Merging upstream version 1.68.2+dfsg1.

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

10 files changed, 640 insertions, 210 deletions

diff --git a/compiler/rustc_errors/Cargo.toml b/compiler/rustc_errors/Cargo.toml
index dee7a31ec..cadd53fbd 100644
--- a/compiler/rustc_errors/Cargo.toml
+++ b/compiler/rustc_errors/Cargo.toml
@@ -17,6 +17,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_target = { path = "../rustc_target" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
+rustc_type_ir = { path = "../rustc_type_ir" }
 unicode-width = "0.1.4"
 termcolor = "1.0"
 annotate-snippets = "0.9"
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 06bb5edc0..51b2ff6a0 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -114,9 +114,9 @@ pub struct Diagnostic {
     pub suggestions: Result<Vec<CodeSuggestion>, SuggestionsDisabled>,
     args: FxHashMap<DiagnosticArgName<'static>, DiagnosticArgValue<'static>>,
 
-    /// This is not used for highlighting or rendering any error message.  Rather, it can be used
-    /// as a sort key to sort a buffer of diagnostics.  By default, it is the primary span of
-    /// `span` if there is one.  Otherwise, it is `DUMMY_SP`.
+    /// This is not used for highlighting or rendering any error message. Rather, it can be used
+    /// as a sort key to sort a buffer of diagnostics. By default, it is the primary span of
+    /// `span` if there is one. Otherwise, it is `DUMMY_SP`.
     pub sort_span: Span,
 
     /// If diagnostic is from Lint, custom hash function ignores notes
@@ -365,12 +365,16 @@ impl Diagnostic {
         self
     }
 
-    pub fn replace_span_with(&mut self, after: Span) -> &mut Self {
+    pub fn replace_span_with(&mut self, after: Span, keep_label: bool) -> &mut Self {
         let before = self.span.clone();
         self.set_span(after);
         for span_label in before.span_labels() {
             if let Some(label) = span_label.label {
-                self.span.push_span_label(after, label);
+                if span_label.is_primary && keep_label {
+                    self.span.push_span_label(after, label);
+                } else {
+                    self.span.push_span_label(span_label.span, label);
+                }
             }
         }
         self
@@ -802,7 +806,7 @@ impl Diagnostic {
         debug_assert!(
             !(suggestions
                 .iter()
-                .flat_map(|suggs| suggs)
+                .flatten()
                 .any(|(sp, suggestion)| sp.is_empty() && suggestion.is_empty())),
             "Span must not be empty and have no suggestion"
         );
diff --git a/compiler/rustc_errors/src/diagnostic_builder.rs b/compiler/rustc_errors/src/diagnostic_builder.rs
index a2ed98864..cbfee582d 100644
--- a/compiler/rustc_errors/src/diagnostic_builder.rs
+++ b/compiler/rustc_errors/src/diagnostic_builder.rs
@@ -1,7 +1,7 @@
 use crate::diagnostic::IntoDiagnosticArg;
 use crate::{
     Diagnostic, DiagnosticId, DiagnosticMessage, DiagnosticStyledString, ErrorGuaranteed,
-    SubdiagnosticMessage,
+    ExplicitBug, SubdiagnosticMessage,
 };
 use crate::{Handler, Level, MultiSpan, StashKey};
 use rustc_lint_defs::Applicability;
@@ -12,6 +12,7 @@ use std::borrow::Cow;
 use std::fmt::{self, Debug};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
+use std::panic;
 use std::thread::panicking;
 
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
@@ -308,6 +309,58 @@ impl EmissionGuarantee for Noted {
     }
 }
 
+/// Marker type which enables implementation of `create_bug` and `emit_bug` functions for
+/// bug struct diagnostics.
+#[derive(Copy, Clone)]
+pub struct Bug;
+
+impl<'a> DiagnosticBuilder<'a, Bug> {
+    /// Convenience function for internal use, clients should use one of the
+    /// `struct_*` methods on [`Handler`].
+    #[track_caller]
+    pub(crate) fn new_bug(handler: &'a Handler, message: impl Into<DiagnosticMessage>) -> Self {
+        let diagnostic = Diagnostic::new_with_code(Level::Bug, None, message);
+        Self::new_diagnostic_bug(handler, diagnostic)
+    }
+
+    /// Creates a new `DiagnosticBuilder` with an already constructed
+    /// diagnostic.
+    pub(crate) fn new_diagnostic_bug(handler: &'a Handler, diagnostic: Diagnostic) -> Self {
+        debug!("Created new diagnostic bug");
+        Self {
+            inner: DiagnosticBuilderInner {
+                state: DiagnosticBuilderState::Emittable(handler),
+                diagnostic: Box::new(diagnostic),
+            },
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl EmissionGuarantee for Bug {
+    fn diagnostic_builder_emit_producing_guarantee(db: &mut DiagnosticBuilder<'_, Self>) -> Self {
+        match db.inner.state {
+            // First `.emit()` call, the `&Handler` is still available.
+            DiagnosticBuilderState::Emittable(handler) => {
+                db.inner.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
+
+                handler.emit_diagnostic(&mut db.inner.diagnostic);
+            }
+            // `.emit()` was previously called, disallowed from repeating it.
+            DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation => {}
+        }
+        // Then panic. No need to return the marker type.
+        panic::panic_any(ExplicitBug);
+    }
+
+    fn make_diagnostic_builder(
+        handler: &Handler,
+        msg: impl Into<DiagnosticMessage>,
+    ) -> DiagnosticBuilder<'_, Self> {
+        DiagnosticBuilder::new_bug(handler, msg)
+    }
+}
+
 impl<'a> DiagnosticBuilder<'a, !> {
     /// Convenience function for internal use, clients should use one of the
     /// `struct_*` methods on [`Handler`].
diff --git a/compiler/rustc_errors/src/diagnostic_impls.rs b/compiler/rustc_errors/src/diagnostic_impls.rs
index 7155db32e..dad5e98aa 100644
--- a/compiler/rustc_errors/src/diagnostic_impls.rs
+++ b/compiler/rustc_errors/src/diagnostic_impls.rs
@@ -9,6 +9,7 @@ use rustc_span::edition::Edition;
 use rustc_span::symbol::{Ident, MacroRulesNormalizedIdent, Symbol};
 use rustc_target::abi::TargetDataLayoutErrors;
 use rustc_target::spec::{PanicStrategy, SplitDebuginfo, StackProtector, TargetTriple};
+use rustc_type_ir as type_ir;
 use std::borrow::Cow;
 use std::fmt;
 use std::num::ParseIntError;
@@ -59,7 +60,7 @@ into_diagnostic_arg_using_display!(
     i128,
     u128,
     std::io::Error,
-    std::boxed::Box<dyn std::error::Error>,
+    Box<dyn std::error::Error>,
     std::num::NonZeroU32,
     hir::Target,
     Edition,
@@ -152,6 +153,12 @@ impl IntoDiagnosticArg for ast::Path {
     }
 }
 
