diff --git a/compiler/rustc_attr/src/session_diagnostics.rs b/compiler/rustc_attr/src/session_diagnostics.rs
index ed8400391c28d..a4f51871f67af 100644
--- a/compiler/rustc_attr/src/session_diagnostics.rs
+++ b/compiler/rustc_attr/src/session_diagnostics.rs
@@ -1,7 +1,7 @@
 use std::num::IntErrorKind;
 
 use rustc_ast as ast;
-use rustc_errors::SessionDiagnostic;
+use rustc_errors::DiagnosticHandler;
 use rustc_errors::{
     error_code, fluent, Applicability, DiagnosticBuilder, ErrorGuaranteed, Handler,
 };
@@ -50,7 +50,7 @@ pub(crate) struct UnknownMetaItem<'a> {
 }
 
 // Manual implementation to be able to format `expected` items correctly.
-impl<'a> SessionDiagnostic<'a> for UnknownMetaItem<'_> {
+impl<'a> DiagnosticHandler<'a> for UnknownMetaItem<'_> {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         let expected = self.expected.iter().map(|name| format!("`{}`", name)).collect::<Vec<_>>();
         let mut diag = handler.struct_span_err_with_code(
@@ -209,7 +209,7 @@ pub(crate) struct UnsupportedLiteral {
     pub start_point_span: Span,
 }
 
-impl<'a> SessionDiagnostic<'a> for UnsupportedLiteral {
+impl<'a> DiagnosticHandler<'a> for UnsupportedLiteral {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         let mut diag = handler.struct_span_err_with_code(
             self.span,
diff --git a/compiler/rustc_error_messages/locales/en-US/lint.ftl b/compiler/rustc_error_messages/locales/en-US/lint.ftl
index 7f9918e4f128f..726c9619a4f5e 100644
--- a/compiler/rustc_error_messages/locales/en-US/lint.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/lint.ftl
@@ -51,7 +51,7 @@ lint_non_existant_doc_keyword = found non-existing keyword `{$keyword}` used in
     .help = only existing keywords are allowed in core/std
 
 lint_diag_out_of_impl =
-    diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
+    diagnostics should only be created in `DiagnosticHandler`/`AddSubdiagnostic` impls
 
 lint_untranslatable_diag = diagnostics should be created using translatable messages
 
diff --git a/compiler/rustc_errors/src/diagnostic_builder.rs b/compiler/rustc_errors/src/diagnostic_builder.rs
index 71e21373d0da1..1eaca60c0898c 100644
--- a/compiler/rustc_errors/src/diagnostic_builder.rs
+++ b/compiler/rustc_errors/src/diagnostic_builder.rs
@@ -16,7 +16,7 @@ use std::thread::panicking;
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(SessionDiagnostic)]` -- see [rustc_macros::SessionDiagnostic].
 #[rustc_diagnostic_item = "SessionDiagnostic"]
-pub trait SessionDiagnostic<'a, T: EmissionGuarantee = ErrorGuaranteed> {
+pub trait DiagnosticHandler<'a, T: EmissionGuarantee = ErrorGuaranteed> {
     /// Write out as a diagnostic out of `Handler`.
     #[must_use]
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, T>;
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index b2a3cb0823d18..e99a0e96f305a 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -61,7 +61,7 @@ mod snippet;
 mod styled_buffer;
 pub mod translation;
 
-pub use diagnostic_builder::SessionDiagnostic;
+pub use diagnostic_builder::DiagnosticHandler;
 pub use snippet::Style;
 
 pub type PResult<'a, T> = Result<T, DiagnosticBuilder<'a, ErrorGuaranteed>>;
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index a9c690a4fb9c5..5141122cb864a 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -11,7 +11,7 @@ use rustc_attr::{self as attr, Deprecation, Stability};
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::sync::{self, Lrc};
 use rustc_errors::{
-    Applicability, DiagnosticBuilder, ErrorGuaranteed, MultiSpan, PResult, SessionDiagnostic,
+    Applicability, DiagnosticBuilder, DiagnosticHandler, ErrorGuaranteed, MultiSpan, PResult,
 };
 use rustc_lint_defs::builtin::PROC_MACRO_BACK_COMPAT;
 use rustc_lint_defs::{BufferedEarlyLint, BuiltinLintDiagnostics};
@@ -1104,12 +1104,12 @@ impl<'a> ExtCtxt<'a> {
 
     pub fn create_err(
         &self,
-        err: impl SessionDiagnostic<'a>,
+        err: impl DiagnosticHandler<'a>,
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         self.sess.create_err(err)
     }
 
