Auto merge of rust-lang#94737 - lcnr:pass-stuff-by-value, r=davidtwco

add `#[rustc_pass_by_value]` to more types

the only interesting changes here should be to `TransitiveRelation`, but I believe to be highly unlikely that we will ever use a non `Copy` type with this type.

Author: bors

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -220,8 +220,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             PlaceRef {
                 local,
                 projection:
-                    [
-                        proj_base @ ..,
+                    &[
+                        ref proj_base @ ..,
                         ProjectionElem::Deref,
                         ProjectionElem::Field(field, _),
                         ProjectionElem::Deref,
@@ -342,7 +342,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     Applicability::MachineApplicable,
                 );
                 let tcx = self.infcx.tcx;
-                if let ty::Closure(id, _) = the_place_err.ty(self.body, tcx).ty.kind() {
+                if let ty::Closure(id, _) = *the_place_err.ty(self.body, tcx).ty.kind() {
                     self.show_mutating_upvar(tcx, id, the_place_err, &mut err);
                 }
             }
@@ -382,7 +382,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 let tcx = self.infcx.tcx;
                 if let ty::Ref(_, ty, Mutability::Mut) = the_place_err.ty(self.body, tcx).ty.kind()
                 {
-                    if let ty::Closure(id, _) = ty.kind() {
+                    if let ty::Closure(id, _) = *ty.kind() {
                         self.show_mutating_upvar(tcx, id, the_place_err, &mut err);
                     }
                 }
@@ -687,7 +687,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn show_mutating_upvar(
         &self,
         tcx: TyCtxt<'_>,
-        id: &hir::def_id::DefId,
+        id: hir::def_id::DefId,
         the_place_err: PlaceRef<'tcx>,
         err: &mut Diagnostic,
     ) {
@@ -701,7 +701,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 let upvar = ty::place_to_string_for_capture(tcx, closure_kind_origin);
                 let root_hir_id = upvar_id.var_path.hir_id;
                 // we have an origin for this closure kind starting at this root variable so it's safe to unwrap here
-                let captured_places = tables.closure_min_captures[id].get(&root_hir_id).unwrap();
+                let captured_places = tables.closure_min_captures[&id].get(&root_hir_id).unwrap();
 
                 let origin_projection = closure_kind_origin
                     .projections
@@ -1083,7 +1083,7 @@ fn is_closure_or_generator(ty: Ty<'_>) -> bool {
 fn get_mut_span_in_struct_field<'tcx>(
     tcx: TyCtxt<'tcx>,
     ty: Ty<'tcx>,
-    field: &mir::Field,
+    field: mir::Field,
 ) -> Option<Span> {
     // Expect our local to be a reference to a struct of some kind.
     if let ty::Ref(_, ty, _) = ty.kind()

compiler/rustc_borrowck/src/location.rs

@@ -100,7 +100,7 @@ impl LocationTable {
 }
 
 impl LocationIndex {
-    fn is_start(&self) -> bool {
+    fn is_start(self) -> bool {
         // even indices are start points; odd indices are mid points
         (self.index() % 2) == 0
     }

compiler/rustc_borrowck/src/nll.rs

@@ -85,7 +85,7 @@ fn populate_polonius_move_facts(
 ) {
     all_facts
         .path_is_var
-        .extend(move_data.rev_lookup.iter_locals_enumerated().map(|(v, &m)| (m, v)));
+        .extend(move_data.rev_lookup.iter_locals_enumerated().map(|(l, r)| (r, l)));
 
     for (child, move_path) in move_data.move_paths.iter_enumerated() {
         if let Some(parent) = move_path.parent {
@@ -135,7 +135,7 @@ fn populate_polonius_move_facts(
         }
     }
 
-    for (local, &path) in move_data.rev_lookup.iter_locals_enumerated() {
+    for (local, path) in move_data.rev_lookup.iter_locals_enumerated() {
         if body.local_kind(local) != LocalKind::Arg {
             // Non-arguments start out deinitialised; we simulate this with an
             // initial move:
@@ -226,7 +226,7 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
                      fr1={:?}, fr2={:?}",
                     fr1, fr2
                 );
-                all_facts.known_placeholder_subset.push((*fr1, *fr2));
+                all_facts.known_placeholder_subset.push((fr1, fr2));
             }
         }
     }

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -942,14 +942,14 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
             debug!("try_promote_type_test: ur={:?}", ur);
 
