pattern_analysis: Remove Ty: Copy bound

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -1130,7 +1130,7 @@ fn collect_non_exhaustive_tys<'tcx>(
         non_exhaustive_tys.insert(pat.ty().inner());
     }
     if let Constructor::IntRange(range) = pat.ctor() {
-        if cx.is_range_beyond_boundaries(range, pat.ty()) {
+        if cx.is_range_beyond_boundaries(range, *pat.ty()) {
             // The range denotes the values before `isize::MIN` or the values after `usize::MAX`/`isize::MAX`.
             non_exhaustive_tys.insert(pat.ty().inner());
         }

compiler/rustc_pattern_analysis/src/lib.rs

@@ -82,7 +82,7 @@ impl<'a, T: ?Sized> Captures<'a> for T {}
 /// Most of the crate is parameterized on a type that implements this trait.
 pub trait TypeCx: Sized + fmt::Debug {
     /// The type of a pattern.
-    type Ty: Copy + Clone + fmt::Debug; // FIXME: remove Copy
+    type Ty: Clone + fmt::Debug;
     /// Errors that can abort analysis.
     type Error: fmt::Debug;
     /// The index of an enum variant.
@@ -97,16 +97,16 @@ pub trait TypeCx: Sized + fmt::Debug {
     fn is_exhaustive_patterns_feature_on(&self) -> bool;
 
     /// The number of fields for this constructor.
-    fn ctor_arity(&self, ctor: &Constructor<Self>, ty: Self::Ty) -> usize;
+    fn ctor_arity(&self, ctor: &Constructor<Self>, ty: &Self::Ty) -> usize;
 
     /// The types of the fields for this constructor. The result must have a length of
     /// `ctor_arity()`.
-    fn ctor_sub_tys(&self, ctor: &Constructor<Self>, ty: Self::Ty) -> &[Self::Ty];
+    fn ctor_sub_tys(&self, ctor: &Constructor<Self>, ty: &Self::Ty) -> &[Self::Ty];
 
     /// The set of all the constructors for `ty`.
     ///
     /// This must follow the invariants of `ConstructorSet`
-    fn ctors_for_ty(&self, ty: Self::Ty) -> Result<ConstructorSet<Self>, Self::Error>;
+    fn ctors_for_ty(&self, ty: &Self::Ty) -> Result<ConstructorSet<Self>, Self::Error>;
 
     /// Best-effort `Debug` implementation.
     fn debug_pat(f: &mut fmt::Formatter<'_>, pat: &DeconstructedPat<'_, Self>) -> fmt::Result;

compiler/rustc_pattern_analysis/src/lints.rs

@@ -46,7 +46,7 @@ impl<'p, 'tcx> PatternColumn<'p, 'tcx> {
     }
 
     fn head_ty(&self) -> Option<RevealedTy<'tcx>> {
-        self.patterns.first().map(|pat| pat.ty())
+        self.patterns.first().map(|pat| *pat.ty())
     }
 
     /// Do constructor splitting on the constructors of the column.
@@ -101,7 +101,7 @@ fn collect_nonexhaustive_missing_variants<'a, 'p, 'tcx>(
     let Some(ty) = column.head_ty() else {
         return Ok(Vec::new());
     };
-    let pcx = &PlaceCtxt::new_dummy(cx, ty);
+    let pcx = &PlaceCtxt::new_dummy(cx, &ty);
 
     let set = column.analyze_ctors(pcx)?;
     if set.present.is_empty() {

compiler/rustc_pattern_analysis/src/pat.rs

@@ -54,8 +54,8 @@ impl<'p, Cx: TypeCx> DeconstructedPat<'p, Cx> {
     pub fn ctor(&self) -> &Constructor<Cx> {
         &self.ctor
     }
-    pub fn ty(&self) -> Cx::Ty {
-        self.ty
+    pub fn ty(&self) -> &Cx::Ty {
+        &self.ty
     }
     /// Returns the extra data stored in a pattern. Returns `None` if the pattern is a wildcard that
     /// does not correspond to a user-supplied pattern.
@@ -242,15 +242,15 @@ impl<Cx: TypeCx> WitnessPat<Cx> {
     /// `Some(_)`.
     pub(crate) fn wild_from_ctor(pcx: &PlaceCtxt<'_, Cx>, ctor: Constructor<Cx>) -> Self {
         let field_tys = pcx.ctor_sub_tys(&ctor);
-        let fields = field_tys.iter().map(|ty| Self::wildcard(*ty)).collect();
-        Self::new(ctor, fields, pcx.ty)
+        let fields = field_tys.iter().cloned().map(|ty| Self::wildcard(ty)).collect();
+        Self::new(ctor, fields, pcx.ty.clone())
     }
 
     pub fn ctor(&self) -> &Constructor<Cx> {
         &self.ctor
     }
-    pub fn ty(&self) -> Cx::Ty {
-        self.ty
+    pub fn ty(&self) -> &Cx::Ty {
+        &self.ty
     }
 
