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Merge #10484

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10484: internal: Update match checking algorithm r=lnicola a=iDawer

Sync match checking algorithm with rust-lang/rust f31622a50 2021-11-12 (https://github.com/rust-lang/rust/pull/90813)

This update brings huge simplification to the match checking and introduces an easy to use machinery for pattern destructuring and also:

1. Add a function to do post-inference normalization `hir_ty::infer::normalize(...)`.
2. Store binding modes in `InferenceResult`.

Todo:

- [x] Rebase & test (https://github.com/rust-analyzer/rust-analyzer/pull/10484#issuecomment-996669665)

Co-authored-by: Dawer <7803845+iDawer@users.noreply.github.com>
Co-authored-by: iDawer <ilnur.iskhakov.oss@outlook.com>
This commit is contained in:
bors[bot] 2021-12-20 12:05:23 +00:00 committed by GitHub
commit 48d6cef436
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9 changed files with 721 additions and 908 deletions
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7
Cargo.lock generated
View File

@ -559,6 +559,7 @@ dependencies = [
"tracing",
"tracing-subscriber",
"tracing-tree",
"typed-arena",
]
[[package]]
@ -1775,6 +1776,12 @@ dependencies = [
"stdx",
]
[[package]]
name = "typed-arena"
version = "2.0.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "0685c84d5d54d1c26f7d3eb96cd41550adb97baed141a761cf335d3d33bcd0ae"
[[package]]
name = "ungrammar"
version = "1.14.9"

1
crates/hir_ty/Cargo.toml
View File

@ -23,6 +23,7 @@ chalk-ir = "0.75"
chalk-recursive = { version = "0.75", default-features = false }
la-arena = { version = "0.3.0", path = "../../lib/arena" }
once_cell = { version = "1.5.0" }
typed-arena = "2.0.1"
stdx = { path = "../stdx", version = "0.0.0" }
hir_def = { path = "../hir_def", version = "0.0.0" }

50
crates/hir_ty/src/diagnostics/expr.rs
View File

@ -2,7 +2,7 @@
//! through the body using inference results: mismatched arg counts, missing
//! fields, etc.
use std::{cell::RefCell, sync::Arc};
use std::sync::Arc;
use hir_def::{
expr::Statement, path::path, resolver::HasResolver, type_ref::Mutability, AssocItemId,
@ -11,12 +11,14 @@
use hir_expand::name;
use itertools::Either;
use rustc_hash::FxHashSet;
use typed_arena::Arena;
use crate::{
db::HirDatabase,
diagnostics::match_check::{
self,
usefulness::{compute_match_usefulness, expand_pattern, MatchCheckCtx, PatternArena},
deconstruct_pat::DeconstructedPat,
usefulness::{compute_match_usefulness, MatchCheckCtx},
},
AdtId, InferenceResult, Interner, Ty, TyExt, TyKind,
};
@ -275,15 +277,20 @@ fn validate_match(
) {
let body = db.body(self.owner);
let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() {
let match_expr_ty = &infer[match_expr];
if match_expr_ty.is_unknown() {
return;
} else {
&infer.type_of_expr[match_expr]
}
let pattern_arena = Arena::new();
let cx = MatchCheckCtx {
module: self.owner.module(db.upcast()),
body: self.owner,
db,
pattern_arena: &pattern_arena,
};
let pattern_arena = RefCell::new(PatternArena::new());
let mut m_arms = Vec::new();
let mut m_arms = Vec::with_capacity(arms.len());
let mut has_lowering_errors = false;
for arm in arms {
if let Some(pat_ty) = infer.type_of_pat.get(arm.pat) {
@ -308,13 +315,7 @@ fn validate_match(
// check the usefulness of each pattern as we added it
// to the matrix here.
let m_arm = match_check::MatchArm {
pat: self.lower_pattern(
arm.pat,
&mut pattern_arena.borrow_mut(),
db,
&body,
&mut has_lowering_errors,
),
pat: self.lower_pattern(&cx, arm.pat, db, &body, &mut has_lowering_errors),
has_guard: arm.guard.is_some(),
};
m_arms.push(m_arm);
@ -332,17 +333,10 @@ fn validate_match(
return;
}
let cx = MatchCheckCtx {
module: self.owner.module(db.upcast()),
match_expr,
infer: &infer,
db,
pattern_arena: &pattern_arena,
};
let report = compute_match_usefulness(&cx, &m_arms);
let report = compute_match_usefulness(&cx, &m_arms, match_expr_ty);
// FIXME Report unreacheble arms
// https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200-L201
// https://github.com/rust-lang/rust/blob/f31622a50/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200
let witnesses = report.non_exhaustiveness_witnesses;
// FIXME Report witnesses
@ -352,17 +346,17 @@ fn validate_match(
}
}
fn lower_pattern(
fn lower_pattern<'p>(
&self,
cx: &MatchCheckCtx<'_, 'p>,
pat: PatId,
pattern_arena: &mut PatternArena,
db: &dyn HirDatabase,
body: &Body,
have_errors: &mut bool,
) -> match_check::PatId {
) -> &'p DeconstructedPat<'p> {
let mut patcx = match_check::PatCtxt::new(db, &self.infer, body);
let pattern = patcx.lower_pattern(pat);
let pattern = pattern_arena.alloc(expand_pattern(pattern));
let pattern = cx.pattern_arena.alloc(DeconstructedPat::from_pat(cx, &pattern));
if !patcx.errors.is_empty() {
*have_errors = true;
}