-    pub fn emit_err(&self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
+    pub fn emit_err(&self, err: impl DiagnosticHandler<'a>) -> ErrorGuaranteed {
         self.sess.emit_err(err)
     }
 
diff --git a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
index 0b814305ff2ed..1b70a9760c44f 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
@@ -4,7 +4,7 @@ use crate::errors::{
 };
 use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::infer::InferCtxt;
-use rustc_errors::SessionDiagnostic;
+use rustc_errors::DiagnosticHandler;
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, IntoDiagnosticArg};
 use rustc_hir as hir;
 use rustc_hir::def::Res;
diff --git a/compiler/rustc_lint/src/errors.rs b/compiler/rustc_lint/src/errors.rs
index ac98948189ba1..9e88defbc2701 100644
--- a/compiler/rustc_lint/src/errors.rs
+++ b/compiler/rustc_lint/src/errors.rs
@@ -1,4 +1,4 @@
-use rustc_errors::{fluent, AddSubdiagnostic, ErrorGuaranteed, Handler, SessionDiagnostic};
+use rustc_errors::{fluent, AddSubdiagnostic, DiagnosticHandler, ErrorGuaranteed, Handler};
 use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
 use rustc_session::lint::Level;
 use rustc_span::{Span, Symbol};
@@ -119,7 +119,7 @@ pub struct CheckNameUnknown {
     pub sub: RequestedLevel,
 }
 
-impl SessionDiagnostic<'_> for CheckNameUnknown {
+impl DiagnosticHandler<'_> for CheckNameUnknown {
     fn into_diagnostic(
         self,
         handler: &Handler,
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic.rs b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
index 891b6a118ded5..dc31d942ba28c 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
@@ -81,15 +81,15 @@ impl<'a> SessionDiagnosticDerive<'a> {
         };
 
         structure.gen_impl(quote! {
-            gen impl<'__session_diagnostic_sess, G>
-                    rustc_errors::SessionDiagnostic<'__session_diagnostic_sess, G>
+            gen impl<'__diagnostic_handler_sess, G>
+                    rustc_errors::DiagnosticHandler<'__diagnostic_handler_sess, G>
                     for @Self
                 where G: rustc_errors::EmissionGuarantee
             {
                 fn into_diagnostic(
                     self,
-                    #sess: &'__session_diagnostic_sess rustc_errors::Handler
-                ) -> rustc_errors::DiagnosticBuilder<'__session_diagnostic_sess, G> {
+                    #sess: &'__diagnostic_handler_sess rustc_errors::Handler
+                ) -> rustc_errors::DiagnosticBuilder<'__diagnostic_handler_sess, G> {
                     use rustc_errors::IntoDiagnosticArg;
                     #implementation
                 }
diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
index 40357ec0701ad..4b853cd643a90 100644
--- a/compiler/rustc_metadata/src/errors.rs
+++ b/compiler/rustc_metadata/src/errors.rs
@@ -3,7 +3,7 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use rustc_errors::{error_code, ErrorGuaranteed, SessionDiagnostic};
+use rustc_errors::{error_code, DiagnosticHandler, ErrorGuaranteed};
 use rustc_macros::SessionDiagnostic;
 use rustc_session::config;
 use rustc_span::{sym, Span, Symbol};
@@ -421,7 +421,7 @@ pub(crate) struct MultipleCandidates {
     pub candidates: Vec<PathBuf>,
 }
 
-impl SessionDiagnostic<'_> for MultipleCandidates {
+impl DiagnosticHandler<'_> for MultipleCandidates {
     fn into_diagnostic(
         self,
         handler: &'_ rustc_errors::Handler,
@@ -537,7 +537,7 @@ pub struct InvalidMetadataFiles {
     pub crate_rejections: Vec<String>,
 }
 
-impl SessionDiagnostic<'_> for InvalidMetadataFiles {
+impl DiagnosticHandler<'_> for InvalidMetadataFiles {
     fn into_diagnostic(
         self,
         handler: &'_ rustc_errors::Handler,
@@ -565,7 +565,7 @@ pub struct CannotFindCrate {
     pub locator_triple: TargetTriple,
 }
 
