Use `.into_diagnostic()` less.

This commit replaces this pattern:
```
err.into_diagnostic(dcx)
```
with this pattern:
```
dcx.create_err(err)
```
in a lot of places.

It's a little shorter, makes the error level explicit, avoids some
`IntoDiagnostic` imports, and is a necessary prerequisite for the next
commit which will add a `level` arg to `into_diagnostic`.

This requires adding `track_caller` on `create_err` to avoid mucking up
the output of `tests/ui/track-diagnostics/track4.rs`. It probably should
have been there already.

8 files changed, 76 insertions, 84 deletions

diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 56e52baf98b..53b29eccc2c 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -5,7 +5,7 @@ use super::{AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle
 use rustc_ast as ast;
 use rustc_ast::attr;
 use rustc_ast::token::{self, Delimiter, Nonterminal};
-use rustc_errors::{error_code, Diagnostic, IntoDiagnostic, PResult};
+use rustc_errors::{error_code, Diagnostic, PResult};
 use rustc_span::{sym, BytePos, Span};
 use thin_vec::ThinVec;
 use tracing::debug;
@@ -416,8 +416,9 @@ impl<'a> Parser<'a> {
             Err(err) => err.cancel(),
         }
 
-        Err(InvalidMetaItem { span: self.token.span, token: self.token.clone() }
-            .into_diagnostic(self.dcx()))
+        Err(self
+            .dcx()
+            .create_err(InvalidMetaItem { span: self.token.span, token: self.token.clone() }))
     }
 }
 
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 9e3637ea9f3..fb31815c302 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -35,7 +35,7 @@ use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{
     pluralize, AddToDiagnostic, Applicability, DiagCtxt, Diagnostic, DiagnosticBuilder,
-    DiagnosticMessage, ErrorGuaranteed, FatalError, IntoDiagnostic, MultiSpan, PResult,
+    DiagnosticMessage, ErrorGuaranteed, FatalError, MultiSpan, PResult,
 };
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::Spanned;
@@ -280,11 +280,10 @@ impl<'a> Parser<'a> {
         recover: bool,
     ) -> PResult<'a, (Ident, /* is_raw */ bool)> {
         if let TokenKind::DocComment(..) = self.prev_token.kind {
-            return Err(DocCommentDoesNotDocumentAnything {
+            return Err(self.dcx().create_err(DocCommentDoesNotDocumentAnything {
                 span: self.prev_token.span,
                 missing_comma: None,
-            }
-            .into_diagnostic(self.dcx()));
+            }));
         }
 
         let valid_follow = &[
@@ -347,7 +346,7 @@ impl<'a> Parser<'a> {
             suggest_remove_comma,
             help_cannot_start_number,
         };
-        let mut err = err.into_diagnostic(self.dcx());
+        let mut err = self.dcx().create_err(err);
 
         // if the token we have is a `<`
         // it *might* be a misplaced generic
@@ -1410,7 +1409,7 @@ impl<'a> Parser<'a> {
                                 // Not entirely sure now, but we bubble the error up with the
                                 // suggestion.
                                 self.restore_snapshot(snapshot);
-                                Err(err.into_diagnostic(self.dcx()))
+                                Err(self.dcx().create_err(err))
                             }
                         }
                     } else if token::OpenDelim(Delimiter::Parenthesis) == self.token.kind {
@@ -1425,7 +1424,7 @@ impl<'a> Parser<'a> {
                         }
                         // Consume the fn call arguments.
                         match self.consume_fn_args() {
-                            Err(()) => Err(err.into_diagnostic(self.dcx())),
+                            Err(()) => Err(self.dcx().create_err(err)),
                             Ok(()) => {
                                 self.sess.emit_err(err);
                                 // FIXME: actually check that the two expressions in the binop are
@@ -1451,7 +1450,7 @@ impl<'a> Parser<'a> {
                             mk_err_expr(self, inner_op.span.to(self.prev_token.span))
                         } else {
                             // These cases cause too many knock-down errors, bail out (#61329).
-                            Err(err.into_diagnostic(self.dcx()))
+                            Err(self.dcx().create_err(err))
                         }
                     };
                 }
@@ -2539,7 +2538,7 @@ impl<'a> Parser<'a> {
             Ok(Some(GenericArg::Const(self.parse_const_arg()?)))
         } else {
             let after_kw_const = self.token.span;
-            self.recover_const_arg(after_kw_const, err.into_diagnostic(self.dcx())).map(Some)
+            self.recover_const_arg(after_kw_const, self.dcx().create_err(err)).map(Some)
         }
     }
 
