From 07b9bb1855596ac84a80d898b40c4b403f1dcc3f Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Thu, 19 Jun 2025 13:02:04 -0500
Subject: [PATCH 1/3] Extract Translator struct

---
 compiler/rustc_codegen_ssa/src/back/write.rs  | 20 ++----
 compiler/rustc_driver_impl/src/lib.rs         | 10 ++-
 compiler/rustc_error_messages/src/lib.rs      | 10 +--
 .../src/annotate_snippet_emitter_writer.rs    | 36 +++-------
 compiler/rustc_errors/src/emitter.rs          | 67 +++++++++----------
 compiler/rustc_errors/src/json.rs             | 40 ++++-------
 compiler/rustc_errors/src/json/tests.rs       |  6 +-
 compiler/rustc_errors/src/lib.rs              | 15 ++---
 compiler/rustc_errors/src/tests.rs            | 43 +++++-------
 compiler/rustc_errors/src/translation.rs      | 43 ++++++++----
 compiler/rustc_parse/src/parser/tests.rs      |  6 +-
 compiler/rustc_session/src/parse.rs           | 12 ++--
 compiler/rustc_session/src/session.rs         | 44 ++++++------
 src/librustdoc/core.rs                        |  9 +--
 src/librustdoc/doctest/make.rs                |  9 +--
 .../passes/lint/check_code_block_syntax.rs    | 28 +++-----
 .../src/doc/needless_doctest_main.rs          |  5 +-
 src/tools/rustfmt/src/parse/session.rs        | 37 +++-------
 18 files changed, 190 insertions(+), 250 deletions(-)

diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index bbf9cceef2a0..c3bfe4c13cdf 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -14,10 +14,10 @@
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::profiling::{SelfProfilerRef, VerboseTimingGuard};
 use rustc_errors::emitter::Emitter;
-use rustc_errors::translation::Translate;
+use rustc_errors::translation::Translator;
 use rustc_errors::{
-    Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalError, FluentBundle, Level, MultiSpan,
-    Style, Suggestions,
+    Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalError, Level, MultiSpan, Style,
+    Suggestions,
 };
 use rustc_fs_util::link_or_copy;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
@@ -1889,16 +1889,6 @@ fn fatal(&self, msg: &str) {
     }
 }
 
-impl Translate for SharedEmitter {
-    fn fluent_bundle(&self) -> Option<&FluentBundle> {
-        None
-    }
-
-    fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        panic!("shared emitter attempted to translate a diagnostic");
-    }
-}
-
 impl Emitter for SharedEmitter {
     fn emit_diagnostic(
         &mut self,
@@ -1932,6 +1922,10 @@ fn emit_diagnostic(
     fn source_map(&self) -> Option<&SourceMap> {
         None
     }
+
+    fn translator(&self) -> &Translator {
+        panic!("shared emitter attempted to translate a diagnostic");
+    }
 }
 
 impl SharedEmitterMain {
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index d53126d04143..daeca43169d4 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -38,6 +38,7 @@
 };
 use rustc_errors::emitter::stderr_destination;
 use rustc_errors::registry::Registry;
+use rustc_errors::translation::Translator;
 use rustc_errors::{ColorConfig, DiagCtxt, ErrCode, FatalError, PResult, markdown};
 use rustc_feature::find_gated_cfg;
 // This avoids a false positive with `-Wunused_crate_dependencies`.
@@ -109,6 +110,10 @@ pub(super) fn install() {}
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
+pub fn default_translator() -> Translator {
+    Translator::with_fallback_bundle(DEFAULT_LOCALE_RESOURCES.to_vec(), false)
+}
+
 pub static DEFAULT_LOCALE_RESOURCES: &[&str] = &[
     // tidy-alphabetical-start
     crate::DEFAULT_LOCALE_RESOURCE,
@@ -1413,11 +1418,10 @@ fn report_ice(
     extra_info: fn(&DiagCtxt),
     using_internal_features: &AtomicBool,
 ) {
-    let fallback_bundle =
-        rustc_errors::fallback_fluent_bundle(crate::DEFAULT_LOCALE_RESOURCES.to_vec(), false);
+    let translator = default_translator();
     let emitter = Box::new(rustc_errors::emitter::HumanEmitter::new(
         stderr_destination(rustc_errors::ColorConfig::Auto),
-        fallback_bundle,
+        translator,
     ));
     let dcx = rustc_errors::DiagCtxt::new(emitter);
     let dcx = dcx.handle();
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 1d3b5b20751a..194fc2450ba4 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -18,7 +18,7 @@
 use fluent_syntax::parser::ParserError;
 use icu_provider_adapters::fallback::{LocaleFallbackProvider, LocaleFallbacker};
 use intl_memoizer::concurrent::IntlLangMemoizer;
-use rustc_data_structures::sync::IntoDynSyncSend;
+use rustc_data_structures::sync::{DynSend, IntoDynSyncSend};
 use rustc_macros::{Decodable, Encodable};
 use rustc_span::Span;
 use smallvec::SmallVec;
@@ -204,16 +204,16 @@ fn register_functions(bundle: &mut FluentBundle) {
 
 /// Type alias for the result of `fallback_fluent_bundle` - a reference-counted pointer to a lazily
 /// evaluated fluent bundle.
-pub type LazyFallbackBundle = Arc<LazyLock<FluentBundle, impl FnOnce() -> FluentBundle>>;
+pub type LazyFallbackBundle =
+    Arc<LazyLock<FluentBundle, Box<dyn FnOnce() -> FluentBundle + DynSend>>>;
 
 /// Return the default `FluentBundle` with standard "en-US" diagnostic messages.
 #[instrument(level = "trace", skip(resources))]
-#[define_opaque(LazyFallbackBundle)]
 pub fn fallback_fluent_bundle(
     resources: Vec<&'static str>,
     with_directionality_markers: bool,
 ) -> LazyFallbackBundle {
-    Arc::new(LazyLock::new(move || {
+    Arc::new(LazyLock::new(Box::new(move || {
         let mut fallback_bundle = new_bundle(vec![langid!("en-US")]);
 
         register_functions(&mut fallback_bundle);
@@ -228,7 +228,7 @@ pub fn fallback_fluent_bundle(
         }
 
         fallback_bundle
-    }))
+    })))
 }
 
 /// Identifier for the Fluent message/attribute corresponding to a diagnostic message.
diff --git a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
index f3aeb8d224b9..2eb3c23259ff 100644
--- a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
+++ b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
@@ -15,17 +15,15 @@
 use crate::emitter::FileWithAnnotatedLines;
 use crate::registry::Registry;
 use crate::snippet::Line;
-use crate::translation::{Translate, to_fluent_args};
+use crate::translation::{Translator, to_fluent_args};
 use crate::{
-    CodeSuggestion, DiagInner, DiagMessage, Emitter, ErrCode, FluentBundle, LazyFallbackBundle,
-    Level, MultiSpan, Style, Subdiag,
+    CodeSuggestion, DiagInner, DiagMessage, Emitter, ErrCode, Level, MultiSpan, Style, Subdiag,
 };
 
 /// Generates diagnostics using annotate-snippet
 pub struct AnnotateSnippetEmitter {
     source_map: Option<Arc<SourceMap>>,
-    fluent_bundle: Option<Arc<FluentBundle>>,
-    fallback_bundle: LazyFallbackBundle,
+    translator: Translator,
 
     /// If true, hides the longer explanation text
     short_message: bool,
@@ -35,16 +33,6 @@ pub struct AnnotateSnippetEmitter {
     macro_backtrace: bool,
 }
 
-impl Translate for AnnotateSnippetEmitter {
-    fn fluent_bundle(&self) -> Option<&FluentBundle> {
-        self.fluent_bundle.as_deref()
-    }
-
-    fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        &self.fallback_bundle
-    }
-}
-
 impl Emitter for AnnotateSnippetEmitter {
     /// The entry point for the diagnostics generation
     fn emit_diagnostic(&mut self, mut diag: DiagInner, _registry: &Registry) {
@@ -78,6 +66,10 @@ fn source_map(&self) -> Option<&SourceMap> {
     fn should_show_explain(&self) -> bool {
         !self.short_message
     }
+
+    fn translator(&self) -> &Translator {
+        &self.translator
+    }
 }
 
