Rollup merge of #124218 - Xiretza:subsubdiagnostics, r=davidtwco

Allow nesting subdiagnostics in #[derive(Subdiagnostic)]

compiler/rustc_lint/src/context/diagnostics.rs

@@ -2,7 +2,7 @@
 #![allow(rustc::untranslatable_diagnostic)]
 
 use rustc_ast::util::unicode::TEXT_FLOW_CONTROL_CHARS;
-use rustc_errors::{add_elided_lifetime_in_path_suggestion, Diag};
+use rustc_errors::{elided_lifetime_in_path_suggestion, Diag};
 use rustc_errors::{Applicability, SuggestionStyle};
 use rustc_middle::middle::stability;
 use rustc_session::lint::BuiltinLintDiag;
@@ -74,13 +74,15 @@ pub(super) fn builtin(sess: &Session, diagnostic: BuiltinLintDiag, diag: &mut Di
             diag.span_note(span_def, "the macro is defined here");
         }
         BuiltinLintDiag::ElidedLifetimesInPaths(n, path_span, incl_angl_brckt, insertion_span) => {
-            add_elided_lifetime_in_path_suggestion(
-                sess.source_map(),
-                diag,
-                n,
-                path_span,
-                incl_angl_brckt,
-                insertion_span,
+            diag.subdiagnostic(
+                sess.dcx(),
+                elided_lifetime_in_path_suggestion(
+                    sess.source_map(),
+                    n,
+                    path_span,
+                    incl_angl_brckt,
+                    insertion_span,
+                ),
             );
         }
         BuiltinLintDiag::UnknownCrateTypes(span, note, sugg) => {

compiler/rustc_lint/src/errors.rs

@@ -27,7 +27,7 @@ impl Subdiagnostic for OverruledAttributeSub {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         match self {
             OverruledAttributeSub::DefaultSource { id } => {

compiler/rustc_lint/src/lints.rs

@@ -274,7 +274,7 @@ impl<'a, 'b> Subdiagnostic for SuggestChangingAssocTypes<'a, 'b> {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
         // bound. Let's see if this type does that.
@@ -330,7 +330,7 @@ impl Subdiagnostic for BuiltinTypeAliasGenericBoundsSuggestion {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         diag.multipart_suggestion(
             fluent::lint_suggestion,
@@ -451,7 +451,7 @@ impl Subdiagnostic for BuiltinUnpermittedTypeInitSub {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         let mut err = self.err;
         loop {
@@ -506,7 +506,7 @@ impl Subdiagnostic for BuiltinClashingExternSub<'_> {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         let mut expected_str = DiagStyledString::new();
         expected_str.push(self.expected.fn_sig(self.tcx).to_string(), false);
@@ -788,7 +788,7 @@ impl Subdiagnostic for HiddenUnicodeCodepointsDiagLabels {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         for (c, span) in self.spans {
             diag.span_label(span, format!("{c:?}"));
@@ -806,7 +806,7 @@ impl Subdiagnostic for HiddenUnicodeCodepointsDiagSub {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         match self {
             HiddenUnicodeCodepointsDiagSub::Escape { spans } => {
@@ -954,7 +954,7 @@ impl Subdiagnostic for NonBindingLetSub {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         let can_suggest_binding = self.drop_fn_start_end.is_some() || !self.is_assign_desugar;
 
@@ -1240,7 +1240,7 @@ impl Subdiagnostic for NonSnakeCaseDiagSub {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         match self {
             NonSnakeCaseDiagSub::Label { span } => {
@@ -1482,7 +1482,7 @@ impl Subdiagnostic for OverflowingBinHexSign {
     fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
         self,
         diag: &mut Diag<'_, G>,
-        _f: F,
+        _f: &F,
     ) {
         match self {
             OverflowingBinHexSign::Positive => {