46
crates/hir_ty/src/diagnostics/match_check.rs
View File

@ -5,25 +5,26 @@
//!
//! It is modeled on the rustc module `rustc_mir_build::thir::pattern`.
mod deconstruct_pat;
mod pat_util;
pub(crate) mod deconstruct_pat;
pub(crate) mod usefulness;
use hir_def::{body::Body, EnumVariantId, LocalFieldId, VariantId};
use la_arena::Idx;
use hir_def::{body::Body, expr::PatId, EnumVariantId, LocalFieldId, VariantId};
use stdx::never;
use crate::{db::HirDatabase, InferenceResult, Interner, Substitution, Ty, TyKind};
use crate::{
db::HirDatabase, infer::BindingMode, InferenceResult, Interner, Substitution, Ty, TyKind,
};
use self::pat_util::EnumerateAndAdjustIterator;
pub(crate) use self::usefulness::MatchArm;
pub(crate) type PatId = Idx<Pat>;
#[derive(Clone, Debug)]
pub(crate) enum PatternError {
Unimplemented,
UnexpectedType,
UnresolvedVariant,
MissingField,
ExtraFields,
@ -41,12 +42,6 @@ pub(crate) struct Pat {
pub(crate) kind: Box<PatKind>,
}
impl Pat {
pub(crate) fn wildcard_from_ty(ty: Ty) -> Self {
Pat { ty, kind: Box::new(PatKind::Wild) }
}
}
/// Close relative to `rustc_mir_build::thir::pattern::PatKind`
#[derive(Clone, Debug, PartialEq)]
pub(crate) enum PatKind {
@ -100,7 +95,7 @@ pub(crate) fn new(db: &'a dyn HirDatabase, infer: &'a InferenceResult, body: &'a
Self { db, infer, body, errors: Vec::new() }
}
pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat {
pub(crate) fn lower_pattern(&mut self, pat: PatId) -> Pat {
// XXX(iDawer): Collecting pattern adjustments feels imprecise to me.
// When lowering of & and box patterns are implemented this should be tested
// in a manner of `match_ergonomics_issue_9095` test.
@ -116,7 +111,7 @@ pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat {
)
}
fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat {
fn lower_pattern_unadjusted(&mut self, pat: PatId) -> Pat {
let mut ty = &self.infer[pat];
let variant = self.infer.variant_resolution_for_pat(pat);
@ -138,9 +133,16 @@ fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat {
PatKind::Leaf { subpatterns }
}
hir_def::expr::Pat::Bind { subpat, .. } => {
if let TyKind::Ref(.., rty) = ty.kind(Interner) {
ty = rty;
hir_def::expr::Pat::Bind { ref name, subpat, .. } => {
let bm = self.infer.pat_binding_modes[&pat];
match (bm, ty.kind(Interner)) {
(BindingMode::Ref(_), TyKind::Ref(.., rty)) => ty = rty,
(BindingMode::Ref(_), _) => {
never!("`ref {}` has wrong type {:?}", name, ty);
self.errors.push(PatternError::UnexpectedType);
return Pat { ty: ty.clone(), kind: PatKind::Wild.into() };
}
_ => (),
}
PatKind::Binding { subpattern: self.lower_opt_pattern(subpat) }
}
@ -189,7 +191,7 @@ fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat {
fn lower_tuple_subpats(
&mut self,
pats: &[hir_def::expr::PatId],
pats: &[PatId],
expected_len: usize,
ellipsis: Option<usize>,
) -> Vec<FieldPat> {
@ -207,17 +209,17 @@ fn lower_tuple_subpats(
.collect()
}
fn lower_patterns(&mut self, pats: &[hir_def::expr::PatId]) -> Vec<Pat> {
fn lower_patterns(&mut self, pats: &[PatId]) -> Vec<Pat> {
pats.iter().map(|&p| self.lower_pattern(p)).collect()
}
fn lower_opt_pattern(&mut self, pat: Option<hir_def::expr::PatId>) -> Option<Pat> {
fn lower_opt_pattern(&mut self, pat: Option<PatId>) -> Option<Pat> {
pat.map(|p| self.lower_pattern(p))
}
fn lower_variant_or_leaf(
&mut self,
pat: hir_def::expr::PatId,
pat: PatId,
ty: &Ty,
subpatterns: Vec<FieldPat>,
) -> PatKind {
@ -244,7 +246,7 @@ fn lower_variant_or_leaf(
kind
}
fn lower_path(&mut self, pat: hir_def::expr::PatId, _path: &hir_def::path::Path) -> Pat {
fn lower_path(&mut self, pat: PatId, _path: &hir_def::path::Path) -> Pat {
let ty = &self.infer[pat];
let pat_from_kind = |kind| Pat { ty: ty.clone(), kind: Box::new(kind) };

