From c91edc3888073d0ddf2e0ff7741437e483a4f21e Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Tue, 18 Jun 2024 09:43:28 +0000
Subject: [PATCH] Prefer `dcx` methods over fields or fields' methods

---
 compiler/rustc_attr/src/builtin.rs            |  2 +-
 compiler/rustc_builtin_macros/src/asm.rs      |  8 ++---
 .../rustc_builtin_macros/src/cmdline_attrs.rs |  2 +-
 compiler/rustc_expand/src/base.rs             |  2 +-
 compiler/rustc_expand/src/mbe/macro_check.rs  | 10 +++----
 compiler/rustc_expand/src/mbe/macro_rules.rs  |  2 +-
 compiler/rustc_expand/src/mbe/metavar_expr.rs | 29 ++++++++++---------
 compiler/rustc_expand/src/mbe/transcribe.rs   |  2 +-
 .../rustc_expand/src/proc_macro_server.rs     |  2 +-
 compiler/rustc_hir_analysis/src/check/errs.rs |  2 +-
 compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs  |  2 +-
 .../src/infer/error_reporting/mod.rs          |  2 +-
 compiler/rustc_metadata/src/creader.rs        |  2 +-
 compiler/rustc_parse/src/lexer/mod.rs         |  9 +++---
 compiler/rustc_parse/src/lexer/tokentrees.rs  |  4 +--
 .../rustc_parse/src/lexer/unicode_chars.rs    |  2 +-
 compiler/rustc_parse/src/lib.rs               |  6 ++--
 .../rustc_parse/src/parser/attr_wrapper.rs    |  2 +-
 .../rustc_parse/src/parser/diagnostics.rs     |  2 +-
 compiler/rustc_parse/src/parser/mod.rs        |  2 +-
 compiler/rustc_parse/src/validate_attr.rs     | 10 +++----
 compiler/rustc_session/src/errors.rs          |  2 +-
 compiler/rustc_session/src/parse.rs           | 12 +++++---
 compiler/rustc_session/src/session.rs         |  2 +-
 24 files changed, 62 insertions(+), 58 deletions(-)

diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index 5113c5adc8f..34c24a26f7b 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -596,7 +596,7 @@ pub fn eval_condition(
     features: Option<&Features>,
     eval: &mut impl FnMut(Condition) -> bool,
 ) -> bool {
-    let dcx = &sess.psess.dcx;
+    let dcx = sess.dcx();
     match &cfg.kind {
         ast::MetaItemKind::List(mis) if cfg.name_or_empty() == sym::version => {
             try_gate_cfg(sym::version, cfg.span, sess, features);
diff --git a/compiler/rustc_builtin_macros/src/asm.rs b/compiler/rustc_builtin_macros/src/asm.rs
index 1a7961bf70c..64238e81b26 100644
--- a/compiler/rustc_builtin_macros/src/asm.rs
+++ b/compiler/rustc_builtin_macros/src/asm.rs
@@ -46,7 +46,7 @@ pub fn parse_asm_args<'a>(
     sp: Span,
     is_global_asm: bool,
 ) -> PResult<'a, AsmArgs> {
-    let dcx = &p.psess.dcx;
+    let dcx = p.dcx();
 
     if p.token == token::Eof {
         return Err(dcx.create_err(errors::AsmRequiresTemplate { span: sp }));
@@ -307,7 +307,7 @@ pub fn parse_asm_args<'a>(
 fn err_duplicate_option(p: &Parser<'_>, symbol: Symbol, span: Span) {
     // Tool-only output
     let full_span = if p.token.kind == token::Comma { span.to(p.token.span) } else { span };
-    p.psess.dcx.emit_err(errors::AsmOptAlreadyprovided { span, symbol, full_span });
+    p.dcx().emit_err(errors::AsmOptAlreadyprovided { span, symbol, full_span });
 }
 