+impl IntoDiagnosticArg for &ast::Path {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::Owned(pprust::path_to_string(self)))
+    }
+}
+
 impl IntoDiagnosticArg for ast::token::Token {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
         DiagnosticArgValue::Str(pprust::token_to_string(&self))
@@ -164,18 +171,15 @@ impl IntoDiagnosticArg for ast::token::TokenKind {
     }
 }
 
+impl IntoDiagnosticArg for type_ir::FloatTy {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::Borrowed(self.name_str()))
+    }
+}
+
 impl IntoDiagnosticArg for Level {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
-        DiagnosticArgValue::Str(Cow::Borrowed(match self {
-            Level::Allow => "-A",
-            Level::Warn => "-W",
-            Level::ForceWarn(_) => "--force-warn",
-            Level::Deny => "-D",
-            Level::Forbid => "-F",
-            Level::Expect(_) => {
-                unreachable!("lints with the level of `expect` should not run this code");
-            }
-        }))
+        DiagnosticArgValue::Str(Cow::Borrowed(self.to_cmd_flag()))
     }
 }
 
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 4df2198fb..628e19999 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -28,6 +28,7 @@ use rustc_error_messages::{FluentArgs, SpanLabel};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use std::borrow::Cow;
 use std::cmp::{max, min, Reverse};
+use std::error::Report;
 use std::io::prelude::*;
 use std::io::{self, IsTerminal};
 use std::iter;
@@ -250,7 +251,7 @@ pub trait Emitter: Translate {
         let mut primary_span = diag.span.clone();
         let suggestions = diag.suggestions.as_deref().unwrap_or(&[]);
         if let Some((sugg, rest)) = suggestions.split_first() {
-            let msg = self.translate_message(&sugg.msg, fluent_args);
+            let msg = self.translate_message(&sugg.msg, fluent_args).map_err(Report::new).unwrap();
             if rest.is_empty() &&
                // ^ if there is only one suggestion
                // don't display multi-suggestions as labels
@@ -845,7 +846,10 @@ impl EmitterWriter {
         // 3 | |
         // 4 | | }
         //   | |_^ test
-        if let [ann] = &line.annotations[..] {
+        let mut buffer_ops = vec![];
+        let mut annotations = vec![];
+        let mut short_start = true;
+        for ann in &line.annotations {
             if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
                 if source_string.chars().take(ann.start_col).all(|c| c.is_whitespace()) {
                     let style = if ann.is_primary {
@@ -853,11 +857,24 @@ impl EmitterWriter {
                     } else {
                         Style::UnderlineSecondary
                     };
-                    buffer.putc(line_offset, width_offset + depth - 1, '/', style);
-                    return vec![(depth, style)];
+                    annotations.push((depth, style));
+                    buffer_ops.push((line_offset, width_offset + depth - 1, '/', style));
+                } else {
+                    short_start = false;
+                    break;
                 }
+            } else if let AnnotationType::MultilineLine(_) = ann.annotation_type {
+            } else {
+                short_start = false;
+                break;
             }
         }
+        if short_start {
+            for (y, x, c, s) in buffer_ops {
+                buffer.putc(y, x, c, s);
+            }
+            return annotations;
+        }
 
         // We want to display like this:
         //
@@ -1308,8 +1325,8 @@ impl EmitterWriter {
         //                see how it *looks* with
         //                very *weird* formats
         //                see?
-        for &(ref text, ref style) in msg.iter() {
-            let text = self.translate_message(text, args);
+        for (text, style) in msg.iter() {
+            let text = self.translate_message(text, args).map_err(Report::new).unwrap();
             let lines = text.split('\n').collect::<Vec<_>>();
             if lines.len() > 1 {
                 for (i, line) in lines.iter().enumerate() {
@@ -1370,8 +1387,8 @@ impl EmitterWriter {
                 buffer.append(0, ": ", header_style);
                 label_width += 2;
             }
-            for &(ref text, _) in msg.iter() {
-                let text = self.translate_message(text, args);
+            for (text, _) in msg.iter() {
+                let text = self.translate_message(text, args).map_err(Report::new).unwrap();
                 // Account for newlines to align output to its label.
                 for (line, text) in normalize_whitespace(&text).lines().enumerate() {
                     buffer.append(
@@ -1408,49 +1425,58 @@ impl EmitterWriter {
             if !sm.ensure_source_file_source_present(annotated_file.file.clone()) {
                 if !self.short_message {
                     // We'll just print an unannotated message.
-                    for (annotation_id, line) in annotated_file.lines.into_iter().enumerate() {
+                    for (annotation_id, line) in annotated_file.lines.iter().enumerate() {
                         let mut annotations = line.annotations.clone();
                         annotations.sort_by_key(|a| Reverse(a.start_col));
                         let mut line_idx = buffer.num_lines();
-                        buffer.append(
-                            line_idx,
-                            &format!(
-                                "{}:{}:{}",
-                                sm.filename_for_diagnostics(&annotated_file.file.name),
-                                sm.doctest_offset_line(&annotated_file.file.name, line.line_index),
-                                annotations[0].start_col + 1,
-                            ),
-                            Style::LineAndColumn,
-                        );
-                        if annotation_id == 0 {
-                            buffer.prepend(line_idx, "--> ", Style::LineNumber);
+
+                        let labels: Vec<_> = annotations
+                            .iter()
+                            .filter_map(|a| Some((a.label.as_ref()?, a.is_primary)))
+                            .filter(|(l, _)| !l.is_empty())
+                            .collect();
+
+                        if annotation_id == 0 || !labels.is_empty() {
+                            buffer.append(
+                                line_idx,
+                                &format!(
+                                    "{}:{}:{}",
+                                    sm.filename_for_diagnostics(&annotated_file.file.name),
+                                    sm.doctest_offset_line(
+                                        &annotated_file.file.name,
+                                        line.line_index
+                                    ),
+                                    annotations[0].start_col + 1,
+                                ),
+                                Style::LineAndColumn,
+                            );
+                            if annotation_id == 0 {
+                                buffer.prepend(line_idx, "--> ", Style::LineNumber);
+                            } else {
+                                buffer.prepend(line_idx, "::: ", Style::LineNumber);
+                            }
                             for _ in 0..max_line_num_len {
                                 buffer.prepend(line_idx, " ", Style::NoStyle);
                             }
                             line_idx += 1;
-                        };
-                        for (i, annotation) in annotations.into_iter().enumerate() {
-                            if let Some(label) = &annotation.label {
-                                let style = if annotation.is_primary {
-                                    Style::LabelPrimary
-                                } else {
-                                    Style::LabelSecondary
-                                };
-                                if annotation_id == 0 {
-                                    buffer.prepend(line_idx, " |", Style::LineNumber);
-                                    for _ in 0..max_line_num_len {
-                                        buffer.prepend(line_idx, " ", Style::NoStyle);
-                                    }
-                                    line_idx += 1;
-                                    buffer.append(line_idx + i, " = note: ", style);
-                                    for _ in 0..max_line_num_len {
-                                        buffer.prepend(line_idx, " ", Style::NoStyle);
-                                    }
-                                } else {
-                                    buffer.append(line_idx + i, ": ", style);
-                                }
-                                buffer.append(line_idx + i, label, style);
+                        }
+                        for (label, is_primary) in labels.into_iter() {
+                            let style = if is_primary {
+                                Style::LabelPrimary
+                            } else {
+                                Style::LabelSecondary
+                            };
+                            buffer.prepend(line_idx, " |", Style::LineNumber);
+                            for _ in 0..max_line_num_len {
+                                buffer.prepend(line_idx, " ", Style::NoStyle);
                             }
+                            line_idx += 1;
+                            buffer.append(line_idx, " = note: ", style);
+                            for _ in 0..max_line_num_len {
+                                buffer.prepend(line_idx, " ", Style::NoStyle);
+                            }
+                            buffer.append(line_idx, label, style);
+                            line_idx += 1;
                         }
                     }
                 }
@@ -1765,7 +1791,7 @@ impl EmitterWriter {
 
