Rollup merge of #122434 - Nadrieril:renames, r=compiler-errors

pattern analysis: rename a few types

A few long overdue renames. `ValidityConstraint` was supposed to serve double purpose but I don't need that anymore. I don't know what I was thinking with `TypeCx` I think I was trying to be clever. That's fixed now :smile:

r? ``@compiler-errors``

8 files changed, 106 insertions, 119 deletions

diff --git a/compiler/rustc_pattern_analysis/src/constructor.rs b/compiler/rustc_pattern_analysis/src/constructor.rs
index 2d55785cd06..1faecb7e1dd 100644
--- a/compiler/rustc_pattern_analysis/src/constructor.rs
+++ b/compiler/rustc_pattern_analysis/src/constructor.rs
@@ -40,7 +40,7 @@
 //! - That have no non-trivial intersection with any of the constructors in the column (i.e. they're
 //!     each either disjoint with or covered by any given column constructor).
 //!
-//! We compute this in two steps: first [`TypeCx::ctors_for_ty`] determines the
+//! We compute this in two steps: first [`PatCx::ctors_for_ty`] determines the
 //! set of all possible constructors for the type. Then [`ConstructorSet::split`] looks at the
 //! column of constructors and splits the set into groups accordingly. The precise invariants of
 //! [`ConstructorSet::split`] is described in [`SplitConstructorSet`].
@@ -136,7 +136,7 @@
 //! the algorithm can't distinguish them from a nonempty constructor. The only known case where this
 //! could happen is the `[..]` pattern on `[!; N]` with `N > 0` so we must take care to not emit it.
 //!
-//! This is all handled by [`TypeCx::ctors_for_ty`] and
+//! This is all handled by [`PatCx::ctors_for_ty`] and
 //! [`ConstructorSet::split`]. The invariants of [`SplitConstructorSet`] are also of interest.
 //!
 //!
@@ -162,7 +162,7 @@ use self::MaybeInfiniteInt::*;
 use self::SliceKind::*;
 
 use crate::index;
-use crate::TypeCx;
+use crate::PatCx;
 
 /// Whether we have seen a constructor in the column or not.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
@@ -651,7 +651,7 @@ impl OpaqueId {
 /// constructor. `Constructor::apply` reconstructs the pattern from a pair of `Constructor` and
 /// `Fields`.
 #[derive(Debug)]
-pub enum Constructor<Cx: TypeCx> {
+pub enum Constructor<Cx: PatCx> {
     /// Tuples and structs.
     Struct,
     /// Enum variants.
@@ -696,7 +696,7 @@ pub enum Constructor<Cx: TypeCx> {
     PrivateUninhabited,
 }
 
-impl<Cx: TypeCx> Clone for Constructor<Cx> {
+impl<Cx: PatCx> Clone for Constructor<Cx> {
     fn clone(&self) -> Self {
         match self {
             Constructor::Struct => Constructor::Struct,
@@ -720,7 +720,7 @@ impl<Cx: TypeCx> Clone for Constructor<Cx> {
     }
 }
 
-impl<Cx: TypeCx> Constructor<Cx> {
+impl<Cx: PatCx> Constructor<Cx> {
     pub(crate) fn is_non_exhaustive(&self) -> bool {
         matches!(self, NonExhaustive)
     }
@@ -838,7 +838,7 @@ pub enum VariantVisibility {
 /// In terms of division of responsibility, [`ConstructorSet::split`] handles all of the
 /// `exhaustive_patterns` feature.
 #[derive(Debug)]
-pub enum ConstructorSet<Cx: TypeCx> {
+pub enum ConstructorSet<Cx: PatCx> {
     /// The type is a tuple or struct. `empty` tracks whether the type is empty.
     Struct { empty: bool },
     /// This type has the following list of constructors. If `variants` is empty and
@@ -889,13 +889,13 @@ pub enum ConstructorSet<Cx: TypeCx> {
 /// of the `ConstructorSet` for the type, yet if we forgot to include them in `present` we would be
 /// ignoring any row with `Opaque`s in the algorithm. Hence the importance of point 4.
 #[derive(Debug)]
-pub struct SplitConstructorSet<Cx: TypeCx> {
+pub struct SplitConstructorSet<Cx: PatCx> {
     pub present: SmallVec<[Constructor<Cx>; 1]>,
     pub missing: Vec<Constructor<Cx>>,
     pub missing_empty: Vec<Constructor<Cx>>,
 }
 
-impl<Cx: TypeCx> ConstructorSet<Cx> {
+impl<Cx: PatCx> ConstructorSet<Cx> {
     /// This analyzes a column of constructors to 1/ determine which constructors of the type (if
     /// any) are missing; 2/ split constructors to handle non-trivial intersections e.g. on ranges
     /// or slices. This can get subtle; see [`SplitConstructorSet`] for details of this operation
diff --git a/compiler/rustc_pattern_analysis/src/errors.rs b/compiler/rustc_pattern_analysis/src/errors.rs
index 21a61d46ccb..75b7b7c8f67 100644
--- a/compiler/rustc_pattern_analysis/src/errors.rs
+++ b/compiler/rustc_pattern_analysis/src/errors.rs
@@ -4,7 +4,7 @@ use rustc_middle::thir::Pat;
 use rustc_middle::ty::Ty;
 use rustc_span::Span;
 
-use crate::rustc::{RustcMatchCheckCtxt, WitnessPat};
+use crate::rustc::{RustcPatCtxt, WitnessPat};
 