 /// Try to set the provided option in the provided `AsmArgs`.
@@ -379,7 +379,7 @@ fn parse_clobber_abi<'a>(p: &mut Parser<'a>, args: &mut AsmArgs) -> PResult<'a,
     p.expect(&token::OpenDelim(Delimiter::Parenthesis))?;
 
     if p.eat(&token::CloseDelim(Delimiter::Parenthesis)) {
-        return Err(p.psess.dcx.create_err(errors::NonABI { span: p.token.span }));
+        return Err(p.dcx().create_err(errors::NonABI { span: p.token.span }));
     }
 
     let mut new_abis = Vec::new();
@@ -390,7 +390,7 @@ fn parse_clobber_abi<'a>(p: &mut Parser<'a>, args: &mut AsmArgs) -> PResult<'a,
             }
             Err(opt_lit) => {
                 let span = opt_lit.map_or(p.token.span, |lit| lit.span);
-                let mut err = p.psess.dcx.struct_span_err(span, "expected string literal");
+                let mut err = p.dcx().struct_span_err(span, "expected string literal");
                 err.span_label(span, "not a string literal");
                 return Err(err);
             }
diff --git a/compiler/rustc_builtin_macros/src/cmdline_attrs.rs b/compiler/rustc_builtin_macros/src/cmdline_attrs.rs
index 16184ec7511..58928815e89 100644
--- a/compiler/rustc_builtin_macros/src/cmdline_attrs.rs
+++ b/compiler/rustc_builtin_macros/src/cmdline_attrs.rs
@@ -26,7 +26,7 @@ pub fn inject(krate: &mut ast::Crate, psess: &ParseSess, attrs: &[String]) {
         };
         let end_span = parser.token.span;
         if parser.token != token::Eof {
-            psess.dcx.emit_err(errors::InvalidCrateAttr { span: start_span.to(end_span) });
+            psess.dcx().emit_err(errors::InvalidCrateAttr { span: start_span.to(end_span) });
             continue;
         }
 
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index b3f6a35f3a4..b06b1f31c26 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -1358,7 +1358,7 @@ fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) {
         if crate_matches {
             // FIXME: make this translatable
             #[allow(rustc::untranslatable_diagnostic)]
-            sess.psess.dcx.emit_fatal(errors::ProcMacroBackCompat {
+            sess.dcx().emit_fatal(errors::ProcMacroBackCompat {
                 crate_name: "rental".to_string(),
                 fixed_version: "0.5.6".to_string(),
             });
diff --git a/compiler/rustc_expand/src/mbe/macro_check.rs b/compiler/rustc_expand/src/mbe/macro_check.rs
index 72dbbde54b3..d9a945a3215 100644
--- a/compiler/rustc_expand/src/mbe/macro_check.rs
+++ b/compiler/rustc_expand/src/mbe/macro_check.rs
@@ -206,7 +206,7 @@ pub(super) fn check_meta_variables(
     rhses: &[TokenTree],
 ) -> Result<(), ErrorGuaranteed> {
     if lhses.len() != rhses.len() {
-        psess.dcx.span_bug(span, "length mismatch between LHSes and RHSes")
+        psess.dcx().span_bug(span, "length mismatch between LHSes and RHSes")
     }
     let mut guar = None;
     for (lhs, rhs) in iter::zip(lhses, rhses) {
@@ -245,7 +245,7 @@ fn check_binders(
         // MetaVar(fragment) and not as MetaVarDecl(y, fragment).
         TokenTree::MetaVar(span, name) => {
             if macros.is_empty() {
-                psess.dcx.span_bug(span, "unexpected MetaVar in lhs");
+                psess.dcx().span_bug(span, "unexpected MetaVar in lhs");
             }
             let name = MacroRulesNormalizedIdent::new(name);
             // There are 3 possibilities:
@@ -276,7 +276,7 @@ fn check_binders(
                 );
             }
             if !macros.is_empty() {
-                psess.dcx.span_bug(span, "unexpected MetaVarDecl in nested lhs");
+                psess.dcx().span_bug(span, "unexpected MetaVarDecl in nested lhs");
             }
             let name = MacroRulesNormalizedIdent::new(name);
             if let Some(prev_info) = get_binder_info(macros, binders, name) {
@@ -284,7 +284,7 @@ fn check_binders(
                 // for nested macro definitions.
                 *guar = Some(
                     psess
-                        .dcx
+                        .dcx()
                         .emit_err(errors::DuplicateMatcherBinding { span, prev: prev_info.span }),
                 );
             } else {
@@ -344,7 +344,7 @@ fn check_occurrences(
     match *rhs {
         TokenTree::Token(..) => {}
         TokenTree::MetaVarDecl(span, _name, _kind) => {
-            psess.dcx.span_bug(span, "unexpected MetaVarDecl in rhs")
+            psess.dcx().span_bug(span, "unexpected MetaVarDecl in rhs")
         }
         TokenTree::MetaVar(span, name) => {
             let name = MacroRulesNormalizedIdent::new(name);
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 5d3ba5d3223..fd1aa44fd70 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -383,7 +383,7 @@ pub fn compile_declarative_macro(
     };
     let dummy_syn_ext = |guar| (mk_syn_ext(Box::new(DummyExpander(guar))), Vec::new());
 