-            let non_local_ub = self.universal_region_relations.non_local_upper_bounds(&ur);
+            let non_local_ub = self.universal_region_relations.non_local_upper_bounds(ur);
             debug!("try_promote_type_test: non_local_ub={:?}", non_local_ub);
 
             // This is slightly too conservative. To show T: '1, given `'2: '1`
             // and `'3: '1` we only need to prove that T: '2 *or* T: '3, but to
             // avoid potential non-determinism we approximate this by requiring
             // T: '1 and T: '2.
-            for &upper_bound in non_local_ub {
+            for upper_bound in non_local_ub {
                 debug_assert!(self.universal_regions.is_universal_region(upper_bound));
                 debug_assert!(!self.universal_regions.is_local_free_region(upper_bound));
 
@@ -1588,12 +1588,12 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 // always will.)  We'll call them `shorter_fr+` -- they're ever
                 // so slightly larger than `shorter_fr`.
                 let shorter_fr_plus =
-                    self.universal_region_relations.non_local_upper_bounds(&shorter_fr);
+                    self.universal_region_relations.non_local_upper_bounds(shorter_fr);
                 debug!(
                     "try_propagate_universal_region_error: shorter_fr_plus={:?}",
                     shorter_fr_plus
                 );
-                for &&fr in &shorter_fr_plus {
+                for fr in shorter_fr_plus {
                     // Push the constraint `fr-: shorter_fr+`
                     propagated_outlives_requirements.push(ClosureOutlivesRequirement {
                         subject: ClosureOutlivesSubject::Region(fr_minus),

compiler/rustc_borrowck/src/type_check/free_region_relations.rs

@@ -99,18 +99,17 @@ impl UniversalRegionRelations<'_> {
     crate fn postdom_upper_bound(&self, fr1: RegionVid, fr2: RegionVid) -> RegionVid {
         assert!(self.universal_regions.is_universal_region(fr1));
         assert!(self.universal_regions.is_universal_region(fr2));
-        *self
-            .inverse_outlives
-            .postdom_upper_bound(&fr1, &fr2)
-            .unwrap_or(&self.universal_regions.fr_static)
+        self.inverse_outlives
+            .postdom_upper_bound(fr1, fr2)
+            .unwrap_or(self.universal_regions.fr_static)
     }
 
     /// Finds an "upper bound" for `fr` that is not local. In other
     /// words, returns the smallest (*) known region `fr1` that (a)
     /// outlives `fr` and (b) is not local.
     ///
     /// (*) If there are multiple competing choices, we return all of them.
-    crate fn non_local_upper_bounds<'a>(&'a self, fr: &'a RegionVid) -> Vec<&'a RegionVid> {
+    crate fn non_local_upper_bounds<'a>(&'a self, fr: RegionVid) -> Vec<RegionVid> {
         debug!("non_local_upper_bound(fr={:?})", fr);
         let res = self.non_local_bounds(&self.inverse_outlives, fr);
         assert!(!res.is_empty(), "can't find an upper bound!?");
@@ -120,7 +119,7 @@ impl UniversalRegionRelations<'_> {
     /// Returns the "postdominating" bound of the set of
     /// `non_local_upper_bounds` for the given region.
     crate fn non_local_upper_bound(&self, fr: RegionVid) -> RegionVid {
-        let upper_bounds = self.non_local_upper_bounds(&fr);
+        let upper_bounds = self.non_local_upper_bounds(fr);
 
         // In case we find more than one, reduce to one for
         // convenience.  This is to prevent us from generating more
@@ -130,7 +129,7 @@ impl UniversalRegionRelations<'_> {
         debug!("non_local_bound: post_dom={:?}", post_dom);
 
         post_dom
-            .and_then(|&post_dom| {
+            .and_then(|post_dom| {
                 // If the mutual immediate postdom is not local, then
                 // there is no non-local result we can return.
                 if !self.universal_regions.is_local_free_region(post_dom) {
@@ -150,7 +149,7 @@ impl UniversalRegionRelations<'_> {
     /// one. See `TransitiveRelation::postdom_upper_bound` for details.
     crate fn non_local_lower_bound(&self, fr: RegionVid) -> Option<RegionVid> {
         debug!("non_local_lower_bound(fr={:?})", fr);
-        let lower_bounds = self.non_local_bounds(&self.outlives, &fr);
+        let lower_bounds = self.non_local_bounds(&self.outlives, fr);
 
         // In case we find more than one, reduce to one for
         // convenience.  This is to prevent us from generating more
@@ -159,7 +158,7 @@ impl UniversalRegionRelations<'_> {
 
         debug!("non_local_bound: post_dom={:?}", post_dom);
 
