diff --git a/compiler/rustc_ast_lowering/src/errors.rs b/compiler/rustc_ast_lowering/src/errors.rs
index 052979d6d456..1ad5fa21d853 100644
--- a/compiler/rustc_ast_lowering/src/errors.rs
+++ b/compiler/rustc_ast_lowering/src/errors.rs
@@ -335,7 +335,7 @@ pub struct InclusiveRangeWithNoEnd {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic, Clone, Copy)]
+#[derive(Diagnostic, Clone, Copy)]
 #[diag(ast_lowering::trait_fn_async, code = "E0706")]
 #[note]
 #[note(ast_lowering::note2)]
diff --git a/compiler/rustc_attr/src/session_diagnostics.rs b/compiler/rustc_attr/src/session_diagnostics.rs
index 940a48ed915d..d3e9a16a9a80 100644
--- a/compiler/rustc_attr/src/session_diagnostics.rs
+++ b/compiler/rustc_attr/src/session_diagnostics.rs
@@ -2,8 +2,7 @@
 
 use rustc_ast as ast;
 use rustc_errors::{
-    error_code, fluent, Applicability, DiagnosticBuilder, IntoDiagnostic, ErrorGuaranteed,
-    Handler,
+    error_code, fluent, Applicability, DiagnosticBuilder, ErrorGuaranteed, Handler, IntoDiagnostic,
 };
 use rustc_macros::Diagnostic;
 use rustc_span::{Span, Symbol};
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index c66889189add..a52e95e92d55 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -178,7 +178,7 @@ fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(Subdiagnostic)]` -- see [rustc_macros::Subdiagnostic].
 #[cfg_attr(bootstrap, rustc_diagnostic_item = "AddSubdiagnostic")]
-#[cfg_attr(not(bootstrap), rustc_diagnostic_item = "Subdiagnostic")]
+#[cfg_attr(not(bootstrap), rustc_diagnostic_item = "AddToDiagnostic")]
 pub trait AddToDiagnostic {
     /// Add a subdiagnostic to an existing diagnostic.
     fn add_to_diagnostic(self, diag: &mut Diagnostic);
diff --git a/compiler/rustc_errors/src/diagnostic_builder.rs b/compiler/rustc_errors/src/diagnostic_builder.rs
index f9b46053486b..b4ba65ca96d3 100644
--- a/compiler/rustc_errors/src/diagnostic_builder.rs
+++ b/compiler/rustc_errors/src/diagnostic_builder.rs
@@ -16,7 +16,7 @@
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(Diagnostic)]` -- see [rustc_macros::Diagnostic].
 #[cfg_attr(bootstrap, rustc_diagnostic_item = "SessionDiagnostic")]
-#[cfg_attr(not(bootstrap), rustc_diagnostic_item = "Diagnostic")]
+#[cfg_attr(not(bootstrap), rustc_diagnostic_item = "IntoDiagnostic")]
 pub trait IntoDiagnostic<'a, T: EmissionGuarantee = ErrorGuaranteed> {
     /// Write out as a diagnostic out of `Handler`.
     #[must_use]
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 19cae2c90775..68971cebc352 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -437,11 +437,11 @@ struct HandlerInner {
     /// have been converted.
     check_unstable_expect_diagnostics: bool,
 
-    /// Expected [`Diagnostic`]s store a [`LintExpectationId`] as part of
+    /// Expected [`Diagnostic`][diagnostic::Diagnostic]s store a [`LintExpectationId`] as part of
     /// the lint level. [`LintExpectationId`]s created early during the compilation
     /// (before `HirId`s have been defined) are not stable and can therefore not be
     /// stored on disk. This buffer stores these diagnostics until the ID has been
-    /// replaced by a stable [`LintExpectationId`]. The [`Diagnostic`]s are the
+    /// replaced by a stable [`LintExpectationId`]. The [`Diagnostic`][diagnostic::Diagnostic]s are the
     /// submitted for storage and added to the list of fulfilled expectations.
     unstable_expect_diagnostics: Vec<Diagnostic>,
 
@@ -647,8 +647,6 @@ pub fn emit_stashed_diagnostics(&self) -> Option<ErrorGuaranteed> {
 