-impl SessionDiagnostic<'_> for CannotFindCrate {
+impl DiagnosticHandler<'_> for CannotFindCrate {
     fn into_diagnostic(
         self,
         handler: &'_ rustc_errors::Handler,
diff --git a/compiler/rustc_monomorphize/src/errors.rs b/compiler/rustc_monomorphize/src/errors.rs
index 883380dca08a2..43337287a94e7 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::DiagnosticHandler;
 use rustc_errors::ErrorGuaranteed;
-use rustc_errors::SessionDiagnostic;
 use rustc_macros::{LintDiagnostic, SessionDiagnostic};
 use rustc_span::Span;
 
@@ -44,7 +44,7 @@ pub struct UnusedGenericParams {
     pub param_names: Vec<String>,
 }
 
-impl SessionDiagnostic<'_> for UnusedGenericParams {
+impl DiagnosticHandler<'_> for UnusedGenericParams {
     fn into_diagnostic(
         self,
         handler: &'_ rustc_errors::Handler,
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 7a7fbe3b34665..ee50775a72708 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -35,7 +35,7 @@ use rustc_ast::{AnonConst, BinOp, BinOpKind, FnDecl, FnRetTy, MacCall, Param, Ty
 use rustc_ast::{Arm, Async, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLimits};
 use rustc_ast::{ClosureBinder, StmtKind};
 use rustc_ast_pretty::pprust;
-use rustc_errors::SessionDiagnostic;
+use rustc_errors::DiagnosticHandler;
 use rustc_errors::{Applicability, Diagnostic, PResult};
 use rustc_session::lint::builtin::BREAK_WITH_LABEL_AND_LOOP;
 use rustc_session::lint::BuiltinLintDiagnostics;
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index cfeb8695f2d81..c5d4c41b2be2d 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -4,7 +4,7 @@ use crate::query::{QueryContext, QueryStackFrame};
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{
-    Diagnostic, DiagnosticBuilder, ErrorGuaranteed, Handler, Level, SessionDiagnostic,
+    Diagnostic, DiagnosticBuilder, DiagnosticHandler, ErrorGuaranteed, Handler, Level,
 };
 use rustc_hir::def::DefKind;
 use rustc_session::Session;
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 433c1cdbc5402..03a8e85700434 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -11,8 +11,8 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_errors::{emitter::SilentEmitter, ColorConfig, Handler};
 use rustc_errors::{
-    fallback_fluent_bundle, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticId,
-    DiagnosticMessage, EmissionGuarantee, ErrorGuaranteed, MultiSpan, SessionDiagnostic, StashKey,
+    fallback_fluent_bundle, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticHandler,
+    DiagnosticId, DiagnosticMessage, EmissionGuarantee, ErrorGuaranteed, MultiSpan, StashKey,
 };
 use rustc_feature::{find_feature_issue, GateIssue, UnstableFeatures};
 use rustc_span::edition::Edition;
@@ -340,34 +340,34 @@ impl ParseSess {
 
     pub fn create_err<'a>(
         &'a self,
-        err: impl SessionDiagnostic<'a>,
+        err: impl DiagnosticHandler<'a>,
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         err.into_diagnostic(&self.span_diagnostic)
     }
 
-    pub fn emit_err<'a>(&'a self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
+    pub fn emit_err<'a>(&'a self, err: impl DiagnosticHandler<'a>) -> ErrorGuaranteed {
         self.create_err(err).emit()
     }
 
     pub fn create_warning<'a>(
         &'a self,
-        warning: impl SessionDiagnostic<'a, ()>,
+        warning: impl DiagnosticHandler<'a, ()>,
     ) -> DiagnosticBuilder<'a, ()> {
         warning.into_diagnostic(&self.span_diagnostic)
     }
 
-    pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
+    pub fn emit_warning<'a>(&'a self, warning: impl DiagnosticHandler<'a, ()>) {
         self.create_warning(warning).emit()
     }
 
     pub fn create_fatal<'a>(
         &'a self,
-        fatal: impl SessionDiagnostic<'a, !>,
+        fatal: impl DiagnosticHandler<'a, !>,
     ) -> DiagnosticBuilder<'a, !> {
         fatal.into_diagnostic(&self.span_diagnostic)
     }
 
