bjoernager/rust
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Rollup merge of #120331 - Nadrieril:no-arena, r=compiler-errors

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pattern_analysis: use a plain `Vec` in `DeconstructedPat`

The use of an arena-allocated slice in `DeconstructedPat` dates to when we needed the arena anyway for lifetime reasons. Now that we don't, I'm thinking that if `thir::Pat` can use plain old `Vec`s, maybe so can I.

r? ```@ghost```
This commit is contained in:
Matthias Krüger 2024-02-06 22:45:40 +01:00 • committed by GitHub
commit ce32d4862b
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7 changed files with 61 additions and 64 deletions
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69
compiler/rustc_pattern_analysis/src/rustc.rs
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@ -1,8 +1,7 @@
use smallvec::SmallVec;
use std::fmt;
use std::iter::once;
use rustc_arena::{DroplessArena, TypedArena};
use rustc_arena::DroplessArena;
use rustc_hir::def_id::DefId;
use rustc_hir::HirId;
use rustc_index::{Idx, IndexVec};
@ -27,8 +26,7 @@ use crate::constructor::Constructor::*;
pub type Constructor<'p, 'tcx> = crate::constructor::Constructor<RustcMatchCheckCtxt<'p, 'tcx>>;
pub type ConstructorSet<'p, 'tcx> =
crate::constructor::ConstructorSet<RustcMatchCheckCtxt<'p, 'tcx>>;
pub type DeconstructedPat<'p, 'tcx> =
crate::pat::DeconstructedPat<'p, RustcMatchCheckCtxt<'p, 'tcx>>;
pub type DeconstructedPat<'p, 'tcx> = crate::pat::DeconstructedPat<RustcMatchCheckCtxt<'p, 'tcx>>;
pub type MatchArm<'p, 'tcx> = crate::MatchArm<'p, RustcMatchCheckCtxt<'p, 'tcx>>;
pub type Usefulness<'p, 'tcx> = crate::usefulness::Usefulness<'p, RustcMatchCheckCtxt<'p, 'tcx>>;
pub type UsefulnessReport<'p, 'tcx> =
@ -64,7 +62,7 @@ impl<'tcx> RevealedTy<'tcx> {
}
#[derive(Clone)]
pub struct RustcMatchCheckCtxt<'p, 'tcx> {
pub struct RustcMatchCheckCtxt<'p, 'tcx: 'p> {
pub tcx: TyCtxt<'tcx>,
pub typeck_results: &'tcx ty::TypeckResults<'tcx>,
/// The module in which the match occurs. This is necessary for
@ -74,8 +72,6 @@ pub struct RustcMatchCheckCtxt<'p, 'tcx> {
/// outside its module and should not be matchable with an empty match statement.
pub module: DefId,
pub param_env: ty::ParamEnv<'tcx>,
/// To allocate lowered patterns
pub pattern_arena: &'p TypedArena<DeconstructedPat<'p, 'tcx>>,
/// To allocate the result of `self.ctor_sub_tys()`
pub dropless_arena: &'p DroplessArena,
/// Lint level at the match.
@ -91,13 +87,13 @@ pub struct RustcMatchCheckCtxt<'p, 'tcx> {
pub known_valid_scrutinee: bool,
}
impl<'p, 'tcx> fmt::Debug for RustcMatchCheckCtxt<'p, 'tcx> {
impl<'p, 'tcx: 'p> fmt::Debug for RustcMatchCheckCtxt<'p, 'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("RustcMatchCheckCtxt").finish()
}
}
impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
/// Type inference occasionally gives us opaque types in places where corresponding patterns
/// have more specific types. To avoid inconsistencies as well as detect opaque uninhabited
/// types, we use the corresponding concrete type if possible.
@ -459,21 +455,20 @@ 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: &'p Pat<'tcx>) -> DeconstructedPat<'p, 'tcx> {
let singleton = |pat| std::slice::from_ref(self.pattern_arena.alloc(pat));
let cx = self;
let ty = cx.reveal_opaque_ty(pat.ty);
let ctor;
let fields: &[_];
let mut fields: Vec<_>;
match &pat.kind {
PatKind::AscribeUserType { subpattern, .. }
| PatKind::InlineConstant { subpattern, .. } => return self.lower_pat(subpattern),
PatKind::Binding { subpattern: Some(subpat), .. } => return self.lower_pat(subpat),
PatKind::Binding { subpattern: None, .. } | PatKind::Wild => {
ctor = Wildcard;
fields = &[];
fields = vec![];
}
PatKind::Deref { subpattern } => {
fields = singleton(self.lower_pat(subpattern));
fields = vec![self.lower_pat(subpattern)];
ctor = match ty.kind() {
// This is a box pattern.
ty::Adt(adt, ..) if adt.is_box() => Struct,
@ -485,15 +480,14 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
match ty.kind() {
ty::Tuple(fs) => {
ctor = Struct;
let mut wilds: SmallVec<[_; 2]> = fs
fields = fs
.iter()
.map(|ty| cx.reveal_opaque_ty(ty))
.map(|ty| DeconstructedPat::wildcard(ty))
.collect();
for pat in subpatterns {
wilds[pat.field.index()] = self.lower_pat(&pat.pattern);
fields[pat.field.index()] = self.lower_pat(&pat.pattern);
}
fields = cx.pattern_arena.alloc_from_iter(wilds);
}
ty::Adt(adt, args) if adt.is_box() => {
// The only legal patterns of type `Box` (outside `std`) are `_` and box
@ -515,7 +509,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