-    let dcx = &sess.psess.dcx;
+    let dcx = sess.dcx();
     let lhs_nm = Ident::new(sym::lhs, def.span);
     let rhs_nm = Ident::new(sym::rhs, def.span);
     let tt_spec = Some(NonterminalKind::TT);
diff --git a/compiler/rustc_expand/src/mbe/metavar_expr.rs b/compiler/rustc_expand/src/mbe/metavar_expr.rs
index 3295a91029e..25958e03028 100644
--- a/compiler/rustc_expand/src/mbe/metavar_expr.rs
+++ b/compiler/rustc_expand/src/mbe/metavar_expr.rs
@@ -42,7 +42,7 @@ impl MetaVarExpr {
         let ident = parse_ident(&mut tts, psess, outer_span)?;
         let Some(TokenTree::Delimited(.., Delimiter::Parenthesis, args)) = tts.next() else {
             let msg = "meta-variable expression parameter must be wrapped in parentheses";
-            return Err(psess.dcx.struct_span_err(ident.span, msg));
+            return Err(psess.dcx().struct_span_err(ident.span, msg));
         };
         check_trailing_token(&mut tts, psess)?;
         let mut iter = args.trees();
@@ -62,12 +62,12 @@ impl MetaVarExpr {
                         break;
                     }
                     if !try_eat_comma(&mut iter) {
-                        return Err(psess.dcx.struct_span_err(outer_span, "expected comma"));
+                        return Err(psess.dcx().struct_span_err(outer_span, "expected comma"));
                     }
                 }
                 if result.len() < 2 {
                     return Err(psess
-                        .dcx
+                        .dcx()
                         .struct_span_err(ident.span, "`concat` must have at least two elements"));
                 }
                 MetaVarExpr::Concat(result.into())
@@ -81,7 +81,7 @@ impl MetaVarExpr {
             "len" => MetaVarExpr::Len(parse_depth(&mut iter, psess, ident.span)?),
             _ => {
                 let err_msg = "unrecognized meta-variable expression";
-                let mut err = psess.dcx.struct_span_err(ident.span, err_msg);
+                let mut err = psess.dcx().struct_span_err(ident.span, err_msg);
                 err.span_suggestion(
                     ident.span,
                     "supported expressions are count, ignore, index and len",
@@ -120,7 +120,7 @@ fn check_trailing_token<'psess>(
 ) -> PResult<'psess, ()> {
     if let Some(tt) = iter.next() {
         let mut diag = psess
-            .dcx
+            .dcx()
             .struct_span_err(tt.span(), format!("unexpected token: {}", pprust::tt_to_string(tt)));
         diag.span_note(tt.span(), "meta-variable expression must not have trailing tokens");
         Err(diag)
@@ -139,7 +139,7 @@ fn parse_count<'psess>(
     let ident = parse_ident(iter, psess, span)?;
     let depth = if try_eat_comma(iter) {
         if iter.look_ahead(0).is_none() {
-            return Err(psess.dcx.struct_span_err(
+            return Err(psess.dcx().struct_span_err(
                 span,
                 "`count` followed by a comma must have an associated index indicating its depth",
             ));
@@ -160,7 +160,7 @@ fn parse_depth<'psess>(
     let Some(tt) = iter.next() else { return Ok(0) };
     let TokenTree::Token(token::Token { kind: token::TokenKind::Literal(lit), .. }, _) = tt else {
         return Err(psess
-            .dcx
+            .dcx()
             .struct_span_err(span, "meta-variable expression depth must be a literal"));
     };
     if let Ok(lit_kind) = LitKind::from_token_lit(*lit)
@@ -170,7 +170,7 @@ fn parse_depth<'psess>(
         Ok(n_usize)
     } else {
         let msg = "only unsuffixes integer literals are supported in meta-variable expressions";
-        Err(psess.dcx.struct_span_err(span, msg))
+        Err(psess.dcx().struct_span_err(span, msg))
     }
 }
 
