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Remove DiagnosticBuilder::forget_guarantee.

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It's unused. And this means `DiagnosticBuilderInner` no longer needs to
be separate from `DiagnosticBuilder`.
This commit is contained in:
Nicholas Nethercote 2023-12-22 10:55:54 +11:00
parent 00e8485057
commit 2cd14bc939
1 changed files with 24 additions and 52 deletions
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72
compiler/rustc_errors/src/diagnostic_builder.rs
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@ -44,23 +44,6 @@ fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'
#[must_use]
#[derive(Clone)]
pub struct DiagnosticBuilder<'a, G: EmissionGuarantee = ErrorGuaranteed> {
inner: DiagnosticBuilderInner<'a>,
_marker: PhantomData<G>,
}
/// This type exists only for `DiagnosticBuilder::forget_guarantee`, because it:
/// 1. lacks the `G` parameter and therefore `DiagnosticBuilder<G1>` can be
/// converted into `DiagnosticBuilder<G2>` while reusing the `inner` field
/// 2. can implement the `Drop` "bomb" instead of `DiagnosticBuilder`, as it
/// contains all of the data (`state` + `diagnostic`) of `DiagnosticBuilder`
///
/// The `diagnostic` field is not `Copy` and can't be moved out of whichever
/// type implements the `Drop` "bomb", but because of the above two facts, that
/// never needs to happen - instead, the whole `inner: DiagnosticBuilderInner`
/// can be moved out of a `DiagnosticBuilder` and into another.
#[must_use]
#[derive(Clone)]
struct DiagnosticBuilderInner<'a> {
state: DiagnosticBuilderState<'a>,
/// `Diagnostic` is a large type, and `DiagnosticBuilder` is often used as a
@ -68,6 +51,8 @@ struct DiagnosticBuilderInner<'a> {
/// In theory, return value optimization (RVO) should avoid unnecessary
/// copying. In practice, it does not (at the time of writing).
diagnostic: Box<Diagnostic>,
_marker: PhantomData<G>,
}
#[derive(Clone)]
@ -83,7 +68,7 @@ enum DiagnosticBuilderState<'a> {
/// assumed that `.emit()` was previously called, to end up in this state.
///
/// While this is also used by `.cancel()`, this state is only observed by
/// the `Drop` `impl` of `DiagnosticBuilderInner`, as `.cancel()` takes
/// the `Drop` `impl` of `DiagnosticBuilder`, because `.cancel()` takes
/// `self` by-value specifically to prevent any attempts to `.emit()`.
///
// FIXME(eddyb) currently this doesn't prevent extending the `Diagnostic`,
@ -115,12 +100,11 @@ pub trait EmissionGuarantee: Sized {
impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
/// Most `emit_producing_guarantee` functions use this as a starting point.
fn emit_producing_nothing(&mut self) {
match self.inner.state {
match self.state {
// First `.emit()` call, the `&DiagCtxt` is still available.
DiagnosticBuilderState::Emittable(dcx) => {
self.inner.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
dcx.emit_diagnostic_without_consuming(&mut self.inner.diagnostic);
self.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
dcx.emit_diagnostic_without_consuming(&mut self.diagnostic);
}
// `.emit()` was previously called, disallowed from repeating it.
DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation => {}
@ -128,34 +112,24 @@ fn emit_producing_nothing(&mut self) {
}
}
impl<'a> DiagnosticBuilder<'a> {
/// Discard the guarantee `.emit()` would return, in favor of having the
/// type `DiagnosticBuilder<'a, ()>`. This may be necessary whenever there
/// is a common codepath handling both errors and warnings.
pub fn forget_guarantee(self) -> DiagnosticBuilder<'a, ()> {
DiagnosticBuilder { inner: self.inner, _marker: PhantomData }
}
}
// FIXME(eddyb) make `ErrorGuaranteed` impossible to create outside `.emit()`.
impl EmissionGuarantee for ErrorGuaranteed {
fn emit_producing_guarantee(db: &mut DiagnosticBuilder<'_, Self>) -> Self::EmitResult {
// Contrast this with `emit_producing_nothing`.
match db.inner.state {
match db.state {
// First `.emit()` call, the `&DiagCtxt` is still available.
