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Rollup merge of #119307 - compiler-errors:pat-lifetimes, r=Nadrieril

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Clean up some lifetimes in `rustc_pattern_analysis`

This PR removes some redundant lifetimes. I figured out that we were shortening the lifetime of an arena-allocated `&'p DeconstructedPat<'p>` to `'a DeconstructedPat<'p>`, which forced us to carry both lifetimes when we could otherwise carry just one.

This PR also removes and elides some unnecessary lifetimes.

I also cherry-picked 0292eb9bb9b897f5c0926c6a8530877f67e7cc9b, and then simplified more lifetimes in `MatchVisitor`, which should make #119233 a very simple PR!

r? Nadrieril
This commit is contained in:
Michael Goulet 2023-12-26 13:29:14 -05:00 • committed by GitHub
commit e1be642b41
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10 changed files with 111 additions and 104 deletions
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7
compiler/rustc_pattern_analysis/src/constructor.rs
View file

@ -861,12 +861,9 @@ impl<Cx: TypeCx> ConstructorSet<Cx> {
#[instrument(level = "debug", skip(self, pcx, ctors), ret)]
pub(crate) fn split<'a>(
&self,
pcx: &PlaceCtxt<'_, '_, Cx>,
pcx: &PlaceCtxt<'a, '_, Cx>,
ctors: impl Iterator<Item = &'a Constructor<Cx>> + Clone,
) -> SplitConstructorSet<Cx>
where
Cx: 'a,
{
) -> SplitConstructorSet<Cx> {
let mut present: SmallVec<[_; 1]> = SmallVec::new();
// Empty constructors found missing.
let mut missing_empty = Vec::new();

2
compiler/rustc_pattern_analysis/src/lib.rs
View file

@ -91,7 +91,7 @@ pub struct MatchCtxt<'a, 'p, Cx: TypeCx> {
/// The context for type information.
pub tycx: &'a Cx,
/// An arena to store the wildcards we produce during analysis.
pub wildcard_arena: &'a TypedArena<DeconstructedPat<'p, Cx>>,
pub wildcard_arena: &'p TypedArena<DeconstructedPat<'p, Cx>>,
}
/// The arm of a match expression.

20
compiler/rustc_pattern_analysis/src/lints.rs
View file

@ -28,11 +28,11 @@ use crate::TypeCx;
///
/// This is not used in the main algorithm; only in lints.
#[derive(Debug)]
pub(crate) struct PatternColumn<'a, 'p, 'tcx> {
patterns: Vec<&'a DeconstructedPat<'p, 'tcx>>,
pub(crate) struct PatternColumn<'p, 'tcx> {
patterns: Vec<&'p DeconstructedPat<'p, 'tcx>>,
}
impl<'a, 'p, 'tcx> PatternColumn<'a, 'p, 'tcx> {
impl<'p, 'tcx> PatternColumn<'p, 'tcx> {
pub(crate) fn new(arms: &[MatchArm<'p, 'tcx>]) -> Self {
let mut patterns = Vec::with_capacity(arms.len());
for arm in arms {
@ -48,7 +48,7 @@ impl<'a, 'p, 'tcx> PatternColumn<'a, 'p, 'tcx> {
fn is_empty(&self) -> bool {
self.patterns.is_empty()
}
fn head_ty(&self, cx: MatchCtxt<'a, 'p, 'tcx>) -> Option<Ty<'tcx>> {
fn head_ty(&self, cx: MatchCtxt<'_, 'p, 'tcx>) -> Option<Ty<'tcx>> {
if self.patterns.len() == 0 {
return None;
}
@ -64,7 +64,7 @@ impl<'a, 'p, 'tcx> PatternColumn<'a, 'p, 'tcx> {
pcx.ctors_for_ty().split(pcx, column_ctors)
}
fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, 'tcx>> + Captures<'b> {
fn iter(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Captures<'_> {
self.patterns.iter().copied()
}
@ -75,9 +75,9 @@ impl<'a, 'p, 'tcx> PatternColumn<'a, 'p, 'tcx> {
/// which may change the lengths.
fn specialize(
&self,
pcx: &PlaceCtxt<'a, 'p, 'tcx>,
pcx: &PlaceCtxt<'_, 'p, 'tcx>,
ctor: &Constructor<'p, 'tcx>,
) -> Vec<PatternColumn<'a, 'p, 'tcx>> {
) -> Vec<PatternColumn<'p, 'tcx>> {
let arity = ctor.arity(pcx);
if arity == 0 {
return Vec::new();
@ -115,7 +115,7 @@ impl<'a, 'p, 'tcx> PatternColumn<'a, 'p, 'tcx> {
#[instrument(level = "debug", skip(cx), ret)]
fn collect_nonexhaustive_missing_variants<'a, 'p, 'tcx>(
cx: MatchCtxt<'a, 'p, 'tcx>,
column: &PatternColumn<'a, 'p, 'tcx>,
column: &PatternColumn<'p, 'tcx>,
) -> Vec<WitnessPat<'p, 'tcx>> {
let Some(ty) = column.head_ty(cx) else {
return Vec::new();
@ -163,7 +163,7 @@ fn collect_nonexhaustive_missing_variants<'a, 'p, 'tcx>(
pub(crate) fn lint_nonexhaustive_missing_variants<'a, 'p, 'tcx>(
cx: MatchCtxt<'a, 'p, 'tcx>,
arms: &[MatchArm<'p, 'tcx>],
pat_column: &PatternColumn<'a, 'p, 'tcx>,
pat_column: &PatternColumn<'p, 'tcx>,
scrut_ty: Ty<'tcx>,
) {
let rcx: &RustcMatchCheckCtxt<'_, '_> = cx.tycx;
@ -216,7 +216,7 @@ pub(crate) fn lint_nonexhaustive_missing_variants<'a, 'p, 'tcx>(
#[instrument(level = "debug", skip(cx))]
pub(crate) fn lint_overlapping_range_endpoints<'a, 'p, 'tcx>(
cx: MatchCtxt<'a, 'p, 'tcx>,
column: &PatternColumn<'a, 'p, 'tcx>,
column: &PatternColumn<'p, 'tcx>,
) {
let Some(ty) = column.head_ty(cx) else {
return;