 /// Provides the source string for the given `line` of `file`
@@ -104,19 +96,11 @@ fn annotation_level_for_level(level: Level) -> annotate_snippets::Level {
 impl AnnotateSnippetEmitter {
     pub fn new(
         source_map: Option<Arc<SourceMap>>,
-        fluent_bundle: Option<Arc<FluentBundle>>,
-        fallback_bundle: LazyFallbackBundle,
+        translator: Translator,
         short_message: bool,
         macro_backtrace: bool,
     ) -> Self {
-        Self {
-            source_map,
-            fluent_bundle,
-            fallback_bundle,
-            short_message,
-            ui_testing: false,
-            macro_backtrace,
-        }
+        Self { source_map, translator, short_message, ui_testing: false, macro_backtrace }
     }
 
     /// Allows to modify `Self` to enable or disable the `ui_testing` flag.
@@ -137,7 +121,7 @@ fn emit_messages_default(
         _children: &[Subdiag],
         _suggestions: &[CodeSuggestion],
     ) {
-        let message = self.translate_messages(messages, args);
+        let message = self.translator.translate_messages(messages, args);
         if let Some(source_map) = &self.source_map {
             // Make sure our primary file comes first
             let primary_lo = if let Some(primary_span) = msp.primary_span().as_ref() {
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 6ab6f96079eb..494f15cc6390 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -35,10 +35,10 @@
 };
 use crate::styled_buffer::StyledBuffer;
 use crate::timings::TimingRecord;
-use crate::translation::{Translate, to_fluent_args};
+use crate::translation::{Translator, to_fluent_args};
 use crate::{
-    CodeSuggestion, DiagInner, DiagMessage, ErrCode, FluentBundle, LazyFallbackBundle, Level,
-    MultiSpan, Subdiag, SubstitutionHighlight, SuggestionStyle, TerminalUrl,
+    CodeSuggestion, DiagInner, DiagMessage, ErrCode, Level, MultiSpan, Subdiag,
+    SubstitutionHighlight, SuggestionStyle, TerminalUrl,
 };
 
 /// Default column width, used in tests and when terminal dimensions cannot be determined.
@@ -175,7 +175,7 @@ pub enum TimingEvent {
 pub type DynEmitter = dyn Emitter + DynSend;
 
 /// Emitter trait for emitting errors and other structured information.
-pub trait Emitter: Translate {
+pub trait Emitter {
     /// Emit a structured diagnostic.
     fn emit_diagnostic(&mut self, diag: DiagInner, registry: &Registry);
 
@@ -212,6 +212,8 @@ fn supports_color(&self) -> bool {
 
     fn source_map(&self) -> Option<&SourceMap>;
 
+    fn translator(&self) -> &Translator;
+
     /// Formats the substitutions of the primary_span
     ///
     /// There are a lot of conditions to this method, but in short:
@@ -224,13 +226,17 @@ fn supports_color(&self) -> bool {
     /// * If the current `DiagInner` has multiple suggestions,
     ///   we leave `primary_span` and the suggestions untouched.
     fn primary_span_formatted(
-        &mut self,
+        &self,
         primary_span: &mut MultiSpan,
         suggestions: &mut Vec<CodeSuggestion>,
         fluent_args: &FluentArgs<'_>,
     ) {
         if let Some((sugg, rest)) = suggestions.split_first() {
-            let msg = self.translate_message(&sugg.msg, fluent_args).map_err(Report::new).unwrap();
+            let msg = self
+                .translator()
+                .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
@@ -491,16 +497,6 @@ fn fix_multispan_in_extern_macros(&self, span: &mut MultiSpan) {
     }
 }
 
-impl Translate for HumanEmitter {
-    fn fluent_bundle(&self) -> Option<&FluentBundle> {
-        self.fluent_bundle.as_deref()
-    }
-
-    fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        &self.fallback_bundle
-    }
-}
-
 impl Emitter for HumanEmitter {
     fn source_map(&self) -> Option<&SourceMap> {
         self.sm.as_deref()
@@ -538,6 +534,10 @@ fn should_show_explain(&self) -> bool {
     fn supports_color(&self) -> bool {
         self.dst.supports_color()
     }
+
+    fn translator(&self) -> &Translator {
+        &self.translator
+    }
 }
 
 /// An emitter that does nothing when emitting a non-fatal diagnostic.
@@ -549,16 +549,6 @@ pub struct SilentEmitter {
     pub emit_fatal_diagnostic: bool,
 }
 
-impl Translate for SilentEmitter {
-    fn fluent_bundle(&self) -> Option<&FluentBundle> {
-        None
-    }
-
-    fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        self.fatal_emitter.fallback_fluent_bundle()
-    }
-}
-
 impl Emitter for SilentEmitter {
     fn source_map(&self) -> Option<&SourceMap> {
         None
@@ -572,6 +562,10 @@ fn emit_diagnostic(&mut self, mut diag: DiagInner, registry: &Registry) {
             self.fatal_emitter.emit_diagnostic(diag, registry);
         }
     }
+
+    fn translator(&self) -> &Translator {
+        self.fatal_emitter.translator()
+    }
 }
 
 /// Maximum number of suggestions to be shown
@@ -615,9 +609,8 @@ pub struct HumanEmitter {
     #[setters(skip)]
     dst: IntoDynSyncSend<Destination>,
     sm: Option<Arc<SourceMap>>,
-    fluent_bundle: Option<Arc<FluentBundle>>,
     #[setters(skip)]
-    fallback_bundle: LazyFallbackBundle,
+    translator: Translator,
     short_message: bool,
     ui_testing: bool,
     ignored_directories_in_source_blocks: Vec<String>,
@@ -637,12 +630,11 @@ pub(crate) struct FileWithAnnotatedLines {
 }
 
 impl HumanEmitter {
-    pub fn new(dst: Destination, fallback_bundle: LazyFallbackBundle) -> HumanEmitter {
+    pub fn new(dst: Destination, translator: Translator) -> HumanEmitter {
         HumanEmitter {
             dst: IntoDynSyncSend(dst),
             sm: None,
-            fluent_bundle: None,
-            fallback_bundle,
+            translator,
             short_message: false,
             ui_testing: false,
             ignored_directories_in_source_blocks: Vec::new(),
@@ -1433,7 +1425,7 @@ fn style_or_override(style: Style, override_: Option<Style>) -> Style {
         //                very *weird* formats
         //                see?
         for (text, style) in msgs.iter() {
-            let text = self.translate_message(text, args).map_err(Report::new).unwrap();
+            let text = self.translator.translate_message(text, args).map_err(Report::new).unwrap();
             let text = &normalize_whitespace(&text);
             let lines = text.split('\n').collect::<Vec<_>>();
             if lines.len() > 1 {
@@ -1528,7 +1520,8 @@ fn emit_messages_default_inner(
             }
             let mut line = 0;
             for (text, style) in msgs.iter() {
-                let text = self.translate_message(text, args).map_err(Report::new).unwrap();
+                let text =
+                    self.translator.translate_message(text, args).map_err(Report::new).unwrap();
                 // Account for newlines to align output to its label.
                 for text in normalize_whitespace(&text).lines() {
                     buffer.append(
@@ -1560,7 +1553,7 @@ fn emit_messages_default_inner(
                     .into_iter()
                     .filter_map(|label| match label.label {
                         Some(msg) if label.is_primary => {
-                            let text = self.translate_message(&msg, args).ok()?;
+                            let text = self.translator.translate_message(&msg, args).ok()?;
                             if !text.trim().is_empty() { Some(text.to_string()) } else { None }
                         }
                         _ => None,
@@ -3104,7 +3097,11 @@ fn add_annotation_to_file(
 
                 let label = label.as_ref().map(|m| {
                     normalize_whitespace(
-                        &emitter.translate_message(m, args).map_err(Report::new).unwrap(),
+                        &emitter
+                            .translator()
+                            .translate_message(m, args)
+                            .map_err(Report::new)
+                            .unwrap(),
                     )
                 });
 
