diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
index 8ff7030717a..7fd1c0d2743 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
@@ -2,6 +2,7 @@ pub mod ambiguity;
 pub mod call_kind;
 mod fulfillment_errors;
 pub mod on_unimplemented;
+pub mod on_unimplemented_format;
 mod overflow;
 pub mod suggestions;
 
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
index f0c6e51f2a4..9914e828a93 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
@@ -7,18 +7,18 @@ use rustc_errors::codes::*;
 use rustc_errors::{ErrorGuaranteed, struct_span_code_err};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{AttrArgs, Attribute};
-use rustc_macros::LintDiagnostic;
 use rustc_middle::bug;
 use rustc_middle::ty::print::PrintTraitRefExt as _;
 use rustc_middle::ty::{self, GenericArgsRef, GenericParamDefKind, TyCtxt};
 use rustc_parse_format::{ParseMode, Parser, Piece, Position};
 use rustc_session::lint::builtin::UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES;
-use rustc_span::{Ident, Span, Symbol, kw, sym};
+use rustc_span::{Span, Symbol, kw, sym};
 use tracing::{debug, info};
 use {rustc_attr_parsing as attr, rustc_hir as hir};
 
 use super::{ObligationCauseCode, PredicateObligation};
 use crate::error_reporting::TypeErrCtxt;
+use crate::error_reporting::traits::on_unimplemented_format::errors::*;
 use crate::errors::{
     EmptyOnClauseInOnUnimplemented, InvalidOnClauseInOnUnimplemented, NoValueInOnUnimplemented,
 };
@@ -320,81 +320,6 @@ pub enum AppendConstMessage {
     Custom(Symbol, Span),
 }
 
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_malformed_on_unimplemented_attr)]
-#[help]
-pub struct MalformedOnUnimplementedAttrLint {
-    #[label]
-    pub span: Span,
-}
-
-impl MalformedOnUnimplementedAttrLint {
-    fn new(span: Span) -> Self {
-        Self { span }
-    }
-}
-
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_missing_options_for_on_unimplemented_attr)]
-#[help]
-pub struct MissingOptionsForOnUnimplementedAttr;
-
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_ignored_diagnostic_option)]
-pub struct IgnoredDiagnosticOption {
-    pub option_name: &'static str,
-    #[label]
-    pub span: Span,
-    #[label(trait_selection_other_label)]
-    pub prev_span: Span,
-}
-
-impl IgnoredDiagnosticOption {
-    fn maybe_emit_warning<'tcx>(
-        tcx: TyCtxt<'tcx>,
-        item_def_id: DefId,
-        new: Option<Span>,
-        old: Option<Span>,
-        option_name: &'static str,
-    ) {
-        if let (Some(new_item), Some(old_item)) = (new, old) {
-            if let Some(item_def_id) = item_def_id.as_local() {
-                tcx.emit_node_span_lint(
-                    UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
-                    tcx.local_def_id_to_hir_id(item_def_id),
-                    new_item,
-                    IgnoredDiagnosticOption { span: new_item, prev_span: old_item, option_name },
-                );
-            }
-        }
-    }
-}
-
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_unknown_format_parameter_for_on_unimplemented_attr)]
-#[help]
-pub struct UnknownFormatParameterForOnUnimplementedAttr {
-    argument_name: Symbol,
-    trait_name: Ident,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_disallowed_positional_argument)]
-#[help]
-pub struct DisallowedPositionalArgument;
-
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_invalid_format_specifier)]
-#[help]
-pub struct InvalidFormatSpecifier;
-
-#[derive(LintDiagnostic)]
-#[diag(trait_selection_wrapped_parser_error)]
-pub struct WrappedParserError {
-    description: String,
-    label: String,
-}
-
 impl<'tcx> OnUnimplementedDirective {
     fn parse(
         tcx: TyCtxt<'tcx>,
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs
new file mode 100644
index 00000000000..40a47921fc1
--- /dev/null
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs
@@ -0,0 +1,86 @@
+pub mod errors {
+    use rustc_macros::LintDiagnostic;
+    use rustc_middle::ty::TyCtxt;
+    use rustc_session::lint::builtin::UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES;
+    use rustc_span::Ident;
+
+    use super::*;
+
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_unknown_format_parameter_for_on_unimplemented_attr)]
+    #[help]
+    pub struct UnknownFormatParameterForOnUnimplementedAttr {
+        pub argument_name: Symbol,
+        pub trait_name: Ident,
+    }
+
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_disallowed_positional_argument)]
+    #[help]
+    pub struct DisallowedPositionalArgument;
+
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_invalid_format_specifier)]
+    #[help]
+    pub struct InvalidFormatSpecifier;
+
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_wrapped_parser_error)]
+    pub struct WrappedParserError {
+        pub description: String,
+        pub label: String,
+    }
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_malformed_on_unimplemented_attr)]
+    #[help]
+    pub struct MalformedOnUnimplementedAttrLint {
+        #[label]
+        pub span: Span,
+    }
+
+    impl MalformedOnUnimplementedAttrLint {
+        pub fn new(span: Span) -> Self {
+            Self { span }
+        }
+    }
+
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_missing_options_for_on_unimplemented_attr)]
+    #[help]
+    pub struct MissingOptionsForOnUnimplementedAttr;
+
+    #[derive(LintDiagnostic)]
+    #[diag(trait_selection_ignored_diagnostic_option)]
+    pub struct IgnoredDiagnosticOption {
+        pub option_name: &'static str,
+        #[label]
+        pub span: Span,
+        #[label(trait_selection_other_label)]
+        pub prev_span: Span,
+    }
+
+    impl IgnoredDiagnosticOption {
+        pub fn maybe_emit_warning<'tcx>(
+            tcx: TyCtxt<'tcx>,
+            item_def_id: DefId,
+            new: Option<Span>,
+            old: Option<Span>,
+            option_name: &'static str,
+        ) {
+            if let (Some(new_item), Some(old_item)) = (new, old) {
+                if let Some(item_def_id) = item_def_id.as_local() {
+                    tcx.emit_node_span_lint(
+                        UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
+                        tcx.local_def_id_to_hir_id(item_def_id),
+                        new_item,
+                        IgnoredDiagnosticOption {
+                            span: new_item,
+                            prev_span: old_item,
+                            option_name,
+                        },
+                    );
+                }
+            }
+        }
+    }
+}