12
compiler/rustc_pattern_analysis/src/pat.rs
View file

@ -71,19 +71,17 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> {
self.data.as_ref()
}
pub fn iter_fields<'a>(
&'a self,
) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'a> {
pub fn iter_fields(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'_> {
self.fields.iter()
}
/// Specialize this pattern with a constructor.
/// `other_ctor` can be different from `self.ctor`, but must be covered by it.
pub(crate) fn specialize<'a>(
pub(crate) fn specialize(
&self,
pcx: &PlaceCtxt<'a, 'p, Cx>,
pcx: &PlaceCtxt<'_, 'p, Cx>,
other_ctor: &Constructor<Cx>,
) -> SmallVec<[&'a DeconstructedPat<'p, Cx>; 2]> {
) -> SmallVec<[&'p DeconstructedPat<'p, Cx>; 2]> {
let wildcard_sub_tys = || {
let tys = pcx.ctor_sub_tys(other_ctor);
tys.iter()
@ -196,7 +194,7 @@ impl<Cx: TypeCx> WitnessPat<Cx> {
self.ty
}
pub fn iter_fields<'a>(&'a self) -> impl Iterator<Item = &'a WitnessPat<Cx>> {
pub fn iter_fields(&self) -> impl Iterator<Item = &WitnessPat<Cx>> {
self.fields.iter()
}
}

10
compiler/rustc_pattern_analysis/src/rustc.rs
View file

@ -128,11 +128,11 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
// In the cases of either a `#[non_exhaustive]` field list or a non-public field, we hide
// uninhabited fields in order not to reveal the uninhabitedness of the whole variant.
// This lists the fields we keep along with their types.
pub(crate) fn list_variant_nonhidden_fields<'a>(
&'a self,
pub(crate) fn list_variant_nonhidden_fields(
&self,
ty: Ty<'tcx>,
variant: &'a VariantDef,
) -> impl Iterator<Item = (FieldIdx, Ty<'tcx>)> + Captures<'p> + Captures<'a> {
variant: &'tcx VariantDef,
) -> impl Iterator<Item = (FieldIdx, Ty<'tcx>)> + Captures<'p> + Captures<'_> {
let cx = self;
let ty::Adt(adt, args) = ty.kind() else { bug!() };
// Whether we must not match the fields of this variant exhaustively.
@ -399,7 +399,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
/// Note: the input patterns must have been lowered through
/// `rustc_mir_build::thir::pattern::check_match::MatchVisitor::lower_pattern`.
pub fn lower_pat(&self, pat: &Pat<'tcx>) -> DeconstructedPat<'p, 'tcx> {
pub fn lower_pat(&self, pat: &'p Pat<'tcx>) -> DeconstructedPat<'p, 'tcx> {
let singleton = |pat| std::slice::from_ref(self.pattern_arena.alloc(pat));
let cx = self;
let ctor;