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index d67e2ba2d60e..6d600f896a0f 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -32,11 +32,8 @@
 };
 use crate::registry::Registry;
 use crate::timings::{TimingRecord, TimingSection};
-use crate::translation::{Translate, to_fluent_args};
-use crate::{
-    CodeSuggestion, FluentBundle, LazyFallbackBundle, MultiSpan, SpanLabel, Subdiag, Suggestions,
-    TerminalUrl,
-};
+use crate::translation::{Translator, to_fluent_args};
+use crate::{CodeSuggestion, MultiSpan, SpanLabel, Subdiag, Suggestions, TerminalUrl};
 
 #[cfg(test)]
 mod tests;
@@ -47,9 +44,8 @@ pub struct JsonEmitter {
     dst: IntoDynSyncSend<Box<dyn Write + Send>>,
     #[setters(skip)]
     sm: Option<Arc<SourceMap>>,
-    fluent_bundle: Option<Arc<FluentBundle>>,
     #[setters(skip)]
-    fallback_bundle: LazyFallbackBundle,
+    translator: Translator,
     #[setters(skip)]
     pretty: bool,
     ui_testing: bool,
@@ -67,7 +63,7 @@ impl JsonEmitter {
     pub fn new(
         dst: Box<dyn Write + Send>,
         sm: Option<Arc<SourceMap>>,
-        fallback_bundle: LazyFallbackBundle,
+        translator: Translator,
         pretty: bool,
         json_rendered: HumanReadableErrorType,
         color_config: ColorConfig,
@@ -75,8 +71,7 @@ pub fn new(
         JsonEmitter {
             dst: IntoDynSyncSend(dst),
             sm,
-            fluent_bundle: None,
-            fallback_bundle,
+            translator,
             pretty,
             ui_testing: false,
             ignored_directories_in_source_blocks: Vec::new(),
@@ -110,16 +105,6 @@ enum EmitTyped<'a> {
     UnusedExtern(UnusedExterns<'a>),
 }
 
-impl Translate for JsonEmitter {
-    fn fluent_bundle(&self) -> Option<&FluentBundle> {
-        self.fluent_bundle.as_deref()
-    }
-
-    fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        &self.fallback_bundle
-    }
-}
-
 impl Emitter for JsonEmitter {
     fn emit_diagnostic(&mut self, diag: crate::DiagInner, registry: &Registry) {
         let data = Diagnostic::from_errors_diagnostic(diag, self, registry);
@@ -194,6 +179,10 @@ fn source_map(&self) -> Option<&SourceMap> {
     fn should_show_explain(&self) -> bool {
         !self.json_rendered.short()
     }
+
+    fn translator(&self) -> &Translator {
+        &self.translator
+    }
 }
 
 // The following data types are provided just for serialisation.
@@ -324,7 +313,7 @@ fn from_errors_diagnostic(
         let args = to_fluent_args(diag.args.iter());
         let sugg_to_diag = |sugg: &CodeSuggestion| {
             let translated_message =
-                je.translate_message(&sugg.msg, &args).map_err(Report::new).unwrap();
+                je.translator.translate_message(&sugg.msg, &args).map_err(Report::new).unwrap();
             Diagnostic {
                 message: translated_message.to_string(),
                 code: None,
@@ -368,7 +357,7 @@ fn reset(&mut self) -> io::Result<()> {
             }
         }
 
-        let translated_message = je.translate_messages(&diag.messages, &args);
+        let translated_message = je.translator.translate_messages(&diag.messages, &args);
 
         let code = if let Some(code) = diag.code {
             Some(DiagnosticCode {
@@ -396,10 +385,9 @@ fn reset(&mut self) -> io::Result<()> {
             ColorConfig::Always | ColorConfig::Auto => dst = Box::new(termcolor::Ansi::new(dst)),
             ColorConfig::Never => {}
         }
-        HumanEmitter::new(dst, Arc::clone(&je.fallback_bundle))
+        HumanEmitter::new(dst, je.translator.clone())
             .short_message(short)
             .sm(je.sm.clone())
-            .fluent_bundle(je.fluent_bundle.clone())
             .diagnostic_width(je.diagnostic_width)
             .macro_backtrace(je.macro_backtrace)
             .track_diagnostics(je.track_diagnostics)
@@ -430,7 +418,7 @@ fn from_sub_diagnostic(
         args: &FluentArgs<'_>,
         je: &JsonEmitter,
     ) -> Diagnostic {
-        let translated_message = je.translate_messages(&subdiag.messages, args);
+        let translated_message = je.translator.translate_messages(&subdiag.messages, args);
         Diagnostic {
             message: translated_message.to_string(),
             code: None,
@@ -454,7 +442,7 @@ fn from_span_label(
             span.is_primary,
             span.label
                 .as_ref()
-                .map(|m| je.translate_message(m, args).unwrap())
+                .map(|m| je.translator.translate_message(m, args).unwrap())
                 .map(|m| m.to_string()),
             suggestion,
             je,
diff --git a/compiler/rustc_errors/src/json/tests.rs b/compiler/rustc_errors/src/json/tests.rs
index 40973e8e5d8a..8cf81f467d84 100644
--- a/compiler/rustc_errors/src/json/tests.rs
+++ b/compiler/rustc_errors/src/json/tests.rs
@@ -41,14 +41,14 @@ fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
     rustc_span::create_default_session_globals_then(|| {
         let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
         sm.new_source_file(Path::new("test.rs").to_owned().into(), code.to_owned());
-        let fallback_bundle =
-            crate::fallback_fluent_bundle(vec![crate::DEFAULT_LOCALE_RESOURCE], false);
+        let translator =
+            Translator::with_fallback_bundle(vec![crate::DEFAULT_LOCALE_RESOURCE], false);
 
         let output = Arc::new(Mutex::new(Vec::new()));
         let je = JsonEmitter::new(
             Box::new(Shared { data: output.clone() }),
             Some(sm),
-            fallback_bundle,
+            translator,
             true, // pretty
             HumanReadableErrorType::Short,
             ColorConfig::Never,
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 0bd259366def..70f294b696a2 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -761,14 +761,8 @@ fn emit_diagnostic(&mut self, _: DiagInner, _: &Registry) {
             fn source_map(&self) -> Option<&SourceMap> {
                 unimplemented!("false emitter must only used during `make_silent`")
             }
-        }
 
-        impl translation::Translate for FalseEmitter {
-            fn fluent_bundle(&self) -> Option<&FluentBundle> {
-                unimplemented!("false emitter must only used during `make_silent`")
-            }
-
-            fn fallback_fluent_bundle(&self) -> &FluentBundle {
+            fn translator(&self) -> &translation::Translator {
                 unimplemented!("false emitter must only used during `make_silent`")
             }
         }
@@ -1771,7 +1765,12 @@ fn eagerly_translate_to_string<'a>(
         args: impl Iterator<Item = DiagArg<'a>>,
     ) -> String {
         let args = crate::translation::to_fluent_args(args);
-        self.emitter.translate_message(&message, &args).map_err(Report::new).unwrap().to_string()
+        self.emitter
+            .translator()
+            .translate_message(&message, &args)
+            .map_err(Report::new)
+            .unwrap()
+            .to_string()
     }
 
     fn eagerly_translate_for_subdiag(
diff --git a/compiler/rustc_errors/src/tests.rs b/compiler/rustc_errors/src/tests.rs
index 376fd24d57ba..34ebac0fde11 100644
--- a/compiler/rustc_errors/src/tests.rs
+++ b/compiler/rustc_errors/src/tests.rs
@@ -1,3 +1,5 @@
+use std::sync::{Arc, LazyLock};
+
 use rustc_data_structures::sync::IntoDynSyncSend;
 use rustc_error_messages::fluent_bundle::resolver::errors::{ReferenceKind, ResolverError};
 use rustc_error_messages::{DiagMessage, langid};
@@ -5,23 +7,9 @@
 use crate::FluentBundle;
 use crate::error::{TranslateError, TranslateErrorKind};
 use crate::fluent_bundle::*;
-use crate::translation::Translate;
+use crate::translation::Translator;
 