@@ -2893,11 +2892,10 @@ impl<'a> Parser<'a> {
                 let (a_span, b_span) = (a.span(), b.span());
                 let between_span = a_span.shrink_to_hi().to(b_span.shrink_to_lo());
                 if self.span_to_snippet(between_span).as_deref() == Ok(":: ") {
-                    return Err(DoubleColonInBound {
+                    return Err(self.dcx().create_err(DoubleColonInBound {
                         span: path.span.shrink_to_hi(),
                         between: between_span,
-                    }
-                    .into_diagnostic(self.dcx()));
+                    }));
                 }
             }
         }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index cd3e8b92f2f..a21a1533848 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -26,8 +26,8 @@ use rustc_ast::{ClosureBinder, MetaItemLit, StmtKind};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::{
-    AddToDiagnostic, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic,
-    PResult, StashKey,
+    AddToDiagnostic, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, PResult,
+    StashKey,
 };
 use rustc_macros::Subdiagnostic;
 use rustc_session::errors::{report_lit_error, ExprParenthesesNeeded};
@@ -1255,21 +1255,21 @@ impl<'a> Parser<'a> {
                             // that of the open delim in `TokenTreesReader::parse_token_tree`, even if they are different.
                             self.span_to_snippet(close_paren).is_ok_and(|snippet| snippet == ")")
                         {
-                            let mut replacement_err = errors::ParenthesesWithStructFields {
-                                span,
-                                r#type: path,
-                                braces_for_struct: errors::BracesForStructLiteral {
-                                    first: open_paren,
-                                    second: close_paren,
-                                },
-                                no_fields_for_fn: errors::NoFieldsForFnCall {
-                                    fields: fields
-                                        .into_iter()
-                                        .map(|field| field.span.until(field.expr.span))
-                                        .collect(),
-                                },
-                            }
-                            .into_diagnostic(self.dcx());
+                            let mut replacement_err =
+                                self.dcx().create_err(errors::ParenthesesWithStructFields {
+                                    span,
+                                    r#type: path,
+                                    braces_for_struct: errors::BracesForStructLiteral {
+                                        first: open_paren,
+                                        second: close_paren,
+                                    },
+                                    no_fields_for_fn: errors::NoFieldsForFnCall {
+                                        fields: fields
+                                            .into_iter()
+                                            .map(|field| field.span.until(field.expr.span))
+                                            .collect(),
+                                    },
+                                });
                             replacement_err.emit();
 
                             let old_err = mem::replace(err, replacement_err);
@@ -1883,8 +1883,7 @@ impl<'a> Parser<'a> {
         self.bump(); // `#`
 
