Delete unused InvalidDeprecationVersion diagnostic

Author: dtolnay

compiler/rustc_passes/messages.ftl

@@ -396,11 +396,6 @@ passes_invalid_attr_at_crate_level =
 passes_invalid_attr_at_crate_level_item =
     the inner attribute doesn't annotate this {$kind}
 
-passes_invalid_deprecation_version =
-    invalid deprecation version found
-    .label = invalid deprecation version
-    .item = the stability attribute annotates this item
-
 passes_invalid_macro_export_arguments = `{$name}` isn't a valid `#[macro_export]` argument
 
 passes_invalid_macro_export_arguments_too_many_items = `#[macro_export]` can only take 1 or 0 arguments

compiler/rustc_passes/src/errors.rs

@@ -1524,16 +1524,6 @@ pub struct CannotStabilizeDeprecated {
     pub item_sp: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(passes_invalid_deprecation_version)]
-pub struct InvalidDeprecationVersion {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-    #[label(passes_item)]
-    pub item_sp: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(passes_missing_stability_attr)]
 pub struct MissingStabilityAttr<'a> {