 #[derive(Subdiagnostic)]
 #[label(pattern_analysis_uncovered)]
@@ -21,7 +21,7 @@ pub struct Uncovered<'tcx> {
 impl<'tcx> Uncovered<'tcx> {
     pub fn new<'p>(
         span: Span,
-        cx: &RustcMatchCheckCtxt<'p, 'tcx>,
+        cx: &RustcPatCtxt<'p, 'tcx>,
         witnesses: Vec<WitnessPat<'p, 'tcx>>,
     ) -> Self
     where
diff --git a/compiler/rustc_pattern_analysis/src/lib.rs b/compiler/rustc_pattern_analysis/src/lib.rs
index f632eaf7ea4..5c57c990323 100644
--- a/compiler/rustc_pattern_analysis/src/lib.rs
+++ b/compiler/rustc_pattern_analysis/src/lib.rs
@@ -84,7 +84,7 @@ pub struct PrivateUninhabitedField(pub bool);
 /// Context that provides type information about constructors.
 ///
 /// Most of the crate is parameterized on a type that implements this trait.
-pub trait TypeCx: Sized + fmt::Debug {
+pub trait PatCx: Sized + fmt::Debug {
     /// The type of a pattern.
     type Ty: Clone + fmt::Debug;
     /// Errors that can abort analysis.
@@ -155,34 +155,34 @@ pub trait TypeCx: Sized + fmt::Debug {
 
 /// The arm of a match expression.
 #[derive(Debug)]
-pub struct MatchArm<'p, Cx: TypeCx> {
+pub struct MatchArm<'p, Cx: PatCx> {
     pub pat: &'p DeconstructedPat<Cx>,
     pub has_guard: bool,
     pub arm_data: Cx::ArmData,
 }
 
-impl<'p, Cx: TypeCx> Clone for MatchArm<'p, Cx> {
+impl<'p, Cx: PatCx> Clone for MatchArm<'p, Cx> {
     fn clone(&self) -> Self {
         Self { pat: self.pat, has_guard: self.has_guard, arm_data: self.arm_data }
     }
 }
 
-impl<'p, Cx: TypeCx> Copy for MatchArm<'p, Cx> {}
+impl<'p, Cx: PatCx> Copy for MatchArm<'p, Cx> {}
 
 /// The entrypoint for this crate. Computes whether a match is exhaustive and which of its arms are
 /// useful, and runs some lints.
 #[cfg(feature = "rustc")]
 pub fn analyze_match<'p, 'tcx>(
-    tycx: &rustc::RustcMatchCheckCtxt<'p, 'tcx>,
+    tycx: &rustc::RustcPatCtxt<'p, 'tcx>,
     arms: &[rustc::MatchArm<'p, 'tcx>],
     scrut_ty: Ty<'tcx>,
     pattern_complexity_limit: Option<usize>,
 ) -> Result<rustc::UsefulnessReport<'p, 'tcx>, ErrorGuaranteed> {
     use lints::lint_nonexhaustive_missing_variants;
-    use usefulness::{compute_match_usefulness, ValidityConstraint};
+    use usefulness::{compute_match_usefulness, PlaceValidity};
 
     let scrut_ty = tycx.reveal_opaque_ty(scrut_ty);
-    let scrut_validity = ValidityConstraint::from_bool(tycx.known_valid_scrutinee);
+    let scrut_validity = PlaceValidity::from_bool(tycx.known_valid_scrutinee);
     let report =
         compute_match_usefulness(tycx, arms, scrut_ty, scrut_validity, pattern_complexity_limit)?;
 
diff --git a/compiler/rustc_pattern_analysis/src/lints.rs b/compiler/rustc_pattern_analysis/src/lints.rs
index 072a8e4bfe5..3ca5ebdb0dd 100644
--- a/compiler/rustc_pattern_analysis/src/lints.rs
+++ b/compiler/rustc_pattern_analysis/src/lints.rs
@@ -4,15 +4,15 @@ use rustc_span::ErrorGuaranteed;
 use crate::constructor::Constructor;
 use crate::errors::{NonExhaustiveOmittedPattern, NonExhaustiveOmittedPatternLintOnArm, Uncovered};
 use crate::pat_column::PatternColumn;
-use crate::rustc::{RevealedTy, RustcMatchCheckCtxt, WitnessPat};
+use crate::rustc::{RevealedTy, RustcPatCtxt, WitnessPat};
 use crate::MatchArm;
 
 /// Traverse the patterns to collect any variants of a non_exhaustive enum that fail to be mentioned
 /// in a given column.
 #[instrument(level = "debug", skip(cx), ret)]
 fn collect_nonexhaustive_missing_variants<'p, 'tcx>(
-    cx: &RustcMatchCheckCtxt<'p, 'tcx>,
-    column: &PatternColumn<'p, RustcMatchCheckCtxt<'p, 'tcx>>,
+    cx: &RustcPatCtxt<'p, 'tcx>,
+    column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>,
 ) -> Result<Vec<WitnessPat<'p, 'tcx>>, ErrorGuaranteed> {
     let Some(&ty) = column.head_ty() else {
         return Ok(Vec::new());
@@ -57,9 +57,9 @@ fn collect_nonexhaustive_missing_variants<'p, 'tcx>(
 }
 
