Rollup merge of #129281 - Nadrieril:tweak-unreachable-lint-wording, r=estebank

Tweak unreachable lint wording

Some tweaks to the notes added in #128034.

r? `@estebank`

Author: matthiaskrgr

compiler/rustc_mir_build/messages.ftl

@@ -327,14 +327,17 @@ mir_build_union_pattern = cannot use unions in constant patterns
 
 mir_build_unreachable_making_this_unreachable = collectively making this unreachable
 
+mir_build_unreachable_making_this_unreachable_n_more = ...and {$covered_by_many_n_more_count} other patterns collectively make this unreachable
+
 mir_build_unreachable_matches_same_values = matches some of the same values
 
 mir_build_unreachable_pattern = unreachable pattern
-    .label = unreachable pattern
-    .unreachable_matches_no_values = this pattern matches no values because `{$ty}` is uninhabited
+    .label = no value can reach this
+    .unreachable_matches_no_values = matches no values because `{$matches_no_values_ty}` is uninhabited
+    .unreachable_uninhabited_note = to learn more about uninhabited types, see https://doc.rust-lang.org/nomicon/exotic-sizes.html#empty-types
     .unreachable_covered_by_catchall = matches any value
-    .unreachable_covered_by_one = matches all the values already
-    .unreachable_covered_by_many = these patterns collectively make the last one unreachable
+    .unreachable_covered_by_one = matches all the relevant values
+    .unreachable_covered_by_many = multiple earlier patterns match some of the same values
 
 mir_build_unsafe_fn_safe_body = an unsafe function restricts its caller, but its body is safe by default
 mir_build_unsafe_not_inherited = items do not inherit unsafety from separate enclosing items

compiler/rustc_mir_build/src/errors.rs

@@ -586,20 +586,18 @@ pub(crate) struct NonConstPath {
 pub(crate) struct UnreachablePattern<'tcx> {
     #[label]
     pub(crate) span: Option<Span>,
-    #[subdiagnostic]
-    pub(crate) matches_no_values: Option<UnreachableMatchesNoValues<'tcx>>,
+    #[label(mir_build_unreachable_matches_no_values)]
+    pub(crate) matches_no_values: Option<Span>,
+    pub(crate) matches_no_values_ty: Ty<'tcx>,
+    #[note(mir_build_unreachable_uninhabited_note)]
+    pub(crate) uninhabited_note: Option<()>,
     #[label(mir_build_unreachable_covered_by_catchall)]
     pub(crate) covered_by_catchall: Option<Span>,
     #[label(mir_build_unreachable_covered_by_one)]
     pub(crate) covered_by_one: Option<Span>,
     #[note(mir_build_unreachable_covered_by_many)]
     pub(crate) covered_by_many: Option<MultiSpan>,
-}
-
-#[derive(Subdiagnostic)]
-#[note(mir_build_unreachable_matches_no_values)]
-pub(crate) struct UnreachableMatchesNoValues<'tcx> {
-    pub(crate) ty: Ty<'tcx>,
+    pub(crate) covered_by_many_n_more_count: usize,
 }
 
 #[derive(Diagnostic)]