             if let Some(span) = span.primary_span() {
                 // Compare the primary span of the diagnostic with the span of the suggestion
-                // being emitted.  If they belong to the same file, we don't *need* to show the
+                // being emitted. If they belong to the same file, we don't *need* to show the
                 // file name, saving in verbosity, but if it *isn't* we do need it, otherwise we're
                 // telling users to make a change but not clarifying *where*.
                 let loc = sm.lookup_char_pos(parts[0].span.lo());
@@ -2276,7 +2302,9 @@ impl FileWithAnnotatedLines {
                     hi.col_display += 1;
                 }
 
-                let label = label.as_ref().map(|m| emitter.translate_message(m, args).to_string());
+                let label = label.as_ref().map(|m| {
+                    emitter.translate_message(m, args).map_err(Report::new).unwrap().to_string()
+                });
 
                 if lo.line != hi.line {
                     let ml = MultilineAnnotation {
@@ -2304,7 +2332,7 @@ impl FileWithAnnotatedLines {
         }
 
         // Find overlapping multiline annotations, put them at different depths
-        multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, usize::MAX - ml.line_end));
+        multiline_annotations.sort_by_key(|(_, ml)| (ml.line_start, usize::MAX - ml.line_end));
         for (_, ann) in multiline_annotations.clone() {
             for (_, a) in multiline_annotations.iter_mut() {
                 // Move all other multiline annotations overlapping with this one
@@ -2501,11 +2529,11 @@ fn emit_to_destination(
     //
     // On Unix systems, we write into a buffered terminal rather than directly to a terminal. When
     // the .flush() is called we take the buffer created from the buffered writes and write it at
-    // one shot.  Because the Unix systems use ANSI for the colors, which is a text-based styling
+    // one shot. Because the Unix systems use ANSI for the colors, which is a text-based styling
     // scheme, this buffered approach works and maintains the styling.
     //
     // On Windows, styling happens through calls to a terminal API. This prevents us from using the
-    // same buffering approach.  Instead, we use a global Windows mutex, which we acquire long
+    // same buffering approach. Instead, we use a global Windows mutex, which we acquire long
     // enough to output the full error message, then we release.
     let _buffer_lock = lock::acquire_global_lock("rustc_errors");
     for (pos, line) in rendered_buffer.iter().enumerate() {
diff --git a/compiler/rustc_errors/src/error.rs b/compiler/rustc_errors/src/error.rs
new file mode 100644
index 000000000..ec0a2fe8c
--- /dev/null
+++ b/compiler/rustc_errors/src/error.rs
@@ -0,0 +1,137 @@
+use rustc_error_messages::{
+    fluent_bundle::resolver::errors::{ReferenceKind, ResolverError},
+    FluentArgs, FluentError,
+};
+use std::borrow::Cow;
+use std::error::Error;
+use std::fmt;
+
+#[derive(Debug)]
+pub enum TranslateError<'args> {
+    One {
+        id: &'args Cow<'args, str>,
+        args: &'args FluentArgs<'args>,
+        kind: TranslateErrorKind<'args>,
+    },
+    Two {
+        primary: Box<TranslateError<'args>>,
+        fallback: Box<TranslateError<'args>>,
+    },
+}
+
+impl<'args> TranslateError<'args> {
+    pub fn message(id: &'args Cow<'args, str>, args: &'args FluentArgs<'args>) -> Self {
+        Self::One { id, args, kind: TranslateErrorKind::MessageMissing }
+    }
+    pub fn primary(id: &'args Cow<'args, str>, args: &'args FluentArgs<'args>) -> Self {
+        Self::One { id, args, kind: TranslateErrorKind::PrimaryBundleMissing }
+    }
+    pub fn attribute(
+        id: &'args Cow<'args, str>,
+        args: &'args FluentArgs<'args>,
+        attr: &'args str,
+    ) -> Self {
+        Self::One { id, args, kind: TranslateErrorKind::AttributeMissing { attr } }
+    }
+    pub fn value(id: &'args Cow<'args, str>, args: &'args FluentArgs<'args>) -> Self {
+        Self::One { id, args, kind: TranslateErrorKind::ValueMissing }
+    }
+
+    pub fn fluent(
+        id: &'args Cow<'args, str>,
+        args: &'args FluentArgs<'args>,
+        errs: Vec<FluentError>,
+    ) -> Self {
+        Self::One { id, args, kind: TranslateErrorKind::Fluent { errs } }
+    }
+
+    pub fn and(self, fallback: TranslateError<'args>) -> TranslateError<'args> {
+        Self::Two { primary: Box::new(self), fallback: Box::new(fallback) }
+    }
+}
+
+#[derive(Debug)]
+pub enum TranslateErrorKind<'args> {
+    MessageMissing,
+    PrimaryBundleMissing,
+    AttributeMissing { attr: &'args str },
+    ValueMissing,
+    Fluent { errs: Vec<FluentError> },
+}
+
+impl fmt::Display for TranslateError<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use TranslateErrorKind::*;
+
+        match self {
+            Self::One { id, args, kind } => {
+                writeln!(f, "failed while formatting fluent string `{id}`: ")?;
+                match kind {
+                    MessageMissing => writeln!(f, "message was missing")?,
+                    PrimaryBundleMissing => writeln!(f, "the primary bundle was missing")?,
+                    AttributeMissing { attr } => {
+                        writeln!(f, "the attribute `{attr}` was missing")?;
+                        writeln!(f, "help: add `.{attr} = <message>`")?;
+                    }
+                    ValueMissing => writeln!(f, "the value was missing")?,
+                    Fluent { errs } => {
+                        for err in errs {
+                            match err {
+                                FluentError::ResolverError(ResolverError::Reference(
+                                    ReferenceKind::Message { id, .. }
+                                    | ReferenceKind::Variable { id, .. },
+                                )) => {
+                                    if args.iter().any(|(arg_id, _)| arg_id == id) {
+                                        writeln!(