 pub(crate) fn lint_nonexhaustive_missing_variants<'p, 'tcx>(
-    rcx: &RustcMatchCheckCtxt<'p, 'tcx>,
-    arms: &[MatchArm<'p, RustcMatchCheckCtxt<'p, 'tcx>>],
-    pat_column: &PatternColumn<'p, RustcMatchCheckCtxt<'p, 'tcx>>,
+    rcx: &RustcPatCtxt<'p, 'tcx>,
+    arms: &[MatchArm<'p, RustcPatCtxt<'p, 'tcx>>],
+    pat_column: &PatternColumn<'p, RustcPatCtxt<'p, 'tcx>>,
     scrut_ty: RevealedTy<'tcx>,
 ) -> Result<(), ErrorGuaranteed> {
     if !matches!(
diff --git a/compiler/rustc_pattern_analysis/src/pat.rs b/compiler/rustc_pattern_analysis/src/pat.rs
index cefc1d8e3b3..e3667d44bc9 100644
--- a/compiler/rustc_pattern_analysis/src/pat.rs
+++ b/compiler/rustc_pattern_analysis/src/pat.rs
@@ -5,7 +5,7 @@ use std::fmt;
 use smallvec::{smallvec, SmallVec};
 
 use crate::constructor::{Constructor, Slice, SliceKind};
-use crate::{PrivateUninhabitedField, TypeCx};
+use crate::{PatCx, PrivateUninhabitedField};
 
 use self::Constructor::*;
 
@@ -21,7 +21,7 @@ impl PatId {
 }
 
 /// A pattern with an index denoting which field it corresponds to.
-pub struct IndexedPat<Cx: TypeCx> {
+pub struct IndexedPat<Cx: PatCx> {
     pub idx: usize,
     pub pat: DeconstructedPat<Cx>,
 }
@@ -29,7 +29,7 @@ pub struct IndexedPat<Cx: TypeCx> {
 /// Values and patterns can be represented as a constructor applied to some fields. This represents
 /// a pattern in this form. A `DeconstructedPat` will almost always come from user input; the only
 /// exception are some `Wildcard`s introduced during pattern lowering.
-pub struct DeconstructedPat<Cx: TypeCx> {
+pub struct DeconstructedPat<Cx: PatCx> {
     ctor: Constructor<Cx>,
     fields: Vec<IndexedPat<Cx>>,
     /// The number of fields in this pattern. E.g. if the pattern is `SomeStruct { field12: true, ..
@@ -43,7 +43,7 @@ pub struct DeconstructedPat<Cx: TypeCx> {
     pub(crate) uid: PatId,
 }
 
-impl<Cx: TypeCx> DeconstructedPat<Cx> {
+impl<Cx: PatCx> DeconstructedPat<Cx> {
     pub fn new(
         ctor: Constructor<Cx>,
         fields: Vec<IndexedPat<Cx>>,
@@ -136,7 +136,7 @@ impl<Cx: TypeCx> DeconstructedPat<Cx> {
 }
 
 /// This is best effort and not good enough for a `Display` impl.
-impl<Cx: TypeCx> fmt::Debug for DeconstructedPat<Cx> {
+impl<Cx: PatCx> fmt::Debug for DeconstructedPat<Cx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let pat = self;
         let mut first = true;
@@ -219,14 +219,14 @@ impl<Cx: TypeCx> fmt::Debug for DeconstructedPat<Cx> {
 /// algorithm. Do not use `Wild` to represent a wildcard pattern comping from user input.
 ///
 /// This is morally `Option<&'p DeconstructedPat>` where `None` is interpreted as a wildcard.
-pub(crate) enum PatOrWild<'p, Cx: TypeCx> {
+pub(crate) enum PatOrWild<'p, Cx: PatCx> {
     /// A non-user-provided wildcard, created during specialization.
     Wild,
     /// A user-provided pattern.
     Pat(&'p DeconstructedPat<Cx>),
 }
 
-impl<'p, Cx: TypeCx> Clone for PatOrWild<'p, Cx> {
+impl<'p, Cx: PatCx> Clone for PatOrWild<'p, Cx> {
     fn clone(&self) -> Self {
         match self {
             PatOrWild::Wild => PatOrWild::Wild,
@@ -235,9 +235,9 @@ impl<'p, Cx: TypeCx> Clone for PatOrWild<'p, Cx> {
     }
 }
 
-impl<'p, Cx: TypeCx> Copy for PatOrWild<'p, Cx> {}
+impl<'p, Cx: PatCx> Copy for PatOrWild<'p, Cx> {}
 
-impl<'p, Cx: TypeCx> PatOrWild<'p, Cx> {
+impl<'p, Cx: PatCx> PatOrWild<'p, Cx> {
     pub(crate) fn as_pat(&self) -> Option<&'p DeconstructedPat<Cx>> {
         match self {
             PatOrWild::Wild => None,
@@ -283,7 +283,7 @@ impl<'p, Cx: TypeCx> PatOrWild<'p, Cx> {
     }
 }
 
-impl<'p, Cx: TypeCx> fmt::Debug for PatOrWild<'p, Cx> {
+impl<'p, Cx: PatCx> fmt::Debug for PatOrWild<'p, Cx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             PatOrWild::Wild => write!(f, "_"),
@@ -295,19 +295,19 @@ impl<'p, Cx: TypeCx> fmt::Debug for PatOrWild<'p, Cx> {
 /// Same idea as `DeconstructedPat`, except this is a fictitious pattern built up for diagnostics
 /// purposes. As such they don't use interning and can be cloned.
 #[derive(Debug)]
-pub struct WitnessPat<Cx: TypeCx> {
+pub struct WitnessPat<Cx: PatCx> {
     ctor: Constructor<Cx>,
     pub(crate) fields: Vec<WitnessPat<Cx>>,
     ty: Cx::Ty,
 }
 