@@ -181,20 +181,21 @@ fn parse_ident<'psess>(
     fallback_span: Span,
 ) -> PResult<'psess, Ident> {
     let Some(tt) = iter.next() else {
-        return Err(psess.dcx.struct_span_err(fallback_span, "expected identifier"));
+        return Err(psess.dcx().struct_span_err(fallback_span, "expected identifier"));
     };
     let TokenTree::Token(token, _) = tt else {
-        return Err(psess.dcx.struct_span_err(tt.span(), "expected identifier"));
+        return Err(psess.dcx().struct_span_err(tt.span(), "expected identifier"));
     };
     if let Some((elem, is_raw)) = token.ident() {
         if let IdentIsRaw::Yes = is_raw {
-            return Err(psess.dcx.struct_span_err(elem.span, RAW_IDENT_ERR));
+            return Err(psess.dcx().struct_span_err(elem.span, RAW_IDENT_ERR));
         }
         return Ok(elem);
     }
     let token_str = pprust::token_to_string(token);
-    let mut err =
-        psess.dcx.struct_span_err(token.span, format!("expected identifier, found `{token_str}`"));
+    let mut err = psess
+        .dcx()
+        .struct_span_err(token.span, format!("expected identifier, found `{token_str}`"));
     err.span_suggestion(
         token.span,
         format!("try removing `{token_str}`"),
@@ -236,7 +237,7 @@ fn eat_dollar<'psess>(
         let _ = iter.next();
         return Ok(());
     }
-    Err(psess.dcx.struct_span_err(
+    Err(psess.dcx().struct_span_err(
         span,
         "meta-variables within meta-variable expressions must be referenced using a dollar sign",
     ))
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index 914bd03675a..6e6afe74df1 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -141,7 +141,7 @@ pub(super) fn transcribe<'a>(
     let mut result_stack = Vec::new();
     let mut marker = Marker(expand_id, transparency, Default::default());
 
-    let dcx = &psess.dcx;
+    let dcx = psess.dcx();
     loop {
         // Look at the last frame on the stack.
         // If it still has a TokenTree we have not looked at yet, use that tree.
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 93f8682090d..5508358f53b 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -522,7 +522,7 @@ impl server::FreeFunctions for Rustc<'_, '_> {
     fn emit_diagnostic(&mut self, diagnostic: Diagnostic<Self::Span>) {
         let message = rustc_errors::DiagMessage::from(diagnostic.message);
         let mut diag: Diag<'_, ()> =
-            Diag::new(&self.psess().dcx, diagnostic.level.to_internal(), message);
+            Diag::new(self.psess().dcx(), diagnostic.level.to_internal(), message);
         diag.span(MultiSpan::from_spans(diagnostic.spans));
         for child in diagnostic.children {
             // This message comes from another diagnostic, and we are just reconstructing the
diff --git a/compiler/rustc_hir_analysis/src/check/errs.rs b/compiler/rustc_hir_analysis/src/check/errs.rs
index 2cdcc06f53c..17cb20df754 100644
--- a/compiler/rustc_hir_analysis/src/check/errs.rs
+++ b/compiler/rustc_hir_analysis/src/check/errs.rs
@@ -63,7 +63,7 @@ fn handle_static_mut_ref(
         } else {
             (errors::StaticMutRefSugg::Shared { span, var }, "shared")
         };
-        tcx.sess.psess.dcx.emit_err(errors::StaticMutRef { span, sugg, shared });
+        tcx.dcx().emit_err(errors::StaticMutRef { span, sugg, shared });
     } else {
         let (sugg, shared) = if mutable == Mutability::Mut {
             (errors::RefOfMutStaticSugg::Mut { span, var }, "mutable")
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index 2ef27e6a0ba..ee4eec99b2b 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -146,7 +146,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     pub(crate) fn dcx(&self) -> &'tcx DiagCtxt {
-        self.tcx.dcx()
+        self.infcx.dcx()
     }
 
     pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index e15866f3f0f..4717e3d6047 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -140,7 +140,7 @@ pub struct TypeErrCtxt<'a, 'tcx> {
 
 impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     pub fn dcx(&self) -> &'tcx DiagCtxt {
-        self.infcx.tcx.dcx()
+        self.infcx.dcx()
     }
 