706
crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
View File

@ -42,6 +42,7 @@
//! wildcards, see [`SplitWildcard`]; for integer ranges, see [`SplitIntRange`].
use std::{
cell::Cell,
cmp::{max, min},
iter::once,
ops::RangeInclusive,
@ -52,15 +53,32 @@
use stdx::never;
use syntax::SmolStr;
use crate::{AdtId, Interner, Scalar, Ty, TyExt, TyKind};
use crate::{infer::normalize, AdtId, Interner, Scalar, Ty, TyExt, TyKind};
use super::{
usefulness::{MatchCheckCtx, PatCtxt},
FieldPat, Pat, PatId, PatKind,
usefulness::{helper::Captures, MatchCheckCtx, PatCtxt},
Pat, PatKind,
};
use self::Constructor::*;
/// Recursively expand this pattern into its subpatterns. Only useful for or-patterns.
fn expand_or_pat(pat: &Pat) -> Vec<&Pat> {
fn expand<'p>(pat: &'p Pat, vec: &mut Vec<&'p Pat>) {
if let PatKind::Or { pats } = pat.kind.as_ref() {
for pat in pats {
expand(pat, vec);
}
} else {
vec.push(pat)
}
}
let mut pats = Vec::new();
expand(pat, &mut pats);
pats
}
/// [Constructor] uses this in umimplemented variants.
/// It allows porting match expressions from upstream algorithm without losing semantics.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
@ -241,6 +259,10 @@ pub(super) struct Slice {
}
impl Slice {
fn arity(self) -> usize {
unimplemented!()
}
/// See `Constructor::is_covered_by`
fn is_covered_by(self, _other: Self) -> bool {
unimplemented!() // never called as Slice contains Void
@ -278,10 +300,13 @@ pub(super) enum Constructor {
/// for those types for which we cannot list constructors explicitly, like `f64` and `str`.
NonExhaustive,
/// Stands for constructors that are not seen in the matrix, as explained in the documentation
/// for [`SplitWildcard`].
Missing,
/// for [`SplitWildcard`]. The carried `bool` is used for the `non_exhaustive_omitted_patterns`
/// lint.
Missing { nonexhaustive_enum_missing_real_variants: bool },
/// Wildcard pattern.
Wildcard,
/// Or-pattern.
Or,
}
impl Constructor {
@ -289,6 +314,10 @@ pub(super) fn is_wildcard(&self) -> bool {
matches!(self, Wildcard)
}
pub(super) fn is_non_exhaustive(&self) -> bool {
matches!(self, NonExhaustive)
}
fn as_int_range(&self) -> Option<&IntRange> {
match self {
IntRange(range) => Some(range),
@ -303,6 +332,14 @@ fn as_slice(&self) -> Option<Slice> {
}
}
pub(super) fn is_unstable_variant(&self, _pcx: PatCtxt<'_, '_>) -> bool {
false //FIXME: implement this
}
pub(super) fn is_doc_hidden_variant(&self, _pcx: PatCtxt<'_, '_>) -> bool {
false //FIXME: implement this
}
fn variant_id_for_adt(&self, adt: hir_def::AdtId) -> VariantId {
match *self {
Variant(id) => id.into(),
@ -318,16 +355,39 @@ fn variant_id_for_adt(&self, adt: hir_def::AdtId) -> VariantId {
}
}
/// Determines the constructor that the given pattern can be specialized to.
pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self {
match cx.pattern_arena.borrow()[pat].kind.as_ref() {
PatKind::Binding { .. } | PatKind::Wild => Wildcard,
PatKind::Leaf { .. } | PatKind::Deref { .. } => Single,
&PatKind::Variant { enum_variant, .. } => Variant(enum_variant),
&PatKind::LiteralBool { value } => IntRange(IntRange::from_bool(value)),
PatKind::Or { .. } => {
never!("Or-pattern should have been expanded earlier on.");
Wildcard
/// The number of fields for this constructor. This must be kept in sync with
/// `Fields::wildcards`.
pub(super) fn arity(&self, pcx: PatCtxt<'_, '_>) -> usize {
match self {
Single | Variant(_) => match *pcx.ty.kind(Interner) {
TyKind::Tuple(arity, ..) => arity,
TyKind::Ref(..) => 1,
TyKind::Adt(adt, ..) => {
if adt_is_box(adt.0, pcx.cx) {
// The only legal patterns of type `Box` (outside `std`) are `_` and box
// patterns. If we're here we can assume this is a box pattern.
1
} else {
let variant = self.variant_id_for_adt(adt.0);
Fields::list_variant_nonhidden_fields(pcx.cx, pcx.ty, variant).count()
}
}
_ => {
never!("Unexpected type for `Single` constructor: {:?}", pcx.ty);
0
}
},
Slice(slice) => slice.arity(),
Str(..)
| FloatRange(..)
| IntRange(..)
| NonExhaustive
| Opaque
| Missing { .. }
| Wildcard => 0,
Or => {
never!("The `Or` constructor doesn't have a fixed arity");
0
}
}
}
@ -347,7 +407,7 @@ pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self {
/// matrix, unless all of them are.
pub(super) fn split<'a>(
&self,
pcx: PatCtxt<'_>,
pcx: PatCtxt<'_, '_>,
ctors: impl Iterator<Item = &'a Constructor> + Clone,
) -> SmallVec<[Self; 1]> {
match self {
@ -375,13 +435,13 @@ pub(super) fn split<'a>(
/// this checks for inclusion.
// We inline because this has a single call site in `Matrix::specialize_constructor`.
#[inline]
pub(super) fn is_covered_by(&self, _pcx: PatCtxt<'_>, other: &Self) -> bool {
pub(super) fn is_covered_by(&self, _pcx: PatCtxt<'_, '_>, other: &Self) -> bool {
// This must be kept in sync with `is_covered_by_any`.
match (self, other) {
// Wildcards cover anything
(_, Wildcard) => true,
// The missing ctors are not covered by anything in the matrix except wildcards.
(Missing | Wildcard, _) => false,
(Missing { .. } | Wildcard, _) => false,
(Single, Single) => true,
(Variant(self_id), Variant(other_id)) => self_id == other_id,
@ -411,7 +471,7 @@ pub(super) fn is_covered_by(&self, _pcx: PatCtxt<'_>, other: &Self) -> bool {
/// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is
/// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is
/// assumed to have been split from a wildcard.
fn is_covered_by_any(&self, _pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool {
fn is_covered_by_any(&self, _pcx: PatCtxt<'_, '_>, used_ctors: &[Constructor]) -> bool {
if used_ctors.is_empty() {
return false;
}
@ -431,7 +491,7 @@ fn is_covered_by_any(&self, _pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bo
.any(|other| slice.is_covered_by(other)),
// This constructor is never covered by anything else
NonExhaustive => false,
Str(..) | FloatRange(..) | Opaque | Missing | Wildcard => {
Str(..) | FloatRange(..) | Opaque | Missing { .. } | Wildcard | Or => {
never!("found unexpected ctor in all_ctors: {:?}", self);
true
}
@ -463,7 +523,7 @@ pub(super) struct SplitWildcard {
}
impl SplitWildcard {
pub(super) fn new(pcx: PatCtxt<'_>) -> Self {
pub(super) fn new(pcx: PatCtxt<'_, '_>) -> Self {
let cx = pcx.cx;
let make_range = |start, end, scalar| IntRange(IntRange::from_range(start, end, scalar));
