Auto merge of #54743 - ljedrz:cleanup_ty_p2, r=zackmdavis

Cleanup rustc/ty part 2

The second part of cleanups and minor improvements for rustc/ty.
- improve allocations
- calculate span after a possible early continue
- simplify some patterns
- mark a comment as FIXME
- whitespace fixes

The PR is independent from from the first part.

src/librustc/ty/fold.rs

@@ -782,11 +782,10 @@ impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector {
     }
 
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
-        match *r {
-            ty::ReLateBound(debruijn, br) if debruijn == self.current_index => {
+        if let ty::ReLateBound(debruijn, br) = *r {
+             if debruijn == self.current_index {
                 self.regions.insert(br);
             }
-            _ => { }
         }
         false
     }

src/librustc/ty/instance.rs

@@ -231,11 +231,11 @@ impl<'a, 'b, 'tcx> Instance<'tcx> {
     }
 
     pub fn resolve_closure(
-                    tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                    def_id: DefId,
-                    substs: ty::ClosureSubsts<'tcx>,
-                    requested_kind: ty::ClosureKind)
-    -> Instance<'tcx>
+        tcx: TyCtxt<'a, 'tcx, 'tcx>,
+        def_id: DefId,
+        substs: ty::ClosureSubsts<'tcx>,
+        requested_kind: ty::ClosureKind)
+        -> Instance<'tcx>
     {
         let actual_kind = substs.closure_kind(def_id, tcx);
 
@@ -255,8 +255,8 @@ fn resolve_associated_item<'a, 'tcx>(
 ) -> Option<Instance<'tcx>> {
     let def_id = trait_item.def_id;
     debug!("resolve_associated_item(trait_item={:?}, \
-                                    trait_id={:?}, \
-           rcvr_substs={:?})",
+            trait_id={:?}, \
+            rcvr_substs={:?})",
            def_id, trait_id, rcvr_substs);
 
     let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
@@ -280,7 +280,7 @@ fn resolve_associated_item<'a, 'tcx>(
         traits::VtableClosure(closure_data) => {
             let trait_closure_kind = tcx.lang_items().fn_trait_kind(trait_id).unwrap();
             Some(Instance::resolve_closure(tcx, closure_data.closure_def_id, closure_data.substs,
-                                 trait_closure_kind))
+                                           trait_closure_kind))
         }
         traits::VtableFnPointer(ref data) => {
             Some(Instance {
@@ -310,7 +310,7 @@ fn resolve_associated_item<'a, 'tcx>(
 }
 
 fn needs_fn_once_adapter_shim<'a, 'tcx>(actual_closure_kind: ty::ClosureKind,
-                              trait_closure_kind: ty::ClosureKind)
+                                        trait_closure_kind: ty::ClosureKind)
     -> Result<bool, ()>
 {
     match (actual_closure_kind, trait_closure_kind) {
@@ -344,13 +344,14 @@ fn needs_fn_once_adapter_shim<'a, 'tcx>(actual_closure_kind: ty::ClosureKind,
 }
 
 fn fn_once_adapter_instance<'a, 'tcx>(
-                            tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                            closure_did: DefId,
-                            substs: ty::ClosureSubsts<'tcx>,
-                            ) -> Instance<'tcx> {
+    tcx: TyCtxt<'a, 'tcx, 'tcx>,
+    closure_did: DefId,
+    substs: ty::ClosureSubsts<'tcx>)
+    -> Instance<'tcx>
+{
     debug!("fn_once_adapter_shim({:?}, {:?})",
-    closure_did,
-    substs);
+           closure_did,
+           substs);
     let fn_once = tcx.lang_items().fn_once_trait().unwrap();
     let call_once = tcx.associated_items(fn_once)
         .find(|it| it.kind == ty::AssociatedKind::Method)

src/librustc/ty/item_path.rs

@@ -221,7 +221,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
             let data = cur_def_key.disambiguated_data.data;
             let symbol = data.get_opt_name().map(|n| n.as_str()).unwrap_or_else(|| {
-                if let DefPathData::CrateRoot = data {  // reexported `extern crate` (#43189)
+                if let DefPathData::CrateRoot = data { // reexported `extern crate` (#43189)
                     self.original_crate_name(cur_def.krate).as_str()
                 } else {
                     Symbol::intern("<unnamed>").as_str()
@@ -365,9 +365,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
         if let Some(trait_ref) = impl_trait_ref {
             // Trait impls.
-            buffer.push(&format!("<{} as {}>",
-                                 self_ty,
-                                 trait_ref));
+            buffer.push(&format!("<{} as {}>", self_ty, trait_ref));
             return;
         }
 