79
compiler/rustc_pattern_analysis/src/usefulness.rs
View file

@ -821,22 +821,21 @@ impl fmt::Display for ValidityConstraint {
/// Represents a pattern-tuple under investigation.
// The three lifetimes are:
// - 'a allocated by us
// - 'p coming from the input
// - Cx global compilation context
#[derive(derivative::Derivative)]
#[derivative(Clone(bound = ""))]
struct PatStack<'a, 'p, Cx: TypeCx> {
struct PatStack<'p, Cx: TypeCx> {
// Rows of len 1 are very common, which is why `SmallVec[_; 2]` works well.
pats: SmallVec<[&'a DeconstructedPat<'p, Cx>; 2]>,
pats: SmallVec<[&'p DeconstructedPat<'p, Cx>; 2]>,
/// Sometimes we know that as far as this row is concerned, the current case is already handled
/// by a different, more general, case. When the case is irrelevant for all rows this allows us
/// to skip a case entirely. This is purely an optimization. See at the top for details.
relevant: bool,
}
impl<'a, 'p, Cx: TypeCx> PatStack<'a, 'p, Cx> {
fn from_pattern(pat: &'a DeconstructedPat<'p, Cx>) -> Self {
impl<'p, Cx: TypeCx> PatStack<'p, Cx> {
fn from_pattern(pat: &'p DeconstructedPat<'p, Cx>) -> Self {
PatStack { pats: smallvec![pat], relevant: true }
}
@ -848,17 +847,17 @@ impl<'a, 'p, Cx: TypeCx> PatStack<'a, 'p, Cx> {
self.pats.len()
}
fn head(&self) -> &'a DeconstructedPat<'p, Cx> {
fn head(&self) -> &'p DeconstructedPat<'p, Cx> {
self.pats[0]
}
fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, Cx>> + Captures<'b> {
fn iter(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'_> {
self.pats.iter().copied()
}
// Recursively expand the first or-pattern into its subpatterns. Only useful if the pattern is
// an or-pattern. Panics if `self` is empty.
fn expand_or_pat<'b>(&'b self) -> impl Iterator<Item = PatStack<'a, 'p, Cx>> + Captures<'b> {
fn expand_or_pat(&self) -> impl Iterator<Item = PatStack<'p, Cx>> + Captures<'_> {
self.head().flatten_or_pat().into_iter().map(move |pat| {
let mut new = self.clone();
new.pats[0] = pat;
@ -870,10 +869,10 @@ impl<'a, 'p, Cx: TypeCx> PatStack<'a, 'p, Cx> {
/// Only call if `ctor.is_covered_by(self.head().ctor())` is true.
fn pop_head_constructor(
&self,
pcx: &PlaceCtxt<'a, 'p, Cx>,
pcx: &PlaceCtxt<'_, 'p, Cx>,
ctor: &Constructor<Cx>,
ctor_is_relevant: bool,
) -> PatStack<'a, 'p, Cx> {
) -> PatStack<'p, Cx> {
// We pop the head pattern and push the new fields extracted from the arguments of
// `self.head()`.
let mut new_pats = self.head().specialize(pcx, ctor);
@ -886,7 +885,7 @@ impl<'a, 'p, Cx: TypeCx> PatStack<'a, 'p, Cx> {
}
}
impl<'a, 'p, Cx: TypeCx> fmt::Debug for PatStack<'a, 'p, Cx> {
impl<'p, Cx: TypeCx> fmt::Debug for PatStack<'p, Cx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// We pretty-print similarly to the `Debug` impl of `Matrix`.
write!(f, "+")?;
@ -899,9 +898,9 @@ impl<'a, 'p, Cx: TypeCx> fmt::Debug for PatStack<'a, 'p, Cx> {
/// A row of the matrix.
#[derive(Clone)]
struct MatrixRow<'a, 'p, Cx: TypeCx> {
struct MatrixRow<'p, Cx: TypeCx> {
// The patterns in the row.
pats: PatStack<'a, 'p, Cx>,