-        post_dom.and_then(|&post_dom| {
+        post_dom.and_then(|post_dom| {
             // If the mutual immediate postdom is not local, then
             // there is no non-local result we can return.
             if !self.universal_regions.is_local_free_region(post_dom) {
@@ -176,19 +175,19 @@ impl UniversalRegionRelations<'_> {
     fn non_local_bounds<'a>(
         &self,
         relation: &'a TransitiveRelation<RegionVid>,
-        fr0: &'a RegionVid,
-    ) -> Vec<&'a RegionVid> {
+        fr0: RegionVid,
+    ) -> Vec<RegionVid> {
         // This method assumes that `fr0` is one of the universally
         // quantified region variables.
-        assert!(self.universal_regions.is_universal_region(*fr0));
+        assert!(self.universal_regions.is_universal_region(fr0));
 
         let mut external_parents = vec![];
         let mut queue = vec![fr0];
 
         // Keep expanding `fr` into its parents until we reach
         // non-local regions.
         while let Some(fr) = queue.pop() {
-            if !self.universal_regions.is_local_free_region(*fr) {
+            if !self.universal_regions.is_local_free_region(fr) {
                 external_parents.push(fr);
                 continue;
             }
@@ -205,17 +204,17 @@ impl UniversalRegionRelations<'_> {
     ///
     /// This will only ever be true for universally quantified regions.
     crate fn outlives(&self, fr1: RegionVid, fr2: RegionVid) -> bool {
-        self.outlives.contains(&fr1, &fr2)
+        self.outlives.contains(fr1, fr2)
     }
 
     /// Returns a vector of free regions `x` such that `fr1: x` is
     /// known to hold.
-    crate fn regions_outlived_by(&self, fr1: RegionVid) -> Vec<&RegionVid> {
-        self.outlives.reachable_from(&fr1)
+    crate fn regions_outlived_by(&self, fr1: RegionVid) -> Vec<RegionVid> {
+        self.outlives.reachable_from(fr1)
     }
 
     /// Returns the _non-transitive_ set of known `outlives` constraints between free regions.
-    crate fn known_outlives(&self) -> impl Iterator<Item = (&RegionVid, &RegionVid)> {
+    crate fn known_outlives(&self) -> impl Iterator<Item = (RegionVid, RegionVid)> + '_ {
         self.outlives.base_edges()
     }
 }

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1198,7 +1198,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 tcx,
                 self.param_env,
                 proj,
-                |this, field, &()| {
+                |this, field, ()| {
                     let ty = this.field_ty(tcx, field);
                     self.normalize(ty, locations)
                 },

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -90,7 +90,7 @@ impl<'ll, 'tcx> CoverageInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     /// call. Since the function is never called, all other `CodeRegion`s can be
     /// added as `unreachable_region`s.
     fn define_unused_fn(&self, def_id: DefId) {
-        let instance = declare_unused_fn(self, &def_id);
+        let instance = declare_unused_fn(self, def_id);
         codegen_unused_fn_and_counter(self, instance);
         add_unused_function_coverage(self, instance, def_id);
     }
@@ -184,12 +184,12 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
     }
 }
 
-fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: &DefId) -> Instance<'tcx> {
+fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<'tcx> {
     let tcx = cx.tcx;
 
     let instance = Instance::new(
-        *def_id,
-        InternalSubsts::for_item(tcx, *def_id, |param, _| {
+        def_id,
+        InternalSubsts::for_item(tcx, def_id, |param, _| {
             if let ty::GenericParamDefKind::Lifetime = param.kind {
                 tcx.lifetimes.re_erased.into()
             } else {

compiler/rustc_data_structures/src/transitive_relation.rs

@@ -49,7 +49,7 @@ struct Edge {
     target: Index,
 }
 
-impl<T: Eq + Hash> TransitiveRelation<T> {
+impl<T: Eq + Hash + Copy> TransitiveRelation<T> {
     pub fn is_empty(&self) -> bool {
         self.edges.is_empty()
     }
@@ -58,8 +58,8 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
         self.elements.iter()
     }
 