-impl<Cx: TypeCx> Clone for WitnessPat<Cx> {
+impl<Cx: PatCx> Clone for WitnessPat<Cx> {
     fn clone(&self) -> Self {
         Self { ctor: self.ctor.clone(), fields: self.fields.clone(), ty: self.ty.clone() }
     }
 }
 
-impl<Cx: TypeCx> WitnessPat<Cx> {
+impl<Cx: PatCx> WitnessPat<Cx> {
     pub(crate) fn new(ctor: Constructor<Cx>, fields: Vec<Self>, ty: Cx::Ty) -> Self {
         Self { ctor, fields, ty }
     }
diff --git a/compiler/rustc_pattern_analysis/src/pat_column.rs b/compiler/rustc_pattern_analysis/src/pat_column.rs
index ce14fdc364f..eb4e095c1c6 100644
--- a/compiler/rustc_pattern_analysis/src/pat_column.rs
+++ b/compiler/rustc_pattern_analysis/src/pat_column.rs
@@ -1,6 +1,6 @@
 use crate::constructor::{Constructor, SplitConstructorSet};
 use crate::pat::{DeconstructedPat, PatOrWild};
-use crate::{Captures, MatchArm, TypeCx};
+use crate::{Captures, MatchArm, PatCx};
 
 /// A column of patterns in a match, where a column is the intuitive notion of "subpatterns that
 /// inspect the same subvalue/place".
@@ -11,12 +11,12 @@ use crate::{Captures, MatchArm, TypeCx};
 ///
 /// This is not used in the usefulness algorithm; only in lints.
 #[derive(Debug)]
-pub struct PatternColumn<'p, Cx: TypeCx> {
+pub struct PatternColumn<'p, Cx: PatCx> {
     /// This must not contain an or-pattern. `expand_and_push` takes care to expand them.
     patterns: Vec<&'p DeconstructedPat<Cx>>,
 }
 
-impl<'p, Cx: TypeCx> PatternColumn<'p, Cx> {
+impl<'p, Cx: PatCx> PatternColumn<'p, Cx> {
     pub fn new(arms: &[MatchArm<'p, Cx>]) -> Self {
         let patterns = Vec::with_capacity(arms.len());
         let mut column = PatternColumn { patterns };
diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs
index 53a32d3237e..d00faadccb0 100644
--- a/compiler/rustc_pattern_analysis/src/rustc.rs
+++ b/compiler/rustc_pattern_analysis/src/rustc.rs
@@ -18,20 +18,19 @@ use rustc_target::abi::{FieldIdx, Integer, VariantIdx, FIRST_VARIANT};
 use crate::constructor::{
     IntRange, MaybeInfiniteInt, OpaqueId, RangeEnd, Slice, SliceKind, VariantVisibility,
 };
-use crate::{errors, Captures, PrivateUninhabitedField, TypeCx};
+use crate::{errors, Captures, PatCx, PrivateUninhabitedField};
 
 use crate::constructor::Constructor::*;
 
 // Re-export rustc-specific versions of all these types.
-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<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 Constructor<'p, 'tcx> = crate::constructor::Constructor<RustcPatCtxt<'p, 'tcx>>;
+pub type ConstructorSet<'p, 'tcx> = crate::constructor::ConstructorSet<RustcPatCtxt<'p, 'tcx>>;
+pub type DeconstructedPat<'p, 'tcx> = crate::pat::DeconstructedPat<RustcPatCtxt<'p, 'tcx>>;
+pub type MatchArm<'p, 'tcx> = crate::MatchArm<'p, RustcPatCtxt<'p, 'tcx>>;
+pub type Usefulness<'p, 'tcx> = crate::usefulness::Usefulness<'p, RustcPatCtxt<'p, 'tcx>>;
 pub type UsefulnessReport<'p, 'tcx> =
-    crate::usefulness::UsefulnessReport<'p, RustcMatchCheckCtxt<'p, 'tcx>>;
-pub type WitnessPat<'p, 'tcx> = crate::pat::WitnessPat<RustcMatchCheckCtxt<'p, 'tcx>>;
+    crate::usefulness::UsefulnessReport<'p, RustcPatCtxt<'p, 'tcx>>;
+pub type WitnessPat<'p, 'tcx> = crate::pat::WitnessPat<RustcPatCtxt<'p, 'tcx>>;
 
 /// A type which has gone through `cx.reveal_opaque_ty`, i.e. if it was opaque it was replaced by
 /// the hidden type if allowed in the current body. This ensures we consistently inspect the hidden
@@ -62,7 +61,7 @@ impl<'tcx> RevealedTy<'tcx> {
 }
 
 #[derive(Clone)]
-pub struct RustcMatchCheckCtxt<'p, 'tcx: 'p> {
+pub struct RustcPatCtxt<'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
@@ -87,22 +86,19 @@ pub struct RustcMatchCheckCtxt<'p, 'tcx: 'p> {
     pub known_valid_scrutinee: bool,
 }
 
-impl<'p, 'tcx: 'p> fmt::Debug for RustcMatchCheckCtxt<'p, 'tcx> {
+impl<'p, 'tcx: 'p> fmt::Debug for RustcPatCtxt<'p, 'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RustcMatchCheckCtxt").finish()
+        f.debug_struct("RustcPatCtxt").finish()
     }
 }
 
-impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
+impl<'p, 'tcx: 'p> RustcPatCtxt<'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.
     #[inline]
     pub fn reveal_opaque_ty(&self, ty: Ty<'tcx>) -> RevealedTy<'tcx> {
-        fn reveal_inner<'tcx>(
-            cx: &RustcMatchCheckCtxt<'_, 'tcx>,
-            ty: Ty<'tcx>,
-        ) -> RevealedTy<'tcx> {
+        fn reveal_inner<'tcx>(cx: &RustcPatCtxt<'_, 'tcx>, ty: Ty<'tcx>) -> RevealedTy<'tcx> {
             let ty::Alias(ty::Opaque, alias_ty) = *ty.kind() else { bug!() };
             if let Some(local_def_id) = alias_ty.def_id.as_local() {
                 let key = ty::OpaqueTypeKey { def_id: local_def_id, args: alias_ty.args };
@@ -199,7 +195,7 @@ impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
     + ExactSizeIterator
     + Captures<'a> {
         fn reveal_and_alloc<'a, 'tcx>(
-            cx: &'a RustcMatchCheckCtxt<'_, 'tcx>,
+            cx: &'a RustcPatCtxt<'_, 'tcx>,
             iter: impl Iterator<Item = Ty<'tcx>>,
         ) -> &'a [(RevealedTy<'tcx>, PrivateUninhabitedField)] {
             cx.dropless_arena.alloc_from_iter(
@@ -218,7 +214,7 @@ impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
                         reveal_and_alloc(cx, once(args.type_at(0)))
                     } else {
                         let variant =
-                            &adt.variant(RustcMatchCheckCtxt::variant_index_for_adt(&ctor, *adt));
+                            &adt.variant(RustcPatCtxt::variant_index_for_adt(&ctor, *adt));
 
                         // In the cases of either a `#[non_exhaustive]` field list or a non-public
                         // field, we skip uninhabited fields in order not to reveal the
@@ -270,7 +266,7 @@ impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
                         // patterns. If we're here we can assume this is a box pattern.
                         1
                     } else {
-                        let variant_idx = RustcMatchCheckCtxt::variant_index_for_adt(&ctor, *adt);
+                        let variant_idx = RustcPatCtxt::variant_index_for_adt(&ctor, *adt);
                         adt.variant(variant_idx).fields.len()
                     }
                 }
@@ -506,7 +502,7 @@ impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
                             _ => bug!(),
                         };
                         let variant =
-                            &adt.variant(RustcMatchCheckCtxt::variant_index_for_adt(&ctor, *adt));
+                            &adt.variant(RustcPatCtxt::variant_index_for_adt(&ctor, *adt));
                         arity = variant.fields.len();
                         fields = subpatterns
                             .iter()
@@ -774,8 +770,7 @@ impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
                     PatKind::Deref { subpattern: subpatterns.next().unwrap() }
                 }
                 ty::Adt(adt_def, args) => {
-                    let variant_index =
-                        RustcMatchCheckCtxt::variant_index_for_adt(&pat.ctor(), *adt_def);
+                    let variant_index = RustcPatCtxt::variant_index_for_adt(&pat.ctor(), *adt_def);
                     let subpatterns = subpatterns
                         .enumerate()
                         .map(|(i, pattern)| FieldPat { field: FieldIdx::new(i), pattern })
@@ -843,7 +838,7 @@ impl<'p, 'tcx: 'p> RustcMatchCheckCtxt<'p, 'tcx> {
     }
 }
 
-impl<'p, 'tcx: 'p> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
+impl<'p, 'tcx: 'p> PatCx for RustcPatCtxt<'p, 'tcx> {
     type Ty = RevealedTy<'tcx>;
     type Error = ErrorGuaranteed;
     type VariantIdx = VariantIdx;
diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs
index 0834d08106f..3760db8b688 100644
--- a/compiler/rustc_pattern_analysis/src/usefulness.rs
+++ b/compiler/rustc_pattern_analysis/src/usefulness.rs
@@ -242,7 +242,7 @@
 //! Therefore `usefulness(tp_1, tp_2, tq)` returns the single witness-tuple `[Variant2(Some(true), 0)]`.
 //!
 //!
-//! Computing the set of constructors for a type is done in [`TypeCx::ctors_for_ty`]. See
+//! Computing the set of constructors for a type is done in [`PatCx::ctors_for_ty`]. See
 //! the following sections for more accurate versions of the algorithm and corresponding links.
 //!
 //!
@@ -540,8 +540,8 @@
 //! We track in the algorithm whether a given place is known to contain valid data. This is done
 //! first by inspecting the scrutinee syntactically (which gives us `cx.known_valid_scrutinee`), and
 //! then by tracking validity of each column of the matrix (which correspond to places) as we
-//! recurse into subpatterns. That second part is done through [`ValidityConstraint`], most notably
-//! [`ValidityConstraint::specialize`].
+//! recurse into subpatterns. That second part is done through [`PlaceValidity`], most notably
+//! [`PlaceValidity::specialize`].
 //!
 //! Having said all that, in practice we don't fully follow what's been presented in this section.
 //! Let's call "toplevel exception" the case where the match scrutinee itself has type `!` or
@@ -716,9 +716,9 @@ use std::fmt;
 
 use crate::constructor::{Constructor, ConstructorSet, IntRange};
 use crate::pat::{DeconstructedPat, PatId, PatOrWild, WitnessPat};
-use crate::{Captures, MatchArm, PrivateUninhabitedField, TypeCx};
+use crate::{Captures, MatchArm, PatCx, PrivateUninhabitedField};
 
