Use a dedicated type instead of a reference for the diagnostic context

This paves the way for tracking more state (e.g. error tainting) in the diagnostic context handle

compiler/rustc_session/src/errors.rs

@@ -3,8 +3,8 @@ use std::num::NonZero;
 use rustc_ast::token;
 use rustc_ast::util::literal::LitError;
 use rustc_errors::{
-    codes::*, Diag, DiagCtxt, DiagMessage, Diagnostic, EmissionGuarantee, ErrorGuaranteed, Level,
-    MultiSpan,
+    codes::*, Diag, DiagCtxtHandle, DiagMessage, Diagnostic, EmissionGuarantee, ErrorGuaranteed,
+    Level, MultiSpan,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
@@ -19,7 +19,7 @@ pub(crate) struct FeatureGateError {
 
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for FeatureGateError {
     #[track_caller]
-    fn into_diag(self, dcx: &'a DiagCtxt, level: Level) -> Diag<'a, G> {
+    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
         Diag::new(dcx, level, self.explain).with_span(self.span).with_code(E0658)
     }
 }

compiler/rustc_session/src/parse.rs

@@ -15,8 +15,8 @@ use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_data_structures::sync::{AppendOnlyVec, Lock, Lrc};
 use rustc_errors::emitter::{stderr_destination, HumanEmitter, SilentEmitter};
 use rustc_errors::{
-    fallback_fluent_bundle, ColorConfig, Diag, DiagCtxt, DiagMessage, EmissionGuarantee, MultiSpan,
-    StashKey,
+    fallback_fluent_bundle, ColorConfig, Diag, DiagCtxt, DiagCtxtHandle, DiagMessage,
+    EmissionGuarantee, MultiSpan, StashKey,
 };
 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
 use rustc_span::edition::Edition;
@@ -327,7 +327,7 @@ impl ParseSess {
         self.proc_macro_quoted_spans.iter_enumerated()
     }
 
-    pub fn dcx(&self) -> &DiagCtxt {
-        &self.dcx
+    pub fn dcx(&self) -> DiagCtxtHandle<'_> {
+        self.dcx.handle()
     }
 }

compiler/rustc_session/src/session.rs

@@ -22,8 +22,8 @@ use rustc_errors::emitter::{stderr_destination, DynEmitter, HumanEmitter, HumanR
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::registry::Registry;
 use rustc_errors::{
-    codes::*, fallback_fluent_bundle, Diag, DiagCtxt, DiagMessage, Diagnostic, ErrorGuaranteed,
-    FatalAbort, FluentBundle, LazyFallbackBundle, TerminalUrl,
+    codes::*, fallback_fluent_bundle, Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, Diagnostic,
+    ErrorGuaranteed, FatalAbort, FluentBundle, LazyFallbackBundle, TerminalUrl,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -328,7 +328,7 @@ impl Session {
     }
 
     #[inline]
-    pub fn dcx(&self) -> &DiagCtxt {
+    pub fn dcx(&self) -> DiagCtxtHandle<'_> {
         self.psess.dcx()
     }
 
@@ -1065,7 +1065,7 @@ pub fn build_session(
         match profiler {
             Ok(profiler) => Some(Arc::new(profiler)),
             Err(e) => {
-                dcx.emit_warn(errors::FailedToCreateProfiler { err: e.to_string() });
+                dcx.handle().emit_warn(errors::FailedToCreateProfiler { err: e.to_string() });
                 None
             }
         }
@@ -1366,7 +1366,7 @@ impl EarlyDiagCtxt {
     /// format. Any errors prior to that will cause an abort and all stashed diagnostics of the
     /// previous dcx will be emitted.
     pub fn abort_if_error_and_set_error_format(&mut self, output: ErrorOutputType) {
-        self.dcx.abort_if_errors();
+        self.dcx.handle().abort_if_errors();
 
         let emitter = mk_emitter(output);
         self.dcx = DiagCtxt::new(emitter);
@@ -1375,44 +1375,44 @@ impl EarlyDiagCtxt {
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn early_note(&self, msg: impl Into<DiagMessage>) {
-        self.dcx.note(msg)
+        self.dcx.handle().note(msg)
     }
 
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn early_help(&self, msg: impl Into<DiagMessage>) {
-        self.dcx.struct_help(msg).emit()
+        self.dcx.handle().struct_help(msg).emit()
     }
 
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     #[must_use = "ErrorGuaranteed must be returned from `run_compiler` in order to exit with a non-zero status code"]
     pub fn early_err(&self, msg: impl Into<DiagMessage>) -> ErrorGuaranteed {
-        self.dcx.err(msg)
+        self.dcx.handle().err(msg)
     }
 
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn early_fatal(&self, msg: impl Into<DiagMessage>) -> ! {
-        self.dcx.fatal(msg)
+        self.dcx.handle().fatal(msg)
     }
 
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn early_struct_fatal(&self, msg: impl Into<DiagMessage>) -> Diag<'_, FatalAbort> {
-        self.dcx.struct_fatal(msg)
+        self.dcx.handle().struct_fatal(msg)
     }
 
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn early_warn(&self, msg: impl Into<DiagMessage>) {
-        self.dcx.warn(msg)
+        self.dcx.handle().warn(msg)
     }
 
     #[allow(rustc::untranslatable_diagnostic)]
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub fn early_struct_warn(&self, msg: impl Into<DiagMessage>) -> Diag<'_, ()> {
-        self.dcx.struct_warn(msg)
+        self.dcx.handle().struct_warn(msg)
     }
 }