-    pub fn emit_fatal<'a>(&'a self, fatal: impl SessionDiagnostic<'a, !>) -> ! {
+    pub fn emit_fatal<'a>(&'a self, fatal: impl DiagnosticHandler<'a, !>) -> ! {
         self.create_fatal(fatal).emit()
     }
 
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index c5fc70f6de71e..4334604577161 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -20,8 +20,8 @@ use rustc_errors::emitter::{Emitter, EmitterWriter, HumanReadableErrorType};
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::registry::Registry;
 use rustc_errors::{
-    error_code, fallback_fluent_bundle, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
-    ErrorGuaranteed, FluentBundle, LazyFallbackBundle, MultiSpan, SessionDiagnostic,
+    error_code, fallback_fluent_bundle, DiagnosticBuilder, DiagnosticHandler, DiagnosticId,
+    DiagnosticMessage, ErrorGuaranteed, FluentBundle, LazyFallbackBundle, MultiSpan,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -454,13 +454,13 @@ impl Session {
     }
     pub fn create_err<'a>(
         &'a self,
-        err: impl SessionDiagnostic<'a>,
+        err: impl DiagnosticHandler<'a>,
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         self.parse_sess.create_err(err)
     }
     pub fn create_feature_err<'a>(
         &'a self,
-        err: impl SessionDiagnostic<'a>,
+        err: impl DiagnosticHandler<'a>,
         feature: Symbol,
     ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         let mut err = self.parse_sess.create_err(err);
@@ -470,25 +470,25 @@ impl Session {
         add_feature_diagnostics(&mut err, &self.parse_sess, feature);
         err
     }
-    pub fn emit_err<'a>(&'a self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
+    pub fn emit_err<'a>(&'a self, err: impl DiagnosticHandler<'a>) -> ErrorGuaranteed {
         self.parse_sess.emit_err(err)
     }
     pub fn create_warning<'a>(
         &'a self,
-        err: impl SessionDiagnostic<'a, ()>,
+        err: impl DiagnosticHandler<'a, ()>,
     ) -> DiagnosticBuilder<'a, ()> {
         self.parse_sess.create_warning(err)
     }
-    pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
+    pub fn emit_warning<'a>(&'a self, warning: impl DiagnosticHandler<'a, ()>) {
         self.parse_sess.emit_warning(warning)
     }
     pub fn create_fatal<'a>(
         &'a self,
-        fatal: impl SessionDiagnostic<'a, !>,
+        fatal: impl DiagnosticHandler<'a, !>,
     ) -> DiagnosticBuilder<'a, !> {
         self.parse_sess.create_fatal(fatal)
     }
-    pub fn emit_fatal<'a>(&'a self, fatal: impl SessionDiagnostic<'a, !>) -> ! {
+    pub fn emit_fatal<'a>(&'a self, fatal: impl DiagnosticHandler<'a, !>) -> ! {
         self.parse_sess.emit_fatal(fatal)
     }
     #[inline]
diff --git a/compiler/rustc_trait_selection/src/errors.rs b/compiler/rustc_trait_selection/src/errors.rs
index dc7078d9ada3c..595f539240d02 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, ErrorGuaranteed, Handler, SessionDiagnostic};
+use rustc_errors::{fluent, DiagnosticHandler, ErrorGuaranteed, Handler};
 use rustc_macros::SessionDiagnostic;
 use rustc_middle::ty::{PolyTraitRef, Ty, Unevaluated};
 use rustc_session::Limit;
@@ -66,7 +66,7 @@ pub struct NegativePositiveConflict<'a> {
     pub positive_impl_span: Result<Span, Symbol>,
 }
 
-impl SessionDiagnostic<'_> for NegativePositiveConflict<'_> {
+impl DiagnosticHandler<'_> for NegativePositiveConflict<'_> {
     fn into_diagnostic(
         self,
         handler: &Handler,
diff --git a/compiler/rustc_typeck/src/errors.rs b/compiler/rustc_typeck/src/errors.rs
index ed4c4f688bf18..0704177e7136e 100644
--- a/compiler/rustc_typeck/src/errors.rs
+++ b/compiler/rustc_typeck/src/errors.rs
@@ -1,5 +1,5 @@
 //! Errors emitted by typeck.
-use rustc_errors::SessionDiagnostic;
+use rustc_errors::DiagnosticHandler;
 use rustc_errors::{error_code, Applicability, DiagnosticBuilder, ErrorGuaranteed, Handler};
 use rustc_macros::{LintDiagnostic, SessionDiagnostic, SessionSubdiagnostic};
 use rustc_middle::ty::Ty;
@@ -250,7 +250,7 @@ pub struct MissingTypeParams {
 }
 