@ -483,7 +543,7 @@ pub(super) fn new(pcx: PatCtxt<'_>) -> Self {
TyKind::Scalar(Scalar::Bool) => smallvec![make_range(0, 1, Scalar::Bool)],
// TyKind::Array(..) if ... => unhandled(),
TyKind::Array(..) | TyKind::Slice(..) => unhandled(),
&TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref _substs) => {
&TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ..) => {
let enum_data = cx.db.enum_data(enum_id);
// If the enum is declared as `#[non_exhaustive]`, we treat it as if it had an
@ -502,27 +562,35 @@ pub(super) fn new(pcx: PatCtxt<'_>) -> Self {
//
// we don't want to show every possible IO error, but instead have only `_` as the
// witness.
let is_declared_nonexhaustive = cx.is_foreign_non_exhaustive_enum(enum_id);
let is_declared_nonexhaustive = cx.is_foreign_non_exhaustive_enum(pcx.ty);
let is_exhaustive_pat_feature = cx.feature_exhaustive_patterns();
// If `exhaustive_patterns` is disabled and our scrutinee is an empty enum, we treat it
// as though it had an "unknown" constructor to avoid exposing its emptiness. The
// exception is if the pattern is at the top level, because we want empty matches to be
// considered exhaustive.
let is_secretly_empty = enum_data.variants.is_empty()
&& !cx.feature_exhaustive_patterns()
&& !is_exhaustive_pat_feature
&& !pcx.is_top_level;
let mut ctors: SmallVec<[_; 1]> = enum_data
.variants
.iter()
.filter(|&(_, _v)| {
// If `exhaustive_patterns` is enabled, we exclude variants known to be
// uninhabited.
let is_uninhabited = is_exhaustive_pat_feature
&& unimplemented!("after MatchCheckCtx.feature_exhaustive_patterns()");
!is_uninhabited
})
.map(|(local_id, _)| Variant(EnumVariantId { parent: enum_id, local_id }))
.collect();
if is_secretly_empty || is_declared_nonexhaustive {
smallvec![NonExhaustive]
} else if cx.feature_exhaustive_patterns() {
unimplemented!() // see MatchCheckCtx.feature_exhaustive_patterns()
} else {
enum_data
.variants
.iter()
.map(|(local_id, ..)| Variant(EnumVariantId { parent: enum_id, local_id }))
.collect()
ctors.push(NonExhaustive);
}
ctors
}
TyKind::Scalar(Scalar::Char) => unhandled(),
TyKind::Scalar(Scalar::Int(..) | Scalar::Uint(..)) => unhandled(),
@ -535,6 +603,7 @@ pub(super) fn new(pcx: PatCtxt<'_>) -> Self {
// This type is one for which we cannot list constructors, like `str` or `f64`.
_ => smallvec![NonExhaustive],
};
SplitWildcard { matrix_ctors: Vec::new(), all_ctors }
}
@ -542,7 +611,7 @@ pub(super) fn new(pcx: PatCtxt<'_>) -> Self {
/// do what you want.
pub(super) fn split<'a>(
&mut self,
pcx: PatCtxt<'_>,
pcx: PatCtxt<'_, '_>,
ctors: impl Iterator<Item = &'a Constructor> + Clone,
) {
// Since `all_ctors` never contains wildcards, this won't recurse further.
@ -552,21 +621,21 @@ pub(super) fn split<'a>(
}
/// Whether there are any value constructors for this type that are not present in the matrix.
fn any_missing(&self, pcx: PatCtxt<'_>) -> bool {
fn any_missing(&self, pcx: PatCtxt<'_, '_>) -> bool {
self.iter_missing(pcx).next().is_some()
}
/// Iterate over the constructors for this type that are not present in the matrix.
pub(super) fn iter_missing<'a>(
pub(super) fn iter_missing<'a, 'p>(
&'a self,
pcx: PatCtxt<'a>,
) -> impl Iterator<Item = &'a Constructor> {
pcx: PatCtxt<'a, 'p>,
) -> impl Iterator<Item = &'a Constructor> + Captures<'p> {
self.all_ctors.iter().filter(move |ctor| !ctor.is_covered_by_any(pcx, &self.matrix_ctors))
}
/// Return the set of constructors resulting from splitting the wildcard. As explained at the
/// top of the file, if any constructors are missing we can ignore the present ones.
fn into_ctors(self, pcx: PatCtxt<'_>) -> SmallVec<[Constructor; 1]> {
fn into_ctors(self, pcx: PatCtxt<'_, '_>) -> SmallVec<[Constructor; 1]> {
if self.any_missing(pcx) {
// Some constructors are missing, thus we can specialize with the special `Missing`
// constructor, which stands for those constructors that are not seen in the matrix,
@ -597,7 +666,15 @@ pub(super) fn iter_missing<'a>(
// sometimes prefer reporting the list of constructors instead of just `_`.
let report_when_all_missing = pcx.is_top_level && !IntRange::is_integral(pcx.ty);
let ctor = if !self.matrix_ctors.is_empty() || report_when_all_missing {
Missing
if pcx.is_non_exhaustive {
Missing {
nonexhaustive_enum_missing_real_variants: self
.iter_missing(pcx)
.any(|c| !(c.is_non_exhaustive() || c.is_unstable_variant(pcx))),
}
} else {
Missing { nonexhaustive_enum_missing_real_variants: false }
}
} else {
Wildcard
};
@ -611,291 +688,334 @@ pub(super) fn iter_missing<'a>(
/// A value can be decomposed into a constructor applied to some fields. This struct represents
/// those fields, generalized to allow patterns in each field. See also `Constructor`.
/// This is constructed from a constructor using [`Fields::wildcards()`].
///
/// If a private or `non_exhaustive` field is uninhabited, the code mustn't observe that it is
/// uninhabited. For that, we filter these fields out of the matrix. This is handled automatically
/// in `Fields`. This filtering is uncommon in practice, because uninhabited fields are rarely used,
/// so we avoid it when possible to preserve performance.
#[derive(Debug, Clone)]
pub(super) enum Fields {
/// Lists of patterns that don't contain any filtered fields.
/// `Slice` and `Vec` behave the same; the difference is only to avoid allocating and
/// triple-dereferences when possible. Frankly this is premature optimization, I (Nadrieril)
/// have not measured if it really made a difference.
Vec(SmallVec<[PatId; 2]>),
/// This is constructed for a constructor using [`Fields::wildcards()`]. The idea is that
/// [`Fields::wildcards()`] constructs a list of fields where all entries are wildcards, and then
/// given a pattern we fill some of the fields with its subpatterns.
/// In the following example `Fields::wildcards` returns `[_, _, _, _]`. Then in
/// `extract_pattern_arguments` we fill some of the entries, and the result is
/// `[Some(0), _, _, _]`.
/// ```rust
/// let x: [Option<u8>; 4] = foo();
/// match x {
/// [Some(0), ..] => {}
/// }
/// ```
///
/// Note that the number of fields of a constructor may not match the fields declared in the
/// original struct/variant. This happens if a private or `non_exhaustive` field is uninhabited,
