            panic!("failed to print unused externs: {:?}", e);
+            panic!("failed to print unused externs: {e:?}");
         }
     }
 
@@ -356,20 +357,29 @@ impl Diagnostic {
                 self.0.lock().unwrap().flush()
             }
         }
+        impl WriteColor for BufWriter {
+            fn supports_color(&self) -> bool {
+                false
+            }
+
+            fn set_color(&mut self, _spec: &ColorSpec) -> io::Result<()> {
+                Ok(())
+            }
+
+            fn reset(&mut self) -> io::Result<()> {
+                Ok(())
+            }
+        }
         let buf = BufWriter::default();
         let output = buf.clone();
         je.json_rendered
-            .new_emitter(
-                Box::new(buf),
-                Some(je.sm.clone()),
-                je.fluent_bundle.clone(),
-                je.fallback_bundle.clone(),
-                false,
-                je.diagnostic_width,
-                je.macro_backtrace,
-                je.track_diagnostics,
-                je.terminal_url,
-            )
+            .new_emitter(Box::new(buf), je.fallback_bundle.clone())
+            .sm(Some(je.sm.clone()))
+            .fluent_bundle(je.fluent_bundle.clone())
+            .diagnostic_width(je.diagnostic_width)
+            .macro_backtrace(je.macro_backtrace)
+            .track_diagnostics(je.track_diagnostics)
+            .terminal_url(je.terminal_url)
             .ui_testing(je.ui_testing)
             .emit_diagnostic(diag);
         let output = Arc::try_unwrap(output.0).unwrap().into_inner().unwrap();
diff --git a/compiler/rustc_errors/src/json/tests.rs b/compiler/rustc_errors/src/json/tests.rs
index 671dc449e..1f9a2981e 100644
--- a/compiler/rustc_errors/src/json/tests.rs
+++ b/compiler/rustc_errors/src/json/tests.rs
@@ -64,7 +64,7 @@ fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
         );
 
         let span = Span::with_root_ctxt(BytePos(span.0), BytePos(span.1));
-        let handler = Handler::with_emitter(true, None, Box::new(je));
+        let handler = Handler::with_emitter(Box::new(je));
         handler.span_err(span, "foo");
 
         let bytes = output.lock().unwrap();
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index b9db25103..34518b537 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -15,6 +15,7 @@
 #![feature(box_patterns)]
 #![feature(error_reporter)]
 #![allow(incomplete_features)]
+#![cfg_attr(not(bootstrap), allow(internal_features))]
 
 #[macro_use]
 extern crate rustc_macros;
@@ -22,6 +23,8 @@ extern crate rustc_macros;
 #[macro_use]
 extern crate tracing;
 
+extern crate self as rustc_errors;
+
 pub use emitter::ColorConfig;
 
 use rustc_lint_defs::LintExpectationId;
@@ -47,9 +50,10 @@ use std::borrow::Cow;
 use std::error::Report;
 use std::fmt;
 use std::hash::Hash;
+use std::io::Write;
 use std::num::NonZeroUsize;
 use std::panic;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use termcolor::{Color, ColorSpec};
 
@@ -376,13 +380,16 @@ pub struct ExplicitBug;
 /// rather than a failed assertion, etc.
 pub struct DelayedBugPanic;
 
+use crate::diagnostic_impls::{DelayedAtWithNewline, DelayedAtWithoutNewline};
 pub use diagnostic::{
     AddToDiagnostic, DecorateLint, Diagnostic, DiagnosticArg, DiagnosticArgValue, DiagnosticId,
     DiagnosticStyledString, IntoDiagnosticArg, SubDiagnostic,
 };
 pub use diagnostic_builder::{DiagnosticBuilder, EmissionGuarantee, Noted};
 pub use diagnostic_impls::{
-    DiagnosticArgFromDisplay, DiagnosticSymbolList, LabelKind, SingleLabelManySpans,
+    DiagnosticArgFromDisplay, DiagnosticSymbolList, ExpectedLifetimeParameter,
+    IndicateAnonymousLifetime, InvalidFlushedDelayedDiagnosticLevel, LabelKind,
+    SingleLabelManySpans,
 };
 use std::backtrace::{Backtrace, BacktraceStatus};
 