+                                            f,
+                                            "argument `{id}` exists but was not referenced correctly"
+                                        )?;
+                                        writeln!(f, "help: try using `{{${id}}}` instead")?;
+                                    } else {
+                                        writeln!(
+                                            f,
+                                            "the fluent string has an argument `{id}` that was not found."
+                                        )?;
+                                        let vars: Vec<&str> =
+                                            args.iter().map(|(a, _v)| a).collect();
+                                        match &*vars {
+                                            [] => writeln!(f, "help: no arguments are available")?,
+                                            [one] => writeln!(
+                                                f,
+                                                "help: the argument `{one}` is available"
+                                            )?,
+                                            [first, middle @ .., last] => {
+                                                write!(f, "help: the arguments `{first}`")?;
+                                                for a in middle {
+                                                    write!(f, ", `{a}`")?;
+                                                }
+                                                writeln!(f, " and `{last}` are available")?;
+                                            }
+                                        }
+                                    }
+                                }
+                                _ => writeln!(f, "{err}")?,
+                            }
+                        }
+                    }
+                }
+            }
+            // If someone cares about primary bundles, they'll probably notice it's missing
+            // regardless or will be using `debug_assertions`
+            // so we skip the arm below this one to avoid confusing the regular user.
+            Self::Two { primary: box Self::One { kind: PrimaryBundleMissing, .. }, fallback } => {
+                fmt::Display::fmt(fallback, f)?;
+            }
+            Self::Two { primary, fallback } => {
+                writeln!(
+                    f,
+                    "first, fluent formatting using the primary bundle failed:\n {primary}\n \
+                    while attempting to recover by using the fallback bundle instead, another error occurred:\n{fallback}"
+                )?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl Error for TranslateError<'_> {}
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index a37073d8f..dc38b8725 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -24,6 +24,7 @@ use rustc_data_structures::sync::Lrc;
 use rustc_error_messages::FluentArgs;
 use rustc_span::hygiene::ExpnData;
 use rustc_span::Span;
+use std::error::Report;
 use std::io::{self, Write};
 use std::path::Path;
 use std::sync::{Arc, Mutex};
@@ -321,7 +322,8 @@ impl Diagnostic {
     fn from_errors_diagnostic(diag: &crate::Diagnostic, je: &JsonEmitter) -> Diagnostic {
         let args = to_fluent_args(diag.args());
         let sugg = diag.suggestions.iter().flatten().map(|sugg| {
-            let translated_message = je.translate_message(&sugg.msg, &args);
+            let translated_message =
+                je.translate_message(&sugg.msg, &args).map_err(Report::new).unwrap();
             Diagnostic {
                 message: translated_message.to_string(),
                 code: None,
@@ -411,7 +413,10 @@ impl DiagnosticSpan {
         Self::from_span_etc(
             span.span,
             span.is_primary,
-            span.label.as_ref().map(|m| je.translate_message(m, args)).map(|m| m.to_string()),
+            span.label
+                .as_ref()
+                .map(|m| je.translate_message(m, args).unwrap())
+                .map(|m| m.to_string()),
             suggestion,
             je,
         )
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index eb0506c45..535812fb0 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -11,6 +11,10 @@
 #![feature(never_type)]
 #![feature(result_option_inspect)]
 #![feature(rustc_attrs)]
+#![feature(yeet_expr)]
+#![feature(try_blocks)]
+#![feature(box_patterns)]
+#![feature(error_reporter)]
 #![allow(incomplete_features)]
 
 #[macro_use]
@@ -41,11 +45,12 @@ use rustc_span::HashStableContext;
 use rustc_span::{Loc, Span};
 
 use std::borrow::Cow;
+use std::error::Report;
+use std::fmt;
 use std::hash::Hash;
 use std::num::NonZeroUsize;
 use std::panic;
 use std::path::Path;
-use std::{error, fmt};
 
 use termcolor::{Color, ColorSpec};
 
@@ -54,11 +59,14 @@ mod diagnostic;
 mod diagnostic_builder;
 mod diagnostic_impls;
 pub mod emitter;
+pub mod error;
 pub mod json;
 mod lock;
 pub mod registry;
 mod snippet;
 mod styled_buffer;
+#[cfg(test)]
+mod tests;
 pub mod translation;
 
 pub use diagnostic_builder::IntoDiagnostic;
@@ -324,7 +332,7 @@ impl CodeSuggestion {
                         // Account for the difference between the width of the current code and the
                         // snippet being suggested, so that the *later* suggestions are correctly
                         // aligned on the screen.
-                        acc += len as isize - (cur_hi.col.0 - cur_lo.col.0) as isize;
+                        acc += len - (cur_hi.col.0 - cur_lo.col.0) as isize;
                     }
                     prev_hi = cur_hi;
                     prev_line = sf.get_line(prev_hi.line - 1);
@@ -361,16 +369,11 @@ pub use rustc_span::fatal_error::{FatalError, FatalErrorMarker};
 
 /// Signifies that the compiler died with an explicit call to `.bug`
 /// or `.span_bug` rather than a failed assertion, etc.
-#[derive(Copy, Clone, Debug)]
 pub struct ExplicitBug;
 