-use self::ValidityConstraint::*;
+use self::PlaceValidity::*;
 
 #[cfg(feature = "rustc")]
 use rustc_data_structures::stack::ensure_sufficient_stack;
@@ -728,7 +728,7 @@ pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R {
 }
 
 /// Context that provides information for usefulness checking.
-struct UsefulnessCtxt<'a, Cx: TypeCx> {
+struct UsefulnessCtxt<'a, Cx: PatCx> {
     /// The context for type information.
     tycx: &'a Cx,
     /// Collect the patterns found useful during usefulness checking. This is used to lint
@@ -738,7 +738,7 @@ struct UsefulnessCtxt<'a, Cx: TypeCx> {
     complexity_level: usize,
 }
 
-impl<'a, Cx: TypeCx> UsefulnessCtxt<'a, Cx> {
+impl<'a, Cx: PatCx> UsefulnessCtxt<'a, Cx> {
     fn increase_complexity_level(&mut self, complexity_add: usize) -> Result<(), Cx::Error> {
         self.complexity_level += complexity_add;
         if self
@@ -752,26 +752,26 @@ impl<'a, Cx: TypeCx> UsefulnessCtxt<'a, Cx> {
 }
 
 /// Context that provides information local to a place under investigation.
-struct PlaceCtxt<'a, Cx: TypeCx> {
+struct PlaceCtxt<'a, Cx: PatCx> {
     cx: &'a Cx,
     /// Type of the place under investigation.
     ty: &'a Cx::Ty,
 }
 
-impl<'a, Cx: TypeCx> Copy for PlaceCtxt<'a, Cx> {}
-impl<'a, Cx: TypeCx> Clone for PlaceCtxt<'a, Cx> {
+impl<'a, Cx: PatCx> Copy for PlaceCtxt<'a, Cx> {}
+impl<'a, Cx: PatCx> Clone for PlaceCtxt<'a, Cx> {
     fn clone(&self) -> Self {
         Self { cx: self.cx, ty: self.ty }
     }
 }
 
-impl<'a, Cx: TypeCx> fmt::Debug for PlaceCtxt<'a, Cx> {
+impl<'a, Cx: PatCx> fmt::Debug for PlaceCtxt<'a, Cx> {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt.debug_struct("PlaceCtxt").field("ty", self.ty).finish()
     }
 }
 
-impl<'a, Cx: TypeCx> PlaceCtxt<'a, Cx> {
+impl<'a, Cx: PatCx> PlaceCtxt<'a, Cx> {
     fn ctor_arity(&self, ctor: &Constructor<Cx>) -> usize {
         self.cx.ctor_arity(ctor, self.ty)
     }
@@ -780,18 +780,14 @@ impl<'a, Cx: TypeCx> PlaceCtxt<'a, Cx> {
     }
 }
 
-/// Serves two purposes:
-/// - in a wildcard, tracks whether the wildcard matches only valid values (i.e. is a binding `_a`)
-///     or also invalid values (i.e. is a true `_` pattern).
-/// - in the matrix, track whether a given place (aka column) is known to contain a valid value or
-///     not.
+/// Track whether a given place (aka column) is known to contain a valid value or not.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub enum ValidityConstraint {
+pub enum PlaceValidity {
     ValidOnly,
     MaybeInvalid,
 }
 
-impl ValidityConstraint {
+impl PlaceValidity {
     pub fn from_bool(is_valid_only: bool) -> Self {
         if is_valid_only { ValidOnly } else { MaybeInvalid }
     }
@@ -806,7 +802,7 @@ impl ValidityConstraint {
     ///
     /// Pending further opsem decisions, the current behavior is: validity is preserved, except
     /// inside `&` and union fields where validity is reset to `MaybeInvalid`.
-    fn specialize<Cx: TypeCx>(self, ctor: &Constructor<Cx>) -> Self {
+    fn specialize<Cx: PatCx>(self, ctor: &Constructor<Cx>) -> Self {
         // We preserve validity except when we go inside a reference or a union field.
         if matches!(ctor, Constructor::Ref | Constructor::UnionField) {
             // Validity of `x: &T` does not imply validity of `*x: T`.
@@ -817,7 +813,7 @@ impl ValidityConstraint {
     }
 }
 
-impl fmt::Display for ValidityConstraint {
+impl fmt::Display for PlaceValidity {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let s = match self {
             ValidOnly => "✓",
@@ -829,19 +825,19 @@ impl fmt::Display for ValidityConstraint {
 
 /// Data about a place under investigation. Its methods contain a lot of the logic used to analyze
 /// the constructors in the matrix.
-struct PlaceInfo<Cx: TypeCx> {
+struct PlaceInfo<Cx: PatCx> {
     /// The type of the place.
     ty: Cx::Ty,
     /// Whether the place is a private uninhabited field. If so we skip this field during analysis
     /// so that we don't observe its emptiness.
     private_uninhabited: bool,
     /// Whether the place is known to contain valid data.
-    validity: ValidityConstraint,
+    validity: PlaceValidity,
     /// Whether the place is the scrutinee itself or a subplace of it.
     is_scrutinee: bool,
 }
 
-impl<Cx: TypeCx> PlaceInfo<Cx> {
+impl<Cx: PatCx> PlaceInfo<Cx> {
     /// Given a constructor for the current place, we return one `PlaceInfo` for each field of the
     /// constructor.
     fn specialize<'a>(
@@ -936,7 +932,7 @@ impl<Cx: TypeCx> PlaceInfo<Cx> {
     }
 }
 
