errors: share SilentEmitter between rustc and rustfmt

Signed-off-by: David Wood <david@davidtw.co>

compiler/rustc_errors/src/emitter.rs

@@ -10,7 +10,6 @@
 use rustc_span::source_map::SourceMap;
 use rustc_span::{FileLines, FileName, SourceFile, Span};
 
-use crate::error::TranslateError;
 use crate::snippet::{
     Annotation, AnnotationColumn, AnnotationType, Line, MultilineAnnotation, Style, StyledString,
 };
@@ -556,20 +555,9 @@ impl Emitter for HumanEmitter {
 /// Fatal diagnostics are forwarded to `fatal_dcx` to avoid silent
 /// failures of rustc, as witnessed e.g. in issue #89358.
 pub struct SilentEmitter {
+    pub fallback_bundle: LazyFallbackBundle,
     pub fatal_dcx: DiagCtxt,
-    pub fatal_note: String,
-}
-
-pub fn silent_translate<'a>(
-    message: &'a DiagnosticMessage,
-) -> Result<Cow<'_, str>, TranslateError<'_>> {
-    match message {
-        DiagnosticMessage::Str(msg) | DiagnosticMessage::Translated(msg) => Ok(Cow::Borrowed(msg)),
-        DiagnosticMessage::FluentIdentifier(identifier, _) => {
-            // Any value works here.
-            Ok(identifier.clone())
-        }
-    }
+    pub fatal_note: Option<String>,
 }
 
 impl Translate for SilentEmitter {
@@ -578,17 +566,9 @@ impl Translate for SilentEmitter {
     }
 
     fn fallback_fluent_bundle(&self) -> &FluentBundle {
-        panic!("silent emitter attempted to translate message")
-    }
-
-    // Override `translate_message` for the silent emitter because eager translation of
-    // subdiagnostics result in a call to this.
-    fn translate_message<'a>(
-        &'a self,
-        message: &'a DiagnosticMessage,
-        _: &'a FluentArgs<'_>,
-    ) -> Result<Cow<'_, str>, TranslateError<'_>> {
-        silent_translate(message)
+        // Ideally this field wouldn't be necessary and the fallback bundle in `fatal_dcx` would be
+        // used but the lock prevents this.
+        &self.fallback_bundle
     }
 }
 
@@ -599,7 +579,9 @@ impl Emitter for SilentEmitter {
 
     fn emit_diagnostic(&mut self, mut diag: Diagnostic) {
         if diag.level == Level::Fatal {
-            diag.sub(Level::Note, self.fatal_note.clone(), MultiSpan::new());
+            if let Some(fatal_note) = &self.fatal_note {
+                diag.sub(Level::Note, fatal_note.clone(), MultiSpan::new());
+            }
             self.fatal_dcx.emit_diagnostic(diag);
         }
     }

compiler/rustc_interface/src/interface.rs

@@ -45,9 +45,10 @@ pub struct Compiler {
 pub(crate) fn parse_cfg(dcx: &DiagCtxt, cfgs: Vec<String>) -> Cfg {
     cfgs.into_iter()
         .map(|s| {
-            let sess = ParseSess::with_silent_emitter(format!(
-                "this error occurred on the command line: `--cfg={s}`"
-            ));
+            let sess = ParseSess::with_silent_emitter(
+                vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
+                format!("this error occurred on the command line: `--cfg={s}`"),
+            );
             let filename = FileName::cfg_spec_source_code(&s);
 
             macro_rules! error {
@@ -107,9 +108,10 @@ pub(crate) fn parse_check_cfg(dcx: &DiagCtxt, specs: Vec<String>) -> CheckCfg {
     let mut check_cfg = CheckCfg { exhaustive_names, exhaustive_values, ..CheckCfg::default() };
 
     for s in specs {
-        let sess = ParseSess::with_silent_emitter(format!(
-            "this error occurred on the command line: `--check-cfg={s}`"
-        ));
+        let sess = ParseSess::with_silent_emitter(
+            vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
+            format!("this error occurred on the command line: `--check-cfg={s}`"),
+        );
         let filename = FileName::cfg_spec_source_code(&s);
 
         macro_rules! error {

compiler/rustc_session/src/parse.rs

@@ -263,12 +263,17 @@ impl ParseSess {
         }
     }
 
-    pub fn with_silent_emitter(fatal_note: String) -> Self {
-        let fallback_bundle = fallback_fluent_bundle(Vec::new(), false);
+    pub fn with_silent_emitter(locale_resources: Vec<&'static str>, fatal_note: String) -> Self {
+        let fallback_bundle = fallback_fluent_bundle(locale_resources, false);
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
-        let fatal_dcx = DiagCtxt::with_tty_emitter(None, fallback_bundle).disable_warnings();
-        let dcx = DiagCtxt::with_emitter(Box::new(SilentEmitter { fatal_dcx, fatal_note }))
-            .disable_warnings();
+        let fatal_dcx =
+            DiagCtxt::with_tty_emitter(None, fallback_bundle.clone()).disable_warnings();
+        let dcx = DiagCtxt::with_emitter(Box::new(SilentEmitter {
+            fallback_bundle,
+            fatal_dcx,
+            fatal_note: Some(fatal_note),
+        }))
+        .disable_warnings();
         ParseSess::with_dcx(dcx, sm)
     }
 