-impl fmt::Display for ExplicitBug {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "parser internal bug")
-    }
-}
-
-impl error::Error for ExplicitBug {}
+/// Signifies that the compiler died with an explicit call to `.delay_*_bug`
+/// rather than a failed assertion, etc.
+pub struct DelayedBugPanic;
 
 pub use diagnostic::{
     AddToDiagnostic, DecorateLint, Diagnostic, DiagnosticArg, DiagnosticArgValue, DiagnosticId,
@@ -403,7 +406,7 @@ struct HandlerInner {
     warn_count: usize,
     deduplicated_err_count: usize,
     emitter: Box<dyn Emitter + sync::Send>,
-    delayed_span_bugs: Vec<Diagnostic>,
+    delayed_span_bugs: Vec<DelayedDiagnostic>,
     delayed_good_path_bugs: Vec<DelayedDiagnostic>,
     /// This flag indicates that an expected diagnostic was emitted and suppressed.
     /// This is used for the `delayed_good_path_bugs` check.
@@ -473,10 +476,12 @@ pub enum StashKey {
     CallAssocMethod,
 }
 
-fn default_track_diagnostic(_: &Diagnostic) {}
+fn default_track_diagnostic(d: &mut Diagnostic, f: &mut dyn FnMut(&mut Diagnostic)) {
+    (*f)(d)
+}
 
-pub static TRACK_DIAGNOSTICS: AtomicRef<fn(&Diagnostic)> =
-    AtomicRef::new(&(default_track_diagnostic as fn(&_)));
+pub static TRACK_DIAGNOSTICS: AtomicRef<fn(&mut Diagnostic, &mut dyn FnMut(&mut Diagnostic))> =
+    AtomicRef::new(&(default_track_diagnostic as _));
 
 #[derive(Copy, Clone, Default)]
 pub struct HandlerFlags {
@@ -518,7 +523,7 @@ impl Drop for HandlerInner {
         if !self.has_any_message() && !self.suppressed_expected_diag {
             let bugs = std::mem::replace(&mut self.delayed_good_path_bugs, Vec::new());
             self.flush_delayed(
-                bugs.into_iter().map(DelayedDiagnostic::decorate),
+                bugs,
                 "no warnings or errors encountered even though `delayed_good_path_bugs` issued",
             );
         }
@@ -619,7 +624,14 @@ impl Handler {
     ) -> SubdiagnosticMessage {
         let inner = self.inner.borrow();
         let args = crate::translation::to_fluent_args(args);
-        SubdiagnosticMessage::Eager(inner.emitter.translate_message(&message, &args).to_string())
+        SubdiagnosticMessage::Eager(
+            inner
+                .emitter
+                .translate_message(&message, &args)
+                .map_err(Report::new)
+                .unwrap()
+                .to_string(),
+        )
     }
 
     // This is here to not allow mutation of flags;
@@ -653,17 +665,19 @@ impl Handler {
     /// Retrieve a stashed diagnostic with `steal_diagnostic`.
     pub fn stash_diagnostic(&self, span: Span, key: StashKey, diag: Diagnostic) {
         let mut inner = self.inner.borrow_mut();
-        inner.stash((span, key), diag);
+        inner.stash((span.with_parent(None), key), diag);
     }
 
     /// Steal a previously stashed diagnostic with the given `Span` and [`StashKey`] as the key.
     pub fn steal_diagnostic(&self, span: Span, key: StashKey) -> Option<DiagnosticBuilder<'_, ()>> {
         let mut inner = self.inner.borrow_mut();
-        inner.steal((span, key)).map(|diag| DiagnosticBuilder::new_diagnostic(self, diag))
+        inner
+            .steal((span.with_parent(None), key))
+            .map(|diag| DiagnosticBuilder::new_diagnostic(self, diag))
     }
 
     pub fn has_stashed_diagnostic(&self, span: Span, key: StashKey) -> bool {
-        self.inner.borrow().stashed_diagnostics.get(&(span, key)).is_some()
+        self.inner.borrow().stashed_diagnostics.get(&(span.with_parent(None), key)).is_some()
     }
 
     /// Emit all stashed diagnostics.
@@ -973,6 +987,7 @@ impl Handler {
         self.inner.borrow_mut().span_bug(span, msg)
     }
 
+    /// For documentation on this, see `Session::delay_span_bug`.
     #[track_caller]
     pub fn delay_span_bug(
         &self,
@@ -1127,6 +1142,20 @@ impl Handler {
         self.create_fatal(fatal).emit()
     }
 
+    pub fn create_bug<'a>(
+        &'a self,
+        bug: impl IntoDiagnostic<'a, diagnostic_builder::Bug>,
+    ) -> DiagnosticBuilder<'a, diagnostic_builder::Bug> {
+        bug.into_diagnostic(self)
+    }
+
+    pub fn emit_bug<'a>(
+        &'a self,
+        bug: impl IntoDiagnostic<'a, diagnostic_builder::Bug>,
+    ) -> diagnostic_builder::Bug {
+        self.create_bug(bug).emit()
+    }
+
     fn emit_diag_at_span(
         &self,
         mut diag: Diagnostic,
@@ -1212,8 +1241,8 @@ impl HandlerInner {
         self.taught_diagnostics.insert(code.clone())
     }
 
-    fn force_print_diagnostic(&mut self, mut db: Diagnostic) {
-        self.emitter.emit_diagnostic(&mut db);
+    fn force_print_diagnostic(&mut self, db: Diagnostic) {
+        self.emitter.emit_diagnostic(&db);
     }
 
     /// Emit all stashed diagnostics.
@@ -1263,7 +1292,9 @@ impl HandlerInner {
             // once *any* errors were emitted (and truncate `delayed_span_bugs`
             // when an error is first emitted, also), but maybe there's a case
             // in which that's not sound? otherwise this is really inefficient.
-            self.delayed_span_bugs.push(diagnostic.clone());
+            let backtrace = std::backtrace::Backtrace::force_capture();
+            self.delayed_span_bugs
+                .push(DelayedDiagnostic::with_backtrace(diagnostic.clone(), backtrace));
 
             if !self.flags.report_delayed_bugs {
                 return Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
@@ -1288,67 +1319,69 @@ impl HandlerInner {
             && !diagnostic.is_force_warn()
         {
             if diagnostic.has_future_breakage() {
-                (*TRACK_DIAGNOSTICS)(diagnostic);
+                (*TRACK_DIAGNOSTICS)(diagnostic, &mut |_| {});
             }
             return None;
         }
 