pats: PatStack<'p, Cx>,
/// Whether the original arm had a guard. This is inherited when specializing.
is_under_guard: bool,
/// When we specialize, we remember which row of the original matrix produced a given row of the
@ -914,7 +913,7 @@ struct MatrixRow<'a, 'p, Cx: TypeCx> {
useful: bool,
}
impl<'a, 'p, Cx: TypeCx> MatrixRow<'a, 'p, Cx> {
impl<'p, Cx: TypeCx> MatrixRow<'p, Cx> {
fn is_empty(&self) -> bool {
self.pats.is_empty()
}
@ -923,17 +922,17 @@ impl<'a, 'p, Cx: TypeCx> MatrixRow<'a, 'p, Cx> {
self.pats.len()
}
fn head(&self) -> &'a DeconstructedPat<'p, Cx> {
fn head(&self) -> &'p DeconstructedPat<'p, Cx> {
self.pats.head()
}
fn iter<'b>(&'b self) -> impl Iterator<Item = &'a DeconstructedPat<'p, Cx>> + Captures<'b> {
fn iter(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'_> {
self.pats.iter()
}
// Recursively expand the first or-pattern into its subpatterns. Only useful if the pattern is
// an or-pattern. Panics if `self` is empty.
fn expand_or_pat<'b>(&'b self) -> impl Iterator<Item = MatrixRow<'a, 'p, Cx>> + Captures<'b> {
fn expand_or_pat(&self) -> impl Iterator<Item = MatrixRow<'p, Cx>> + Captures<'_> {
self.pats.expand_or_pat().map(|patstack| MatrixRow {
pats: patstack,
parent_row: self.parent_row,
@ -946,11 +945,11 @@ impl<'a, 'p, Cx: TypeCx> MatrixRow<'a, 'p, Cx> {
/// Only call if `ctor.is_covered_by(self.head().ctor())` is true.
fn pop_head_constructor(
&self,
pcx: &PlaceCtxt<'a, 'p, Cx>,
pcx: &PlaceCtxt<'_, 'p, Cx>,
ctor: &Constructor<Cx>,
ctor_is_relevant: bool,
parent_row: usize,
) -> MatrixRow<'a, 'p, Cx> {
) -> MatrixRow<'p, Cx> {
MatrixRow {
pats: self.pats.pop_head_constructor(pcx, ctor, ctor_is_relevant),
parent_row,
@ -960,7 +959,7 @@ impl<'a, 'p, Cx: TypeCx> MatrixRow<'a, 'p, Cx> {
}
}
impl<'a, 'p, Cx: TypeCx> fmt::Debug for MatrixRow<'a, 'p, Cx> {
impl<'p, Cx: TypeCx> fmt::Debug for MatrixRow<'p, Cx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.pats.fmt(f)
}
@ -977,22 +976,22 @@ impl<'a, 'p, Cx: TypeCx> fmt::Debug for MatrixRow<'a, 'p, Cx> {
/// specializing `(,)` and `Some` on a pattern of type `(Option<u32>, bool)`, the first column of
/// the matrix will correspond to `scrutinee.0.Some.0` and the second column to `scrutinee.1`.
#[derive(Clone)]
struct Matrix<'a, 'p, Cx: TypeCx> {
struct Matrix<'p, Cx: TypeCx> {
/// Vector of rows. The rows must form a rectangular 2D array. Moreover, all the patterns of
/// each column must have the same type. Each column corresponds to a place within the
/// scrutinee.
rows: Vec<MatrixRow<'a, 'p, Cx>>,
rows: Vec<MatrixRow<'p, Cx>>,
/// Stores an extra fictitious row full of wildcards. Mostly used to keep track of the type of
/// each column. This must obey the same invariants as the real rows.
wildcard_row: PatStack<'a, 'p, Cx>,
wildcard_row: PatStack<'p, Cx>,
/// Track for each column/place whether it contains a known valid value.
place_validity: SmallVec<[ValidityConstraint; 2]>,
}
impl<'a, 'p, Cx: TypeCx> Matrix<'a, 'p, Cx> {
impl<'p, Cx: TypeCx> Matrix<'p, Cx> {