@@ -390,7 +397,6 @@ use std::backtrace::{Backtrace, BacktraceStatus};
 /// Certain errors (fatal, bug, unimpl) may cause immediate exit,
 /// others log errors for later reporting.
 pub struct Handler {
-    flags: HandlerFlags,
     inner: Lock<HandlerInner>,
 }
 
@@ -446,11 +452,11 @@ struct HandlerInner {
     /// have been converted.
     check_unstable_expect_diagnostics: bool,
 
-    /// Expected [`Diagnostic`][diagnostic::Diagnostic]s store a [`LintExpectationId`] as part of
+    /// Expected [`Diagnostic`][struct@diagnostic::Diagnostic]s store a [`LintExpectationId`] as part of
     /// the lint level. [`LintExpectationId`]s created early during the compilation
     /// (before `HirId`s have been defined) are not stable and can therefore not be
     /// stored on disk. This buffer stores these diagnostics until the ID has been
-    /// replaced by a stable [`LintExpectationId`]. The [`Diagnostic`][diagnostic::Diagnostic]s are the
+    /// replaced by a stable [`LintExpectationId`]. The [`Diagnostic`][struct@diagnostic::Diagnostic]s are the
     /// submitted for storage and added to the list of fulfilled expectations.
     unstable_expect_diagnostics: Vec<Diagnostic>,
 
@@ -461,6 +467,10 @@ struct HandlerInner {
     ///
     /// [RFC-2383]: https://rust-lang.github.io/rfcs/2383-lint-reasons.html
     fulfilled_expectations: FxHashSet<LintExpectationId>,
+
+    /// The file where the ICE information is stored. This allows delayed_span_bug backtraces to be
+    /// stored along side the main panic backtrace.
+    ice_file: Option<PathBuf>,
 }
 
 /// A key denoting where from a diagnostic was stashed.
@@ -544,63 +554,36 @@ impl Drop for HandlerInner {
 
 impl Handler {
     pub fn with_tty_emitter(
-        color_config: ColorConfig,
-        can_emit_warnings: bool,
-        treat_err_as_bug: Option<NonZeroUsize>,
         sm: Option<Lrc<SourceMap>>,
-        fluent_bundle: Option<Lrc<FluentBundle>>,
         fallback_bundle: LazyFallbackBundle,
     ) -> Self {
-        Self::with_tty_emitter_and_flags(
-            color_config,
-            sm,
-            fluent_bundle,
-            fallback_bundle,
-            HandlerFlags { can_emit_warnings, treat_err_as_bug, ..Default::default() },
-        )
+        let emitter = Box::new(EmitterWriter::stderr(ColorConfig::Auto, fallback_bundle).sm(sm));
+        Self::with_emitter(emitter)
+    }
+    pub fn disable_warnings(mut self) -> Self {
+        self.inner.get_mut().flags.can_emit_warnings = false;
+        self
     }
 
-    pub fn with_tty_emitter_and_flags(
-        color_config: ColorConfig,
-        sm: Option<Lrc<SourceMap>>,
-        fluent_bundle: Option<Lrc<FluentBundle>>,
-        fallback_bundle: LazyFallbackBundle,
-        flags: HandlerFlags,
-    ) -> Self {
-        let emitter = Box::new(EmitterWriter::stderr(
-            color_config,
-            sm,
-            fluent_bundle,
-            fallback_bundle,
-            false,
-            false,
-            None,
-            flags.macro_backtrace,
-            flags.track_diagnostics,
-            TerminalUrl::No,
-        ));
-        Self::with_emitter_and_flags(emitter, flags)
-    }
-
-    pub fn with_emitter(
-        can_emit_warnings: bool,
-        treat_err_as_bug: Option<NonZeroUsize>,
-        emitter: Box<dyn Emitter + sync::Send>,
-    ) -> Self {
-        Handler::with_emitter_and_flags(
-            emitter,
-            HandlerFlags { can_emit_warnings, treat_err_as_bug, ..Default::default() },
-        )
+    pub fn treat_err_as_bug(mut self, treat_err_as_bug: NonZeroUsize) -> Self {
+        self.inner.get_mut().flags.treat_err_as_bug = Some(treat_err_as_bug);
+        self
     }
 