         let Some((ident, false)) = self.token.ident() else {
-            let err =
-                errors::ExpectedBuiltinIdent { span: self.token.span }.into_diagnostic(self.dcx());
+            let err = self.dcx().create_err(errors::ExpectedBuiltinIdent { span: self.token.span });
             return Err(err);
         };
         self.sess.gated_spans.gate(sym::builtin_syntax, ident.span);
@@ -1894,8 +1893,10 @@ impl<'a> Parser<'a> {
         let ret = if let Some(res) = parse(self, lo, ident)? {
             Ok(res)
         } else {
-            let err = errors::UnknownBuiltinConstruct { span: lo.to(ident.span), name: ident.name }
-                .into_diagnostic(self.dcx());
+            let err = self.dcx().create_err(errors::UnknownBuiltinConstruct {
+                span: lo.to(ident.span),
+                name: ident.name,
+            });
             return Err(err);
         };
         self.expect(&TokenKind::CloseDelim(Delimiter::Parenthesis))?;
@@ -1958,8 +1959,9 @@ impl<'a> Parser<'a> {
             && let token::NtExpr(e) | token::NtLiteral(e) = &nt.0
             && matches!(e.kind, ExprKind::Err)
         {
-            let mut err = errors::InvalidInterpolatedExpression { span: self.token.span }
-                .into_diagnostic(self.dcx());
+            let mut err = self
+                .dcx()
+                .create_err(errors::InvalidInterpolatedExpression { span: self.token.span });
             err.downgrade_to_delayed_bug();
             return Err(err);
         }
@@ -2168,10 +2170,10 @@ impl<'a> Parser<'a> {
                         .span_to_snippet(snapshot.token.span)
                         .is_ok_and(|snippet| snippet == "]") =>
                 {
-                    return Err(errors::MissingSemicolonBeforeArray {
+                    return Err(self.dcx().create_err(errors::MissingSemicolonBeforeArray {
                         open_delim: open_delim_span,
                         semicolon: prev_span.shrink_to_hi(),
-                    }.into_diagnostic(self.dcx()));
+                    }));
                 }
                 Ok(_) => (),
                 Err(err) => err.cancel(),
@@ -2318,8 +2320,9 @@ impl<'a> Parser<'a> {
             // Check for `move async` and recover
             if self.check_keyword(kw::Async) {
                 let move_async_span = self.token.span.with_lo(self.prev_token.span.data().lo);
-                Err(errors::AsyncMoveOrderIncorrect { span: move_async_span }
-                    .into_diagnostic(self.dcx()))
+                Err(self
+                    .dcx()
+                    .create_err(errors::AsyncMoveOrderIncorrect { span: move_async_span }))
             } else {
                 Ok(CaptureBy::Value { move_kw: move_kw_span })
             }
@@ -2509,7 +2512,7 @@ impl<'a> Parser<'a> {
             };
             if self.prev_token.kind == token::BinOp(token::Or) {
                 // This was part of a closure, the that part of the parser recover.
-                return Err(err.into_diagnostic(self.dcx()));
+                return Err(self.dcx().create_err(err));
             } else {
                 Some(self.sess.emit_err(err))
             }
@@ -3193,7 +3196,7 @@ impl<'a> Parser<'a> {
     fn parse_try_block(&mut self, span_lo: Span) -> PResult<'a, P<Expr>> {
         let (attrs, body) = self.parse_inner_attrs_and_block()?;
         if self.eat_keyword(kw::Catch) {
-            Err(errors::CatchAfterTry { span: self.prev_token.span }.into_diagnostic(self.dcx()))
+            Err(self.dcx().create_err(errors::CatchAfterTry { span: self.prev_token.span }))
         } else {
             let span = span_lo.to(body.span);
             self.sess.gated_spans.gate(sym::try_blocks, span);
@@ -3530,12 +3533,11 @@ impl<'a> Parser<'a> {
                         || t == &token::CloseDelim(Delimiter::Parenthesis)
                 });
             if is_wrong {
-                return Err(errors::ExpectedStructField {
+                return Err(this.dcx().create_err(errors::ExpectedStructField {
                     span: this.look_ahead(1, |t| t.span),
                     ident_span: this.token.span,
                     token: this.look_ahead(1, |t| t.clone()),
-                }
-                .into_diagnostic(&self.sess.dcx));
+                }));
             }
             let (ident, expr) = if is_shorthand {
                 // Mimic `x: x` for the `x` field shorthand.
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index bf619daba50..32c5bef7c8e 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -10,10 +10,7 @@ use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
 use rustc_ast::util::case::Case;
 use rustc_ast::{self as ast};
 use rustc_ast_pretty::pprust;
-use rustc_errors::{
-    struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, PResult,
-    StashKey,
-};
+use rustc_errors::{struct_span_err, Applicability, PResult, StashKey};
 use rustc_span::edit_distance::edit_distance;
 use rustc_span::edition::Edition;
 use rustc_span::source_map;
@@ -438,7 +435,7 @@ impl<'a> Parser<'a> {
             None
         };
 