-impl<Cx: TypeCx> Clone for PlaceInfo<Cx> {
+impl<Cx: PatCx> Clone for PlaceInfo<Cx> {
     fn clone(&self) -> Self {
         Self {
             ty: self.ty.clone(),
@@ -951,7 +947,7 @@ impl<Cx: TypeCx> Clone for PlaceInfo<Cx> {
 // The three lifetimes are:
 // - 'p coming from the input
 // - Cx global compilation context
-struct PatStack<'p, Cx: TypeCx> {
+struct PatStack<'p, Cx: PatCx> {
     // Rows of len 1 are very common, which is why `SmallVec[_; 2]` works well.
     pats: SmallVec<[PatOrWild<'p, Cx>; 2]>,
     /// Sometimes we know that as far as this row is concerned, the current case is already handled
@@ -960,13 +956,13 @@ struct PatStack<'p, Cx: TypeCx> {
     relevant: bool,
 }
 
-impl<'p, Cx: TypeCx> Clone for PatStack<'p, Cx> {
+impl<'p, Cx: PatCx> Clone for PatStack<'p, Cx> {
     fn clone(&self) -> Self {
         Self { pats: self.pats.clone(), relevant: self.relevant }
     }
 }
 
-impl<'p, Cx: TypeCx> PatStack<'p, Cx> {
+impl<'p, Cx: PatCx> PatStack<'p, Cx> {
     fn from_pattern(pat: &'p DeconstructedPat<Cx>) -> Self {
         PatStack { pats: smallvec![PatOrWild::Pat(pat)], relevant: true }
     }
@@ -1026,7 +1022,7 @@ impl<'p, Cx: TypeCx> PatStack<'p, Cx> {
     }
 }
 
-impl<'p, Cx: TypeCx> fmt::Debug for PatStack<'p, Cx> {
+impl<'p, Cx: PatCx> 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, "+")?;
@@ -1039,7 +1035,7 @@ impl<'p, Cx: TypeCx> fmt::Debug for PatStack<'p, Cx> {
 
 /// A row of the matrix.
 #[derive(Clone)]
-struct MatrixRow<'p, Cx: TypeCx> {
+struct MatrixRow<'p, Cx: PatCx> {
     // The patterns in the row.
     pats: PatStack<'p, Cx>,
     /// Whether the original arm had a guard. This is inherited when specializing.
@@ -1059,7 +1055,7 @@ struct MatrixRow<'p, Cx: TypeCx> {
     intersects: BitSet<usize>,
 }
 
-impl<'p, Cx: TypeCx> MatrixRow<'p, Cx> {
+impl<'p, Cx: PatCx> MatrixRow<'p, Cx> {
     fn is_empty(&self) -> bool {
         self.pats.is_empty()
     }
@@ -1108,7 +1104,7 @@ impl<'p, Cx: TypeCx> MatrixRow<'p, Cx> {
     }
 }
 
-impl<'p, Cx: TypeCx> fmt::Debug for MatrixRow<'p, Cx> {
+impl<'p, Cx: PatCx> fmt::Debug for MatrixRow<'p, Cx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.pats.fmt(f)
     }
@@ -1125,7 +1121,7 @@ impl<'p, Cx: TypeCx> fmt::Debug for MatrixRow<'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<'p, Cx: TypeCx> {
+struct Matrix<'p, Cx: PatCx> {
     /// 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.
@@ -1138,7 +1134,7 @@ struct Matrix<'p, Cx: TypeCx> {
     wildcard_row_is_relevant: bool,
 }
 
-impl<'p, Cx: TypeCx> Matrix<'p, Cx> {
+impl<'p, Cx: PatCx> 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, mut row: MatrixRow<'p, Cx>) {
@@ -1155,11 +1151,7 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> {
     }
 
     /// Build a new matrix from an iterator of `MatchArm`s.
-    fn new(
-        arms: &[MatchArm<'p, Cx>],
-        scrut_ty: Cx::Ty,
-        scrut_validity: ValidityConstraint,
-    ) -> Self {
+    fn new(arms: &[MatchArm<'p, Cx>], scrut_ty: Cx::Ty, scrut_validity: PlaceValidity) -> Self {
         let place_info = PlaceInfo {
             ty: scrut_ty,
             private_uninhabited: false,
@@ -1264,7 +1256,7 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> {
 /// + _     + [_, _, tail @ ..] +
 /// | ✓     | ?                 | // column validity
 /// ```
-impl<'p, Cx: TypeCx> fmt::Debug for Matrix<'p, Cx> {
+impl<'p, Cx: PatCx> fmt::Debug for Matrix<'p, Cx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "\n")?;
 
@@ -1355,15 +1347,15 @@ impl<'p, Cx: TypeCx> fmt::Debug for Matrix<'p, Cx> {
 ///
 /// See the top of the file for more detailed explanations and examples.
 #[derive(Debug)]
-struct WitnessStack<Cx: TypeCx>(Vec<WitnessPat<Cx>>);
+struct WitnessStack<Cx: PatCx>(Vec<WitnessPat<Cx>>);
 
-impl<Cx: TypeCx> Clone for WitnessStack<Cx> {
+impl<Cx: PatCx> Clone for WitnessStack<Cx> {
     fn clone(&self) -> Self {
         Self(self.0.clone())
     }
 }
 
