From 3088ca0a53540e0d7ae14f0d18efcad16cad0735 Mon Sep 17 00:00:00 2001
From: Dawer <7803845+iDawer@users.noreply.github.com>
Date: Wed, 19 May 2021 18:08:13 +0500
Subject: [PATCH] Take substitutions into account.
---
crates/hir_ty/src/diagnostics/match_check.rs | 20 +++++++++++++--
.../match_check/deconstruct_pat.rs | 25 +++++++++++--------
.../src/diagnostics/match_check/usefulness.rs | 2 +-
3 files changed, 33 insertions(+), 14 deletions(-)
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index 5fb98ff35c6..992bb868222 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -39,8 +39,8 @@ pub(crate) struct Pat {
}
impl Pat {
- pub(crate) fn wildcard_from_ty(ty: &Ty) -> Self {
- Pat { ty: ty.clone(), kind: Box::new(PatKind::Wild) }
+ pub(crate) fn wildcard_from_ty(ty: Ty) -> Self {
+ Pat { ty, kind: Box::new(PatKind::Wild) }
}
}
@@ -1145,6 +1145,22 @@ fn main() {
);
}
+ #[test]
+ fn pattern_type_is_of_substitution() {
+ cov_mark::check!(match_check_wildcard_expanded_to_substitutions);
+ check_diagnostics(
+ r#"
+struct Foo<T>(T);
+struct Bar;
+fn main() {
+ match Foo(Bar) {
+ _ | Foo(Bar) => {}
+ }
+}
+"#,
+ );
+ }
+
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
diff --git a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
index 15ec5cf4501..a470826174c 100644
--- a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
+++ b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs
@@ -632,10 +632,7 @@ impl Fields {
}
/// Convenience; internal use.
- fn wildcards_from_tys<'a>(
- cx: &MatchCheckCtx<'_>,
- tys: impl IntoIterator<Item = &'a Ty>,
- ) -> Self {
+ 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)
@@ -645,13 +642,13 @@ impl Fields {
pub(crate) fn wildcards(pcx: PatCtxt<'_>, constructor: &Constructor) -> Self {
let ty = pcx.ty;
let cx = pcx.cx;
- let wildcard_from_ty = |ty| cx.alloc_pat(Pat::wildcard_from_ty(ty));
+ let wildcard_from_ty = |ty: &Ty| cx.alloc_pat(Pat::wildcard_from_ty(ty.clone()));
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)
+ Fields::wildcards_from_tys(cx, tys.cloned())
}
TyKind::Ref(.., rty) => Fields::from_single_pattern(wildcard_from_ty(rty)),
&TyKind::Adt(AdtId(adt), ref substs) => {
@@ -666,14 +663,20 @@ impl Fields {
// 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;
- let field_ty_arena = cx.db.field_types(variant_id);
- let field_tys =
- || field_ty_arena.iter().map(|(_, binders)| binders.skip_binders());
+
+ 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));
+ || !field_tys().any(|ty| cx.is_uninhabited(&ty));
if has_no_hidden_fields {
Fields::wildcards_from_tys(cx, field_tys())
@@ -759,7 +762,7 @@ impl Fields {
FloatRange(..) => UNHANDLED,
Constructor::IntRange(_) => UNHANDLED,
NonExhaustive => PatKind::Wild,
- Wildcard => return Pat::wildcard_from_ty(pcx.ty),
+ Wildcard => return Pat::wildcard_from_ty(pcx.ty.clone()),
Opaque => pcx.cx.bug("we should not try to apply an opaque constructor"),
Missing => pcx.cx.bug(
"trying to apply the `Missing` constructor;\
diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
index cb322a3de36..61fba41bf8d 100644
--- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
+++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
@@ -1152,7 +1152,7 @@ pub(crate) fn compute_match_usefulness(
.collect();
let wild_pattern =
- cx.pattern_arena.borrow_mut().alloc(Pat::wildcard_from_ty(&cx.infer[cx.match_expr]));
+ cx.pattern_arena.borrow_mut().alloc(Pat::wildcard_from_ty(cx.infer[cx.match_expr].clone()));
let v = PatStack::from_pattern(wild_pattern);
let usefulness = is_useful(cx, &matrix, &v, ConstructWitness, false, true);
let non_exhaustiveness_witnesses = match usefulness {