-        if let Some(err) = err { Err(err.into_diagnostic(self.dcx())) } else { Ok(()) }
+        if let Some(err) = err { Err(self.dcx().create_err(err)) } else { Ok(()) }
     }
 
     fn parse_item_builtin(&mut self) -> PResult<'a, Option<ItemInfo>> {
@@ -1373,8 +1370,7 @@ impl<'a> Parser<'a> {
         };
 
         let span = self.prev_token.span.shrink_to_hi();
-        let err: DiagnosticBuilder<'_, ErrorGuaranteed> =
-            errors::MissingConstType { span, colon, kind }.into_diagnostic(self.dcx());
+        let err = self.dcx().create_err(errors::MissingConstType { span, colon, kind });
         err.stash(span, StashKey::ItemNoType);
 
         // The user intended that the type be inferred,
@@ -1391,7 +1387,7 @@ impl<'a> Parser<'a> {
                 self.bump();
                 self.sess.emit_err(err);
             } else {
-                return Err(err.into_diagnostic(self.dcx()));
+                return Err(self.dcx().create_err(err));
             }
         }
 
@@ -1591,7 +1587,7 @@ impl<'a> Parser<'a> {
         } else {
             let err =
                 errors::UnexpectedTokenAfterStructName::new(self.token.span, self.token.clone());
-            return Err(err.into_diagnostic(self.dcx()));
+            return Err(self.dcx().create_err(err));
         };
 
         Ok((class_name, ItemKind::Struct(vdata, generics)))
@@ -1787,7 +1783,7 @@ impl<'a> Parser<'a> {
                         let sp = previous_span.shrink_to_hi();
                         err.missing_comma = Some(sp);
                     }
-                    return Err(err.into_diagnostic(self.dcx()));
+                    return Err(self.dcx().create_err(err));
                 }
             }
             _ => {
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index b91432f10c8..0ab2adb404a 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -32,9 +32,7 @@ use rustc_ast::{HasAttrs, HasTokens, Unsafe, Visibility, VisibilityKind};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::PResult;
-use rustc_errors::{
-    Applicability, DiagnosticBuilder, ErrorGuaranteed, FatalError, IntoDiagnostic, MultiSpan,
-};
+use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, FatalError, MultiSpan};
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
@@ -1500,14 +1498,13 @@ pub(crate) fn make_unclosed_delims_error(
     if let Some(sp) = unmatched.unclosed_span {
         spans.push(sp);
     };
-    let err = MismatchedClosingDelimiter {
+    let err = sess.dcx.create_err(MismatchedClosingDelimiter {
         spans,
         delimiter: pprust::token_kind_to_string(&token::CloseDelim(found_delim)).to_string(),
         unmatched: unmatched.found_span,
         opening_candidate: unmatched.candidate_span,
         unclosed: unmatched.unclosed_span,
-    }
-    .into_diagnostic(&sess.dcx);
+    });
     Some(err)
 }
 
diff --git a/compiler/rustc_parse/src/parser/nonterminal.rs b/compiler/rustc_parse/src/parser/nonterminal.rs
index 301a88cd077..071d6b72f3b 100644
--- a/compiler/rustc_parse/src/parser/nonterminal.rs
+++ b/compiler/rustc_parse/src/parser/nonterminal.rs
@@ -2,7 +2,6 @@ use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter, Nonterminal::*, NonterminalKind, Token};
 use rustc_ast::HasTokens;
 use rustc_ast_pretty::pprust;
-use rustc_errors::IntoDiagnostic;
 use rustc_errors::PResult;
 use rustc_span::symbol::{kw, Ident};
 