-        (*TRACK_DIAGNOSTICS)(diagnostic);
-
         if matches!(diagnostic.level, Level::Expect(_) | Level::Allow) {
+            (*TRACK_DIAGNOSTICS)(diagnostic, &mut |_| {});
             return None;
         }
 
-        if let Some(ref code) = diagnostic.code {
-            self.emitted_diagnostic_codes.insert(code.clone());
-        }
-
-        let already_emitted = |this: &mut Self| {
-            let mut hasher = StableHasher::new();
-            diagnostic.hash(&mut hasher);
-            let diagnostic_hash = hasher.finish();
-            !this.emitted_diagnostics.insert(diagnostic_hash)
-        };
+        let mut guaranteed = None;
+        (*TRACK_DIAGNOSTICS)(diagnostic, &mut |diagnostic| {
+            if let Some(ref code) = diagnostic.code {
+                self.emitted_diagnostic_codes.insert(code.clone());
+            }
 
-        // Only emit the diagnostic if we've been asked to deduplicate or
-        // haven't already emitted an equivalent diagnostic.
-        if !(self.flags.deduplicate_diagnostics && already_emitted(self)) {
-            debug!(?diagnostic);
-            debug!(?self.emitted_diagnostics);
-            let already_emitted_sub = |sub: &mut SubDiagnostic| {
-                debug!(?sub);
-                if sub.level != Level::OnceNote {
-                    return false;
-                }
+            let already_emitted = |this: &mut Self| {
                 let mut hasher = StableHasher::new();
-                sub.hash(&mut hasher);
+                diagnostic.hash(&mut hasher);
                 let diagnostic_hash = hasher.finish();
-                debug!(?diagnostic_hash);
-                !self.emitted_diagnostics.insert(diagnostic_hash)
+                !this.emitted_diagnostics.insert(diagnostic_hash)
             };
 
-            diagnostic.children.drain_filter(already_emitted_sub).for_each(|_| {});
-
-            self.emitter.emit_diagnostic(diagnostic);
-            if diagnostic.is_error() {
-                self.deduplicated_err_count += 1;
-            } else if let Warning(_) = diagnostic.level {
-                self.deduplicated_warn_count += 1;
+            // Only emit the diagnostic if we've been asked to deduplicate or
+            // haven't already emitted an equivalent diagnostic.
+            if !(self.flags.deduplicate_diagnostics && already_emitted(self)) {
+                debug!(?diagnostic);
+                debug!(?self.emitted_diagnostics);
+                let already_emitted_sub = |sub: &mut SubDiagnostic| {
+                    debug!(?sub);
+                    if sub.level != Level::OnceNote {
+                        return false;
+                    }
+                    let mut hasher = StableHasher::new();
+                    sub.hash(&mut hasher);
+                    let diagnostic_hash = hasher.finish();
+                    debug!(?diagnostic_hash);
+                    !self.emitted_diagnostics.insert(diagnostic_hash)
+                };
+
+                diagnostic.children.drain_filter(already_emitted_sub).for_each(|_| {});
+
+                self.emitter.emit_diagnostic(diagnostic);
+                if diagnostic.is_error() {
+                    self.deduplicated_err_count += 1;
+                } else if let Warning(_) = diagnostic.level {
+                    self.deduplicated_warn_count += 1;
+                }
             }
-        }
-        if diagnostic.is_error() {
-            if matches!(diagnostic.level, Level::Error { lint: true }) {
-                self.bump_lint_err_count();
+            if diagnostic.is_error() {
+                if matches!(diagnostic.level, Level::Error { lint: true }) {
+                    self.bump_lint_err_count();
+                } else {
+                    self.bump_err_count();
+                }
+
+                guaranteed = Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
             } else {
-                self.bump_err_count();
+                self.bump_warn_count();
             }
+        });
 
-            Some(ErrorGuaranteed::unchecked_claim_error_was_emitted())
-        } else {
-            self.bump_warn_count();
-
-            None
-        }
+        guaranteed
     }
 
     fn emit_artifact_notification(&mut self, path: &Path, artifact_type: &str) {
@@ -1518,6 +1551,7 @@ impl HandlerInner {
         self.emit_diagnostic(diag.set_span(sp));
     }
 
+    /// For documentation on this, see `Session::delay_span_bug`.
     #[track_caller]
     fn delay_span_bug(
         &mut self,
@@ -1535,7 +1569,6 @@ impl HandlerInner {
         }
         let mut diagnostic = Diagnostic::new(Level::DelayedBug, msg);
         diagnostic.set_span(sp.into());
-        diagnostic.note(&format!("delayed at {}", std::panic::Location::caller()));
         self.emit_diagnostic(&mut diagnostic).unwrap()
     }
 
@@ -1578,11 +1611,13 @@ impl HandlerInner {
 
     fn flush_delayed(
         &mut self,
-        bugs: impl IntoIterator<Item = Diagnostic>,
+        bugs: impl IntoIterator<Item = DelayedDiagnostic>,
         explanation: impl Into<DiagnosticMessage> + Copy,
     ) {
         let mut no_bugs = true;
-        for mut bug in bugs {
+        for bug in bugs {
+            let mut bug = bug.decorate();
+
             if no_bugs {
                 // Put the overall explanation before the `DelayedBug`s, to
                 // frame them better (e.g. separate warnings from them).
@@ -1605,9 +1640,9 @@ impl HandlerInner {
             self.emit_diagnostic(&mut bug);
         }
 
