Clean up dead code

Author: Nadrieril

Diff for: compiler/rustc_pattern_analysis/src/constructor.rs

@@ -858,12 +858,14 @@ impl<Cx: TypeCx> ConstructorSet<Cx> {
     /// 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
     /// and its invariants.
-    #[instrument(level = "debug", skip(self, pcx, ctors), ret)]
+    #[instrument(level = "debug", skip(self, ctors), ret)]
     pub(crate) fn split<'a>(
         &self,
-        pcx: &PlaceCtxt<'a, '_, Cx>,
         ctors: impl Iterator<Item = &'a Constructor<Cx>> + Clone,
-    ) -> SplitConstructorSet<Cx> {
+    ) -> SplitConstructorSet<Cx>
+    where
+        Cx: 'a,
+    {
         let mut present: SmallVec<[_; 1]> = SmallVec::new();
         // Empty constructors found missing.
         let mut missing_empty = Vec::new();

Diff for: compiler/rustc_pattern_analysis/src/lints.rs

@@ -54,7 +54,7 @@ impl<'p, 'tcx> PatternColumn<'p, 'tcx> {
     /// Do constructor splitting on the constructors of the column.
     fn analyze_ctors(&self, pcx: &PlaceCtxt<'_, 'p, 'tcx>) -> SplitConstructorSet<'p, 'tcx> {
         let column_ctors = self.patterns.iter().map(|p| p.ctor());
-        pcx.ctors_for_ty().split(pcx, column_ctors)
+        pcx.ctors_for_ty().split(column_ctors)
     }
 
     fn iter(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Captures<'_> {

Diff for: compiler/rustc_pattern_analysis/src/usefulness.rs

@@ -736,15 +736,13 @@ pub(crate) struct PlaceCtxt<'a, 'p, Cx: TypeCx> {
     pub(crate) mcx: MatchCtxt<'a, 'p, Cx>,
     /// Type of the place under investigation.
     pub(crate) ty: Cx::Ty,
-    /// Whether the place is the original scrutinee place, as opposed to a subplace of it.
-    pub(crate) is_scrutinee: bool,
 }
 
 impl<'a, 'p, Cx: TypeCx> PlaceCtxt<'a, 'p, 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, 'p, Cx>, ty: Cx::Ty) -> Self {
-        PlaceCtxt { mcx, ty, is_scrutinee: false }
+        PlaceCtxt { mcx, ty }
     }
 
     pub(crate) fn ctor_arity(&self, ctor: &Constructor<Cx>) -> usize {
@@ -767,30 +765,16 @@ impl<'a, 'p, Cx: TypeCx> PlaceCtxt<'a, 'p, Cx> {
 pub enum ValidityConstraint {
     ValidOnly,
     MaybeInvalid,
-    /// Option for backwards compatibility: the place is not known to be valid but we allow omitting
-    /// `useful && !reachable` arms anyway.
-    MaybeInvalidButAllowOmittingArms,
 }
 
 impl ValidityConstraint {
     pub fn from_bool(is_valid_only: bool) -> Self {
         if is_valid_only { ValidOnly } else { MaybeInvalid }
     }
 
-    fn allow_omitting_side_effecting_arms(self) -> Self {
-        match self {
-            MaybeInvalid | MaybeInvalidButAllowOmittingArms => MaybeInvalidButAllowOmittingArms,
-            // There are no side-effecting empty arms here, nothing to do.
-            ValidOnly => ValidOnly,
-        }
-    }
-
     fn is_known_valid(self) -> bool {
         matches!(self, ValidOnly)
     }
-    fn allows_omitting_empty_arms(self) -> bool {
-        matches!(self, ValidOnly | MaybeInvalidButAllowOmittingArms)
-    }
 
     /// If the place has validity given by `self` and we read that the value at the place has
     /// constructor `ctor`, this computes what we can assume about the validity of the constructor
@@ -813,7 +797,7 @@ impl fmt::Display for ValidityConstraint {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let s = match self {
             ValidOnly => "✓",
-            MaybeInvalid | MaybeInvalidButAllowOmittingArms => "?",
+            MaybeInvalid => "?",
         };
         write!(f, "{s}")
     }
@@ -1374,7 +1358,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
     };
 
     debug!("ty: {ty:?}");
-    let pcx = &PlaceCtxt { mcx, ty, is_scrutinee: is_top_level };
+    let pcx = &PlaceCtxt { mcx, ty };
     let ctors_for_ty = pcx.ctors_for_ty();
     // Whether the place/column we are inspecting is known to contain valid data.
     let place_validity = matrix.place_validity[0];
@@ -1390,7 +1374,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
 
     // Analyze the constructors present in this column.
     let ctors = matrix.heads().map(|p| p.ctor());
-    let split_set = ctors_for_ty.split(pcx, ctors);
+    let split_set = ctors_for_ty.split(ctors);
     let all_missing = split_set.present.is_empty();
     // Build the set of constructors we will specialize with. It must cover the whole type.
     let mut split_ctors = split_set.present;