Fix delayed_good_path_bug ice for expected diagnostics (RFC 2383)

compiler/rustc_errors/src/lib.rs

@@ -401,6 +401,9 @@ struct HandlerInner {
  emitter: Box<dyn Emitter + sync::Send>,
  delayed_span_bugs: Vec<Diagnostic>,
  delayed_good_path_bugs: Vec<DelayedDiagnostic>,
+ /// This flag indicates that an expected diagnostic was emitted and suppressed.
+ /// This is used for the `delayed_good_path_bugs` check.
+ suppressed_expected_diag: bool,
 
  /// This set contains the `DiagnosticId` of all emitted diagnostics to avoid
  /// emitting the same diagnostic with extended help (`--teach`) twice, which
@@ -496,7 +499,7 @@ impl Drop for HandlerInner {
  // instead of "require some error happened". Sadly that isn't ideal, as
  // lints can be `#[allow]`'d, potentially leading to this triggering.
  // Also, "good path" should be replaced with a better naming.
- if !self.has_any_message() {
+ if !self.has_any_message() && !self.suppressed_expected_diag {
  let bugs = std::mem::replace(&mut self.delayed_good_path_bugs, Vec::new());
  self.flush_delayed(
  bugs.into_iter().map(DelayedDiagnostic::decorate),
@@ -578,6 +581,7 @@ impl Handler {
  emitter,
  delayed_span_bugs: Vec::new(),
  delayed_good_path_bugs: Vec::new(),
+ suppressed_expected_diag: false,
  taught_diagnostics: Default::default(),
  emitted_diagnostic_codes: Default::default(),
  emitted_diagnostics: Default::default(),
@@ -1001,20 +1005,20 @@ impl Handler {
  let mut inner = self.inner.borrow_mut();
  let diags = std::mem::take(&mut inner.unstable_expect_diagnostics);
  inner.check_unstable_expect_diagnostics = true;
- if diags.is_empty() {
- return;
- }
 
- for mut diag in diags.into_iter() {
- diag.update_unstable_expectation_id(unstable_to_stable);
+ if !diags.is_empty() {
+ inner.suppressed_expected_diag = true;
+ for mut diag in diags.into_iter() {
+ diag.update_unstable_expectation_id(unstable_to_stable);
 
- let stable_id = diag
- .level
- .get_expectation_id()
- .expect("all diagnostics inside `unstable_expect_diagnostics` must have a `LintExpectationId`");
- inner.fulfilled_expectations.insert(stable_id);
+  let stable_id = diag
+  .level
+  .get_expectation_id()
+  .expect("all diagnostics inside `unstable_expect_diagnostics` must have a `LintExpectationId`");
+  inner.fulfilled_expectations.insert(stable_id);
 
- (*TRACK_DIAGNOSTICS)(&diag);
+ (*TRACK_DIAGNOSTICS)(&diag);
+ }
  }
 
  inner
@@ -1101,6 +1105,7 @@ impl HandlerInner {
  (*TRACK_DIAGNOSTICS)(diagnostic);
 
  if let Level::Expect(expectation_id) = diagnostic.level {
+ self.suppressed_expected_diag = true;
  self.fulfilled_expectations.insert(expectation_id);
  return None;
  } else if diagnostic.level == Allow {

src/test/ui/lint/rfc-2383-lint-reason/avoid_delayed_good_path_ice.rs

@@ -0,0 +1,8 @@
+// check-pass
+#![feature(lint_reasons)]
+
+#[expect(drop_bounds)]
+fn trigger_rustc_lints<T: Drop>() {
+}
+
+fn main() {}