-        // Panic with `ExplicitBug` to avoid "unexpected panic" messages.
+        // Panic with `DelayedBugPanic` to avoid "unexpected panic" messages.
         if !no_bugs {
-            panic::panic_any(ExplicitBug);
+            panic::panic_any(DelayedBugPanic);
         }
     }
 
diff --git a/compiler/rustc_errors/src/tests.rs b/compiler/rustc_errors/src/tests.rs
new file mode 100644
index 000000000..52103e460
--- /dev/null
+++ b/compiler/rustc_errors/src/tests.rs
@@ -0,0 +1,188 @@
+use crate::error::{TranslateError, TranslateErrorKind};
+use crate::fluent_bundle::*;
+use crate::translation::Translate;
+use crate::FluentBundle;
+use rustc_data_structures::sync::Lrc;
+use rustc_error_messages::fluent_bundle::resolver::errors::{ReferenceKind, ResolverError};
+use rustc_error_messages::langid;
+use rustc_error_messages::DiagnosticMessage;
+
+struct Dummy {
+    bundle: FluentBundle,
+}
+
+impl Translate for Dummy {
+    fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
+        None
+    }
+
+    fn fallback_fluent_bundle(&self) -> &FluentBundle {
+        &self.bundle
+    }
+}
+
+fn make_dummy(ftl: &'static str) -> Dummy {
+    let resource = FluentResource::try_new(ftl.into()).expect("Failed to parse an FTL string.");
+
+    let langid_en = langid!("en-US");
+
+    #[cfg(parallel_compiler)]
+    let mut bundle = FluentBundle::new_concurrent(vec![langid_en]);
+
+    #[cfg(not(parallel_compiler))]
+    let mut bundle = FluentBundle::new(vec![langid_en]);
+
+    bundle.add_resource(resource).expect("Failed to add FTL resources to the bundle.");
+
+    Dummy { bundle }
+}
+
+#[test]
+fn wellformed_fluent() {
+    let dummy = make_dummy("mir_build_borrow_of_moved_value = borrow of moved value
+    .label = value moved into `{$name}` here
+    .occurs_because_label = move occurs because `{$name}` has type `{$ty}` which does not implement the `Copy` trait
+    .value_borrowed_label = value borrowed here after move
+    .suggestion = borrow this binding in the pattern to avoid moving the value");
+
+    let mut args = FluentArgs::new();
+    args.set("name", "Foo");
+    args.set("ty", "std::string::String");
+    {
+        let message = DiagnosticMessage::FluentIdentifier(
+            "mir_build_borrow_of_moved_value".into(),
+            Some("suggestion".into()),
+        );
+
+        assert_eq!(
+            dummy.translate_message(&message, &args).unwrap(),
+            "borrow this binding in the pattern to avoid moving the value"
+        );
+    }
+
+    {
+        let message = DiagnosticMessage::FluentIdentifier(
+            "mir_build_borrow_of_moved_value".into(),
+            Some("value_borrowed_label".into()),
+        );
+
+        assert_eq!(
+            dummy.translate_message(&message, &args).unwrap(),
+            "value borrowed here after move"
+        );
+    }
+
+    {
+        let message = DiagnosticMessage::FluentIdentifier(
+            "mir_build_borrow_of_moved_value".into(),
+            Some("occurs_because_label".into()),
+        );
+
+        assert_eq!(
+            dummy.translate_message(&message, &args).unwrap(),
+            "move occurs because `\u{2068}Foo\u{2069}` has type `\u{2068}std::string::String\u{2069}` which does not implement the `Copy` trait"
+        );
+
+        {
+            let message = DiagnosticMessage::FluentIdentifier(
+                "mir_build_borrow_of_moved_value".into(),
+                Some("label".into()),
+            );
+
+            assert_eq!(
+                dummy.translate_message(&message, &args).unwrap(),
+                "value moved into `\u{2068}Foo\u{2069}` here"
+            );
+        }
+    }
+}
+
+#[test]
+fn misformed_fluent() {
+    let dummy = make_dummy("mir_build_borrow_of_moved_value = borrow of moved value
+    .label = value moved into `{name}` here
+    .occurs_because_label = move occurs because `{$oops}` has type `{$ty}` which does not implement the `Copy` trait
+    .suggestion = borrow this binding in the pattern to avoid moving the value");
+
+    let mut args = FluentArgs::new();
+    args.set("name", "Foo");
+    args.set("ty", "std::string::String");
+    {
+        let message = DiagnosticMessage::FluentIdentifier(
+            "mir_build_borrow_of_moved_value".into(),
+            Some("value_borrowed_label".into()),
+        );
+
+        let err = dummy.translate_message(&message, &args).unwrap_err();
+        assert!(
+            matches!(
+                &err,
+                TranslateError::Two {
+                    primary: box TranslateError::One {
+                        kind: TranslateErrorKind::PrimaryBundleMissing,
+                        ..
+                    },
+                    fallback: box TranslateError::One {
+                        kind: TranslateErrorKind::AttributeMissing { attr: "value_borrowed_label" },
+                        ..
+                    }
+                }
+            ),
+            "{err:#?}"
+        );
+        assert_eq!(
+            format!("{err}"),
+            "failed while formatting fluent string `mir_build_borrow_of_moved_value`: \nthe attribute `value_borrowed_label` was missing\nhelp: add `.value_borrowed_label = <message>`\n"
+        );
+    }
+
+    {
+        let message = DiagnosticMessage::FluentIdentifier(
+            "mir_build_borrow_of_moved_value".into(),
+            Some("label".into()),
+        );
+
+        let err = dummy.translate_message(&message, &args).unwrap_err();
+        if let TranslateError::Two {
+            primary: box TranslateError::One { kind: TranslateErrorKind::PrimaryBundleMissing, .. },
+            fallback: box TranslateError::One { kind: TranslateErrorKind::Fluent { errs }, .. },
+        } = &err
+            && let [FluentError::ResolverError(ResolverError::Reference(
+                ReferenceKind::Message { id, .. }
+                    | ReferenceKind::Variable { id, .. },
+            ))] = &**errs
+            && id == "name"
+        {} else {
+            panic!("{err:#?}")
+        };
+        assert_eq!(
+            format!("{err}"),
+            "failed while formatting fluent string `mir_build_borrow_of_moved_value`: \nargument `name` exists but was not referenced correctly\nhelp: try using `{$name}` instead\n"
+        );
+    }
+
+    {
+        let message = DiagnosticMessage::FluentIdentifier(
+            "mir_build_borrow_of_moved_value".into(),
+            Some("occurs_because_label".into()),
+        );
+
+        let err = dummy.translate_message(&message, &args).unwrap_err();
+        if let TranslateError::Two {
+            primary: box TranslateError::One { kind: TranslateErrorKind::PrimaryBundleMissing, .. },
+            fallback: box TranslateError::One { kind: TranslateErrorKind::Fluent { errs }, .. },
+        } = &err
+            && let [FluentError::ResolverError(ResolverError::Reference(
+                ReferenceKind::Message { id, .. }
+                    | ReferenceKind::Variable { id, .. },
+            ))] = &**errs
+            && id == "oops"
+        {} else {
+            panic!("{err:#?}")
+        };
+        assert_eq!(
+            format!("{err}"),
+            "failed while formatting fluent string `mir_build_borrow_of_moved_value`: \nthe fluent string has an argument `oops` that was not found.\nhelp: the arguments `name` and `ty` are available\n"
+        );
+    }
+}
diff --git a/compiler/rustc_errors/src/translation.rs b/compiler/rustc_errors/src/translation.rs
index afd660ff1..addfc9726 100644
--- a/compiler/rustc_errors/src/translation.rs
+++ b/compiler/rustc_errors/src/translation.rs
@@ -1,11 +1,10 @@
+use crate::error::TranslateError;
 use crate::snippet::Style;
 use crate::{DiagnosticArg, DiagnosticMessage, FluentBundle};
 use rustc_data_structures::sync::Lrc;
-use rustc_error_messages::{
-    fluent_bundle::resolver::errors::{ReferenceKind, ResolverError},
-    FluentArgs, FluentError,
-};
+use rustc_error_messages::FluentArgs;
 use std::borrow::Cow;
+use std::error::Report;
 