-    fn index(&self, a: &T) -> Option<Index> {
-        self.elements.get_index_of(a).map(Index)
+    fn index(&self, a: T) -> Option<Index> {
+        self.elements.get_index_of(&a).map(Index)
     }
 
     fn add_index(&mut self, a: T) -> Index {
@@ -76,12 +76,12 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
     /// `None`.
     pub fn maybe_map<F, U>(&self, mut f: F) -> Option<TransitiveRelation<U>>
     where
-        F: FnMut(&T) -> Option<U>,
-        U: Clone + Debug + Eq + Hash + Clone,
+        F: FnMut(T) -> Option<U>,
+        U: Clone + Debug + Eq + Hash + Copy,
     {
         let mut result = TransitiveRelation::default();
         for edge in &self.edges {
-            result.add(f(&self.elements[edge.source.0])?, f(&self.elements[edge.target.0])?);
+            result.add(f(self.elements[edge.source.0])?, f(self.elements[edge.target.0])?);
         }
         Some(result)
     }
@@ -100,7 +100,7 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
     }
 
     /// Checks whether `a < target` (transitively)
-    pub fn contains(&self, a: &T, b: &T) -> bool {
+    pub fn contains(&self, a: T, b: T) -> bool {
         match (self.index(a), self.index(b)) {
             (Some(a), Some(b)) => self.with_closure(|closure| closure.contains(a.0, b.0)),
             (None, _) | (_, None) => false,
@@ -113,10 +113,10 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
     /// Really this probably ought to be `impl Iterator<Item = &T>`, but
     /// I'm too lazy to make that work, and -- given the caching
     /// strategy -- it'd be a touch tricky anyhow.
-    pub fn reachable_from(&self, a: &T) -> Vec<&T> {
+    pub fn reachable_from(&self, a: T) -> Vec<T> {
         match self.index(a) {
             Some(a) => {
-                self.with_closure(|closure| closure.iter(a.0).map(|i| &self.elements[i]).collect())
+                self.with_closure(|closure| closure.iter(a.0).map(|i| self.elements[i]).collect())
             }
             None => vec![],
         }
@@ -157,15 +157,15 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
     /// a -> a1
     /// b -> b1
     /// ```
-    pub fn postdom_upper_bound(&self, a: &T, b: &T) -> Option<&T> {
+    pub fn postdom_upper_bound(&self, a: T, b: T) -> Option<T> {
         let mubs = self.minimal_upper_bounds(a, b);
         self.mutual_immediate_postdominator(mubs)
     }
 
     /// Viewing the relation as a graph, computes the "mutual
     /// immediate postdominator" of a set of points (if one
     /// exists). See `postdom_upper_bound` for details.
-    pub fn mutual_immediate_postdominator<'a>(&'a self, mut mubs: Vec<&'a T>) -> Option<&'a T> {
+    pub fn mutual_immediate_postdominator<'a>(&'a self, mut mubs: Vec<T>) -> Option<T> {
         loop {
             match mubs.len() {
                 0 => return None,
@@ -189,7 +189,7 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
     ///     internal indices).
     ///
     /// Note that this set can, in principle, have any size.
-    pub fn minimal_upper_bounds(&self, a: &T, b: &T) -> Vec<&T> {
+    pub fn minimal_upper_bounds(&self, a: T, b: T) -> Vec<T> {
         let (Some(mut a), Some(mut b)) = (self.index(a), self.index(b)) else {
             return vec![];
         };
@@ -267,7 +267,7 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
         lub_indices
             .into_iter()
             .rev() // (4)
-            .map(|i| &self.elements[i])
+            .map(|i| self.elements[i])
             .collect()
     }
 
@@ -290,7 +290,7 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
     ///
     /// then `parents(a)` returns `[b, c]`. The `postdom_parent` function
     /// would further reduce this to just `f`.
-    pub fn parents(&self, a: &T) -> Vec<&T> {
+    pub fn parents(&self, a: T) -> Vec<T> {
         let Some(a) = self.index(a) else {
             return vec![];
         };
@@ -314,7 +314,7 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
         ancestors
             .into_iter()
             .rev() // (4)
-            .map(|i| &self.elements[i])
+            .map(|i| self.elements[i])
             .collect()
     }
 
@@ -350,10 +350,10 @@ impl<T: Eq + Hash> TransitiveRelation<T> {
 
     /// Lists all the base edges in the graph: the initial _non-transitive_ set of element
     /// relations, which will be later used as the basis for the transitive closure computation.
-    pub fn base_edges(&self) -> impl Iterator<Item = (&T, &T)> {
+    pub fn base_edges(&self) -> impl Iterator<Item = (T, T)> + '_ {
         self.edges
             .iter()
-            .map(move |edge| (&self.elements[edge.source.0], &self.elements[edge.target.0]))
+            .map(move |edge| (self.elements[edge.source.0], self.elements[edge.target.0]))
     }
 }