src/tools/rustfmt/src/parse/session.rs

@@ -1,9 +1,8 @@
-use std::borrow::Cow;
 use std::path::Path;
 use std::sync::atomic::{AtomicBool, Ordering};
 
 use rustc_data_structures::sync::{IntoDynSyncSend, Lrc};
-use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter};
+use rustc_errors::emitter::{DynEmitter, Emitter, HumanEmitter, SilentEmitter};
 use rustc_errors::translation::Translate;
 use rustc_errors::{
     ColorConfig, DiagCtxt, Diagnostic, DiagnosticBuilder, Level as DiagnosticLevel,
@@ -30,41 +29,6 @@ pub(crate) struct ParseSess {
     can_reset_errors: Lrc<AtomicBool>,
 }
 
-/// Emitter which discards every error.
-struct SilentEmitter;
-
-impl Translate for SilentEmitter {
-    fn fluent_bundle(&self) -> Option<&Lrc<rustc_errors::FluentBundle>> {
-        None
-    }
-
-    fn fallback_fluent_bundle(&self) -> &rustc_errors::FluentBundle {
-        panic!("silent emitter attempted to translate a diagnostic");
-    }
-
-    // Override `translate_message` for the silent emitter because eager translation of
-    // subdiagnostics result in a call to this.
-    fn translate_message<'a>(
-        &'a self,
-        message: &'a rustc_errors::DiagnosticMessage,
-        _: &'a rustc_errors::translation::FluentArgs<'_>,
-    ) -> Result<Cow<'_, str>, rustc_errors::error::TranslateError<'_>> {
-        rustc_errors::emitter::silent_translate(message)
-    }
-}
-
-impl Emitter for SilentEmitter {
-    fn source_map(&self) -> Option<&Lrc<SourceMap>> {
-        None
-    }
-
-    fn emit_diagnostic(&mut self, _db: Diagnostic) {}
-}
-
-fn silent_emitter() -> Box<DynEmitter> {
-    Box::new(SilentEmitter {})
-}
-
 /// Emit errors against every files expect ones specified in the `ignore_path_set`.
 struct SilentOnIgnoredFilesEmitter {
     ignore_path_set: IntoDynSyncSend<Lrc<IgnorePathSet>>,
@@ -145,15 +109,24 @@ fn default_dcx(
         ColorConfig::Never
     };
 
-    let emitter = if hide_parse_errors {
-        silent_emitter()
+    let fallback_bundle = rustc_errors::fallback_fluent_bundle(
+        rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
+        false,
+    );
+    let emitter = Box::new(
+        HumanEmitter::stderr(emit_color, fallback_bundle.clone()).sm(Some(source_map.clone())),
+    );
+
+    let emitter: Box<DynEmitter> = if hide_parse_errors {
+        Box::new(SilentEmitter {
+            fallback_bundle,
+            fatal_dcx: DiagCtxt::with_emitter(emitter),
+            fatal_note: None,
+        })
     } else {
-        let fallback_bundle = rustc_errors::fallback_fluent_bundle(
-            rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
-            false,
-        );
-        Box::new(HumanEmitter::stderr(emit_color, fallback_bundle).sm(Some(source_map.clone())))
+        emitter
     };
+
     DiagCtxt::with_emitter(Box::new(SilentOnIgnoredFilesEmitter {
         has_non_ignorable_parser_errors: false,
         source_map,
@@ -231,7 +204,25 @@ impl ParseSess {
     }
 
     pub(crate) fn set_silent_emitter(&mut self) {
-        self.parse_sess.dcx = DiagCtxt::with_emitter(silent_emitter());
+        // Ideally this invocation wouldn't be necessary and the fallback bundle in
+        // `self.parse_sess.dcx` could be used.
+        let fallback_bundle = rustc_errors::fallback_fluent_bundle(
+            rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
+            false,
+        );
+        // SAFETY: `fatal_dcx` will not be dropped while it is referenced by `self.parse_sess.dcx`,
+        // and `self.parse_sess.dcx` is written to by `ptr::write` so won't drop `fatal_dcx`.
+        unsafe {
+            let fatal_dcx = std::ptr::read(&self.parse_sess.dcx);
+            std::ptr::write(
+                &mut self.parse_sess.dcx,
+                DiagCtxt::with_emitter(Box::new(SilentEmitter {
+                    fallback_bundle,
+                    fatal_dcx,
+                    fatal_note: None,
+                })),
+            );
+        }
     }
 
     pub(crate) fn span_to_filename(&self, span: Span) -> FileName {

src/tools/rustfmt/tests/source/issue-6082.rs

@@ -0,0 +1,5 @@
+macro_rules! test {
+    ($T:ident, $b:lifetime) => {
+        Box<$T<$b>>
+    };
+}

src/tools/rustfmt/tests/target/issue-6082.rs

@@ -0,0 +1,5 @@
+macro_rules! test {
+    ($T:ident, $b:lifetime) => {
+        Box<$T<$b>>
+    };
+}