 /// Convert diagnostic arguments (a rustc internal type that exists to implement
 /// `Encodable`/`Decodable`) into `FluentArgs` which is necessary to perform translation.
@@ -46,7 +45,10 @@ pub trait Translate {
         args: &FluentArgs<'_>,
     ) -> Cow<'_, str> {
         Cow::Owned(
-            messages.iter().map(|(m, _)| self.translate_message(m, args)).collect::<String>(),
+            messages
+                .iter()
+                .map(|(m, _)| self.translate_message(m, args).map_err(Report::new).unwrap())
+                .collect::<String>(),
         )
     }
 
@@ -55,83 +57,56 @@ pub trait Translate {
         &'a self,
         message: &'a DiagnosticMessage,
         args: &'a FluentArgs<'_>,
-    ) -> Cow<'_, str> {
+    ) -> Result<Cow<'_, str>, TranslateError<'_>> {
         trace!(?message, ?args);
         let (identifier, attr) = match message {
             DiagnosticMessage::Str(msg) | DiagnosticMessage::Eager(msg) => {
-                return Cow::Borrowed(msg);
+                return Ok(Cow::Borrowed(msg));
             }
             DiagnosticMessage::FluentIdentifier(identifier, attr) => (identifier, attr),
         };
+        let translate_with_bundle =
+            |bundle: &'a FluentBundle| -> Result<Cow<'_, str>, TranslateError<'_>> {
+                let message = bundle
+                    .get_message(identifier)
+                    .ok_or(TranslateError::message(identifier, args))?;
+                let value = match attr {
+                    Some(attr) => message
+                        .get_attribute(attr)
+                        .ok_or(TranslateError::attribute(identifier, args, attr))?
+                        .value(),
+                    None => message.value().ok_or(TranslateError::value(identifier, args))?,
+                };
+                debug!(?message, ?value);
 
-        let translate_with_bundle = |bundle: &'a FluentBundle| -> Option<(Cow<'_, str>, Vec<_>)> {
-            let message = bundle.get_message(identifier)?;
-            let value = match attr {
-                Some(attr) => message.get_attribute(attr)?.value(),
-                None => message.value()?,
+                let mut errs = vec![];
+                let translated = bundle.format_pattern(value, Some(args), &mut errs);
+                debug!(?translated, ?errs);
+                if errs.is_empty() {
+                    Ok(translated)
+                } else {
+                    Err(TranslateError::fluent(identifier, args, errs))
+                }
             };
-            debug!(?message, ?value);
-
-            let mut errs = vec![];
-            let translated = bundle.format_pattern(value, Some(args), &mut errs);
-            debug!(?translated, ?errs);
-            Some((translated, errs))
-        };
 
-        self.fluent_bundle()
-            .and_then(|bundle| translate_with_bundle(bundle))
-            // If `translate_with_bundle` returns `None` with the primary bundle, this is likely
-            // just that the primary bundle doesn't contain the message being translated, so
-            // proceed to the fallback bundle.
-            //
-            // However, when errors are produced from translation, then that means the translation
-            // is broken (e.g. `{$foo}` exists in a translation but `foo` isn't provided).
-            //
-            // In debug builds, assert so that compiler devs can spot the broken translation and
-            // fix it..
-            .inspect(|(_, errs)| {
-                debug_assert!(
-                    errs.is_empty(),
-                    "identifier: {:?}, attr: {:?}, args: {:?}, errors: {:?}",
-                    identifier,
-                    attr,
-                    args,
-                    errs
-                );
-            })
-            // ..otherwise, for end users, an error about this wouldn't be useful or actionable, so
-            // just hide it and try with the fallback bundle.
-            .filter(|(_, errs)| errs.is_empty())
-            .or_else(|| translate_with_bundle(self.fallback_fluent_bundle()))
-            .map(|(translated, errs)| {
-                // Always bail out for errors with the fallback bundle.
+        try {
+            match self.fluent_bundle().map(|b| translate_with_bundle(b)) {
+                // The primary bundle was present and translation succeeded
+                Some(Ok(t)) => t,
 
-                let mut help_messages = vec![];
+                // Always yeet out for errors on debug
+                Some(Err(primary)) if cfg!(debug_assertions) => do yeet primary,
 
-                if !errs.is_empty() {
-                    for error in &errs {
-                        match error {
-                            FluentError::ResolverError(ResolverError::Reference(
-                                ReferenceKind::Message { id, .. },
-                            )) if args.iter().any(|(arg_id, _)| arg_id == id) => {
-                                help_messages.push(format!("Argument `{id}` exists but was not referenced correctly. Try using `{{${id}}}` instead"));
-                            }
-                            _ => {}
-                        }
-                    }
+                // If `translate_with_bundle` returns `Err` with the primary bundle, this is likely
+                // just that the primary bundle doesn't contain the message being translated or
+                // something else went wrong) so proceed to the fallback bundle.
+                Some(Err(primary)) => translate_with_bundle(self.fallback_fluent_bundle())
+                    .map_err(|fallback| primary.and(fallback))?,
 
-                    panic!(
-                        "Encountered errors while formatting message for `{identifier}`\n\
-                        help: {}\n\
-                        attr: `{attr:?}`\n\
-                        args: `{args:?}`\n\
-                        errors: `{errs:?}`",
-                        help_messages.join("\nhelp: ")
-                    );
-                }
-
-                translated
-            })
-            .expect("failed to find message in primary or fallback fluent bundles")
+                // The primary bundle is missing, proceed to the fallback bundle
+                None => translate_with_bundle(self.fallback_fluent_bundle())
+                    .map_err(|fallback| TranslateError::primary(identifier, args).and(fallback))?,
+            }
+        }
     }
 }