/// because the code mustn't observe that it is uninhabited. In that case that field is not
/// included in `fields`. For that reason, when you have a `mir::Field` you must use
/// `index_with_declared_idx`.
#[derive(Clone, Copy)]
pub(super) struct Fields<'p> {
fields: &'p [DeconstructedPat<'p>],
}
impl Fields {
/// Internal use. Use `Fields::wildcards()` instead.
/// Must not be used if the pattern is a field of a struct/tuple/variant.
fn from_single_pattern(pat: PatId) -> Self {
Fields::Vec(smallvec![pat])
impl<'p> Fields<'p> {
fn empty() -> Self {
Fields { fields: &[] }
}
/// Convenience; internal use.
fn wildcards_from_tys(cx: &MatchCheckCtx<'_>, tys: impl IntoIterator<Item = Ty>) -> Self {
let wilds = tys.into_iter().map(Pat::wildcard_from_ty);
let pats = wilds.map(|pat| cx.alloc_pat(pat)).collect();
Fields::Vec(pats)
fn singleton(cx: &MatchCheckCtx<'_, 'p>, field: DeconstructedPat<'p>) -> Self {
let field = cx.pattern_arena.alloc(field);
Fields { fields: std::slice::from_ref(field) }
}
/// Creates a new list of wildcard fields for a given constructor.
pub(crate) fn wildcards(pcx: PatCtxt<'_>, constructor: &Constructor) -> Self {
let ty = pcx.ty;
let cx = pcx.cx;
let wildcard_from_ty = |ty: &Ty| cx.alloc_pat(Pat::wildcard_from_ty(ty.clone()));
pub(super) fn from_iter(
cx: &MatchCheckCtx<'_, 'p>,
fields: impl IntoIterator<Item = DeconstructedPat<'p>>,
) -> Self {
let fields: &[_] = cx.pattern_arena.alloc_extend(fields);
Fields { fields }
}
fn wildcards_from_tys(cx: &MatchCheckCtx<'_, 'p>, tys: impl IntoIterator<Item = Ty>) -> Self {
Fields::from_iter(cx, tys.into_iter().map(DeconstructedPat::wildcard))
}
// 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.
fn list_variant_nonhidden_fields<'a>(
cx: &'a MatchCheckCtx<'a, 'p>,
ty: &'a Ty,
variant: VariantId,
) -> impl Iterator<Item = (LocalFieldId, Ty)> + Captures<'a> + Captures<'p> {
let (adt, substs) = ty.as_adt().unwrap();
let adt_is_local = variant.module(cx.db.upcast()).krate() == cx.module.krate();
// Whether we must not match the fields of this variant exhaustively.
let is_non_exhaustive = is_field_list_non_exhaustive(variant, cx) && !adt_is_local;
let visibility = cx.db.field_visibilities(variant);
let field_ty = cx.db.field_types(variant);
let fields_len = variant.variant_data(cx.db.upcast()).fields().len() as u32;
(0..fields_len).map(|idx| LocalFieldId::from_raw(idx.into())).filter_map(move |fid| {
let ty = field_ty[fid].clone().substitute(Interner, substs);
let ty = normalize(cx.db, cx.body, ty);
let is_visible = matches!(adt, hir_def::AdtId::EnumId(..))
|| visibility[fid].is_visible_from(cx.db.upcast(), cx.module);
let is_uninhabited = cx.is_uninhabited(&ty);
if is_uninhabited && (!is_visible || is_non_exhaustive) {
None
} else {
Some((fid, ty))
}
})
}
/// Creates a new list of wildcard fields for a given constructor. The result must have a
/// length of `constructor.arity()`.
pub(crate) fn wildcards(
cx: &MatchCheckCtx<'_, 'p>,
ty: &Ty,
constructor: &Constructor,
) -> Self {
let ret = match constructor {
Single | Variant(_) => match ty.kind(Interner) {
TyKind::Tuple(_, substs) => {
let tys = substs.iter(Interner).map(|ty| ty.assert_ty_ref(Interner));
Fields::wildcards_from_tys(cx, tys.cloned())
}
TyKind::Ref(.., rty) => Fields::from_single_pattern(wildcard_from_ty(rty)),
TyKind::Ref(.., rty) => Fields::wildcards_from_tys(cx, once(rty.clone())),
&TyKind::Adt(AdtId(adt), ref substs) => {
if adt_is_box(adt, cx) {
// Use T as the sub pattern type of Box<T>.
let subst_ty = substs.at(Interner, 0).assert_ty_ref(Interner);
Fields::from_single_pattern(wildcard_from_ty(subst_ty))
// The only legal patterns of type `Box` (outside `std`) are `_` and box
// patterns. If we're here we can assume this is a box pattern.
let subst_ty = substs.at(Interner, 0).assert_ty_ref(Interner).clone();
Fields::wildcards_from_tys(cx, once(subst_ty))
} else {
let variant_id = constructor.variant_id_for_adt(adt);
let adt_is_local =
variant_id.module(cx.db.upcast()).krate() == cx.module.krate();
// Whether we must not match the fields of this variant exhaustively.
let is_non_exhaustive =
is_field_list_non_exhaustive(variant_id, cx) && !adt_is_local;
cov_mark::hit!(match_check_wildcard_expanded_to_substitutions);
let field_ty_data = cx.db.field_types(variant_id);
let field_tys = || {
field_ty_data
.iter()
.map(|(_, binders)| binders.clone().substitute(Interner, substs))
};
// In the following cases, we don't need to filter out any fields. This is
// the vast majority of real cases, since uninhabited fields are uncommon.
let has_no_hidden_fields = (matches!(adt, hir_def::AdtId::EnumId(_))
&& !is_non_exhaustive)
|| !field_tys().any(|ty| cx.is_uninhabited(&ty));
if has_no_hidden_fields {
Fields::wildcards_from_tys(cx, field_tys())
} else {
//FIXME(iDawer): see MatchCheckCtx::is_uninhabited, has_no_hidden_fields is always true
unimplemented!("exhaustive_patterns feature")
}
let variant = constructor.variant_id_for_adt(adt);
let tys = Fields::list_variant_nonhidden_fields(cx, ty, variant)
.map(|(_, ty)| ty);
Fields::wildcards_from_tys(cx, tys)
}
}
ty_kind => {
never!("Unexpected type for `Single` constructor: {:?}", ty_kind);
Fields::from_single_pattern(wildcard_from_ty(ty))
Fields::wildcards_from_tys(cx, once(ty.clone()))
}
},
Slice(..) => {
unimplemented!()
}
Str(..) | FloatRange(..) | IntRange(..) | NonExhaustive | Opaque | Missing
| Wildcard => Fields::Vec(Default::default()),
Str(..)
| FloatRange(..)
| IntRange(..)
| NonExhaustive
| Opaque
| Missing { .. }
| Wildcard => Fields::empty(),
Or => {
never!("called `Fields::wildcards` on an `Or` ctor");
Fields::empty()
}
};
ret
}
/// Apply a constructor to a list of patterns, yielding a new pattern. `self`
/// must have as many elements as this constructor's arity.
///
/// This is roughly the inverse of `specialize_constructor`.
///
/// Examples:
/// `ctor`: `Constructor::Single`
/// `ty`: `Foo(u32, u32, u32)`
/// `self`: `[10, 20, _]`
/// returns `Foo(10, 20, _)`
///
/// `ctor`: `Constructor::Variant(Option::Some)`
/// `ty`: `Option<bool>`
/// `self`: `[false]`
/// returns `Some(false)`
pub(super) fn apply(self, pcx: PatCtxt<'_>, ctor: &Constructor) -> Pat {
let subpatterns_and_indices = self.patterns_and_indices();