     /// Construct a builder with the `msg` at the level appropriate for the specific `EmissionGuarantee`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_diagnostic<G: EmissionGuarantee>(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -662,8 +660,6 @@ pub fn struct_diagnostic<G: EmissionGuarantee>(
     /// * `can_emit_warnings` is `true`
     /// * `is_force_warn` was set in `DiagnosticId::Lint`
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_warn(
         &self,
         span: impl Into<MultiSpan>,
@@ -680,8 +676,6 @@ pub fn struct_span_warn(
     /// Attempting to `.emit()` the builder will only emit if either:
     /// * `can_emit_warnings` is `true`
     /// * `is_force_warn` was set in `DiagnosticId::Lint`
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_warn_with_expectation(
         &self,
         span: impl Into<MultiSpan>,
@@ -695,8 +689,6 @@ pub fn struct_span_warn_with_expectation(
 
     /// Construct a builder at the `Allow` level at the given `span` and with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_allow(
         &self,
         span: impl Into<MultiSpan>,
@@ -710,8 +702,6 @@ pub fn struct_span_allow(
     /// Construct a builder at the `Warning` level at the given `span` and with the `msg`.
     /// Also include a code.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_warn_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -729,8 +719,6 @@ pub fn struct_span_warn_with_code(
     /// * `can_emit_warnings` is `true`
     /// * `is_force_warn` was set in `DiagnosticId::Lint`
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_warn(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Warning(None), msg)
     }
@@ -741,8 +729,6 @@ pub fn struct_warn(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilde
     /// Attempting to `.emit()` the builder will only emit if either:
     /// * `can_emit_warnings` is `true`
     /// * `is_force_warn` was set in `DiagnosticId::Lint`
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_warn_with_expectation(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -753,16 +739,12 @@ pub fn struct_warn_with_expectation(
 
     /// Construct a builder at the `Allow` level with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_allow(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Allow, msg)
     }
 
     /// Construct a builder at the `Expect` level with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_expect(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -773,8 +755,6 @@ pub fn struct_expect(
 
     /// Construct a builder at the `Error` level at the given `span` and with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_err(
         &self,
         span: impl Into<MultiSpan>,
@@ -787,8 +767,6 @@ pub fn struct_span_err(
 
     /// Construct a builder at the `Error` level at the given `span`, with the `msg`, and `code`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_err_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -803,8 +781,6 @@ pub fn struct_span_err_with_code(
     /// Construct a builder at the `Error` level with the `msg`.
     // FIXME: This method should be removed (every error should have an associated error code).
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_err(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -814,16 +790,12 @@ pub fn struct_err(
 
     /// This should only be used by `rustc_middle::lint::struct_lint_level`. Do not use it for hard errors.
     #[doc(hidden)]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_err_lint(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Error { lint: true }, msg)
     }
 
     /// Construct a builder at the `Error` level with the `msg` and the `code`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_err_with_code(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -836,8 +808,6 @@ pub fn struct_err_with_code(
 
     /// Construct a builder at the `Warn` level with the `msg` and the `code`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_warn_with_code(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -850,8 +820,6 @@ pub fn struct_warn_with_code(
 
     /// Construct a builder at the `Fatal` level at the given `span` and with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_fatal(
         &self,
         span: impl Into<MultiSpan>,
@@ -864,8 +832,6 @@ pub fn struct_span_fatal(
 
     /// Construct a builder at the `Fatal` level at the given `span`, with the `msg`, and `code`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_span_fatal_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -879,24 +845,18 @@ pub fn struct_span_fatal_with_code(
 
     /// Construct a builder at the `Error` level with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
         DiagnosticBuilder::new_fatal(self, msg)
     }
 
     /// Construct a builder at the `Help` level with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_help(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Help, msg)
     }
 