 // Manual implementation of `SessionDiagnostic` to be able to call `span_to_snippet`.
-impl<'a> SessionDiagnostic<'a> for MissingTypeParams {
+impl<'a> DiagnosticHandler<'a> for MissingTypeParams {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         let mut err = handler.struct_span_err_with_code(
             self.span,
diff --git a/src/test/ui-fulldeps/internal-lints/diagnostics.rs b/src/test/ui-fulldeps/internal-lints/diagnostics.rs
index 3b31a290449c9..69f69fbc78e72 100644
--- a/src/test/ui-fulldeps/internal-lints/diagnostics.rs
+++ b/src/test/ui-fulldeps/internal-lints/diagnostics.rs
@@ -12,7 +12,8 @@ extern crate rustc_session;
 extern crate rustc_span;
 
 use rustc_errors::{
-    AddSubdiagnostic, SessionDiagnostic, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, Handler, fluent
+    AddSubdiagnostic, DiagnosticHandler, Diagnostic, DiagnosticBuilder,
+    ErrorGuaranteed, Handler, fluent
 };
 use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
 use rustc_span::Span;
@@ -33,7 +34,7 @@ struct Note {
 
 pub struct UntranslatableInSessionDiagnostic;
 
-impl<'a> SessionDiagnostic<'a, ErrorGuaranteed> for UntranslatableInSessionDiagnostic {
+impl<'a> DiagnosticHandler<'a, ErrorGuaranteed> for UntranslatableInSessionDiagnostic {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         handler.struct_err("untranslatable diagnostic")
         //~^ ERROR diagnostics should be created using translatable messages
@@ -42,7 +43,7 @@ impl<'a> SessionDiagnostic<'a, ErrorGuaranteed> for UntranslatableInSessionDiagn
 
 pub struct TranslatableInSessionDiagnostic;
 
-impl<'a> SessionDiagnostic<'a, ErrorGuaranteed> for TranslatableInSessionDiagnostic {
+impl<'a> DiagnosticHandler<'a, ErrorGuaranteed> for TranslatableInSessionDiagnostic {
     fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
         handler.struct_err(fluent::parser::expect_path)
     }
@@ -67,10 +68,10 @@ impl AddSubdiagnostic for TranslatableInAddSubdiagnostic {
 
 pub fn make_diagnostics<'a>(handler: &'a Handler) {
     let _diag = handler.struct_err(fluent::parser::expect_path);
-    //~^ ERROR diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
+    //~^ ERROR diagnostics should only be created in `DiagnosticHandler`/`AddSubdiagnostic` impls
 
     let _diag = handler.struct_err("untranslatable diagnostic");
-    //~^ ERROR diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
+    //~^ ERROR diagnostics should only be created in `DiagnosticHandler`/`AddSubdiagnostic` impls
     //~^^ ERROR diagnostics should be created using translatable messages
 }
 
diff --git a/src/test/ui-fulldeps/internal-lints/diagnostics.stderr b/src/test/ui-fulldeps/internal-lints/diagnostics.stderr
index e5c5bc2e9987e..e9c4907a859fe 100644
--- a/src/test/ui-fulldeps/internal-lints/diagnostics.stderr
+++ b/src/test/ui-fulldeps/internal-lints/diagnostics.stderr
@@ -16,7 +16,7 @@ error: diagnostics should be created using translatable messages
 LL |         diag.note("untranslatable diagnostic");
    |              ^^^^
 
-error: diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
+error: diagnostics should only be created in `DiagnosticHandler`/`AddSubdiagnostic` impls
   --> $DIR/diagnostics.rs:70:25
    |
 LL |     let _diag = handler.struct_err(fluent::parser::expect_path);
@@ -28,7 +28,7 @@ note: the lint level is defined here
 LL | #![deny(rustc::diagnostic_outside_of_impl)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
+error: diagnostics should only be created in `DiagnosticHandler`/`AddSubdiagnostic` impls
   --> $DIR/diagnostics.rs:73:25
    |
 LL |     let _diag = handler.struct_err("untranslatable diagnostic");