     /// This is just to avoid a potential footgun of accidentally
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index ad283117d7e..62a068d640a 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -92,7 +92,7 @@ impl<'a, 'tcx> std::ops::Deref for CrateLoader<'a, 'tcx> {
 
 impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
     fn dcx(&self) -> &'tcx DiagCtxt {
-        &self.tcx.dcx()
+        self.tcx.dcx()
     }
 }
 
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 43f4963b27a..a5b9ab32a8c 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -114,7 +114,7 @@ struct StringReader<'psess, 'src> {
 
 impl<'psess, 'src> StringReader<'psess, 'src> {
     fn dcx(&self) -> &'psess DiagCtxt {
-        &self.psess.dcx
+        self.psess.dcx()
     }
 
     fn mk_sp(&self, lo: BytePos, hi: BytePos) -> Span {
@@ -248,8 +248,8 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
                     let suffix = if suffix_start < self.pos {
                         let string = self.str_from(suffix_start);
                         if string == "_" {
-                            self.psess
-                                .dcx
+                            self
+                                .dcx()
                                 .emit_err(errors::UnderscoreLiteralSuffix { span: self.mk_sp(suffix_start, self.pos) });
                             None
                         } else {
@@ -597,8 +597,7 @@ impl<'psess, 'src> StringReader<'psess, 'src> {
     }
 
     fn report_non_started_raw_string(&self, start: BytePos, bad_char: char) -> ! {
-        self.psess
-            .dcx
+        self.dcx()
             .struct_span_fatal(
                 self.mk_sp(start, self.pos),
                 format!(
diff --git a/compiler/rustc_parse/src/lexer/tokentrees.rs b/compiler/rustc_parse/src/lexer/tokentrees.rs
index f7645446081..8e543454691 100644
--- a/compiler/rustc_parse/src/lexer/tokentrees.rs
+++ b/compiler/rustc_parse/src/lexer/tokentrees.rs
@@ -71,7 +71,7 @@ impl<'psess, 'src> TokenTreesReader<'psess, 'src> {
 
     fn eof_err(&mut self) -> PErr<'psess> {
         let msg = "this file contains an unclosed delimiter";
-        let mut err = self.string_reader.psess.dcx.struct_span_err(self.token.span, msg);
+        let mut err = self.string_reader.dcx().struct_span_err(self.token.span, msg);
         for &(_, sp) in &self.diag_info.open_braces {
             err.span_label(sp, "unclosed delimiter");
             self.diag_info.unmatched_delims.push(UnmatchedDelim {
@@ -290,7 +290,7 @@ impl<'psess, 'src> TokenTreesReader<'psess, 'src> {
         // An unexpected closing delimiter (i.e., there is no matching opening delimiter).
         let token_str = token_to_string(&self.token);
         let msg = format!("unexpected closing delimiter: `{token_str}`");
-        let mut err = self.string_reader.psess.dcx.struct_span_err(self.token.span, msg);
+        let mut err = self.string_reader.dcx().struct_span_err(self.token.span, msg);
 
         report_suspicious_mismatch_block(
             &mut err,
diff --git a/compiler/rustc_parse/src/lexer/unicode_chars.rs b/compiler/rustc_parse/src/lexer/unicode_chars.rs
index 8eb299108d1..0a82ede3b75 100644
--- a/compiler/rustc_parse/src/lexer/unicode_chars.rs
+++ b/compiler/rustc_parse/src/lexer/unicode_chars.rs
@@ -351,7 +351,7 @@ pub(super) fn check_for_substitution(
 
     let Some((_, ascii_name, token)) = ASCII_ARRAY.iter().find(|&&(s, _, _)| s == ascii_str) else {
         let msg = format!("substitution character not found for '{ch}'");
-        reader.psess.dcx.span_bug(span, msg);
+        reader.dcx().span_bug(span, msg);
     };
 