let mut subpatterns =
subpatterns_and_indices.iter().map(|&(_, p)| pcx.cx.pattern_arena.borrow()[p].clone());
// FIXME(iDawer) witnesses are not yet used
const UNHANDLED: PatKind = PatKind::Wild;
let pat = match ctor {
Single | Variant(_) => match pcx.ty.kind(Interner) {
TyKind::Adt(..) | TyKind::Tuple(..) => {
// We want the real indices here.
let subpatterns = subpatterns_and_indices
.iter()
.map(|&(field, pat)| FieldPat {
field,
pattern: pcx.cx.pattern_arena.borrow()[pat].clone(),
})
.collect();
if let Some((hir_def::AdtId::EnumId(_), substs)) = pcx.ty.as_adt() {
let enum_variant = match ctor {
&Variant(id) => id,
_ => unreachable!(),
};
PatKind::Variant { substs: substs.clone(), enum_variant, subpatterns }
} else {
PatKind::Leaf { subpatterns }
}
}
// Note: given the expansion of `&str` patterns done in `expand_pattern`, we should
// be careful to reconstruct the correct constant pattern here. However a string
// literal pattern will never be reported as a non-exhaustiveness witness, so we
// can ignore this issue.
TyKind::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() },
TyKind::Slice(..) | TyKind::Array(..) => {
never!("bad slice pattern {:?} {:?}", ctor, pcx.ty);
PatKind::Wild
}
_ => PatKind::Wild,
},
Constructor::Slice(_) => UNHANDLED,
Str(_) => UNHANDLED,
FloatRange(..) => UNHANDLED,
Constructor::IntRange(_) => UNHANDLED,
NonExhaustive => PatKind::Wild,
Wildcard => return Pat::wildcard_from_ty(pcx.ty.clone()),
Opaque => {
never!("we should not try to apply an opaque constructor");
PatKind::Wild
}
Missing => {
never!(
"trying to apply the `Missing` constructor; \
this should have been done in `apply_constructors`",
);
PatKind::Wild
}
};
Pat { ty: pcx.ty.clone(), kind: Box::new(pat) }
}
/// Returns the number of patterns. This is the same as the arity of the constructor used to
/// construct `self`.
pub(super) fn len(&self) -> usize {
match self {
Fields::Vec(pats) => pats.len(),
}
}
/// Returns the list of patterns along with the corresponding field indices.
fn patterns_and_indices(&self) -> SmallVec<[(LocalFieldId, PatId); 2]> {
match self {
Fields::Vec(pats) => pats
.iter()
.copied()
.enumerate()
.map(|(i, p)| (LocalFieldId::from_raw((i as u32).into()), p))
.collect(),
}
}
pub(super) fn into_patterns(self) -> SmallVec<[PatId; 2]> {
match self {
Fields::Vec(pats) => pats,
}
}
/// Overrides some of the fields with the provided patterns. Exactly like
/// `replace_fields_indexed`, except that it takes `FieldPat`s as input.
fn replace_with_fieldpats(
&self,
new_pats: impl IntoIterator<Item = (LocalFieldId, PatId)>,
) -> Self {
self.replace_fields_indexed(
new_pats.into_iter().map(|(field, pat)| (u32::from(field.into_raw()) as usize, pat)),
)
}
/// Overrides some of the fields with the provided patterns. This is used when a pattern
/// defines some fields but not all, for example `Foo { field1: Some(_), .. }`: here we start
/// with a `Fields` that is just one wildcard per field of the `Foo` struct, and override the
/// entry corresponding to `field1` with the pattern `Some(_)`. This is also used for slice
/// patterns for the same reason.
fn replace_fields_indexed(&self, new_pats: impl IntoIterator<Item = (usize, PatId)>) -> Self {
let mut fields = self.clone();
match &mut fields {
Fields::Vec(pats) => {
for (i, pat) in new_pats {
if let Some(p) = pats.get_mut(i) {
*p = pat;
}
}
}
}
fields
}
/// Replaces contained fields with the given list of patterns. There must be `len()` patterns
/// in `pats`.
pub(super) fn replace_fields(
&self,
cx: &MatchCheckCtx<'_>,
pats: impl IntoIterator<Item = Pat>,
) -> Self {
let pats = pats.into_iter().map(|pat| cx.alloc_pat(pat)).collect();
match self {
Fields::Vec(_) => Fields::Vec(pats),
}
}
/// Replaces contained fields with the arguments of the given pattern. Only use on a pattern
/// that is compatible with the constructor used to build `self`.
/// This is meant to be used on the result of `Fields::wildcards()`. The idea is that
/// `wildcards` constructs a list of fields where all entries are wildcards, and the pattern
/// provided to this function fills some of the fields with non-wildcards.
/// In the following example `Fields::wildcards` would return `[_, _, _, _]`. If we call
/// `replace_with_pattern_arguments` on it with the pattern, the result will be `[Some(0), _,
/// _, _]`.
/// ```rust
/// let x: [Option<u8>; 4] = foo();
/// match x {
/// [Some(0), ..] => {}
/// }
/// ```
/// This is guaranteed to preserve the number of patterns in `self`.
pub(super) fn replace_with_pattern_arguments(
&self,
pat: PatId,
cx: &MatchCheckCtx<'_>,
) -> Self {
// FIXME(iDawer): Factor out pattern deep cloning. See discussion:
// https://github.com/rust-analyzer/rust-analyzer/pull/8717#discussion_r633086640
let mut arena = cx.pattern_arena.borrow_mut();
match arena[pat].kind.as_ref() {
PatKind::Deref { subpattern } => {
assert_eq!(self.len(), 1);
let subpattern = subpattern.clone();
Fields::from_single_pattern(arena.alloc(subpattern))
}
PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => {
let subpatterns = subpatterns.clone();
let subpatterns = subpatterns
.iter()
.map(|field_pat| (field_pat.field, arena.alloc(field_pat.pattern.clone())));
self.replace_with_fieldpats(subpatterns)
}
PatKind::Wild
| PatKind::Binding { .. }
| PatKind::LiteralBool { .. }
| PatKind::Or { .. } => self.clone(),
}
/// Returns the list of patterns.
pub(super) fn iter_patterns<'a>(
&'a self,
) -> impl Iterator<Item = &'p DeconstructedPat<'p>> + Captures<'a> {
self.fields.iter()
}
}
fn is_field_list_non_exhaustive(variant_id: VariantId, cx: &MatchCheckCtx<'_>) -> bool {
/// Values and patterns can be represented as a constructor applied to some fields. This represents
/// a pattern in this form.
/// This also keeps track of whether the pattern has been found reachable during analysis. For this
/// reason we should be careful not to clone patterns for which we care about that. Use
/// `clone_and_forget_reachability` if you're sure.
pub(crate) struct DeconstructedPat<'p> {
ctor: Constructor,
fields: Fields<'p>,
ty: Ty,
reachable: Cell<bool>,
}
impl<'p> DeconstructedPat<'p> {
pub(super) fn wildcard(ty: Ty) -> Self {
Self::new(Wildcard, Fields::empty(), ty)
}
pub(super) fn new(ctor: Constructor, fields: Fields<'p>, ty: Ty) -> Self {