-struct Dummy {
-    bundle: FluentBundle,
-}
-
-impl Translate for Dummy {
-    fn fluent_bundle(&self) -> Option<&FluentBundle> {
-        None
-    }
-
-    fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        &self.bundle
-    }
-}
-
-fn make_dummy(ftl: &'static str) -> Dummy {
+fn make_translator(ftl: &'static str) -> Translator {
     let resource = FluentResource::try_new(ftl.into()).expect("Failed to parse an FTL string.");
 
     let langid_en = langid!("en-US");
@@ -33,12 +21,15 @@ fn make_dummy(ftl: &'static str) -> Dummy {
 
     bundle.add_resource(resource).expect("Failed to add FTL resources to the bundle.");
 
-    Dummy { bundle }
+    Translator {
+        fluent_bundle: None,
+        fallback_fluent_bundle: Arc::new(LazyLock::new(Box::new(|| bundle))),
+    }
 }
 
 #[test]
 fn wellformed_fluent() {
-    let dummy = make_dummy("mir_build_borrow_of_moved_value = borrow of moved value
+    let translator = make_translator("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
@@ -54,7 +45,7 @@ fn wellformed_fluent() {
         );
 
         assert_eq!(
-            dummy.translate_message(&message, &args).unwrap(),
+            translator.translate_message(&message, &args).unwrap(),
             "borrow this binding in the pattern to avoid moving the value"
         );
     }
@@ -66,7 +57,7 @@ fn wellformed_fluent() {
         );
 
         assert_eq!(
-            dummy.translate_message(&message, &args).unwrap(),
+            translator.translate_message(&message, &args).unwrap(),
             "value borrowed here after move"
         );
     }
@@ -78,7 +69,7 @@ fn wellformed_fluent() {
         );
 
         assert_eq!(
-            dummy.translate_message(&message, &args).unwrap(),
+            translator.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"
         );
 
@@ -89,7 +80,7 @@ fn wellformed_fluent() {
             );
 
             assert_eq!(
-                dummy.translate_message(&message, &args).unwrap(),
+                translator.translate_message(&message, &args).unwrap(),
                 "value moved into `\u{2068}Foo\u{2069}` here"
             );
         }
@@ -98,7 +89,7 @@ fn wellformed_fluent() {
 
 #[test]
 fn misformed_fluent() {
-    let dummy = make_dummy("mir_build_borrow_of_moved_value = borrow of moved value
+    let translator = make_translator("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");
@@ -112,7 +103,7 @@ fn misformed_fluent() {
             Some("value_borrowed_label".into()),
         );
 
-        let err = dummy.translate_message(&message, &args).unwrap_err();
+        let err = translator.translate_message(&message, &args).unwrap_err();
         assert!(
             matches!(
                 &err,
@@ -141,7 +132,7 @@ fn misformed_fluent() {
             Some("label".into()),
         );
 
-        let err = dummy.translate_message(&message, &args).unwrap_err();
+        let err = translator.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 }, .. },
@@ -168,7 +159,7 @@ fn misformed_fluent() {
             Some("occurs_because_label".into()),
         );
 
-        let err = dummy.translate_message(&message, &args).unwrap_err();
+        let err = translator.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 }, .. },
diff --git a/compiler/rustc_errors/src/translation.rs b/compiler/rustc_errors/src/translation.rs
index 156f5e5d26e6..c0bcec093c7e 100644
--- a/compiler/rustc_errors/src/translation.rs
+++ b/compiler/rustc_errors/src/translation.rs
@@ -1,8 +1,9 @@
 use std::borrow::Cow;
 use std::env;
 use std::error::Report;
+use std::sync::Arc;
 
-pub use rustc_error_messages::FluentArgs;
+pub use rustc_error_messages::{FluentArgs, LazyFallbackBundle};
 use tracing::{debug, trace};
 
 use crate::error::{TranslateError, TranslateErrorKind};
@@ -28,19 +29,33 @@ pub fn to_fluent_args<'iter>(iter: impl Iterator<Item = DiagArg<'iter>>) -> Flue
     args
 }
 
-pub trait Translate {
-    /// Return `FluentBundle` with localized diagnostics for the locale requested by the user. If no
-    /// language was requested by the user then this will be `None` and `fallback_fluent_bundle`
-    /// should be used.
-    fn fluent_bundle(&self) -> Option<&FluentBundle>;
-
+#[derive(Clone)]
+pub struct Translator {
+    /// Localized diagnostics for the locale requested by the user. If no language was requested by
+    /// the user then this will be `None` and `fallback_fluent_bundle` should be used.
+    pub fluent_bundle: Option<Arc<FluentBundle>>,
     /// Return `FluentBundle` with localized diagnostics for the default locale of the compiler.
     /// Used when the user has not requested a specific language or when a localized diagnostic is
     /// unavailable for the requested locale.
-    fn fallback_fluent_bundle(&self) -> &FluentBundle;
+    pub fallback_fluent_bundle: LazyFallbackBundle,
+}
+
+impl Translator {
+    pub fn with_fallback_bundle(
+        resources: Vec<&'static str>,
+        with_directionality_markers: bool,
+    ) -> Translator {
+        Translator {
+            fluent_bundle: None,
+            fallback_fluent_bundle: crate::fallback_fluent_bundle(
+                resources,
+                with_directionality_markers,
+            ),
+        }
+    }
 
     /// Convert `DiagMessage`s to a string, performing translation if necessary.
-    fn translate_messages(
+    pub fn translate_messages(
         &self,
         messages: &[(DiagMessage, Style)],
         args: &FluentArgs<'_>,
@@ -54,7 +69,7 @@ fn translate_messages(
     }
 
     /// Convert a `DiagMessage` to a string, performing translation if necessary.
-    fn translate_message<'a>(
+    pub fn translate_message<'a>(
         &'a self,
         message: &'a DiagMessage,
         args: &'a FluentArgs<'_>,
@@ -91,7 +106,7 @@ fn translate_message<'a>(
             };
 
         try {
-            match self.fluent_bundle().map(|b| translate_with_bundle(b)) {
+            match self.fluent_bundle.as_ref().map(|b| translate_with_bundle(b)) {
                 // The primary bundle was present and translation succeeded
                 Some(Ok(t)) => t,
 
@@ -102,7 +117,7 @@ fn translate_message<'a>(
                     primary @ TranslateError::One {
                         kind: TranslateErrorKind::MessageMissing, ..
                     },
-                )) => translate_with_bundle(self.fallback_fluent_bundle())
+                )) => translate_with_bundle(&self.fallback_fluent_bundle)
                     .map_err(|fallback| primary.and(fallback))?,
 
                 // Always yeet out for errors on debug (unless
@@ -118,11 +133,11 @@ fn translate_message<'a>(
 
                 // ..otherwise, for end users, an error about this wouldn't be useful or actionable, so
                 // just hide it and try with the fallback bundle.
-                Some(Err(primary)) => translate_with_bundle(self.fallback_fluent_bundle())
+                Some(Err(primary)) => translate_with_bundle(&self.fallback_fluent_bundle)
                     .map_err(|fallback| primary.and(fallback))?,
 