@@ -114,9 +113,9 @@ impl<'a> Parser<'a> {
             NonterminalKind::Item => match self.parse_item(ForceCollect::Yes)? {
                 Some(item) => NtItem(item),
                 None => {
-                    return Err(
-                        UnexpectedNonterminal::Item(self.token.span).into_diagnostic(self.dcx())
-                    );
+                    return Err(self
+                        .dcx()
+                        .create_err(UnexpectedNonterminal::Item(self.token.span)));
                 }
             },
             NonterminalKind::Block => {
@@ -127,8 +126,9 @@ impl<'a> Parser<'a> {
             NonterminalKind::Stmt => match self.parse_stmt(ForceCollect::Yes)? {
                 Some(s) => NtStmt(P(s)),
                 None => {
-                    return Err(UnexpectedNonterminal::Statement(self.token.span)
-                        .into_diagnostic(self.dcx()));
+                    return Err(self
+                        .dcx()
+                        .create_err(UnexpectedNonterminal::Statement(self.token.span)));
                 }
             },
             NonterminalKind::PatParam { .. } | NonterminalKind::PatWithOr => {
@@ -160,11 +160,10 @@ impl<'a> Parser<'a> {
                 NtIdent(ident, is_raw)
             }
             NonterminalKind::Ident => {
-                return Err(UnexpectedNonterminal::Ident {
+                return Err(self.dcx().create_err(UnexpectedNonterminal::Ident {
                     span: self.token.span,
                     token: self.token.clone(),
-                }
-                .into_diagnostic(self.dcx()));
+                }));
             }
             NonterminalKind::Path => {
                 NtPath(P(self.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))?))
@@ -178,11 +177,10 @@ impl<'a> Parser<'a> {
                 if self.check_lifetime() {
                     NtLifetime(self.expect_lifetime().ident)
                 } else {
-                    return Err(UnexpectedNonterminal::Lifetime {
+                    return Err(self.dcx().create_err(UnexpectedNonterminal::Lifetime {
                         span: self.token.span,
                         token: self.token.clone(),
-                    }
-                    .into_diagnostic(self.dcx()));
+                    }));
                 }
             }
         };
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 80233eddb9b..d32582fd43d 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -18,7 +18,7 @@ use rustc_ast::{
     PatField, PatKind, Path, QSelf, RangeEnd, RangeSyntax,
 };
 use rustc_ast_pretty::pprust;
-use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, PResult};
+use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident};
@@ -872,8 +872,9 @@ impl<'a> Parser<'a> {
         // binding mode then we do not end up here, because the lookahead
         // will direct us over to `parse_enum_variant()`.
         if self.token == token::OpenDelim(Delimiter::Parenthesis) {
-            return Err(EnumPatternInsteadOfIdentifier { span: self.prev_token.span }
-                .into_diagnostic(self.dcx()));
+            return Err(self
+                .dcx()
+                .create_err(EnumPatternInsteadOfIdentifier { span: self.prev_token.span }));
         }
 
         Ok(PatKind::Ident(binding_annotation, ident, sub))
@@ -986,8 +987,8 @@ impl<'a> Parser<'a> {
 
             // check that a comma comes after every field
             if !ate_comma {
-                let mut err = ExpectedCommaAfterPatternField { span: self.token.span }
-                    .into_diagnostic(self.dcx());
+                let mut err =
+                    self.dcx().create_err(ExpectedCommaAfterPatternField { span: self.token.span });
                 if let Some(mut delayed) = delayed_err {
                     delayed.emit();
                 }
diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index 3b92a911983..8970a99f1b7 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -9,7 +9,7 @@ use rustc_ast::{
     AssocConstraintKind, BlockCheckMode, GenericArg, GenericArgs, Generics, ParenthesizedArgs,
     Path, PathSegment, QSelf,
 };
-use rustc_errors::{Applicability, IntoDiagnostic, PResult};
+use rustc_errors::{Applicability, PResult};
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{BytePos, Span};
 use std::mem;
@@ -318,15 +318,14 @@ impl<'a> Parser<'a> {
                             })
                         {
                             err.cancel();
-                            err = PathSingleColon {
+                            err = self.dcx().create_err(PathSingleColon {
                                 span: self.token.span,
                                 type_ascription: self
                                     .sess
                                     .unstable_features
                                     .is_nightly_build()
                                     .then_some(()),
-                            }
-                            .into_diagnostic(self.dcx());
+                            });
                         }
                         // Attempt to find places where a missing `>` might belong.
                         else if let Some(arg) = args