     /// Construct a builder at the `Note` level with the `msg`.
     #[rustc_lint_diagnostics]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    #[allow(rustc::untranslatable_diagnostic)]
     pub fn struct_note_without_error(
         &self,
         msg: impl Into<DiagnosticMessage>,
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index ca429b6adc10..cd8a525e062c 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -11,7 +11,7 @@
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::sync::{self, Lrc};
 use rustc_errors::{
-    Applicability, DiagnosticBuilder, IntoDiagnostic, ErrorGuaranteed, MultiSpan, PResult,
+    Applicability, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, MultiSpan, PResult,
 };
 use rustc_lint_defs::builtin::PROC_MACRO_BACK_COMPAT;
 use rustc_lint_defs::{BufferedEarlyLint, BuiltinLintDiagnostics};
diff --git a/compiler/rustc_infer/src/errors/mod.rs b/compiler/rustc_infer/src/errors/mod.rs
index d232a1864624..85b877652c6a 100644
--- a/compiler/rustc_infer/src/errors/mod.rs
+++ b/compiler/rustc_infer/src/errors/mod.rs
@@ -1,10 +1,10 @@
 use hir::GenericParamKind;
 use rustc_errors::{
-    fluent, AddSubdiagnostic, Applicability, DiagnosticMessage, DiagnosticStyledString, MultiSpan,
+    fluent, AddToDiagnostic, Applicability, DiagnosticMessage, DiagnosticStyledString, MultiSpan,
 };
 use rustc_hir as hir;
 use rustc_hir::{FnRetTy, Ty};
-use rustc_macros::SessionDiagnostic;
+use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_middle::ty::{Region, TyCtxt};
 use rustc_span::symbol::kw;
 use rustc_span::{symbol::Ident, BytePos, Span};
@@ -16,7 +16,7 @@
 
 pub mod note_and_explain;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::opaque_hidden_type)]
 pub struct OpaqueHiddenTypeDiag {
     #[primary_span]
@@ -28,7 +28,7 @@ pub struct OpaqueHiddenTypeDiag {
     pub hidden_type: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::type_annotations_needed, code = "E0282")]
 pub struct AnnotationRequired<'a> {
     #[primary_span]
@@ -46,7 +46,7 @@ pub struct AnnotationRequired<'a> {
 }
 
 // Copy of `AnnotationRequired` for E0283
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::type_annotations_needed, code = "E0283")]
 pub struct AmbigousImpl<'a> {
     #[primary_span]
@@ -64,7 +64,7 @@ pub struct AmbigousImpl<'a> {
 }
 
 // Copy of `AnnotationRequired` for E0284
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::type_annotations_needed, code = "E0284")]
 pub struct AmbigousReturn<'a> {
     #[primary_span]
@@ -81,7 +81,7 @@ pub struct AmbigousReturn<'a> {
     pub multi_suggestions: Vec<SourceKindMultiSuggestion<'a>>,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::need_type_info_in_generator, code = "E0698")]
 pub struct NeedTypeInfoInGenerator<'a> {
     #[primary_span]
@@ -92,7 +92,7 @@ pub struct NeedTypeInfoInGenerator<'a> {
 }
 
 // Used when a better one isn't available
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 #[label(infer::label_bad)]
 pub struct InferenceBadError<'a> {
     #[primary_span]
@@ -106,7 +106,7 @@ pub struct InferenceBadError<'a> {
     pub name: String,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub enum SourceKindSubdiag<'a> {
     #[suggestion_verbose(
         infer::source_kind_subdiag_let,
@@ -147,7 +147,7 @@ pub enum SourceKindSubdiag<'a> {
     },
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub enum SourceKindMultiSuggestion<'a> {
     #[multipart_suggestion_verbose(
         infer::source_kind_fully_qualified,
@@ -228,7 +228,7 @@ pub enum RegionOriginNote<'a> {
     },
 }
 
-impl AddSubdiagnostic for RegionOriginNote<'_> {
+impl AddToDiagnostic for RegionOriginNote<'_> {
     fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
         let mut label_or_note = |span, msg: DiagnosticMessage| {
             let sub_count = diag.children.iter().filter(|d| d.span.is_dummy()).count();
@@ -289,7 +289,7 @@ pub enum LifetimeMismatchLabels {
     },
 }
 
-impl AddSubdiagnostic for LifetimeMismatchLabels {
+impl AddToDiagnostic for LifetimeMismatchLabels {
     fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
         match self {
             LifetimeMismatchLabels::InRet { param_span, ret_span, span, label_var1 } => {
@@ -339,7 +339,7 @@ pub struct AddLifetimeParamsSuggestion<'a> {
     pub add_note: bool,
 }
 
-impl AddSubdiagnostic for AddLifetimeParamsSuggestion<'_> {
+impl AddToDiagnostic for AddLifetimeParamsSuggestion<'_> {
     fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
         let mut mk_suggestion = || {
             let (
@@ -422,7 +422,7 @@ fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
     }
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::lifetime_mismatch, code = "E0623")]
 pub struct LifetimeMismatch<'a> {
     #[primary_span]
@@ -438,7 +438,7 @@ pub struct IntroducesStaticBecauseUnmetLifetimeReq {
     pub binding_span: Span,
 }
 