-impl<Cx: TypeCx> WitnessStack<Cx> {
+impl<Cx: PatCx> WitnessStack<Cx> {
     /// Asserts that the witness contains a single pattern, and returns it.
     fn single_pattern(self) -> WitnessPat<Cx> {
         assert_eq!(self.0.len(), 1);
@@ -1408,15 +1400,15 @@ impl<Cx: TypeCx> WitnessStack<Cx> {
 /// Just as the `Matrix` starts with a single column, by the end of the algorithm, this has a single
 /// column, which contains the patterns that are missing for the match to be exhaustive.
 #[derive(Debug)]
-struct WitnessMatrix<Cx: TypeCx>(Vec<WitnessStack<Cx>>);
+struct WitnessMatrix<Cx: PatCx>(Vec<WitnessStack<Cx>>);
 
-impl<Cx: TypeCx> Clone for WitnessMatrix<Cx> {
+impl<Cx: PatCx> Clone for WitnessMatrix<Cx> {
     fn clone(&self) -> Self {
         Self(self.0.clone())
     }
 }
 
-impl<Cx: TypeCx> WitnessMatrix<Cx> {
+impl<Cx: PatCx> WitnessMatrix<Cx> {
     /// New matrix with no witnesses.
     fn empty() -> Self {
         WitnessMatrix(Vec::new())
@@ -1490,7 +1482,7 @@ impl<Cx: TypeCx> WitnessMatrix<Cx> {
 ///
 /// We can however get false negatives because exhaustiveness does not explore all cases. See the
 /// section on relevancy at the top of the file.
-fn collect_overlapping_range_endpoints<'p, Cx: TypeCx>(
+fn collect_overlapping_range_endpoints<'p, Cx: PatCx>(
     cx: &Cx,
     overlap_range: IntRange,
     matrix: &Matrix<'p, Cx>,
@@ -1549,7 +1541,7 @@ fn collect_overlapping_range_endpoints<'p, Cx: TypeCx>(
 }
 
 /// Collect ranges that have a singleton gap between them.
-fn collect_non_contiguous_range_endpoints<'p, Cx: TypeCx>(
+fn collect_non_contiguous_range_endpoints<'p, Cx: PatCx>(
     cx: &Cx,
     gap_range: &IntRange,
     matrix: &Matrix<'p, Cx>,
@@ -1590,7 +1582,7 @@ fn collect_non_contiguous_range_endpoints<'p, Cx: TypeCx>(
 ///     (using `apply_constructor` and by updating `row.useful` for each parent row).
 /// This is all explained at the top of the file.
 #[instrument(level = "debug", skip(mcx), ret)]
-fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
+fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: PatCx>(
     mcx: &mut UsefulnessCtxt<'a, Cx>,
     matrix: &mut Matrix<'p, Cx>,
 ) -> Result<WitnessMatrix<Cx>, Cx::Error> {
@@ -1687,7 +1679,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
 
 /// Indicates whether or not a given arm is useful.
 #[derive(Clone, Debug)]
-pub enum Usefulness<'p, Cx: TypeCx> {
+pub enum Usefulness<'p, Cx: PatCx> {
     /// The arm is useful. This additionally carries a set of or-pattern branches that have been
     /// found to be redundant despite the overall arm being useful. Used only in the presence of
     /// or-patterns, otherwise it stays empty.
@@ -1698,11 +1690,11 @@ pub enum Usefulness<'p, Cx: TypeCx> {
 }
 
 /// Report whether this pattern was found useful, and its subpatterns that were not useful if any.
-fn collect_pattern_usefulness<'p, Cx: TypeCx>(
+fn collect_pattern_usefulness<'p, Cx: PatCx>(
     useful_subpatterns: &FxHashSet<PatId>,
     pat: &'p DeconstructedPat<Cx>,
 ) -> Usefulness<'p, Cx> {
-    fn pat_is_useful<'p, Cx: TypeCx>(
+    fn pat_is_useful<'p, Cx: PatCx>(
         useful_subpatterns: &FxHashSet<PatId>,
         pat: &'p DeconstructedPat<Cx>,
     ) -> bool {
@@ -1740,7 +1732,7 @@ fn collect_pattern_usefulness<'p, Cx: TypeCx>(
 }
 
 /// The output of checking a match for exhaustiveness and arm usefulness.
-pub struct UsefulnessReport<'p, Cx: TypeCx> {
+pub struct UsefulnessReport<'p, Cx: PatCx> {
     /// For each arm of the input, whether that arm is useful after the arms above it.
     pub arm_usefulness: Vec<(MatchArm<'p, Cx>, Usefulness<'p, Cx>)>,
     /// If the match is exhaustive, this is empty. If not, this contains witnesses for the lack of
@@ -1750,11 +1742,11 @@ pub struct UsefulnessReport<'p, Cx: TypeCx> {
 
 /// Computes whether a match is exhaustive and which of its arms are useful.
 #[instrument(skip(tycx, arms), level = "debug")]
-pub fn compute_match_usefulness<'p, Cx: TypeCx>(
+pub fn compute_match_usefulness<'p, Cx: PatCx>(
     tycx: &Cx,
     arms: &[MatchArm<'p, Cx>],
     scrut_ty: Cx::Ty,
-    scrut_validity: ValidityConstraint,
+    scrut_validity: PlaceValidity,
     complexity_limit: Option<usize>,
 ) -> Result<UsefulnessReport<'p, Cx>, Cx::Error> {
     let mut cx = UsefulnessCtxt {