     // special help suggestion for "directed" double quotes
diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs
index 25cab7252a3..5522127be83 100644
--- a/compiler/rustc_parse/src/lib.rs
+++ b/compiler/rustc_parse/src/lib.rs
@@ -73,7 +73,7 @@ pub fn new_parser_from_file<'a>(
 ) -> Result<Parser<'a>, Vec<Diag<'a>>> {
     let source_file = psess.source_map().load_file(path).unwrap_or_else(|e| {
         let msg = format!("couldn't read {}: {}", path.display(), e);
-        let mut err = psess.dcx.struct_fatal(msg);
+        let mut err = psess.dcx().struct_fatal(msg);
         if let Some(sp) = sp {
             err.span(sp);
         }
@@ -115,7 +115,7 @@ fn source_file_to_stream<'psess>(
     override_span: Option<Span>,
 ) -> Result<TokenStream, Vec<Diag<'psess>>> {
     let src = source_file.src.as_ref().unwrap_or_else(|| {
-        psess.dcx.bug(format!(
+        psess.dcx().bug(format!(
             "cannot lex `source_file` without source: {}",
             psess.source_map().filename_for_diagnostics(&source_file.name)
         ));
@@ -179,7 +179,7 @@ pub fn parse_cfg_attr(
             }
         }
         _ => {
-            psess.dcx.emit_err(errors::MalformedCfgAttr {
+            psess.dcx().emit_err(errors::MalformedCfgAttr {
                 span: attr.span,
                 sugg: CFG_ATTR_GRAMMAR_HELP,
             });
diff --git a/compiler/rustc_parse/src/parser/attr_wrapper.rs b/compiler/rustc_parse/src/parser/attr_wrapper.rs
index 62c8f9f5dac..f5c931034fd 100644
--- a/compiler/rustc_parse/src/parser/attr_wrapper.rs
+++ b/compiler/rustc_parse/src/parser/attr_wrapper.rs
@@ -41,7 +41,7 @@ impl AttrWrapper {
     }
 
     pub(crate) fn take_for_recovery(self, psess: &ParseSess) -> AttrVec {
-        psess.dcx.span_delayed_bug(
+        psess.dcx().span_delayed_bug(
             self.attrs.get(0).map(|attr| attr.span).unwrap_or(DUMMY_SP),
             "AttrVec is taken for recovery but no error is produced",
         );
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 0c326c8eca2..d3f9bb3f274 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -241,7 +241,7 @@ impl<'a> DerefMut for SnapshotParser<'a> {
 
 impl<'a> Parser<'a> {
     pub fn dcx(&self) -> &'a DiagCtxt {
-        &self.psess.dcx
+        self.psess.dcx()
     }
 