-impl AddSubdiagnostic for IntroducesStaticBecauseUnmetLifetimeReq {
+impl AddToDiagnostic for IntroducesStaticBecauseUnmetLifetimeReq {
     fn add_to_diagnostic(mut self, diag: &mut rustc_errors::Diagnostic) {
         self.unmet_requirements
             .push_span_label(self.binding_span, fluent::infer::msl_introduces_static);
@@ -450,7 +450,7 @@ pub struct ImplNote {
     pub impl_span: Option<Span>,
 }
 
-impl AddSubdiagnostic for ImplNote {
+impl AddToDiagnostic for ImplNote {
     fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
         match self.impl_span {
             Some(span) => diag.span_note(span, fluent::infer::msl_impl_note),
@@ -465,7 +465,7 @@ pub enum TraitSubdiag {
 }
 
 // FIXME(#100717) used in `Vec<TraitSubdiag>` so requires eager translation/list support
-impl AddSubdiagnostic for TraitSubdiag {
+impl AddToDiagnostic for TraitSubdiag {
     fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
         match self {
             TraitSubdiag::Note { span } => {
@@ -483,7 +483,7 @@ fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
     }
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(infer::mismatched_static_lifetime)]
 pub struct MismatchedStaticLifetime<'a> {
     #[primary_span]
diff --git a/compiler/rustc_infer/src/errors/note_and_explain.rs b/compiler/rustc_infer/src/errors/note_and_explain.rs
index 7e051835b4bd..7f54918f7361 100644
--- a/compiler/rustc_infer/src/errors/note_and_explain.rs
+++ b/compiler/rustc_infer/src/errors/note_and_explain.rs
@@ -1,5 +1,5 @@
 use crate::infer::error_reporting::nice_region_error::find_anon_type;
-use rustc_errors::{self, fluent, AddSubdiagnostic, IntoDiagnosticArg};
+use rustc_errors::{self, fluent, AddToDiagnostic, IntoDiagnosticArg};
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_span::{symbol::kw, Span};
 
@@ -158,7 +158,7 @@ pub fn new<'tcx>(
     }
 }
 
-impl AddSubdiagnostic for RegionExplanation<'_> {
+impl AddToDiagnostic for RegionExplanation<'_> {
     fn add_to_diagnostic(self, diag: &mut rustc_errors::Diagnostic) {
         if let Some(span) = self.desc.span {
             diag.span_note(span, fluent::infer::region_explanation);
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
index 3a4320a9a8f1..da0271a345e4 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
@@ -11,7 +11,7 @@
 use crate::infer::SubregionOrigin;
 use crate::infer::TyCtxt;
 
-use rustc_errors::AddSubdiagnostic;
+use rustc_errors::AddToDiagnostic;
 use rustc_errors::{Diagnostic, ErrorGuaranteed};
 use rustc_hir::Ty;
 use rustc_middle::ty::Region;
diff --git a/compiler/rustc_lint/src/errors.rs b/compiler/rustc_lint/src/errors.rs
index 3a89d90c88a6..880f3fbd00e6 100644
--- a/compiler/rustc_lint/src/errors.rs
+++ b/compiler/rustc_lint/src/errors.rs
@@ -1,4 +1,4 @@
-use rustc_errors::{fluent, AddToDiagnostic, IntoDiagnostic, ErrorGuaranteed, Handler};
+use rustc_errors::{fluent, AddToDiagnostic, ErrorGuaranteed, Handler, IntoDiagnostic};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_session::lint::Level;
 use rustc_span::{Span, Symbol};
diff --git a/compiler/rustc_lint/src/internal.rs b/compiler/rustc_lint/src/internal.rs
index 942475d31fe3..d8a03024d132 100644
--- a/compiler/rustc_lint/src/internal.rs
+++ b/compiler/rustc_lint/src/internal.rs
@@ -404,7 +404,7 @@ fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
                 let Impl { of_trait: Some(of_trait), .. } = impl_ &&
                 let Some(def_id) = of_trait.trait_def_id() &&
                 let Some(name) = cx.tcx.get_diagnostic_name(def_id) &&
-                matches!(name, sym::Diagnostic | sym::Subdiagnostic | sym::DecorateLint)
+                matches!(name, sym::IntoDiagnostic | sym::AddToDiagnostic | sym::DecorateLint)
             {
                 found_impl = true;
                 break;
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic.rs b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
index c1aae04fceeb..3b8d9594eb91 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
@@ -9,13 +9,13 @@
 use synstructure::Structure;
 
