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Don't call Span::with_parent on the good path in has_stashed_diagnostic #139468

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Merged
merged 1 commit into from
Apr 9, 2025
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Don't call Span::with_parent on the good path in has_stashed_diagnostic #139468

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70 changes: 44 additions & 26 deletions compiler/rustc_errors/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -589,7 +589,8 @@ struct DiagCtxtInner {
/// add more information). All stashed diagnostics must be emitted with
/// `emit_stashed_diagnostics` by the time the `DiagCtxtInner` is dropped,
/// otherwise an assertion failure will occur.
stashed_diagnostics: FxIndexMap<(Span, StashKey), (DiagInner, Option<ErrorGuaranteed>)>,
stashed_diagnostics:
FxIndexMap<StashKey, FxIndexMap<Span, (DiagInner, Option<ErrorGuaranteed>)>>,

future_breakage_diagnostics: Vec<DiagInner>,

Expand Down Expand Up @@ -912,8 +913,12 @@ impl<'a> DiagCtxtHandle<'a> {
// FIXME(Centril, #69537): Consider reintroducing panic on overwriting a stashed diagnostic
// if/when we have a more robust macro-friendly replacement for `(span, key)` as a key.
// See the PR for a discussion.
let key = (span.with_parent(None), key);
self.inner.borrow_mut().stashed_diagnostics.insert(key, (diag, guar));
self.inner
.borrow_mut()
.stashed_diagnostics
.entry(key)
.or_default()
.insert(span.with_parent(None), (diag, guar));

guar
}
Expand All @@ -922,9 +927,10 @@ impl<'a> DiagCtxtHandle<'a> {
/// and [`StashKey`] as the key. Panics if the found diagnostic is an
/// error.
pub fn steal_non_err(self, span: Span, key: StashKey) -> Option<Diag<'a, ()>> {
let key = (span.with_parent(None), key);
// FIXME(#120456) - is `swap_remove` correct?
let (diag, guar) = self.inner.borrow_mut().stashed_diagnostics.swap_remove(&key)?;
let (diag, guar) = self.inner.borrow_mut().stashed_diagnostics.get_mut(&key).and_then(
|stashed_diagnostics| stashed_diagnostics.swap_remove(&span.with_parent(None)),
)?;
assert!(!diag.is_error());
assert!(guar.is_none());
Some(Diag::new_diagnostic(self, diag))
Expand All @@ -943,9 +949,10 @@ impl<'a> DiagCtxtHandle<'a> {
where
F: FnMut(&mut Diag<'_>),
{
let key = (span.with_parent(None), key);
// FIXME(#120456) - is `swap_remove` correct?
let err = self.inner.borrow_mut().stashed_diagnostics.swap_remove(&key);
let err = self.inner.borrow_mut().stashed_diagnostics.get_mut(&key).and_then(
|stashed_diagnostics| stashed_diagnostics.swap_remove(&span.with_parent(None)),
);
err.map(|(err, guar)| {
// The use of `::<ErrorGuaranteed>` is safe because level is `Level::Error`.
assert_eq!(err.level, Error);
Expand All @@ -966,9 +973,10 @@ impl<'a> DiagCtxtHandle<'a> {
key: StashKey,
new_err: Diag<'_>,
) -> ErrorGuaranteed {
let key = (span.with_parent(None), key);
// FIXME(#120456) - is `swap_remove` correct?
let old_err = self.inner.borrow_mut().stashed_diagnostics.swap_remove(&key);
let old_err = self.inner.borrow_mut().stashed_diagnostics.get_mut(&key).and_then(
|stashed_diagnostics| stashed_diagnostics.swap_remove(&span.with_parent(None)),
);
match old_err {
Some((old_err, guar)) => {
assert_eq!(old_err.level, Error);
Expand All @@ -983,7 +991,14 @@ impl<'a> DiagCtxtHandle<'a> {
}

pub fn has_stashed_diagnostic(&self, span: Span, key: StashKey) -> bool {
self.inner.borrow().stashed_diagnostics.get(&(span.with_parent(None), key)).is_some()
let inner = self.inner.borrow();
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You may wonder... is it sufficient here to just call self.inner.borrow().stashed_diagnostics.is_empty() as a fast path, b/c we obviously should never have stashed diagnostics on the good path?

Well no! We stash AssociatedTypeSuggestion in a bunch of places on the good path! What the heck, lol. I'll open a separate PR to gauge the perf impact of that.

if let Some(stashed_diagnostics) = inner.stashed_diagnostics.get(&key)
&& !stashed_diagnostics.is_empty()
{
stashed_diagnostics.contains_key(&span.with_parent(None))
} else {
false
}
}

/// Emit all stashed diagnostics.
Expand All @@ -997,7 +1012,11 @@ impl<'a> DiagCtxtHandle<'a> {
let inner = self.inner.borrow();
inner.err_guars.len()
+ inner.lint_err_guars.len()
+ inner.stashed_diagnostics.values().filter(|(_diag, guar)| guar.is_some()).count()
+ inner
.stashed_diagnostics
.values()
.map(|a| a.values().filter(|(_, guar)| guar.is_some()).count())
.sum::<usize>()
}

/// This excludes lint errors and delayed bugs. Unless absolutely
Expand Down Expand Up @@ -1486,16 +1505,18 @@ impl DiagCtxtInner {
fn emit_stashed_diagnostics(&mut self) -> Option<ErrorGuaranteed> {
let mut guar = None;
let has_errors = !self.err_guars.is_empty();
for (_, (diag, _guar)) in std::mem::take(&mut self.stashed_diagnostics).into_iter() {
if !diag.is_error() {
// Unless they're forced, don't flush stashed warnings when
// there are errors, to avoid causing warning overload. The
// stash would've been stolen already if it were important.
if !diag.is_force_warn() && has_errors {
continue;
for (_, stashed_diagnostics) in std::mem::take(&mut self.stashed_diagnostics).into_iter() {
for (_, (diag, _guar)) in stashed_diagnostics {
if !diag.is_error() {
// Unless they're forced, don't flush stashed warnings when
// there are errors, to avoid causing warning overload. The
// stash would've been stolen already if it were important.
if !diag.is_force_warn() && has_errors {
continue;
}
}
guar = guar.or(self.emit_diagnostic(diag, None));
}
guar = guar.or(self.emit_diagnostic(diag, None));
}
guar
}
Expand Down Expand Up @@ -1688,6 +1709,7 @@ impl DiagCtxtInner {
if let Some((_diag, guar)) = self
.stashed_diagnostics
.values()
.flat_map(|stashed_diagnostics| stashed_diagnostics.values())
.find(|(diag, guar)| guar.is_some() && diag.is_lint.is_none())
{
*guar
Expand All @@ -1700,13 +1722,9 @@ impl DiagCtxtInner {
fn has_errors(&self) -> Option<ErrorGuaranteed> {
self.err_guars.get(0).copied().or_else(|| self.lint_err_guars.get(0).copied()).or_else(
|| {
if let Some((_diag, guar)) =
self.stashed_diagnostics.values().find(|(_diag, guar)| guar.is_some())
{
*guar
} else {
None
}
self.stashed_diagnostics.values().find_map(|stashed_diagnostics| {
stashed_diagnostics.values().find_map(|(_, guar)| *guar)
})
},
)
}
Expand Down
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