DiagnosticBuilderState::Emittable(dcx) => {
db.inner.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
let guar = dcx.emit_diagnostic_without_consuming(&mut db.inner.diagnostic);
db.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
let guar = dcx.emit_diagnostic_without_consuming(&mut db.diagnostic);
// Only allow a guarantee if the `level` wasn't switched to a
// non-error - the field isn't `pub`, but the whole `Diagnostic`
// can be overwritten with a new one, thanks to `DerefMut`.
assert!(
db.inner.diagnostic.is_error(),
db.diagnostic.is_error(),
"emitted non-error ({:?}) diagnostic \
from `DiagnosticBuilder<ErrorGuaranteed>`",
db.inner.diagnostic.level,
db.diagnostic.level,
);
guar.unwrap()
}
@ -167,10 +141,10 @@ fn emit_producing_guarantee(db: &mut DiagnosticBuilder<'_, Self>) -> Self::EmitR
// non-error - the field isn't `pub`, but the whole `Diagnostic`
// can be overwritten with a new one, thanks to `DerefMut`.
assert!(
db.inner.diagnostic.is_error(),
db.diagnostic.is_error(),
"`DiagnosticBuilder<ErrorGuaranteed>`'s diagnostic \
became non-error ({:?}), after original `.emit()`",
db.inner.diagnostic.level,
db.diagnostic.level,
);
#[allow(deprecated)]
ErrorGuaranteed::unchecked_claim_error_was_emitted()
@ -238,7 +212,7 @@ pub fn $n:ident(&mut self, $($name:ident: $ty:ty),* $(,)?) -> &mut Self
$(#[$attrs])*
#[doc = concat!("See [`Diagnostic::", stringify!($n), "()`].")]
pub fn $n(&mut self, $($name: $ty),*) -> &mut Self {
self.inner.diagnostic.$n($($name),*);
self.diagnostic.$n($($name),*);
self
}
};
@ -248,13 +222,13 @@ impl<G: EmissionGuarantee> Deref for DiagnosticBuilder<'_, G> {
type Target = Diagnostic;
fn deref(&self) -> &Diagnostic {
&self.inner.diagnostic
&self.diagnostic
}
}
impl<G: EmissionGuarantee> DerefMut for DiagnosticBuilder<'_, G> {
fn deref_mut(&mut self) -> &mut Diagnostic {
&mut self.inner.diagnostic
&mut self.diagnostic
}
}
@ -271,10 +245,8 @@ pub fn new<M: Into<DiagnosticMessage>>(dcx: &'a DiagCtxt, level: Level, message:
pub(crate) fn new_diagnostic(dcx: &'a DiagCtxt, diagnostic: Diagnostic) -> Self {
debug!("Created new diagnostic");
Self {
inner: DiagnosticBuilderInner {
state: DiagnosticBuilderState::Emittable(dcx),
diagnostic: Box::new(diagnostic),
},
_marker: PhantomData,
}
}
@ -306,7 +278,7 @@ pub fn emit_unless(&mut self, delay: bool) -> G::EmitResult {
/// which may be expected to *guarantee* the emission of an error, either
/// at the time of the call, or through a prior `.emit()` call.
pub fn cancel(mut self) {
self.inner.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
self.state = DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation;
drop(self);
}
@ -324,7 +296,7 @@ pub fn stash(self, span: Span, key: StashKey) {
/// Converts the builder to a `Diagnostic` for later emission,
/// unless dcx has disabled such buffering, or `.emit()` was called.
pub fn into_diagnostic(mut self) -> Option<(Diagnostic, &'a DiagCtxt)> {
let dcx = match self.inner.state {
let dcx = match self.state {
// No `.emit()` calls, the `&DiagCtxt` is still available.
DiagnosticBuilderState::Emittable(dcx) => dcx,
// `.emit()` was previously called, nothing we can do.
@ -342,7 +314,7 @@ pub fn into_diagnostic(mut self) -> Option<(Diagnostic, &'a DiagCtxt)> {
// Take the `Diagnostic` by replacing it with a dummy.
let dummy = Diagnostic::new(Level::Allow, DiagnosticMessage::from(""));
let diagnostic = std::mem::replace(&mut *self.inner.diagnostic, dummy);
let diagnostic = std::mem::replace(&mut *self.diagnostic, dummy);
// Disable the ICE on `Drop`.
self.cancel();
@ -356,7 +328,7 @@ pub fn into_diagnostic(mut self) -> Option<(Diagnostic, &'a DiagCtxt)> {
/// Retrieves the [`DiagCtxt`] if available
pub fn dcx(&self) -> Option<&DiagCtxt> {
match self.inner.state {
match self.state {
DiagnosticBuilderState::Emittable(dcx) => Some(dcx),
DiagnosticBuilderState::AlreadyEmittedOrDuringCancellation => None,
}
@ -544,13 +516,13 @@ pub fn span_labels(
impl<G: EmissionGuarantee> Debug for DiagnosticBuilder<'_, G> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.inner.diagnostic.fmt(f)
self.diagnostic.fmt(f)
}
}
/// Destructor bomb - a `DiagnosticBuilder` must be either emitted or cancelled
/// or we emit a bug.
impl Drop for DiagnosticBuilderInner<'_> {
impl<G: EmissionGuarantee> Drop for DiagnosticBuilder<'_, G> {
fn drop(&mut self) {
match self.state {
// No `.emit()` or `.cancel()` calls.