 /// The central struct for constructing the `into_diagnostic` method from an annotated struct.
-pub(crate) struct SessionDiagnosticDerive<'a> {
+pub(crate) struct DiagnosticDerive<'a> {
     structure: Structure<'a>,
     handler: syn::Ident,
     builder: DiagnosticDeriveBuilder,
 }
 
-impl<'a> SessionDiagnosticDerive<'a> {
+impl<'a> DiagnosticDerive<'a> {
     pub(crate) fn new(diag: syn::Ident, handler: syn::Ident, structure: Structure<'a>) -> Self {
         Self {
             builder: DiagnosticDeriveBuilder {
@@ -31,7 +31,7 @@ pub(crate) fn new(diag: syn::Ident, handler: syn::Ident, structure: Structure<'a
     }
 
     pub(crate) fn into_tokens(self) -> TokenStream {
-        let SessionDiagnosticDerive { mut structure, handler, mut builder } = self;
+        let DiagnosticDerive { mut structure, handler, mut builder } = self;
 
         let ast = structure.ast();
         let implementation = {
diff --git a/compiler/rustc_macros/src/diagnostics/mod.rs b/compiler/rustc_macros/src/diagnostics/mod.rs
index 8eaa8b87c0f3..4166816b5e3c 100644
--- a/compiler/rustc_macros/src/diagnostics/mod.rs
+++ b/compiler/rustc_macros/src/diagnostics/mod.rs
@@ -5,7 +5,7 @@
 mod subdiagnostic;
 mod utils;
 
-use diagnostic::{LintDiagnosticDerive, SessionDiagnosticDerive};
+use diagnostic::{DiagnosticDerive, LintDiagnosticDerive};
 pub(crate) use fluent::fluent_messages;
 use proc_macro2::TokenStream;
 use quote::format_ident;
@@ -59,7 +59,7 @@
 /// See rustc dev guide for more examples on using the `#[derive(Diagnostic)]`:
 /// <https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-structs.html>
 pub fn session_diagnostic_derive(s: Structure<'_>) -> TokenStream {
-    SessionDiagnosticDerive::new(format_ident!("diag"), format_ident!("handler"), s).into_tokens()
+    DiagnosticDerive::new(format_ident!("diag"), format_ident!("handler"), s).into_tokens()
 }
 
 /// Implements `#[derive(LintDiagnostic)]`, which allows for lints to be specified as a struct,
@@ -103,7 +103,7 @@ pub fn session_diagnostic_derive(s: Structure<'_>) -> TokenStream {
 /// ```
 ///
 /// See rustc dev guide for more examples on using the `#[derive(LintDiagnostic)]`:
-/// <https://rustc-dev-guide.rust-lang.org/diagnostics/sessiondiagnostic.html>
+/// <https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-structs.html#reference>
 pub fn lint_diagnostic_derive(s: Structure<'_>) -> TokenStream {
     LintDiagnosticDerive::new(format_ident!("diag"), s).into_tokens()
 }
diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
index 8ff4eb5fdbc6..1cd550644bf4 100644
--- a/compiler/rustc_metadata/src/errors.rs
+++ b/compiler/rustc_metadata/src/errors.rs
@@ -3,7 +3,7 @@
     path::{Path, PathBuf},
 };
 
-use rustc_errors::{error_code, IntoDiagnostic, ErrorGuaranteed};
+use rustc_errors::{error_code, ErrorGuaranteed, IntoDiagnostic};
 use rustc_macros::Diagnostic;
 use rustc_session::config;
 use rustc_span::{sym, Span, Symbol};
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 10c5933574ff..2b5b4017a5a1 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -53,6 +53,7 @@
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_session::config::{CrateType, OutputFilenames};
 use rustc_session::cstore::CrateStoreDyn;
+use rustc_session::errors::TargetDataLayoutErrorsWrapper;
 use rustc_session::lint::Lint;
 use rustc_session::Limit;
 use rustc_session::Session;
@@ -1245,7 +1246,7 @@ pub fn create_global_ctxt(
         output_filenames: OutputFilenames,
     ) -> GlobalCtxt<'tcx> {
         let data_layout = TargetDataLayout::parse(&s.target).unwrap_or_else(|err| {
-            s.emit_fatal(err);
+            s.emit_fatal(TargetDataLayoutErrorsWrapper(err));
         });
         let interners = CtxtInterners::new(arena);
         let common_types = CommonTypes::new(
diff --git a/compiler/rustc_monomorphize/src/errors.rs b/compiler/rustc_monomorphize/src/errors.rs
index cdc2c74ac8ff..cf6e18c013be 100644
--- a/compiler/rustc_monomorphize/src/errors.rs
+++ b/compiler/rustc_monomorphize/src/errors.rs
@@ -1,7 +1,7 @@
 use std::path::PathBuf;
 
