From 68b76a48358e611e31de8e96c56b9e50862a960e Mon Sep 17 00:00:00 2001
From: Nadrieril <nadrieril+git@gmail.com>
Date: Fri, 1 Oct 2021 19:09:43 +0100
Subject: [PATCH] Normalize after substituting via `field.ty()`
---
compiler/rustc_middle/src/ty/mod.rs | 4 +-
.../src/thir/pattern/deconstruct_pat.rs | 4 +-
.../src/thir/pattern/usefulness.rs | 3 +-
.../issue-72476-and-89393-associated-type.rs | 56 +++++++++++++++++++
.../usefulness/issue-72476-associated-type.rs | 22 --------
5 files changed, 62 insertions(+), 27 deletions(-)
create mode 100644 src/test/ui/pattern/usefulness/issue-72476-and-89393-associated-type.rs
delete mode 100644 src/test/ui/pattern/usefulness/issue-72476-associated-type.rs
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 777c6035be8..02c3b391a97 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1627,8 +1627,8 @@ impl ReprOptions {
}
impl<'tcx> FieldDef {
- /// Returns the type of this field. The `subst` is typically obtained
- /// via the second field of `TyKind::AdtDef`.
+ /// Returns the type of this field. The resulting type is not normalized. The `subst` is
+ /// typically obtained via the second field of `TyKind::AdtDef`.
pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
tcx.type_of(self.did).subst(tcx, subst)
}
diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
index 69a7d44ff39..dfcbd0da3a6 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
@@ -1154,6 +1154,8 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
variant.fields.iter().enumerate().filter_map(move |(i, field)| {
let ty = field.ty(cx.tcx, substs);
+ // `field.ty()` doesn't normalize after substituting.
+ let ty = cx.tcx.normalize_erasing_regions(cx.param_env, ty);
let is_visible = adt.is_enum() || field.vis.is_accessible_from(cx.module, cx.tcx);
let is_uninhabited = cx.is_uninhabited(ty);
@@ -1671,7 +1673,7 @@ impl<'p, 'tcx> fmt::Debug for DeconstructedPat<'p, 'tcx> {
write!(f, "{}", hi)
}
IntRange(range) => write!(f, "{:?}", range), // Best-effort, will render e.g. `false` as `0..=0`
- Wildcard | Missing { .. } | NonExhaustive => write!(f, "_"),
+ Wildcard | Missing { .. } | NonExhaustive => write!(f, "_ : {:?}", self.ty),
Or => {
for pat in self.iter_fields() {
write!(f, "{}{:?}", start_or_continue(" | "), pat)?;
diff --git a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
index 650a87b2d88..43adef3d03b 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
@@ -781,8 +781,7 @@ fn is_useful<'p, 'tcx>(
assert!(rows.iter().all(|r| r.len() == v.len()));
- // FIXME(Nadrieril): Hack to work around type normalization issues (see #72476).
- let ty = matrix.heads().next().map_or(v.head().ty(), |r| r.ty());
+ let ty = v.head().ty();
let is_non_exhaustive = cx.is_foreign_non_exhaustive_enum(ty);
let pcx = PatCtxt { cx, ty, span: v.head().span(), is_top_level, is_non_exhaustive };
diff --git a/src/test/ui/pattern/usefulness/issue-72476-and-89393-associated-type.rs b/src/test/ui/pattern/usefulness/issue-72476-and-89393-associated-type.rs
new file mode 100644
index 00000000000..058f4196798
--- /dev/null
+++ b/src/test/ui/pattern/usefulness/issue-72476-and-89393-associated-type.rs
@@ -0,0 +1,56 @@
+// check-pass
+
+// From https://github.com/rust-lang/rust/issues/72476
+// and https://github.com/rust-lang/rust/issues/89393
+
+trait Trait {
+ type Projection;
+}
+
+struct A;
+impl Trait for A {
+ type Projection = bool;
+}
+
+struct B;
+impl Trait for B {
+ type Projection = (u32, u32);
+}
+
+struct Next<T: Trait>(T::Projection);
+
+fn foo1(item: Next<A>) {
+ match item {
+ Next(true) => {}
+ Next(false) => {}
+ }
+}
+
+fn foo2(x: <A as Trait>::Projection) {
+ match x {
+ true => {}
+ false => {}
+ }
+}
+
+fn foo3(x: Next<B>) {
+ let Next((_, _)) = x;
+ match x {
+ Next((_, _)) => {}
+ }
+}
+
+fn foo4(x: <B as Trait>::Projection) {
+ let (_, _) = x;
+ match x {
+ (_, _) => {}
+ }
+}
+
+fn foo5<T: Trait>(x: <T as Trait>::Projection) {
+ match x {
+ _ => {}
+ }
+}
+
+fn main() {}
diff --git a/src/test/ui/pattern/usefulness/issue-72476-associated-type.rs b/src/test/ui/pattern/usefulness/issue-72476-associated-type.rs
deleted file mode 100644
index 1e1d21433b7..00000000000
--- a/src/test/ui/pattern/usefulness/issue-72476-associated-type.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-// check-pass
-
-// From https://github.com/rust-lang/rust/issues/72476
-
-trait A {
- type Projection;
-}
-
-impl A for () {
- type Projection = bool;
-}
-
-struct Next<T: A>(T::Projection);
-
-fn f(item: Next<()>) {
- match item {
- Next(true) => {}
- Next(false) => {}
- }
-}
-
-fn main() {}