     /// Replace `self` with `snapshot.parser`.
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 604959b1cda..6dee913c141 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -1596,7 +1596,7 @@ pub(crate) fn make_unclosed_delims_error(
     if let Some(sp) = unmatched.unclosed_span {
         spans.push(sp);
     };
-    let err = psess.dcx.create_err(MismatchedClosingDelimiter {
+    let err = psess.dcx().create_err(MismatchedClosingDelimiter {
         spans,
         delimiter: pprust::token_kind_to_string(&token::CloseDelim(found_delim)).to_string(),
         unmatched: unmatched.found_span,
diff --git a/compiler/rustc_parse/src/validate_attr.rs b/compiler/rustc_parse/src/validate_attr.rs
index 19d6f512572..4ca52146039 100644
--- a/compiler/rustc_parse/src/validate_attr.rs
+++ b/compiler/rustc_parse/src/validate_attr.rs
@@ -65,7 +65,7 @@ pub fn parse_meta<'a>(psess: &'a ParseSess, attr: &Attribute) -> PResult<'a, Met
                     let res = match res {
                         Ok(lit) => {
                             if token_lit.suffix.is_some() {
-                                let mut err = psess.dcx.struct_span_err(
+                                let mut err = psess.dcx().struct_span_err(
                                     expr.span,
                                     "suffixed literals are not allowed in attributes",
                                 );
@@ -98,7 +98,7 @@ pub fn parse_meta<'a>(psess: &'a ParseSess, attr: &Attribute) -> PResult<'a, Met
                     //   the error because an earlier error will have already
                     //   been reported.
                     let msg = "attribute value must be a literal";
-                    let mut err = psess.dcx.struct_span_err(expr.span, msg);
+                    let mut err = psess.dcx().struct_span_err(expr.span, msg);
                     if let ast::ExprKind::Err(_) = expr.kind {
                         err.downgrade_to_delayed_bug();
                     }
@@ -114,7 +114,7 @@ fn check_meta_bad_delim(psess: &ParseSess, span: DelimSpan, delim: Delimiter) {
     if let Delimiter::Parenthesis = delim {
         return;
     }
-    psess.dcx.emit_err(errors::MetaBadDelim {
+    psess.dcx().emit_err(errors::MetaBadDelim {
         span: span.entire(),
         sugg: errors::MetaBadDelimSugg { open: span.open, close: span.close },
     });
@@ -124,7 +124,7 @@ pub(super) fn check_cfg_attr_bad_delim(psess: &ParseSess, span: DelimSpan, delim
     if let Delimiter::Parenthesis = delim {
         return;
     }
-    psess.dcx.emit_err(errors::CfgAttrBadDelim {
+    psess.dcx().emit_err(errors::CfgAttrBadDelim {
         span: span.entire(),
         sugg: errors::MetaBadDelimSugg { open: span.open, close: span.close },
     });
@@ -191,7 +191,7 @@ fn emit_malformed_attribute(
     } else {
         suggestions.sort();
         psess
-            .dcx
+            .dcx()
             .struct_span_err(span, error_msg)
             .with_span_suggestions(
                 span,
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index dce56382a53..71d11bfdb32 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -401,7 +401,7 @@ pub fn report_lit_error(
         valid.then(|| format!("0{}{}", base_char.to_ascii_lowercase(), &suffix[1..]))
     }
 
-    let dcx = &psess.dcx;
+    let dcx = psess.dcx();
     match err {
         LitError::InvalidSuffix(suffix) => {
             dcx.emit_err(InvalidLiteralSuffix { span, kind: lit.kind.descr(), suffix })
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index df07f81bc45..4e5ee39ffb9 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -106,12 +106,12 @@ pub fn feature_err_issue(
 
     // Cancel an earlier warning for this same error, if it exists.
     if let Some(span) = span.primary_span() {
-        if let Some(err) = sess.psess.dcx.steal_non_err(span, StashKey::EarlySyntaxWarning) {
+        if let Some(err) = sess.dcx().steal_non_err(span, StashKey::EarlySyntaxWarning) {
             err.cancel()
         }
     }
 
-    let mut err = sess.psess.dcx.create_err(FeatureGateError { span, explain: explain.into() });
+    let mut err = sess.dcx().create_err(FeatureGateError { span, explain: explain.into() });
     add_feature_diagnostics_for_issue(&mut err, sess, feature, issue, false, None);
     err
 }
@@ -140,7 +140,7 @@ pub fn feature_warn_issue(
     issue: GateIssue,
     explain: &'static str,
 ) {
-    let mut err = sess.psess.dcx.struct_span_warn(span, explain);
+    let mut err = sess.dcx().struct_span_warn(span, explain);
     add_feature_diagnostics_for_issue(&mut err, sess, feature, issue, false, None);
 
     // Decorate this as a future-incompatibility lint as in rustc_middle::lint::lint_level
@@ -201,7 +201,7 @@ pub fn add_feature_diagnostics_for_issue<G: EmissionGuarantee>(
 
 /// Info about a parsing session.
 pub struct ParseSess {
-    pub dcx: DiagCtxt,
+    dcx: DiagCtxt,
     pub unstable_features: UnstableFeatures,
     pub config: Cfg,
     pub check_config: CheckCfg,
@@ -326,4 +326,8 @@ impl ParseSess {
         // AppendOnlyVec, so we resort to this scheme.
         self.proc_macro_quoted_spans.iter_enumerated()
     }
+
+    pub fn dcx(&self) -> &DiagCtxt {
+        &self.dcx
+    }
 }
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 87bbfcf07c8..82b593a0f40 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -329,7 +329,7 @@ impl Session {
 
     #[inline]
     pub fn dcx(&self) -> &DiagCtxt {
-        &self.psess.dcx
+        self.psess.dcx()
     }
 
     #[inline]