-use rustc_errors::IntoDiagnostic;
 use rustc_errors::ErrorGuaranteed;
+use rustc_errors::IntoDiagnostic;
 use rustc_macros::{Diagnostic, LintDiagnostic};
 use rustc_span::Span;
 
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 78bc29fc3758..dcea11eadcbf 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -434,7 +434,7 @@ pub(crate) struct NotAsNegationOperator {
     pub sub: NotAsNegationOperatorSub,
 }
 
-#[derive(SessionSubdiagnostic)]
+#[derive(Subdiagnostic)]
 pub enum NotAsNegationOperatorSub {
     #[suggestion_short(
         parser::unexpected_token_after_not_default,
@@ -737,7 +737,7 @@ pub(crate) struct RemoveLet {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(parser::use_eq_instead)]
 pub(crate) struct UseEqInstead {
     #[primary_span]
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 52aea9bba432..be67c9e3b82d 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -650,7 +650,7 @@ pub struct RustcLintOptDenyFieldAccess {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(passes::collapse_debuginfo)]
 pub struct CollapseDebuginfo {
     #[primary_span]
diff --git a/compiler/rustc_query_system/src/error.rs b/compiler/rustc_query_system/src/error.rs
index ceec75fce28f..8602a4cf5aef 100644
--- a/compiler/rustc_query_system/src/error.rs
+++ b/compiler/rustc_query_system/src/error.rs
@@ -1,7 +1,7 @@
 use rustc_errors::AddToDiagnostic;
+use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_session::Limit;
 use rustc_span::{Span, Symbol};
-use rustc_macros::{Diagnostic, Subdiagnostic};
 
 pub struct CycleStack {
     pub span: Span,
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index 6d26c8f47f3c..64aba4703ca3 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -4,7 +4,7 @@
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{
-    Diagnostic, DiagnosticBuilder, IntoDiagnostic, ErrorGuaranteed, Handler, Level,
+    Diagnostic, DiagnosticBuilder, ErrorGuaranteed, Handler, IntoDiagnostic, Level,
 };
 use rustc_hir::def::DefKind;
 use rustc_session::Session;
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 8bb3878fbbb4..57c9a3f4822d 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -3,6 +3,7 @@
 
 pub use crate::options::*;
 
+use crate::errors::TargetDataLayoutErrorsWrapper;
 use crate::search_paths::SearchPath;
 use crate::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
 use crate::{early_error, early_warn, Session};
@@ -898,7 +899,7 @@ fn default_configuration(sess: &Session) -> CrateConfig {
     let max_atomic_width = sess.target.max_atomic_width();
     let atomic_cas = sess.target.atomic_cas;
     let layout = TargetDataLayout::parse(&sess.target).unwrap_or_else(|err| {
-        sess.emit_fatal(err);
+        sess.emit_fatal(TargetDataLayoutErrorsWrapper(err));
     });
 
     let mut ret = CrateConfig::default();
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 997a45272bca..e01dafe2102b 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -1,9 +1,10 @@
 use std::num::NonZeroU32;
 
 use crate::cgu_reuse_tracker::CguReuse;
-use crate::{self as rustc_session, SessionDiagnostic};
-use rustc_errors::{fluent, DiagnosticBuilder, ErrorGuaranteed, Handler, MultiSpan};
-use rustc_macros::SessionDiagnostic;
+use rustc_errors::{
+    fluent, DiagnosticBuilder, ErrorGuaranteed, Handler, IntoDiagnostic, MultiSpan,
+};
+use rustc_macros::Diagnostic;
 use rustc_span::{Span, Symbol};
 use rustc_target::abi::TargetDataLayoutErrors;
 use rustc_target::spec::{SplitDebuginfo, StackProtector, TargetTriple};
@@ -46,10 +47,12 @@ pub struct FeatureDiagnosticHelp {
     pub feature: Symbol,
 }
 
