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_parse/src/errors.rs

@@ -3,7 +3,7 @@ use std::borrow::Cow;
 use rustc_ast::token::Token;
 use rustc_ast::{Path, Visibility};
 use rustc_errors::{
-    codes::*, Applicability, Diag, DiagCtxt, Diagnostic, EmissionGuarantee, Level,
+    codes::*, Applicability, Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level,
     SubdiagMessageOp, Subdiagnostic,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
@@ -1052,7 +1052,7 @@ pub(crate) struct ExpectedIdentifier {
 
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for ExpectedIdentifier {
     #[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> {
         let token_descr = TokenDescription::from_token(&self.token);
 
         let mut diag = Diag::new(
@@ -1112,7 +1112,7 @@ pub(crate) struct ExpectedSemi {
 
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for ExpectedSemi {
     #[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> {
         let token_descr = TokenDescription::from_token(&self.token);
 
         let mut diag = Diag::new(

compiler/rustc_parse/src/lexer/mod.rs

@@ -7,7 +7,7 @@ use rustc_ast::ast::{self, AttrStyle};
 use rustc_ast::token::{self, CommentKind, Delimiter, IdentIsRaw, Token, TokenKind};
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::util::unicode::contains_text_flow_control_chars;
-use rustc_errors::{codes::*, Applicability, Diag, DiagCtxt, StashKey};
+use rustc_errors::{codes::*, Applicability, Diag, DiagCtxtHandle, StashKey};
 use rustc_lexer::unescape::{self, EscapeError, Mode};
 use rustc_lexer::{Base, DocStyle, RawStrError};
 use rustc_lexer::{Cursor, LiteralKind};
@@ -113,7 +113,7 @@ struct StringReader<'psess, 'src> {
 }
 
 impl<'psess, 'src> StringReader<'psess, 'src> {
-    fn dcx(&self) -> &'psess DiagCtxt {
+    fn dcx(&self) -> DiagCtxtHandle<'psess> {
         self.psess.dcx()
     }
 

compiler/rustc_parse/src/lexer/unescape_error_reporting.rs

@@ -3,7 +3,7 @@
 use std::iter::once;
 use std::ops::Range;
 
-use rustc_errors::{Applicability, DiagCtxt, ErrorGuaranteed};
+use rustc_errors::{Applicability, DiagCtxtHandle, ErrorGuaranteed};
 use rustc_lexer::unescape::{EscapeError, Mode};
 use rustc_span::{BytePos, Span};
 use tracing::debug;
@@ -11,7 +11,7 @@ use tracing::debug;
 use crate::errors::{MoreThanOneCharNote, MoreThanOneCharSugg, NoBraceUnicodeSub, UnescapeError};
 
 pub(crate) fn emit_unescape_error(
-    dcx: &DiagCtxt,
+    dcx: DiagCtxtHandle<'_>,
     // interior part of the literal, between quotes
     lit: &str,
     // full span of the literal, including quotes and any prefix

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -34,7 +34,7 @@ use rustc_ast::{
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{
-    pluralize, Applicability, Diag, DiagCtxt, ErrorGuaranteed, FatalError, PErr, PResult,
+    pluralize, Applicability, Diag, DiagCtxtHandle, ErrorGuaranteed, FatalError, PErr, PResult,
     Subdiagnostic,
 };
 use rustc_session::errors::ExprParenthesesNeeded;
@@ -240,7 +240,7 @@ impl<'a> DerefMut for SnapshotParser<'a> {
 }
 
 impl<'a> Parser<'a> {
-    pub fn dcx(&self) -> &'a DiagCtxt {
+    pub fn dcx(&self) -> DiagCtxtHandle<'a> {
         self.psess.dcx()
     }
 

compiler/rustc_parse/src/parser/tests.rs

@@ -61,7 +61,7 @@ where
 {
     let mut p = string_to_parser(&psess, s);
     let x = f(&mut p).unwrap();
-    p.psess.dcx.abort_if_errors();
+    p.dcx().abort_if_errors();
     x
 }
 
@@ -193,7 +193,7 @@ impl<T: Write> Write for Shared<T> {
 #[allow(rustc::untranslatable_diagnostic)] // no translation needed for tests
 fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &str) {
     create_default_session_globals_then(|| {
-        let (handler, source_map, output) = create_test_handler();
+        let (dcx, source_map, output) = create_test_handler();
         source_map.new_source_file(Path::new("test.rs").to_owned().into(), file_text.to_owned());
 
         let primary_span = make_span(&file_text, &span_labels[0].start, &span_labels[0].end);
@@ -205,7 +205,7 @@ fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &
             println!("text: {:?}", source_map.span_to_snippet(span));
         }
 
-        handler.span_err(msp, "foo");
+        dcx.handle().span_err(msp, "foo");
 
         assert!(
             expected_output.chars().next() == Some('\n'),