                 // The primary bundle is missing, proceed to the fallback bundle
-                None => translate_with_bundle(self.fallback_fluent_bundle())
+                None => translate_with_bundle(&self.fallback_fluent_bundle)
                     .map_err(|fallback| TranslateError::primary(identifier, args).and(fallback))?,
             }
         }
diff --git a/compiler/rustc_parse/src/parser/tests.rs b/compiler/rustc_parse/src/parser/tests.rs
index 2a44c90abc17..15679d23bc56 100644
--- a/compiler/rustc_parse/src/parser/tests.rs
+++ b/compiler/rustc_parse/src/parser/tests.rs
@@ -14,6 +14,7 @@
 use rustc_ast::{self as ast, PatKind, visit};
 use rustc_ast_pretty::pprust::item_to_string;
 use rustc_errors::emitter::{HumanEmitter, OutputTheme};
+use rustc_errors::translation::Translator;
 use rustc_errors::{DiagCtxt, MultiSpan, PResult};
 use rustc_session::parse::ParseSess;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
@@ -41,9 +42,8 @@ fn string_to_parser(psess: &ParseSess, source_str: String) -> Parser<'_> {
 fn create_test_handler(theme: OutputTheme) -> (DiagCtxt, Arc<SourceMap>, Arc<Mutex<Vec<u8>>>) {
     let output = Arc::new(Mutex::new(Vec::new()));
     let source_map = Arc::new(SourceMap::new(FilePathMapping::empty()));
-    let fallback_bundle =
-        rustc_errors::fallback_fluent_bundle(vec![crate::DEFAULT_LOCALE_RESOURCE], false);
-    let mut emitter = HumanEmitter::new(Box::new(Shared { data: output.clone() }), fallback_bundle)
+    let translator = Translator::with_fallback_bundle(vec![crate::DEFAULT_LOCALE_RESOURCE], false);
+    let mut emitter = HumanEmitter::new(Box::new(Shared { data: output.clone() }), translator)
         .sm(Some(source_map.clone()))
         .diagnostic_width(Some(140));
     emitter = emitter.theme(theme);
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 87c848cf857f..30a61cb411bb 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -9,9 +9,10 @@
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_data_structures::sync::{AppendOnlyVec, Lock};
 use rustc_errors::emitter::{HumanEmitter, SilentEmitter, stderr_destination};
+use rustc_errors::translation::Translator;
 use rustc_errors::{
     ColorConfig, Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, EmissionGuarantee, MultiSpan,
-    StashKey, fallback_fluent_bundle,
+    StashKey,
 };
 use rustc_feature::{GateIssue, UnstableFeatures, find_feature_issue};
 use rustc_span::edition::Edition;
@@ -242,10 +243,10 @@ pub struct ParseSess {
 impl ParseSess {
     /// Used for testing.
     pub fn new(locale_resources: Vec<&'static str>) -> Self {
-        let fallback_bundle = fallback_fluent_bundle(locale_resources, false);
+        let translator = Translator::with_fallback_bundle(locale_resources, false);
         let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
         let emitter = Box::new(
-            HumanEmitter::new(stderr_destination(ColorConfig::Auto), fallback_bundle)
+            HumanEmitter::new(stderr_destination(ColorConfig::Auto), translator)
                 .sm(Some(Arc::clone(&sm))),
         );
         let dcx = DiagCtxt::new(emitter);
@@ -277,12 +278,13 @@ pub fn with_dcx(dcx: DiagCtxt, source_map: Arc<SourceMap>) -> Self {
     pub fn with_silent_emitter(
         locale_resources: Vec<&'static str>,
         fatal_note: String,
+
         emit_fatal_diagnostic: bool,
     ) -> Self {
-        let fallback_bundle = fallback_fluent_bundle(locale_resources, false);
+        let translator = Translator::with_fallback_bundle(locale_resources, false);
         let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
         let fatal_emitter =
-            Box::new(HumanEmitter::new(stderr_destination(ColorConfig::Auto), fallback_bundle));
+            Box::new(HumanEmitter::new(stderr_destination(ColorConfig::Auto), translator));
         let dcx = DiagCtxt::new(Box::new(SilentEmitter {
             fatal_emitter,
             fatal_note: Some(fatal_note),
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index ca42c5a42566..ad58c3c8f7d8 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -19,9 +19,10 @@
 };
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::timings::TimingSectionHandler;
+use rustc_errors::translation::Translator;
 use rustc_errors::{
     Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, Diagnostic, ErrorGuaranteed, FatalAbort,
-    FluentBundle, LazyFallbackBundle, TerminalUrl, fallback_fluent_bundle,
+    TerminalUrl, fallback_fluent_bundle,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -948,8 +949,7 @@ pub fn apple_deployment_target(&self) -> apple::OSVersion {
 fn default_emitter(
     sopts: &config::Options,
     source_map: Arc<SourceMap>,
-    bundle: Option<Arc<FluentBundle>>,
-    fallback_bundle: LazyFallbackBundle,
+    translator: Translator,
 ) -> Box<DynEmitter> {
     let macro_backtrace = sopts.unstable_opts.macro_backtrace;
     let track_diagnostics = sopts.unstable_opts.track_diagnostics;
@@ -974,17 +974,11 @@ fn default_emitter(
             let short = kind.short();
 
             if let HumanReadableErrorType::AnnotateSnippet = kind {
-                let emitter = AnnotateSnippetEmitter::new(
-                    source_map,
-                    bundle,
-                    fallback_bundle,
-                    short,
-                    macro_backtrace,
-                );
+                let emitter =
+                    AnnotateSnippetEmitter::new(source_map, translator, short, macro_backtrace);
                 Box::new(emitter.ui_testing(sopts.unstable_opts.ui_testing))
             } else {
-                let emitter = HumanEmitter::new(stderr_destination(color_config), fallback_bundle)
-                    .fluent_bundle(bundle)
+                let emitter = HumanEmitter::new(stderr_destination(color_config), translator)
                     .sm(source_map)
                     .short_message(short)
                     .diagnostic_width(sopts.diagnostic_width)
@@ -1006,12 +1000,11 @@ fn default_emitter(
             JsonEmitter::new(
                 Box::new(io::BufWriter::new(io::stderr())),
                 source_map,
-                fallback_bundle,
+                translator,
                 pretty,
                 json_rendered,
                 color_config,
             )
-            .fluent_bundle(bundle)
             .ui_testing(sopts.unstable_opts.ui_testing)
             .ignored_directories_in_source_blocks(
                 sopts.unstable_opts.ignore_directory_in_diagnostics_source_blocks.clone(),
@@ -1030,7 +1023,7 @@ fn default_emitter(
 pub fn build_session(
     sopts: config::Options,
     io: CompilerIO,
-    bundle: Option<Arc<rustc_errors::FluentBundle>>,
+    fluent_bundle: Option<Arc<rustc_errors::FluentBundle>>,
     registry: rustc_errors::registry::Registry,
     fluent_resources: Vec<&'static str>,
     driver_lint_caps: FxHashMap<lint::LintId, lint::Level>,
@@ -1052,12 +1045,15 @@ pub fn build_session(
     let cap_lints_allow = sopts.lint_cap.is_some_and(|cap| cap == lint::Allow);
     let can_emit_warnings = !(warnings_allow || cap_lints_allow);
 
-    let fallback_bundle = fallback_fluent_bundle(
-        fluent_resources,
-        sopts.unstable_opts.translate_directionality_markers,
-    );
+    let translator = Translator {
+        fluent_bundle,
+        fallback_fluent_bundle: fallback_fluent_bundle(
+            fluent_resources,
+            sopts.unstable_opts.translate_directionality_markers,
+        ),
+    };
     let source_map = rustc_span::source_map::get_source_map().unwrap();
-    let emitter = default_emitter(&sopts, Arc::clone(&source_map), bundle, fallback_bundle);
+    let emitter = default_emitter(&sopts, Arc::clone(&source_map), translator);
 