     pub fn iter_fields(&self) -> impl Iterator<Item = &WitnessPat<Cx>> {

compiler/rustc_pattern_analysis/src/rustc.rs

@@ -766,7 +766,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
         let mut subpatterns = pat.iter_fields().map(|p| Box::new(cx.hoist_witness_pat(p)));
         let kind = match pat.ctor() {
             Bool(b) => PatKind::Constant { value: mir::Const::from_bool(cx.tcx, *b) },
-            IntRange(range) => return self.hoist_pat_range(range, pat.ty()),
+            IntRange(range) => return self.hoist_pat_range(range, *pat.ty()),
             Struct | Variant(_) | UnionField => match pat.ty().kind() {
                 ty::Tuple(..) => PatKind::Leaf {
                     subpatterns: subpatterns
@@ -785,7 +785,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                         RustcMatchCheckCtxt::variant_index_for_adt(&pat.ctor(), *adt_def);
                     let variant = &adt_def.variant(variant_index);
                     let subpatterns = cx
-                        .list_variant_nonhidden_fields(pat.ty(), variant)
+                        .list_variant_nonhidden_fields(*pat.ty(), variant)
                         .zip(subpatterns)
                         .map(|((field, _ty), pattern)| FieldPat { field, pattern })
                         .collect();
@@ -796,7 +796,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                         PatKind::Leaf { subpatterns }
                     }
                 }
-                _ => bug!("unexpected ctor for type {:?} {:?}", pat.ctor(), pat.ty()),
+                _ => bug!("unexpected ctor for type {:?} {:?}", pat.ctor(), *pat.ty()),
             },
             // 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
@@ -961,21 +961,21 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
         self.tcx.features().exhaustive_patterns
     }
 
-    fn ctor_arity(&self, ctor: &crate::constructor::Constructor<Self>, ty: Self::Ty) -> usize {
-        self.ctor_arity(ctor, ty)
+    fn ctor_arity(&self, ctor: &crate::constructor::Constructor<Self>, ty: &Self::Ty) -> usize {
+        self.ctor_arity(ctor, *ty)
     }
     fn ctor_sub_tys(
         &self,
         ctor: &crate::constructor::Constructor<Self>,
-        ty: Self::Ty,
+        ty: &Self::Ty,
     ) -> &[Self::Ty] {
-        self.ctor_sub_tys(ctor, ty)
+        self.ctor_sub_tys(ctor, *ty)
     }
     fn ctors_for_ty(
         &self,
-        ty: Self::Ty,
+        ty: &Self::Ty,
     ) -> Result<crate::constructor::ConstructorSet<Self>, Self::Error> {
-        self.ctors_for_ty(ty)
+        self.ctors_for_ty(*ty)
     }
 
     fn debug_pat(
@@ -994,7 +994,7 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
         overlaps_on: IntRange,
         overlaps_with: &[&crate::pat::DeconstructedPat<'_, Self>],
     ) {
-        let overlap_as_pat = self.hoist_pat_range(&overlaps_on, pat.ty());
+        let overlap_as_pat = self.hoist_pat_range(&overlaps_on, *pat.ty());
         let overlaps: Vec<_> = overlaps_with
             .iter()
             .map(|pat| pat.data().unwrap().span)

compiler/rustc_pattern_analysis/src/usefulness.rs

@@ -736,13 +736,14 @@ pub(crate) struct PlaceCtxt<'a, Cx: TypeCx> {
     #[derivative(Debug = "ignore")]
     pub(crate) mcx: MatchCtxt<'a, Cx>,
     /// Type of the place under investigation.
-    pub(crate) ty: Cx::Ty,
+    #[derivative(Clone(clone_with = "Clone::clone"))] // See rust-derivative#90
+    pub(crate) ty: &'a Cx::Ty,
 }
 
 impl<'a, Cx: TypeCx> PlaceCtxt<'a, Cx> {
     /// A `PlaceCtxt` when code other than `is_useful` needs one.
     #[cfg_attr(not(feature = "rustc"), allow(dead_code))]
-    pub(crate) fn new_dummy(mcx: MatchCtxt<'a, Cx>, ty: Cx::Ty) -> Self {
+    pub(crate) fn new_dummy(mcx: MatchCtxt<'a, Cx>, ty: &'a Cx::Ty) -> Self {
         PlaceCtxt { mcx, ty }
     }
 
@@ -1023,8 +1024,8 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> {
         matrix
     }
 
-    fn head_ty(&self) -> Option<Cx::Ty> {
-        self.place_ty.first().copied()
+    fn head_ty(&self) -> Option<&Cx::Ty> {
+        self.place_ty.first()
     }
     fn column_count(&self) -> usize {
         self.place_ty.len()
@@ -1058,7 +1059,7 @@ impl<'p, Cx: TypeCx> Matrix<'p, Cx> {
         let ctor_sub_tys = pcx.ctor_sub_tys(ctor);
         let arity = ctor_sub_tys.len();
         let specialized_place_ty =
-            ctor_sub_tys.iter().chain(self.place_ty[1..].iter()).copied().collect();
+            ctor_sub_tys.iter().chain(self.place_ty[1..].iter()).cloned().collect();
         let ctor_sub_validity = self.place_validity[0].specialize(ctor);
         let specialized_place_validity = std::iter::repeat(ctor_sub_validity)
             .take(arity)
@@ -1214,7 +1215,7 @@ impl<Cx: TypeCx> WitnessStack<Cx> {
         let len = self.0.len();
         let arity = ctor.arity(pcx);
         let fields = self.0.drain((len - arity)..).rev().collect();
-        let pat = WitnessPat::new(ctor.clone(), fields, pcx.ty);
+        let pat = WitnessPat::new(ctor.clone(), fields, pcx.ty.clone());
         self.0.push(pat);
     }
 }
@@ -1410,7 +1411,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
         return Ok(WitnessMatrix::empty());
     }
 
-    let Some(ty) = matrix.head_ty() else {
+    let Some(ty) = matrix.head_ty().cloned() else {
         // The base case: there are no columns in the matrix. We are morally pattern-matching on ().
         // A row is useful iff it has no (unguarded) rows above it.
         let mut useful = true; // Whether the next row is useful.
@@ -1431,7 +1432,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
     };
 
     debug!("ty: {ty:?}");
-    let pcx = &PlaceCtxt { mcx, ty };
+    let pcx = &PlaceCtxt { mcx, ty: &ty };
     let ctors_for_ty = pcx.ctors_for_ty()?;
 
     // Whether the place/column we are inspecting is known to contain valid data.