-    pub fn with_emitter_and_flags(
-        emitter: Box<dyn Emitter + sync::Send>,
-        flags: HandlerFlags,
-    ) -> Self {
+    pub fn with_flags(mut self, flags: HandlerFlags) -> Self {
+        self.inner.get_mut().flags = flags;
+        self
+    }
+
+    pub fn with_ice_file(mut self, ice_file: PathBuf) -> Self {
+        self.inner.get_mut().ice_file = Some(ice_file);
+        self
+    }
+
+    pub fn with_emitter(emitter: Box<dyn Emitter + sync::Send>) -> Self {
         Self {
-            flags,
             inner: Lock::new(HandlerInner {
-                flags,
+                flags: HandlerFlags { can_emit_warnings: true, ..Default::default() },
                 lint_err_count: 0,
                 err_count: 0,
                 warn_count: 0,
@@ -618,6 +601,7 @@ impl Handler {
                 check_unstable_expect_diagnostics: false,
                 unstable_expect_diagnostics: Vec::new(),
                 fulfilled_expectations: Default::default(),
+                ice_file: None,
             }),
         }
     }
@@ -645,7 +629,7 @@ impl Handler {
     // This is here to not allow mutation of flags;
     // as of this writing it's only used in tests in librustc_middle.
     pub fn can_emit_warnings(&self) -> bool {
-        self.flags.can_emit_warnings
+        self.inner.lock().flags.can_emit_warnings
     }
 
     /// Resets the diagnostic error count as well as the cached emitted diagnostics.
@@ -991,7 +975,7 @@ impl Handler {
         self.emit_diag_at_span(Diagnostic::new_with_code(Warning(None), Some(code), msg), span);
     }
 
-    pub fn span_bug(&self, span: impl Into<MultiSpan>, msg: impl Into<DiagnosticMessage>) -> ! {
+    pub fn span_bug(&self, span: impl Into<MultiSpan>, msg: impl Into<String>) -> ! {
         self.inner.borrow_mut().span_bug(span, msg)
     }
 
@@ -1000,7 +984,7 @@ impl Handler {
     pub fn delay_span_bug(
         &self,
         span: impl Into<MultiSpan>,
-        msg: impl Into<DiagnosticMessage>,
+        msg: impl Into<String>,
     ) -> ErrorGuaranteed {
         self.inner.borrow_mut().delay_span_bug(span, msg)
     }
@@ -1473,7 +1457,7 @@ impl HandlerInner {
                 let _ = self.fatal(errors);
             }
             (_, _) => {
-                let _ = self.fatal(format!("{}; {}", &errors, &warnings));
+                let _ = self.fatal(format!("{errors}; {warnings}"));
             }
         }
 
@@ -1584,8 +1568,8 @@ impl HandlerInner {
     }
 
     #[track_caller]
-    fn span_bug(&mut self, sp: impl Into<MultiSpan>, msg: impl Into<DiagnosticMessage>) -> ! {
-        self.emit_diag_at_span(Diagnostic::new(Bug, msg), sp);
+    fn span_bug(&mut self, sp: impl Into<MultiSpan>, msg: impl Into<String>) -> ! {
+        self.emit_diag_at_span(Diagnostic::new(Bug, msg.into()), sp);
         panic::panic_any(ExplicitBug);
     }
 