     let mut dcx = DiagCtxt::new(emitter)
         .with_flags(sopts.unstable_opts.dcx_flags(can_emit_warnings))
@@ -1500,13 +1496,13 @@ pub fn early_struct_warn(&self, msg: impl Into<DiagMessage>) -> Diag<'_, ()> {
 fn mk_emitter(output: ErrorOutputType) -> Box<DynEmitter> {
     // FIXME(#100717): early errors aren't translated at the moment, so this is fine, but it will
     // need to reference every crate that might emit an early error for translation to work.
-    let fallback_bundle =
-        fallback_fluent_bundle(vec![rustc_errors::DEFAULT_LOCALE_RESOURCE], false);
+    let translator =
+        Translator::with_fallback_bundle(vec![rustc_errors::DEFAULT_LOCALE_RESOURCE], false);
     let emitter: Box<DynEmitter> = match output {
         config::ErrorOutputType::HumanReadable { kind, color_config } => {
             let short = kind.short();
             Box::new(
-                HumanEmitter::new(stderr_destination(color_config), fallback_bundle)
+                HumanEmitter::new(stderr_destination(color_config), translator)
                     .theme(if let HumanReadableErrorType::Unicode = kind {
                         OutputTheme::Unicode
                     } else {
@@ -1519,7 +1515,7 @@ fn mk_emitter(output: ErrorOutputType) -> Box<DynEmitter> {
             Box::new(JsonEmitter::new(
                 Box::new(io::BufWriter::new(io::stderr())),
                 Some(Arc::new(SourceMap::new(FilePathMapping::empty()))),
-                fallback_bundle,
+                translator,
                 pretty,
                 json_rendered,
                 color_config,
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 204f8decffcc..3b1d89bbecd9 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -149,15 +149,12 @@ pub(crate) fn new_dcx(
     diagnostic_width: Option<usize>,
     unstable_opts: &UnstableOptions,
 ) -> rustc_errors::DiagCtxt {
-    let fallback_bundle = rustc_errors::fallback_fluent_bundle(
-        rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
-        false,
-    );
+    let translator = rustc_driver::default_translator();
     let emitter: Box<DynEmitter> = match error_format {
         ErrorOutputType::HumanReadable { kind, color_config } => {
             let short = kind.short();
             Box::new(
-                HumanEmitter::new(stderr_destination(color_config), fallback_bundle)
+                HumanEmitter::new(stderr_destination(color_config), translator)
                     .sm(source_map.map(|sm| sm as _))
                     .short_message(short)
                     .diagnostic_width(diagnostic_width)
@@ -178,7 +175,7 @@ pub(crate) fn new_dcx(
                 JsonEmitter::new(
                     Box::new(io::BufWriter::new(io::stderr())),
                     Some(source_map),
-                    fallback_bundle,
+                    translator,
                     pretty,
                     json_rendered,
                     color_config,
diff --git a/src/librustdoc/doctest/make.rs b/src/librustdoc/doctest/make.rs
index 3ff6828e52f9..f229f77c9784 100644
--- a/src/librustdoc/doctest/make.rs
+++ b/src/librustdoc/doctest/make.rs
@@ -456,16 +456,13 @@ fn parse_source(
     let filename = FileName::anon_source_code(&wrapped_source);
 
     let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
-    let fallback_bundle = rustc_errors::fallback_fluent_bundle(
-        rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
-        false,
-    );
+    let translator = rustc_driver::default_translator();
     info.supports_color =
-        HumanEmitter::new(stderr_destination(ColorConfig::Auto), fallback_bundle.clone())
+        HumanEmitter::new(stderr_destination(ColorConfig::Auto), translator.clone())
             .supports_color();
     // Any errors in parsing should also appear when the doctest is compiled for real, so just
     // send all the errors that the parser emits directly into a `Sink` instead of stderr.
-    let emitter = HumanEmitter::new(Box::new(io::sink()), fallback_bundle);
+    let emitter = HumanEmitter::new(Box::new(io::sink()), translator);
 
     // FIXME(misdreavus): pass `-Z treat-err-as-bug` to the doctest parser
     let dcx = DiagCtxt::new(Box::new(emitter)).disable_warnings();
diff --git a/src/librustdoc/passes/lint/check_code_block_syntax.rs b/src/librustdoc/passes/lint/check_code_block_syntax.rs
index 9662dd85d678..91cddbe5a5bc 100644
--- a/src/librustdoc/passes/lint/check_code_block_syntax.rs
+++ b/src/librustdoc/passes/lint/check_code_block_syntax.rs
@@ -6,8 +6,8 @@
 use rustc_data_structures::sync::Lock;
 use rustc_errors::emitter::Emitter;
 use rustc_errors::registry::Registry;
-use rustc_errors::translation::{Translate, to_fluent_args};
-use rustc_errors::{Applicability, DiagCtxt, DiagInner, LazyFallbackBundle};
+use rustc_errors::translation::{Translator, to_fluent_args};
+use rustc_errors::{Applicability, DiagCtxt, DiagInner};
 use rustc_parse::{source_str_to_stream, unwrap_or_emit_fatal};
 use rustc_resolve::rustdoc::source_span_for_markdown_range;
 use rustc_session::parse::ParseSess;
@@ -36,11 +36,8 @@ fn check_rust_syntax(
     code_block: RustCodeBlock,
 ) {
     let buffer = Arc::new(Lock::new(Buffer::default()));
-    let fallback_bundle = rustc_errors::fallback_fluent_bundle(
-        rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
-        false,
-    );
-    let emitter = BufferEmitter { buffer: Arc::clone(&buffer), fallback_bundle };
+    let translator = rustc_driver::default_translator();
+    let emitter = BufferEmitter { buffer: Arc::clone(&buffer), translator };
 
     let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
     let dcx = DiagCtxt::new(Box::new(emitter)).disable_warnings();
@@ -149,17 +146,7 @@ struct Buffer {
 
 struct BufferEmitter {
     buffer: Arc<Lock<Buffer>>,
-    fallback_bundle: LazyFallbackBundle,
-}
-
-impl Translate for BufferEmitter {
-    fn fluent_bundle(&self) -> Option<&rustc_errors::FluentBundle> {
-        None
-    }
-
-    fn fallback_fluent_bundle(&self) -> &rustc_errors::FluentBundle {
-        &self.fallback_bundle
-    }
+    translator: Translator,
 }
 
 impl Emitter for BufferEmitter {
@@ -168,6 +155,7 @@ fn emit_diagnostic(&mut self, diag: DiagInner, _registry: &Registry) {
 
         let fluent_args = to_fluent_args(diag.args.iter());
         let translated_main_message = self
+            .translator
             .translate_message(&diag.messages[0].0, &fluent_args)
             .unwrap_or_else(|e| panic!("{e}"));
 
@@ -180,4 +168,8 @@ fn emit_diagnostic(&mut self, diag: DiagInner, _registry: &Registry) {
     fn source_map(&self) -> Option<&SourceMap> {
         None
     }
+
+    fn translator(&self) -> &Translator {
+        &self.translator
+    }
 }
diff --git a/src/tools/clippy/clippy_lints/src/doc/needless_doctest_main.rs b/src/tools/clippy/clippy_lints/src/doc/needless_doctest_main.rs
index ec4538039a91..7ba11c20f456 100644
--- a/src/tools/clippy/clippy_lints/src/doc/needless_doctest_main.rs
+++ b/src/tools/clippy/clippy_lints/src/doc/needless_doctest_main.rs
@@ -42,9 +42,8 @@ fn check_code_sample(code: String, edition: Edition, ignore: bool) -> (bool, Vec
                 let mut test_attr_spans = vec![];
                 let filename = FileName::anon_source_code(&code);
 
-                let fallback_bundle =
-                    rustc_errors::fallback_fluent_bundle(rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(), false);
-                let emitter = HumanEmitter::new(Box::new(io::sink()), fallback_bundle);
+                let translator = rustc_driver::default_translator();
+                let emitter = HumanEmitter::new(Box::new(io::sink()), translator);
                 let dcx = DiagCtxt::new(Box::new(emitter)).disable_warnings();
                 #[expect(clippy::arc_with_non_send_sync)] // `Arc` is expected by with_dcx
                 let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
diff --git a/src/tools/rustfmt/src/parse/session.rs b/src/tools/rustfmt/src/parse/session.rs
index afd847f95157..73a89072f146 100644
--- a/src/tools/rustfmt/src/parse/session.rs
+++ b/src/tools/rustfmt/src/parse/session.rs
@@ -5,7 +5,7 @@
 use rustc_data_structures::sync::IntoDynSyncSend;
 use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter, SilentEmitter, stderr_destination};
 use rustc_errors::registry::Registry;
-use rustc_errors::translation::Translate;
+use rustc_errors::translation::Translator;
 use rustc_errors::{ColorConfig, Diag, DiagCtxt, DiagInner, Level as DiagnosticLevel};
 use rustc_session::parse::ParseSess as RawParseSess;
 use rustc_span::{
@@ -47,16 +47,6 @@ fn handle_non_ignoreable_error(&mut self, diag: DiagInner, registry: &Registry)
     }
 }
 