src/librustc/ty/layout.rs

@@ -32,11 +32,11 @@ pub trait IntegerExt {
     fn to_ty<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, signed: bool) -> Ty<'tcx>;
     fn from_attr<C: HasDataLayout>(cx: C, ity: attr::IntType) -> Integer;
     fn repr_discr<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                  ty: Ty<'tcx>,
-                  repr: &ReprOptions,
-                  min: i128,
-                  max: i128)
-                  -> (Integer, bool);
+                            ty: Ty<'tcx>,
+                            repr: &ReprOptions,
+                            min: i128,
+                            max: i128)
+                            -> (Integer, bool);
 }
 
 impl IntegerExt for Integer {
@@ -76,11 +76,11 @@ impl IntegerExt for Integer {
     /// N.B.: u128 values above i128::MAX will be treated as signed, but
     /// that shouldn't affect anything, other than maybe debuginfo.
     fn repr_discr<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                  ty: Ty<'tcx>,
-                  repr: &ReprOptions,
-                  min: i128,
-                  max: i128)
-                  -> (Integer, bool) {
+                            ty: Ty<'tcx>,
+                            repr: &ReprOptions,
+                            min: i128,
+                            max: i128)
+                            -> (Integer, bool) {
         // Theoretically, negative values could be larger in unsigned representation
         // than the unsigned representation of the signed minimum. However, if there
         // are any negative values, the only valid unsigned representation is u128
@@ -96,7 +96,7 @@ impl IntegerExt for Integer {
             let fit = if ity.is_signed() { signed_fit } else { unsigned_fit };
             if discr < fit {
                 bug!("Integer::repr_discr: `#[repr]` hint too small for \
-                  discriminant range of enum `{}", ty)
+                      discriminant range of enum `{}", ty)
             }
             return (discr, ity.is_signed());
         }
@@ -106,7 +106,7 @@ impl IntegerExt for Integer {
                 // WARNING: the ARM EABI has two variants; the one corresponding
                 // to `at_least == I32` appears to be used on Linux and NetBSD,
                 // but some systems may use the variant corresponding to no
-                // lower bound.  However, we don't run on those yet...?
+                // lower bound. However, we don't run on those yet...?
                 "arm" => min_from_extern = Some(I32),
                 _ => min_from_extern = Some(I32),
             }
@@ -250,6 +250,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
             /// A univariant, but with a prefix of an arbitrary size & alignment (e.g. enum tag).
             Prefixed(Size, Align),
         }
+
         let univariant_uninterned = |fields: &[TyLayout<'_>], repr: &ReprOptions, kind| {
             let packed = repr.packed();
             if packed && repr.align > 0 {
@@ -324,7 +325,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                 let field = fields[i as usize];
                 if !sized {
                     bug!("univariant: field #{} of `{}` comes after unsized field",
-                        offsets.len(), ty);
+                         offsets.len(), ty);
                 }
 
                 if field.is_unsized() {
@@ -628,7 +629,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                 };
 
                 univariant(&tys.iter().map(|ty| self.layout_of(ty)).collect::<Result<Vec<_>, _>>()?,
-                    &ReprOptions::default(), kind)?
+                           &ReprOptions::default(), kind)?
             }
 
             // SIMD vector types.
@@ -640,7 +641,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                     Abi::Scalar(ref scalar) => scalar.clone(),
                     _ => {
                         tcx.sess.fatal(&format!("monomorphising SIMD type `{}` with \
-                                                a non-machine element type `{}`",
+                                                 a non-machine element type `{}`",
                                                 ty, element.ty));
                     }
                 };
@@ -743,7 +744,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                     // Only one variant is present.
                     (present_second.is_none() &&
                     // Representation optimizations are allowed.
-                     !def.repr.inhibit_enum_layout_opt());
+                    !def.repr.inhibit_enum_layout_opt());
                 if is_struct {
                     // Struct, or univariant enum equivalent to a struct.
                     // (Typechecking will reject discriminant-sizing attrs.)
@@ -755,7 +756,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                         let param_env = tcx.param_env(def.did);
                         let last_field = def.variants[v].fields.last().unwrap();
                         let always_sized = tcx.type_of(last_field.did)
-                          .is_sized(tcx.at(DUMMY_SP), param_env);
+                                              .is_sized(tcx.at(DUMMY_SP), param_env);
                         if !always_sized { StructKind::MaybeUnsized }
                         else { StructKind::AlwaysSized }
                     };
@@ -1258,8 +1259,8 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                         let fields: Vec<_> =
                             variant_def.fields.iter().map(|f| f.ident.name).collect();
                         build_variant_info(Some(variant_def.name),
-                                            &fields,
-                                            layout.for_variant(self, i))
+                                           &fields,
+                                           layout.for_variant(self, i))
                     })
                     .collect();
                 record(adt_kind.into(), adt_packed, match layout.variants {