@@ -1598,7 +1582,7 @@ impl HandlerInner {
     fn delay_span_bug(
         &mut self,
         sp: impl Into<MultiSpan>,
-        msg: impl Into<DiagnosticMessage>,
+        msg: impl Into<String>,
     ) -> ErrorGuaranteed {
         // This is technically `self.treat_err_as_bug()` but `delay_span_bug` is called before
         // incrementing `err_count` by one, so we need to +1 the comparing.
@@ -1607,9 +1591,9 @@ impl HandlerInner {
             self.err_count() + self.lint_err_count + self.delayed_bug_count() + 1 >= c.get()
         }) {
             // FIXME: don't abort here if report_delayed_bugs is off
-            self.span_bug(sp, msg);
+            self.span_bug(sp, msg.into());
         }
-        let mut diagnostic = Diagnostic::new(Level::DelayedBug, msg);
+        let mut diagnostic = Diagnostic::new(Level::DelayedBug, msg.into());
         diagnostic.set_span(sp.into());
         self.emit_diagnostic(&mut diagnostic).unwrap()
     }
@@ -1657,8 +1641,21 @@ impl HandlerInner {
         explanation: impl Into<DiagnosticMessage> + Copy,
     ) {
         let mut no_bugs = true;
+        // If backtraces are enabled, also print the query stack
+        let backtrace = std::env::var_os("RUST_BACKTRACE").map_or(true, |x| &x != "0");
         for bug in bugs {
-            let mut bug = bug.decorate();
+            if let Some(file) = self.ice_file.as_ref()
+                && let Ok(mut out) = std::fs::File::options().create(true).append(true).open(file)
+            {
+                let _ = write!(
+                    &mut out,
+                    "delayed span bug: {}\n{}\n",
+                    bug.inner.styled_message().iter().filter_map(|(msg, _)| msg.as_str()).collect::<String>(),
+                    &bug.note
+                );
+            }
+            let mut bug =
+                if backtrace || self.ice_file.is_none() { bug.decorate() } else { bug.inner };
 
             if no_bugs {
                 // Put the overall explanation before the `DelayedBug`s, to
@@ -1671,11 +1668,10 @@ impl HandlerInner {
             if bug.level != Level::DelayedBug {
                 // NOTE(eddyb) not panicking here because we're already producing
                 // an ICE, and the more information the merrier.
-                bug.note(format!(
-                    "`flushed_delayed` got diagnostic with level {:?}, \
-                     instead of the expected `DelayedBug`",
-                    bug.level,
-                ));
+                bug.subdiagnostic(InvalidFlushedDelayedDiagnosticLevel {
+                    span: bug.span.primary_span().unwrap(),
+                    level: bug.level,
+                });
             }
             bug.level = Level::Bug;
 
@@ -1714,13 +1710,11 @@ impl HandlerInner {
                 (count, delayed_count, as_bug) => {
                     if delayed_count > 0 {
                         panic!(
-                            "aborting after {} errors and {} delayed bugs due to `-Z treat-err-as-bug={}`",
-                            count, delayed_count, as_bug,
+                            "aborting after {count} errors and {delayed_count} delayed bugs due to `-Z treat-err-as-bug={as_bug}`",
                         )
                     } else {
                         panic!(
-                            "aborting after {} errors due to `-Z treat-err-as-bug={}`",
-                            count, as_bug,
+                            "aborting after {count} errors due to `-Z treat-err-as-bug={as_bug}`",
                         )
                     }
                 }
@@ -1742,12 +1736,22 @@ impl DelayedDiagnostic {
     fn decorate(mut self) -> Diagnostic {
         match self.note.status() {
             BacktraceStatus::Captured => {
-                self.inner.note(format!("delayed at {}\n{}", self.inner.emitted_at, self.note));
+                let inner = &self.inner;
+                self.inner.subdiagnostic(DelayedAtWithNewline {
+                    span: inner.span.primary_span().unwrap(),
+                    emitted_at: inner.emitted_at.clone(),
+                    note: self.note,
+                });
             }
             // Avoid the needless newline when no backtrace has been captured,
             // the display impl should just be a single line.
             _ => {
-                self.inner.note(format!("delayed at {} - {}", self.inner.emitted_at, self.note));
+                let inner = &self.inner;
+                self.inner.subdiagnostic(DelayedAtWithoutNewline {
+                    span: inner.span.primary_span().unwrap(),
+                    emitted_at: inner.emitted_at.clone(),
+                    note: self.note,
+                });
             }
         }
 