-impl Translate for SilentOnIgnoredFilesEmitter {
-    fn fluent_bundle(&self) -> Option<&rustc_errors::FluentBundle> {
-        self.emitter.fluent_bundle()
-    }
-
-    fn fallback_fluent_bundle(&self) -> &rustc_errors::FluentBundle {
-        self.emitter.fallback_fluent_bundle()
-    }
-}
-
 impl Emitter for SilentOnIgnoredFilesEmitter {
     fn source_map(&self) -> Option<&SourceMap> {
         None
@@ -84,6 +74,10 @@ fn emit_diagnostic(&mut self, diag: DiagInner, registry: &Registry) {
         }
         self.handle_non_ignoreable_error(diag, registry);
     }
+
+    fn translator(&self) -> &Translator {
+        self.emitter.translator()
+    }
 }
 
 impl From<Color> for ColorConfig {
@@ -110,12 +104,9 @@ fn default_dcx(
         ColorConfig::Never
     };
 
-    let fallback_bundle = rustc_errors::fallback_fluent_bundle(
-        rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
-        false,
-    );
+    let translator = rustc_driver::default_translator();
     let emitter = Box::new(
-        HumanEmitter::new(stderr_destination(emit_color), fallback_bundle)
+        HumanEmitter::new(stderr_destination(emit_color), translator)
             .sm(Some(source_map.clone())),
     );
 
@@ -335,16 +326,6 @@ struct TestEmitter {
             num_emitted_errors: Arc<AtomicU32>,
         }
 
-        impl Translate for TestEmitter {
-            fn fluent_bundle(&self) -> Option<&rustc_errors::FluentBundle> {
-                None
-            }
-
-            fn fallback_fluent_bundle(&self) -> &rustc_errors::FluentBundle {
-                panic!("test emitter attempted to translate a diagnostic");
-            }
-        }
-
         impl Emitter for TestEmitter {
             fn source_map(&self) -> Option<&SourceMap> {
                 None
@@ -353,6 +334,10 @@ fn source_map(&self) -> Option<&SourceMap> {
             fn emit_diagnostic(&mut self, _diag: DiagInner, _registry: &Registry) {
                 self.num_emitted_errors.fetch_add(1, Ordering::Release);
             }
+
+            fn translator(&self) -> &Translator {
+                panic!("test emitter attempted to translate a diagnostic");
+            }
         }
 
         fn build_diagnostic(level: DiagnosticLevel, span: Option<MultiSpan>) -> DiagInner {

From 316f63bc48a9bfe26b2a8fc06e7eeef45ac2b7aa Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Tue, 17 Jun 2025 16:59:57 -0500
Subject: [PATCH 2/3] Rename SilentEmitter -> FatalOnlyEmitter

---
 compiler/rustc_errors/src/emitter.rs      | 4 ++--
 compiler/rustc_errors/src/lib.rs          | 2 +-
 compiler/rustc_interface/src/interface.rs | 4 ++--
 compiler/rustc_session/src/parse.rs       | 6 +++---
 src/tools/rustfmt/src/parse/session.rs    | 4 ++--
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 494f15cc6390..4464b45775ad 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -543,13 +543,13 @@ fn translator(&self) -> &Translator {
 /// An emitter that does nothing when emitting a non-fatal diagnostic.
 /// Fatal diagnostics are forwarded to `fatal_emitter` to avoid silent
 /// failures of rustc, as witnessed e.g. in issue #89358.
-pub struct SilentEmitter {
+pub struct FatalOnlyEmitter {
     pub fatal_emitter: Box<dyn Emitter + DynSend>,
     pub fatal_note: Option<String>,
     pub emit_fatal_diagnostic: bool,
 }
 
-impl Emitter for SilentEmitter {
+impl Emitter for FatalOnlyEmitter {
     fn source_map(&self) -> Option<&SourceMap> {
         None
     }
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 70f294b696a2..831a50efa27d 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -770,7 +770,7 @@ fn translator(&self) -> &translation::Translator {
         let mut inner = self.inner.borrow_mut();
         let mut prev_emitter = Box::new(FalseEmitter) as Box<dyn Emitter + DynSend>;
         std::mem::swap(&mut inner.emitter, &mut prev_emitter);
-        let new_emitter = Box::new(emitter::SilentEmitter {
+        let new_emitter = Box::new(emitter::FatalOnlyEmitter {
             fatal_emitter: prev_emitter,
             fatal_note,
             emit_fatal_diagnostic,
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index e824e9d4aa91..ffac9cbdec1a 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -52,7 +52,7 @@ pub struct Compiler {
 pub(crate) fn parse_cfg(dcx: DiagCtxtHandle<'_>, cfgs: Vec<String>) -> Cfg {
     cfgs.into_iter()
         .map(|s| {
-            let psess = ParseSess::with_silent_emitter(
+            let psess = ParseSess::with_fatal_emitter(
                 vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
                 format!("this error occurred on the command line: `--cfg={s}`"),
                 true,
@@ -116,7 +116,7 @@ pub(crate) fn parse_check_cfg(dcx: DiagCtxtHandle<'_>, specs: Vec<String>) -> Ch
     let mut check_cfg = CheckCfg { exhaustive_names, exhaustive_values, ..CheckCfg::default() };
 
     for s in specs {
-        let psess = ParseSess::with_silent_emitter(
+        let psess = ParseSess::with_fatal_emitter(
             vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
             format!("this error occurred on the command line: `--check-cfg={s}`"),
             true,
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 30a61cb411bb..154bed8b809a 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -8,7 +8,7 @@
 use rustc_ast::node_id::NodeId;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_data_structures::sync::{AppendOnlyVec, Lock};
-use rustc_errors::emitter::{HumanEmitter, SilentEmitter, stderr_destination};
+use rustc_errors::emitter::{FatalOnlyEmitter, HumanEmitter, stderr_destination};
 use rustc_errors::translation::Translator;
 use rustc_errors::{
     ColorConfig, Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, EmissionGuarantee, MultiSpan,
@@ -275,7 +275,7 @@ pub fn with_dcx(dcx: DiagCtxt, source_map: Arc<SourceMap>) -> Self {
         }
     }
 
-    pub fn with_silent_emitter(
+    pub fn with_fatal_emitter(
         locale_resources: Vec<&'static str>,
         fatal_note: String,
 
@@ -285,7 +285,7 @@ pub fn with_silent_emitter(
         let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
         let fatal_emitter =
             Box::new(HumanEmitter::new(stderr_destination(ColorConfig::Auto), translator));
-        let dcx = DiagCtxt::new(Box::new(SilentEmitter {
+        let dcx = DiagCtxt::new(Box::new(FatalOnlyEmitter {
             fatal_emitter,
             fatal_note: Some(fatal_note),
             emit_fatal_diagnostic,
diff --git a/src/tools/rustfmt/src/parse/session.rs b/src/tools/rustfmt/src/parse/session.rs
index 73a89072f146..c50d4ef04890 100644
--- a/src/tools/rustfmt/src/parse/session.rs
+++ b/src/tools/rustfmt/src/parse/session.rs
@@ -3,7 +3,7 @@
 use std::sync::atomic::{AtomicBool, Ordering};
 
 use rustc_data_structures::sync::IntoDynSyncSend;
-use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter, SilentEmitter, stderr_destination};
+use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter, FatalOnlyEmitter, stderr_destination};
 use rustc_errors::registry::Registry;
 use rustc_errors::translation::Translator;
 use rustc_errors::{ColorConfig, Diag, DiagCtxt, DiagInner, Level as DiagnosticLevel};
@@ -111,7 +111,7 @@ fn default_dcx(
     );
 
     let emitter: Box<DynEmitter> = if !show_parse_errors {
-        Box::new(SilentEmitter {
+        Box::new(FatalOnlyEmitter {
             fatal_emitter: emitter,
             fatal_note: None,
             emit_fatal_diagnostic: false,