-impl IntoDiagnostic<'_, !> for TargetDataLayoutErrors<'_> {
+pub struct TargetDataLayoutErrorsWrapper<'a>(pub TargetDataLayoutErrors<'a>);
+
+impl IntoDiagnostic<'_, !> for TargetDataLayoutErrorsWrapper<'_> {
     fn into_diagnostic(self, handler: &Handler) -> DiagnosticBuilder<'_, !> {
         let mut diag;
-        match self {
+        match self.0 {
             TargetDataLayoutErrors::InvalidAddressSpace { addr_space, err, cause } => {
                 diag = handler.struct_fatal(fluent::session::target_invalid_address_space);
                 diag.set_arg("addr_space", addr_space);
@@ -97,87 +100,87 @@ fn into_diagnostic(self, handler: &Handler) -> DiagnosticBuilder<'_, !> {
     }
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::not_circumvent_feature)]
 pub struct NotCircumventFeature;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::linker_plugin_lto_windows_not_supported)]
 pub struct LinkerPluginToWindowsNotSupported;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::profile_use_file_does_not_exist)]
 pub struct ProfileUseFileDoesNotExist<'a> {
     pub path: &'a std::path::Path,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::profile_sample_use_file_does_not_exist)]
 pub struct ProfileSampleUseFileDoesNotExist<'a> {
     pub path: &'a std::path::Path,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::target_requires_unwind_tables)]
 pub struct TargetRequiresUnwindTables;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::sanitizer_not_supported)]
 pub struct SanitizerNotSupported {
     pub us: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::sanitizers_not_supported)]
 pub struct SanitizersNotSupported {
     pub us: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::cannot_mix_and_match_sanitizers)]
 pub struct CannotMixAndMatchSanitizers {
     pub first: String,
     pub second: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::cannot_enable_crt_static_linux)]
 pub struct CannotEnableCrtStaticLinux;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::sanitizer_cfi_enabled)]
 pub struct SanitizerCfiEnabled;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::unstable_virtual_function_elimination)]
 pub struct UnstableVirtualFunctionElimination;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::unsupported_dwarf_version)]
 pub struct UnsupportedDwarfVersion {
     pub dwarf_version: u32,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::target_stack_protector_not_supported)]
 pub struct StackProtectorNotSupportedForTarget<'a> {
     pub stack_protector: StackProtector,
     pub target_triple: &'a TargetTriple,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::split_debuginfo_unstable_platform)]
 pub struct SplitDebugInfoUnstablePlatform {
     pub debuginfo: SplitDebuginfo,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::file_is_not_writeable)]
 pub struct FileIsNotWriteable<'a> {
     pub file: &'a std::path::Path,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::crate_name_does_not_match)]
 pub struct CrateNameDoesNotMatch<'a> {
     #[primary_span]
@@ -186,13 +189,13 @@ pub struct CrateNameDoesNotMatch<'a> {
     pub name: Symbol,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::crate_name_invalid)]
 pub struct CrateNameInvalid<'a> {
     pub s: &'a str,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(session::crate_name_empty)]
 pub struct CrateNameEmpty {
     #[primary_span]
@@ -205,11 +208,8 @@ pub struct InvalidCharacterInCrateName<'a> {
     pub crate_name: &'a str,
 }
 