DeconstructedPat::wildcard(self.reveal_opaque_ty(args.type_at(0)))
};
ctor = Struct;
fields = singleton(pat);
fields = vec![pat];
}
ty::Adt(adt, _) => {
ctor = match pat.kind {
@ -535,14 +529,12 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
ty
},
);
let mut wilds: SmallVec<[_; 2]> =
tys.map(|ty| DeconstructedPat::wildcard(ty)).collect();
fields = tys.map(|ty| DeconstructedPat::wildcard(ty)).collect();
for pat in subpatterns {
if let Some(i) = field_id_to_id[pat.field.index()] {
wilds[i] = self.lower_pat(&pat.pattern);
fields[i] = self.lower_pat(&pat.pattern);
}
}
fields = cx.pattern_arena.alloc_from_iter(wilds);
}
_ => bug!("pattern has unexpected type: pat: {:?}, ty: {:?}", pat, ty),
}
@ -554,7 +546,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
Some(b) => Bool(b),
None => Opaque(OpaqueId::new()),
};
fields = &[];
fields = vec![];
}
ty::Char | ty::Int(_) | ty::Uint(_) => {
ctor = match value.try_eval_bits(cx.tcx, cx.param_env) {
@ -570,7 +562,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
}
None => Opaque(OpaqueId::new()),
};
fields = &[];
fields = vec![];
}
ty::Float(ty::FloatTy::F32) => {
ctor = match value.try_eval_bits(cx.tcx, cx.param_env) {
@ -581,7 +573,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
}
None => Opaque(OpaqueId::new()),
};
fields = &[];
fields = vec![];
}
ty::Float(ty::FloatTy::F64) => {
ctor = match value.try_eval_bits(cx.tcx, cx.param_env) {
@ -592,7 +584,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
}
None => Opaque(OpaqueId::new()),
};
fields = &[];
fields = vec![];
}
ty::Ref(_, t, _) if t.is_str() => {
// We want a `&str` constant to behave like a `Deref` pattern, to be compatible
@ -603,16 +595,16 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
// subfields.
// Note: `t` is `str`, not `&str`.
let ty = self.reveal_opaque_ty(*t);
let subpattern = DeconstructedPat::new(Str(*value), &[], ty, pat);
let subpattern = DeconstructedPat::new(Str(*value), Vec::new(), ty, pat);
ctor = Ref;
fields = singleton(subpattern)
fields = vec![subpattern]
}
// All constants that can be structurally matched have already been expanded
// into the corresponding `Pat`s by `const_to_pat`. Constants that remain are
// opaque.
_ => {
ctor = Opaque(OpaqueId::new());
fields = &[];
fields = vec![];
}
}
}
@ -649,7 +641,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
}
_ => bug!("invalid type for range pattern: {}", ty.inner()),
};
fields = &[];
fields = vec![];
}
PatKind::Array { prefix, slice, suffix } | PatKind::Slice { prefix, slice, suffix } => {
let array_len = match ty.kind() {
@ -665,26 +657,23 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
SliceKind::FixedLen(prefix.len() + suffix.len())
};
ctor = Slice(Slice::new(array_len, kind));
fields = cx.pattern_arena.alloc_from_iter(
prefix.iter().chain(suffix.iter()).map(|p| self.lower_pat(&*p)),
)
fields = prefix.iter().chain(suffix.iter()).map(|p| self.lower_pat(&*p)).collect();
}
PatKind::Or { .. } => {
ctor = Or;
let pats = expand_or_pat(pat);
fields =
cx.pattern_arena.alloc_from_iter(pats.into_iter().map(|p| self.lower_pat(p)))
fields = pats.into_iter().map(|p| self.lower_pat(p)).collect();
}
PatKind::Never => {
// A never pattern matches all the values of its type (namely none). Moreover it
// must be compatible with other constructors, since we can use `!` on a type like
// `Result<!, !>` which has other constructors. Hence we lower it as a wildcard.
ctor = Wildcard;
fields = &[];
fields = vec![];
}
PatKind::Error(_) => {
ctor = Opaque(OpaqueId::new());
fields = &[];
fields = vec![];
}
}
DeconstructedPat::new(ctor, fields, ty, pat)
@ -855,7 +844,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
}
}
impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
impl<'p, 'tcx: 'p> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
type Ty = RevealedTy<'tcx>;
type Error = ErrorGuaranteed;
type VariantIdx = VariantIdx;
@ -889,7 +878,7 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
fn write_variant_name(
f: &mut fmt::Formatter<'_>,
pat: &crate::pat::DeconstructedPat<'_, Self>,
pat: &crate::pat::DeconstructedPat<Self>,
) -> fmt::Result {
if let ty::Adt(adt, _) = pat.ty().kind() {
if adt.is_box() {
@ -908,9 +897,9 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
fn lint_overlapping_range_endpoints(
&self,
pat: &crate::pat::DeconstructedPat<'_, Self>,
pat: &crate::pat::DeconstructedPat<Self>,
overlaps_on: IntRange,
overlaps_with: &[&crate::pat::DeconstructedPat<'_, Self>],
overlaps_with: &[&crate::pat::DeconstructedPat<Self>],
) {
let overlap_as_pat = self.hoist_pat_range(&overlaps_on, *pat.ty());
let overlaps: Vec<_> = overlaps_with