/// Pushes a new row to the matrix. If the row starts with an or-pattern, this recursively
/// expands it. Internal method, prefer [`Matrix::new`].
fn expand_and_push(&mut self, row: MatrixRow<'a, 'p, Cx>) {
fn expand_and_push(&mut self, row: MatrixRow<'p, Cx>) {
if !row.is_empty() && row.head().is_or_pat() {
// Expand nested or-patterns.
for new_row in row.expand_or_pat() {
@ -1005,8 +1004,8 @@ impl<'a, 'p, Cx: TypeCx> Matrix<'a, 'p, Cx> {
/// Build a new matrix from an iterator of `MatchArm`s.
fn new(
wildcard_arena: &'a TypedArena<DeconstructedPat<'p, Cx>>,
arms: &'a [MatchArm<'p, Cx>],
wildcard_arena: &'p TypedArena<DeconstructedPat<'p, Cx>>,
arms: &[MatchArm<'p, Cx>],
scrut_ty: Cx::Ty,
scrut_validity: ValidityConstraint,
) -> Self {
@ -1029,7 +1028,7 @@ impl<'a, 'p, Cx: TypeCx> Matrix<'a, 'p, Cx> {
matrix
}
fn head_ty(&self, mcx: MatchCtxt<'a, 'p, Cx>) -> Option<Cx::Ty> {
fn head_ty(&self, mcx: MatchCtxt<'_, 'p, Cx>) -> Option<Cx::Ty> {
if self.column_count() == 0 {
return None;
}
@ -1042,33 +1041,31 @@ impl<'a, 'p, Cx: TypeCx> Matrix<'a, 'p, Cx> {
self.wildcard_row.len()
}
fn rows<'b>(
&'b self,
) -> impl Iterator<Item = &'b MatrixRow<'a, 'p, Cx>> + Clone + DoubleEndedIterator + ExactSizeIterator
fn rows(
&self,
) -> impl Iterator<Item = &MatrixRow<'p, Cx>> + Clone + DoubleEndedIterator + ExactSizeIterator
{
self.rows.iter()
}
fn rows_mut<'b>(
&'b mut self,
) -> impl Iterator<Item = &'b mut MatrixRow<'a, 'p, Cx>> + DoubleEndedIterator + ExactSizeIterator
fn rows_mut(
&mut self,
) -> impl Iterator<Item = &mut MatrixRow<'p, Cx>> + DoubleEndedIterator + ExactSizeIterator
{
self.rows.iter_mut()
}
/// Iterate over the first pattern of each row.
fn heads<'b>(
&'b self,
) -> impl Iterator<Item = &'b DeconstructedPat<'p, Cx>> + Clone + Captures<'a> {
fn heads(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Clone + Captures<'_> {
self.rows().map(|r| r.head())
}
/// This computes `specialize(ctor, self)`. See top of the file for explanations.
fn specialize_constructor(
&self,
pcx: &PlaceCtxt<'a, 'p, Cx>,
pcx: &PlaceCtxt<'_, 'p, Cx>,
ctor: &Constructor<Cx>,
ctor_is_relevant: bool,
) -> Matrix<'a, 'p, Cx> {
) -> Matrix<'p, Cx> {
let wildcard_row = self.wildcard_row.pop_head_constructor(pcx, ctor, ctor_is_relevant);
let new_validity = self.place_validity[0].specialize(ctor);
let new_place_validity = std::iter::repeat(new_validity)
@ -1097,7 +1094,7 @@ impl<'a, 'p, Cx: TypeCx> Matrix<'a, 'p, Cx> {
/// + _ + [_, _, tail @ ..] +
/// | ✓ | ? | // column validity
/// ```
impl<'a, 'p, Cx: TypeCx> fmt::Debug for Matrix<'a, 'p, Cx> {
impl<'p, Cx: TypeCx> fmt::Debug for Matrix<'p, Cx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "\n")?;
@ -1336,7 +1333,7 @@ impl<Cx: TypeCx> WitnessMatrix<Cx> {
#[instrument(level = "debug", skip(mcx, is_top_level), ret)]
fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
mcx: MatchCtxt<'a, 'p, Cx>,
matrix: &mut Matrix<'a, 'p, Cx>,
matrix: &mut Matrix<'p, Cx>,
is_top_level: bool,
) -> WitnessMatrix<Cx> {
debug_assert!(matrix.rows().all(|r| r.len() == matrix.column_count()));