DeconstructedPat { ctor, fields, ty, reachable: Cell::new(false) }
}
/// Construct a pattern that matches everything that starts with this constructor.
/// For example, if `ctor` is a `Constructor::Variant` for `Option::Some`, we get the pattern
/// `Some(_)`.
pub(super) fn wild_from_ctor(pcx: PatCtxt<'_, 'p>, ctor: Constructor) -> Self {
let fields = Fields::wildcards(pcx.cx, pcx.ty, &ctor);
DeconstructedPat::new(ctor, fields, pcx.ty.clone())
}
/// Clone this value. This method emphasizes that cloning loses reachability information and
/// should be done carefully.
pub(super) fn clone_and_forget_reachability(&self) -> Self {
DeconstructedPat::new(self.ctor.clone(), self.fields, self.ty.clone())
}
pub(crate) fn from_pat(cx: &MatchCheckCtx<'_, 'p>, pat: &Pat) -> Self {
let mkpat = |pat| DeconstructedPat::from_pat(cx, pat);
let ctor;
let fields;
match pat.kind.as_ref() {
PatKind::Binding { subpattern: Some(subpat) } => return mkpat(subpat),
PatKind::Binding { subpattern: None } | PatKind::Wild => {
ctor = Wildcard;
fields = Fields::empty();
}
PatKind::Deref { subpattern } => {
ctor = Single;
fields = Fields::singleton(cx, mkpat(subpattern));
}
PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => {
match pat.ty.kind(Interner) {
TyKind::Tuple(_, substs) => {
ctor = Single;
let mut wilds: SmallVec<[_; 2]> = substs
.iter(Interner)
.map(|arg| arg.assert_ty_ref(Interner).clone())
.map(DeconstructedPat::wildcard)
.collect();
for pat in subpatterns {
let idx: u32 = pat.field.into_raw().into();
wilds[idx as usize] = mkpat(&pat.pattern);
}
fields = Fields::from_iter(cx, wilds)
}
TyKind::Adt(adt, substs) if adt_is_box(adt.0, cx) => {
// The only legal patterns of type `Box` (outside `std`) are `_` and box
// patterns. If we're here we can assume this is a box pattern.
// FIXME(Nadrieril): A `Box` can in theory be matched either with `Box(_,
// _)` or a box pattern. As a hack to avoid an ICE with the former, we
// ignore other fields than the first one. This will trigger an error later
// anyway.
// See https://github.com/rust-lang/rust/issues/82772 ,
// explanation: https://github.com/rust-lang/rust/pull/82789#issuecomment-796921977
// The problem is that we can't know from the type whether we'll match
// normally or through box-patterns. We'll have to figure out a proper
// solution when we introduce generalized deref patterns. Also need to
// prevent mixing of those two options.
let pat =
subpatterns.iter().find(|pat| pat.field.into_raw() == 0u32.into());
let field = if let Some(pat) = pat {
mkpat(&pat.pattern)
} else {
let ty = substs.at(Interner, 0).assert_ty_ref(Interner).clone();
DeconstructedPat::wildcard(ty)
};
ctor = Single;
fields = Fields::singleton(cx, field)
}
&TyKind::Adt(adt, _) => {
ctor = match pat.kind.as_ref() {
PatKind::Leaf { .. } => Single,
PatKind::Variant { enum_variant, .. } => Variant(*enum_variant),
_ => {
never!();
Wildcard
}
};
let variant = ctor.variant_id_for_adt(adt.0);
let fields_len = variant.variant_data(cx.db.upcast()).fields().len();
// For each field in the variant, we store the relevant index into `self.fields` if any.
let mut field_id_to_id: Vec<Option<usize>> = vec![None; fields_len];
let tys = Fields::list_variant_nonhidden_fields(cx, &pat.ty, variant)
.enumerate()
.map(|(i, (fid, ty))| {
let field_idx: u32 = fid.into_raw().into();
field_id_to_id[field_idx as usize] = Some(i);
ty
});
let mut wilds: SmallVec<[_; 2]> =
tys.map(DeconstructedPat::wildcard).collect();
for pat in subpatterns {
let field_idx: u32 = pat.field.into_raw().into();
if let Some(i) = field_id_to_id[field_idx as usize] {
wilds[i] = mkpat(&pat.pattern);
}
}
fields = Fields::from_iter(cx, wilds);
}
_ => {
never!("pattern has unexpected type: pat: {:?}, ty: {:?}", pat, &pat.ty);
ctor = Wildcard;
fields = Fields::empty();
}
}
}
&PatKind::LiteralBool { value } => {
ctor = IntRange(IntRange::from_bool(value));
fields = Fields::empty();
}
PatKind::Or { .. } => {
ctor = Or;
let pats: SmallVec<[_; 2]> = expand_or_pat(pat).into_iter().map(mkpat).collect();
fields = Fields::from_iter(cx, pats)
}
}
DeconstructedPat::new(ctor, fields, pat.ty.clone())
}
// // FIXME(iDawer): implement reporting of noncovered patterns
// pub(crate) fn to_pat(&self, _cx: &MatchCheckCtx<'_, 'p>) -> Pat {
// Pat { ty: self.ty.clone(), kind: PatKind::Wild.into() }
// }
pub(super) fn is_or_pat(&self) -> bool {
matches!(self.ctor, Or)
}
pub(super) fn ctor(&self) -> &Constructor {
&self.ctor
}
pub(super) fn ty(&self) -> &Ty {
&self.ty
}
pub(super) fn iter_fields<'a>(&'a self) -> impl Iterator<Item = &'a DeconstructedPat<'a>> + 'a {
self.fields.iter_patterns()
}
/// Specialize this pattern with a constructor.
/// `other_ctor` can be different from `self.ctor`, but must be covered by it.
pub(super) fn specialize<'a>(
&'a self,
cx: &MatchCheckCtx<'_, 'p>,
other_ctor: &Constructor,
) -> SmallVec<[&'p DeconstructedPat<'p>; 2]> {
match (&self.ctor, other_ctor) {
(Wildcard, _) => {
// We return a wildcard for each field of `other_ctor`.
Fields::wildcards(cx, &self.ty, other_ctor).iter_patterns().collect()
}
(Slice(self_slice), Slice(other_slice))
if self_slice.arity() != other_slice.arity() =>
{
unimplemented!()
}
_ => self.fields.iter_patterns().collect(),
}
}
/// We keep track for each pattern if it was ever reachable during the analysis. This is used
/// with `unreachable_spans` to report unreachable subpatterns arising from or patterns.
pub(super) fn set_reachable(&self) {
self.reachable.set(true)
}
pub(super) fn is_reachable(&self) -> bool {
self.reachable.get()
}
}
fn is_field_list_non_exhaustive(variant_id: VariantId, cx: &MatchCheckCtx<'_, '_>) -> bool {
let attr_def_id = match variant_id {
VariantId::EnumVariantId(id) => id.into(),
VariantId::StructId(id) => id.into(),
@ -904,7 +1024,7 @@ fn is_field_list_non_exhaustive(variant_id: VariantId, cx: &MatchCheckCtx<'_>) -
cx.db.attrs(attr_def_id).by_key("non_exhaustive").exists()
}
fn adt_is_box(adt: hir_def::AdtId, cx: &MatchCheckCtx<'_>) -> bool {
fn adt_is_box(adt: hir_def::AdtId, cx: &MatchCheckCtx<'_, '_>) -> bool {
use hir_def::lang_item::LangItemTarget;
match cx.db.lang_item(cx.module.krate(), SmolStr::new_inline("owned_box")) {
Some(LangItemTarget::StructId(box_id)) => adt == box_id.into(),