@@ -1839,20 +1843,36 @@ pub fn add_elided_lifetime_in_path_suggestion(
     incl_angl_brckt: bool,
     insertion_span: Span,
 ) {
-    diag.span_label(path_span, format!("expected lifetime parameter{}", pluralize!(n)));
+    diag.subdiagnostic(ExpectedLifetimeParameter { span: path_span, count: n });
     if !source_map.is_span_accessible(insertion_span) {
         // Do not try to suggest anything if generated by a proc-macro.
         return;
     }
     let anon_lts = vec!["'_"; n].join(", ");
     let suggestion =
-        if incl_angl_brckt { format!("<{}>", anon_lts) } else { format!("{}, ", anon_lts) };
-    diag.span_suggestion_verbose(
-        insertion_span.shrink_to_hi(),
-        format!("indicate the anonymous lifetime{}", pluralize!(n)),
+        if incl_angl_brckt { format!("<{anon_lts}>") } else { format!("{anon_lts}, ") };
+
+    diag.subdiagnostic(IndicateAnonymousLifetime {
+        span: insertion_span.shrink_to_hi(),
+        count: n,
         suggestion,
-        Applicability::MachineApplicable,
-    );
+    });
+}
+
+pub fn report_ambiguity_error<'a, G: EmissionGuarantee>(
+    db: &mut DiagnosticBuilder<'a, G>,
+    ambiguity: rustc_lint_defs::AmbiguityErrorDiag,
+) {
+    db.span_label(ambiguity.label_span, ambiguity.label_msg);
+    db.note(ambiguity.note_msg);
+    db.span_note(ambiguity.b1_span, ambiguity.b1_note_msg);
+    for help_msg in ambiguity.b1_help_msgs {
+        db.help(help_msg);
+    }
+    db.span_note(ambiguity.b2_span, ambiguity.b2_note_msg);
+    for help_msg in ambiguity.b2_help_msgs {
+        db.help(help_msg);
+    }
 }
 
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
diff --git a/compiler/rustc_errors/src/markdown/parse.rs b/compiler/rustc_errors/src/markdown/parse.rs
index 362a451fd..d3a08da62 100644
--- a/compiler/rustc_errors/src/markdown/parse.rs
+++ b/compiler/rustc_errors/src/markdown/parse.rs
@@ -272,7 +272,7 @@ fn parse_ordered_li(buf: &[u8]) -> Parsed<'_> {
 fn get_indented_section(buf: &[u8]) -> (&[u8], &[u8]) {
     let mut end = buf.len();
     for (idx, window) in buf.windows(2).enumerate() {
-        let &[ch, next_ch] = window else {unreachable!("always 2 elements")};
+        let &[ch, next_ch] = window else { unreachable!("always 2 elements") };
         if idx >= buf.len().saturating_sub(2) && next_ch == b'\n' {
             // End of stream
             end = buf.len().saturating_sub(1);
diff --git a/compiler/rustc_errors/src/markdown/term.rs b/compiler/rustc_errors/src/markdown/term.rs
index e45ba6d2c..88c3c8b9f 100644
--- a/compiler/rustc_errors/src/markdown/term.rs
+++ b/compiler/rustc_errors/src/markdown/term.rs
@@ -149,7 +149,7 @@ fn write_wrapping<B: io::Write>(
             let Some((end_idx, _ch)) = iter.nth(ch_count) else {
                 // Write entire line
                 buf.write_all(to_write.as_bytes())?;
-                cur.set(cur.get()+to_write.chars().count());
+                cur.set(cur.get() + to_write.chars().count());
                 break;
             };
 
diff --git a/compiler/rustc_errors/src/markdown/tests/term.rs b/compiler/rustc_errors/src/markdown/tests/term.rs
index 3b31c6d62..6f68fb25a 100644
--- a/compiler/rustc_errors/src/markdown/tests/term.rs
+++ b/compiler/rustc_errors/src/markdown/tests/term.rs
@@ -63,7 +63,7 @@ fn test_wrapping_write() {
 #[test]
 fn test_output() {
     // Capture `--bless` when run via ./x
-    let bless = std::env::var("RUSTC_BLESS").unwrap_or_default() == "1";
+    let bless = std::env::var_os("RUSTC_BLESS").is_some_and(|v| v != "0");
     let ast = MdStream::parse_str(INPUT);
     let bufwtr = BufferWriter::stderr(ColorChoice::Always);
     let mut buffer = bufwtr.buffer();