From 3388d837850eebca505350bc25f017276551a955 Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Thu, 19 Jun 2025 13:05:01 -0500
Subject: [PATCH 3/3] Extract SilentEmitter

---
 compiler/rustc_errors/src/emitter.rs      | 19 ++++++++++++--
 compiler/rustc_errors/src/lib.rs          | 30 +++--------------------
 compiler/rustc_interface/src/interface.rs |  2 --
 compiler/rustc_session/src/parse.rs       |  8 +-----
 src/tools/rustfmt/src/parse/session.rs    | 21 ++++++----------
 5 files changed, 29 insertions(+), 51 deletions(-)

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 4464b45775ad..e333de4b660b 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -546,7 +546,6 @@ fn translator(&self) -> &Translator {
 pub struct FatalOnlyEmitter {
     pub fatal_emitter: Box<dyn Emitter + DynSend>,
     pub fatal_note: Option<String>,
-    pub emit_fatal_diagnostic: bool,
 }
 
 impl Emitter for FatalOnlyEmitter {
@@ -555,7 +554,7 @@ fn source_map(&self) -> Option<&SourceMap> {
     }
 
     fn emit_diagnostic(&mut self, mut diag: DiagInner, registry: &Registry) {
-        if self.emit_fatal_diagnostic && diag.level == Level::Fatal {
+        if diag.level == Level::Fatal {
             if let Some(fatal_note) = &self.fatal_note {
                 diag.sub(Level::Note, fatal_note.clone(), MultiSpan::new());
             }
@@ -568,6 +567,22 @@ fn translator(&self) -> &Translator {
     }
 }
 
+pub struct SilentEmitter {
+    pub translator: Translator,
+}
+
+impl Emitter for SilentEmitter {
+    fn source_map(&self) -> Option<&SourceMap> {
+        None
+    }
+
+    fn emit_diagnostic(&mut self, _diag: DiagInner, _registry: &Registry) {}
+
+    fn translator(&self) -> &Translator {
+        &self.translator
+    }
+}
+
 /// Maximum number of suggestions to be shown
 ///
 /// Arbitrary, but taken from trait import suggestion limit
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 831a50efa27d..207aed8c7554 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -748,34 +748,10 @@ pub fn new(emitter: Box<DynEmitter>) -> Self {
         Self { inner: Lock::new(DiagCtxtInner::new(emitter)) }
     }
 
-    pub fn make_silent(&self, fatal_note: Option<String>, emit_fatal_diagnostic: bool) {
-        // An empty type that implements `Emitter` to temporarily swap in place of the real one,
-        // which will be used in constructing its replacement.
-        struct FalseEmitter;
-
-        impl Emitter for FalseEmitter {
-            fn emit_diagnostic(&mut self, _: DiagInner, _: &Registry) {
-                unimplemented!("false emitter must only used during `make_silent`")
-            }
-
-            fn source_map(&self) -> Option<&SourceMap> {
-                unimplemented!("false emitter must only used during `make_silent`")
-            }
-
-            fn translator(&self) -> &translation::Translator {
-                unimplemented!("false emitter must only used during `make_silent`")
-            }
-        }
-
+    pub fn make_silent(&self) {
         let mut inner = self.inner.borrow_mut();
-        let mut prev_emitter = Box::new(FalseEmitter) as Box<dyn Emitter + DynSend>;
-        std::mem::swap(&mut inner.emitter, &mut prev_emitter);
-        let new_emitter = Box::new(emitter::FatalOnlyEmitter {
-            fatal_emitter: prev_emitter,
-            fatal_note,
-            emit_fatal_diagnostic,
-        });
-        inner.emitter = new_emitter;
+        let translator = inner.emitter.translator().clone();
+        inner.emitter = Box::new(emitter::SilentEmitter { translator });
     }
 
     pub fn set_emitter(&self, emitter: Box<dyn Emitter + DynSend>) {
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index ffac9cbdec1a..d62bf7f85e0e 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -55,7 +55,6 @@ pub(crate) fn parse_cfg(dcx: DiagCtxtHandle<'_>, cfgs: Vec<String>) -> Cfg {
             let psess = ParseSess::with_fatal_emitter(
                 vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
                 format!("this error occurred on the command line: `--cfg={s}`"),
-                true,
             );
             let filename = FileName::cfg_spec_source_code(&s);
 
@@ -119,7 +118,6 @@ pub(crate) fn parse_check_cfg(dcx: DiagCtxtHandle<'_>, specs: Vec<String>) -> Ch
         let psess = ParseSess::with_fatal_emitter(
             vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
             format!("this error occurred on the command line: `--check-cfg={s}`"),
-            true,
         );
         let filename = FileName::cfg_spec_source_code(&s);
 
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 154bed8b809a..0118cdb1fc27 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -275,12 +275,7 @@ pub fn with_dcx(dcx: DiagCtxt, source_map: Arc<SourceMap>) -> Self {
         }
     }
 
-    pub fn with_fatal_emitter(
-        locale_resources: Vec<&'static str>,
-        fatal_note: String,
-
-        emit_fatal_diagnostic: bool,
-    ) -> Self {
+    pub fn with_fatal_emitter(locale_resources: Vec<&'static str>, fatal_note: String) -> Self {
         let translator = Translator::with_fallback_bundle(locale_resources, false);
         let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
         let fatal_emitter =
@@ -288,7 +283,6 @@ pub fn with_fatal_emitter(
         let dcx = DiagCtxt::new(Box::new(FatalOnlyEmitter {
             fatal_emitter,
             fatal_note: Some(fatal_note),
-            emit_fatal_diagnostic,
         }))
         .disable_warnings();
         ParseSess::with_dcx(dcx, sm)
diff --git a/src/tools/rustfmt/src/parse/session.rs b/src/tools/rustfmt/src/parse/session.rs
index c50d4ef04890..10e2809e58bf 100644
--- a/src/tools/rustfmt/src/parse/session.rs
+++ b/src/tools/rustfmt/src/parse/session.rs
@@ -3,7 +3,7 @@
 use std::sync::atomic::{AtomicBool, Ordering};
 
 use rustc_data_structures::sync::IntoDynSyncSend;
-use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter, FatalOnlyEmitter, stderr_destination};
+use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter, SilentEmitter, stderr_destination};
 use rustc_errors::registry::Registry;
 use rustc_errors::translation::Translator;
 use rustc_errors::{ColorConfig, Diag, DiagCtxt, DiagInner, Level as DiagnosticLevel};
@@ -105,19 +105,14 @@ fn default_dcx(
     };
 
     let translator = rustc_driver::default_translator();
-    let emitter = Box::new(
-        HumanEmitter::new(stderr_destination(emit_color), translator)
-            .sm(Some(source_map.clone())),
-    );
 
-    let emitter: Box<DynEmitter> = if !show_parse_errors {
-        Box::new(FatalOnlyEmitter {
-            fatal_emitter: emitter,
-            fatal_note: None,
-            emit_fatal_diagnostic: false,
-        })
+    let emitter: Box<DynEmitter> = if show_parse_errors {
+        Box::new(
+            HumanEmitter::new(stderr_destination(emit_color), translator)
+                .sm(Some(source_map.clone())),
+        )
     } else {
-        emitter
+        Box::new(SilentEmitter { translator })
     };
     DiagCtxt::new(Box::new(SilentOnIgnoredFilesEmitter {
         has_non_ignorable_parser_errors: false,
@@ -196,7 +191,7 @@ pub(crate) fn ignore_file(&self, path: &FileName) -> bool {
     }
 
     pub(crate) fn set_silent_emitter(&mut self) {
-        self.raw_psess.dcx().make_silent(None, false);
+        self.raw_psess.dcx().make_silent();
     }
 
     pub(crate) fn span_to_filename(&self, span: Span) -> FileName {