-impl crate::SessionDiagnostic<'_> for InvalidCharacterInCrateName<'_> {
-    fn into_diagnostic(
-        self,
-        sess: &Handler,
-    ) -> rustc_errors::DiagnosticBuilder<'_, ErrorGuaranteed> {
+impl IntoDiagnostic<'_> for InvalidCharacterInCrateName<'_> {
+    fn into_diagnostic(self, sess: &Handler) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
         let mut diag = sess.struct_err(fluent::session::invalid_character_in_create_name);
         if let Some(sp) = self.span {
             diag.set_span(sp);
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 3189dcb08ade..b9202af2a676 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -11,8 +11,8 @@
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
 use rustc_errors::{
-    fallback_fluent_bundle, Applicability, Diagnostic, DiagnosticBuilder, IntoDiagnostic,
-    DiagnosticId, DiagnosticMessage, EmissionGuarantee, ErrorGuaranteed, MultiSpan, StashKey,
+    fallback_fluent_bundle, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticId,
+    DiagnosticMessage, EmissionGuarantee, ErrorGuaranteed, IntoDiagnostic, MultiSpan, StashKey,
 };
 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
 use rustc_span::edition::Edition;
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index e660b7399284..0142e9817663 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -27,8 +27,8 @@
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::registry::Registry;
 use rustc_errors::{
-    error_code, fallback_fluent_bundle, DiagnosticBuilder, IntoDiagnostic, DiagnosticId,
-    DiagnosticMessage, ErrorGuaranteed, FluentBundle, LazyFallbackBundle, MultiSpan,
+    error_code, fallback_fluent_bundle, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
+    ErrorGuaranteed, FluentBundle, IntoDiagnostic, LazyFallbackBundle, MultiSpan,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 1baad6a9fd7a..7785d29c15f2 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -125,6 +125,7 @@
     Symbols {
         AcqRel,
         Acquire,
+        AddToDiagnostic,
         Alignment,
         Any,
         Arc,
@@ -176,7 +177,6 @@
         DecorateLint,
         Default,
         Deref,
-        Diagnostic,
         DiagnosticMessage,
         DirBuilder,
         Display,
@@ -210,6 +210,7 @@
         Implied,
         Input,
         Into,
+        IntoDiagnostic,
         IntoFuture,
         IntoIterator,
         IoRead,
@@ -282,7 +283,6 @@
         String,
         StructuralEq,
         StructuralPartialEq,
-        Subdiagnostic,
         SubdiagnosticMessage,
         Sync,
         T,
diff --git a/compiler/rustc_trait_selection/src/errors.rs b/compiler/rustc_trait_selection/src/errors.rs
index b02ee593cbef..5e1b80eae393 100644
--- a/compiler/rustc_trait_selection/src/errors.rs
+++ b/compiler/rustc_trait_selection/src/errors.rs
@@ -1,4 +1,4 @@
-use rustc_errors::{fluent, IntoDiagnostic, ErrorGuaranteed, Handler};
+use rustc_errors::{fluent, ErrorGuaranteed, Handler, IntoDiagnostic};
 use rustc_macros::Diagnostic;
 use rustc_middle::ty::{PolyTraitRef, Ty, Unevaluated};
 use rustc_session::Limit;
diff --git a/src/test/ui-fulldeps/internal-lints/diagnostics.rs b/src/test/ui-fulldeps/internal-lints/diagnostics.rs
index 4c2c28dc3368..18e39108ecab 100644
--- a/src/test/ui-fulldeps/internal-lints/diagnostics.rs
+++ b/src/test/ui-fulldeps/internal-lints/diagnostics.rs
@@ -20,7 +20,7 @@
 
 #[derive(Diagnostic)]
 #[diag(parser::expect_path)]
-struct DeriveSessionDiagnostic {
+struct DeriveDiagnostic {
     #[primary_span]
     span: Span,
 }
@@ -32,18 +32,18 @@ struct Note {
     span: Span,
 }
 
-pub struct UntranslatableInSessionDiagnostic;
+pub struct UntranslatableInIntoDiagnostic;
 
-impl<'a> IntoDiagnostic<'a, ErrorGuaranteed> for UntranslatableInSessionDiagnostic {
+impl<'a> IntoDiagnostic<'a, ErrorGuaranteed> for UntranslatableInIntoDiagnostic {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         handler.struct_err("untranslatable diagnostic")
         //~^ ERROR diagnostics should be created using translatable messages
     }
 }
 
-pub struct TranslatableInSessionDiagnostic;
+pub struct TranslatableInIntoDiagnostic;
 
-impl<'a> IntoDiagnostic<'a, ErrorGuaranteed> for TranslatableInSessionDiagnostic {
+impl<'a> IntoDiagnostic<'a, ErrorGuaranteed> for TranslatableInIntoDiagnostic {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         handler.struct_err(fluent::parser::expect_path)
     }
diff --git a/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr b/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
index b07b35f27235..c3972beb5128 100644
--- a/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
+++ b/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
@@ -449,7 +449,7 @@ error[E0277]: the trait bound `Hello: IntoDiagnosticArg` is not satisfied
   --> $DIR/diagnostic-derive.rs:331:10
    |
 LL | #[derive(Diagnostic)]
-   |          ^^^^^^^^^^^^^^^^^ the trait `IntoDiagnosticArg` is not implemented for `Hello`
+   |          ^^^^^^^^^^ the trait `IntoDiagnosticArg` is not implemented for `Hello`
    |
    = help: normalized in stderr
 note: required by a bound in `DiagnosticBuilder::<'a, G>::set_arg`