XXX: emit_diagnostic_without_consuming

compiler/rustc_errors/src/lib.rs

@@ -1387,6 +1387,7 @@ impl DiagCtxtInner {
         &mut self,
         diagnostic: &mut Diagnostic,
     ) -> Option<ErrorGuaranteed> {
+        // njn: Level::Error { .. } | Level::Fatal
         if matches!(diagnostic.level, Level::Error { .. } | Level::Fatal) && self.treat_err_as_bug()
         {
             diagnostic.level = Level::Bug;
@@ -1396,11 +1397,13 @@ impl DiagCtxtInner {
         // Diagnostics created before the definition of `HirId`s are unstable and can not yet
         // be stored. Instead, they are buffered until the `LintExpectationId` is replaced by
         // a stable one by the `LintLevelsBuilder`.
+        // njn: Level::Expect(id) | Level::Warning(Some(id)) => Some(*id),
         if let Some(LintExpectationId::Unstable { .. }) = diagnostic.level.get_expectation_id() {
             self.unstable_expect_diagnostics.push(diagnostic.clone());
             return None;
         }
 
+        // njn: Level::DelayedBug
         if diagnostic.level == Level::DelayedBug {
             // FIXME(eddyb) this should check for `has_errors` and stop pushing
             // once *any* errors were emitted (and truncate `span_delayed_bugs`
@@ -1416,6 +1419,7 @@ impl DiagCtxtInner {
             }
         }
 
+        // njn: self.code... Error only?
         if diagnostic.has_future_breakage() {
             // Future breakages aren't emitted if they're Level::Allowed,
             // but they still need to be constructed and stashed below,