754
crates/hir_ty/src/diagnostics/match_check/usefulness.rs
View File

File diff suppressed because it is too large Load Diff

25
crates/hir_ty/src/infer.rs
View File

@ -16,7 +16,7 @@
use std::ops::Index;
use std::sync::Arc;
use chalk_ir::{cast::Cast, DebruijnIndex, Mutability, Safety, Scalar};
use chalk_ir::{cast::Cast, DebruijnIndex, Mutability, Safety, Scalar, TypeFlags};
use hir_def::{
body::Body,
data::{ConstData, FunctionData, StaticData},
@ -70,6 +70,26 @@ pub(crate) fn infer_query(db: &dyn HirDatabase, def: DefWithBodyId) -> Arc<Infer
Arc::new(ctx.resolve_all())
}
/// Fully normalize all the types found within `ty` in context of `owner` body definition.
///
/// This is appropriate to use only after type-check: it assumes
/// that normalization will succeed, for example.
pub(crate) fn normalize(db: &dyn HirDatabase, owner: DefWithBodyId, ty: Ty) -> Ty {
if !ty.data(Interner).flags.intersects(TypeFlags::HAS_PROJECTION) {
return ty;
}
let krate = owner.module(db.upcast()).krate();
let trait_env = owner
.as_generic_def_id()
.map_or_else(|| Arc::new(TraitEnvironment::empty(krate)), |d| db.trait_environment(d));
let mut table = unify::InferenceTable::new(db, trait_env.clone());
let ty_with_vars = table.normalize_associated_types_in(ty);
table.resolve_obligations_as_possible();
table.propagate_diverging_flag();
table.resolve_completely(ty_with_vars)
}
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
enum ExprOrPatId {
ExprId(ExprId),
@ -80,7 +100,7 @@ enum ExprOrPatId {
/// Binding modes inferred for patterns.
/// <https://doc.rust-lang.org/reference/patterns.html#binding-modes>
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum BindingMode {
pub enum BindingMode {
Move,
Ref(Mutability),
}
@ -272,6 +292,7 @@ pub struct InferenceResult {
standard_types: InternedStandardTypes,
/// Stores the types which were implicitly dereferenced in pattern binding modes.
pub pat_adjustments: FxHashMap<PatId, Vec<Adjustment>>,
pub pat_binding_modes: FxHashMap<PatId, BindingMode>,
pub expr_adjustments: FxHashMap<ExprId, Vec<Adjustment>>,
}

2
crates/hir_ty/src/infer/pat.rs
View File

@ -204,6 +204,8 @@ pub(super) fn infer_pat(
} else {
BindingMode::convert(*mode)
};
self.result.pat_binding_modes.insert(pat, mode);
let inner_ty = match subpat {
Some(subpat) => self.infer_pat(*subpat, &expected, default_bm),
None => expected,

38
crates/ide_diagnostics/src/handlers/missing_match_arms.rs
View File

@ -821,7 +821,6 @@ fn main() {
#[test]
fn pattern_type_is_of_substitution() {
cov_mark::check!(match_check_wildcard_expanded_to_substitutions);
check_diagnostics_no_bails(
r#"
struct Foo<T>(T);
@ -864,6 +863,43 @@ fn main() {
);
}
#[test]
fn normalize_field_ty() {
check_diagnostics_no_bails(
r"
trait Trait { type Projection; }
enum E {Foo, Bar}
struct A;
impl Trait for A { type Projection = E; }
struct Next<T: Trait>(T::Projection);
static __: () = {
let n: Next<A> = Next(E::Foo);
match n { Next(E::Foo) => {} }
// ^ error: missing match arm
match n { Next(E::Foo | E::Bar) => {} }
match n { Next(E::Foo | _ ) => {} }
match n { Next(_ | E::Bar) => {} }
match n { _ | Next(E::Bar) => {} }
match &n { Next(E::Foo | E::Bar) => {} }
match &n { _ | Next(E::Bar) => {} }
};",
);
}
#[test]
fn binding_mode_by_ref() {
check_diagnostics_no_bails(
r"
enum E{ A, B }
fn foo() {
match &E::A {
E::A => {}
x => {}
}
}",
);
}
mod false_negatives {
//! The implementation of match checking here is a work in progress. As we roll this out, we
//! prefer false negatives to false positives (ideally there would be no false positives). This