src/librustc/ty/mod.rs

@@ -862,24 +862,22 @@ pub struct GenericParamDef {
 
 impl GenericParamDef {
     pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
-        match self.kind {
-            GenericParamDefKind::Lifetime => {
-                ty::EarlyBoundRegion {
-                    def_id: self.def_id,
-                    index: self.index,
-                    name: self.name,
-                }
+        if let GenericParamDefKind::Lifetime = self.kind {
+            ty::EarlyBoundRegion {
+                def_id: self.def_id,
+                index: self.index,
+                name: self.name,
             }
-            _ => bug!("cannot convert a non-lifetime parameter def to an early bound region")
+        } else {
+            bug!("cannot convert a non-lifetime parameter def to an early bound region")
         }
     }
 
     pub fn to_bound_region(&self) -> ty::BoundRegion {
-        match self.kind {
-            GenericParamDefKind::Lifetime => {
-                self.to_early_bound_region_data().to_bound_region()
-            }
-            _ => bug!("cannot convert a non-lifetime parameter def to an early bound region")
+        if let GenericParamDefKind::Lifetime = self.kind {
+            self.to_early_bound_region_data().to_bound_region()
+        } else {
+            bug!("cannot convert a non-lifetime parameter def to an early bound region")
         }
     }
 }
@@ -957,7 +955,7 @@ impl<'a, 'gcx, 'tcx> Generics {
             }
         } else {
             tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
-                .region_param(param, tcx)
+               .region_param(param, tcx)
         }
     }
 
@@ -974,7 +972,7 @@ impl<'a, 'gcx, 'tcx> Generics {
             }
         } else {
             tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
-                .type_param(param, tcx)
+               .type_param(param, tcx)
         }
     }
 }
@@ -1376,7 +1374,7 @@ impl<'tcx> Predicate<'tcx> {
             }
         };
 
-        // The only reason to collect into a vector here is that I was
+        // FIXME: The only reason to collect into a vector here is that I was
         // too lazy to make the full (somewhat complicated) iterator
         // type that would be needed here. But I wanted this fn to
         // return an iterator conceptually, rather than a `Vec`, so as
@@ -2224,7 +2222,7 @@ impl<'a, 'gcx, 'tcx> AdtDef {
                 if !expr_did.is_local() {
                     span_bug!(tcx.def_span(expr_did),
                         "variant discriminant evaluation succeeded \
-                            in its crate but failed locally");
+                         in its crate but failed locally");
                 }
                 None
             }
@@ -2360,9 +2358,9 @@ impl<'a, 'gcx, 'tcx> AdtDef {
                 debug!("sized_constraint_for_ty({:?}) intermediate = {:?}",
                        ty, adt_tys);
                 adt_tys.iter()
-                    .map(|ty| ty.subst(tcx, substs))
-                    .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty))
-                    .collect()
+                       .map(|ty| ty.subst(tcx, substs))
+                       .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty))
+                       .collect()
             }
 
             Projection(..) | Opaque(..) => {
@@ -2903,9 +2901,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 }
 
-fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId)
-    -> AssociatedItem
-{
+fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> AssociatedItem {
     let id = tcx.hir.as_local_node_id(def_id).unwrap();
     let parent_id = tcx.hir.get_parent(id);
     let parent_def_id = tcx.hir.local_def_id(parent_id);
@@ -3019,8 +3015,8 @@ pub fn is_impl_trait_defn(tcx: TyCtxt<'_, '_, '_>, def_id: DefId) -> Option<DefI
 /// See `ParamEnv` struct def'n for details.
 fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                        def_id: DefId)
-                       -> ParamEnv<'tcx> {
-
+                       -> ParamEnv<'tcx>
+{
     // The param_env of an impl Trait type is its defining function's param_env
     if let Some(parent) = is_impl_trait_defn(tcx, def_id) {
         return param_env(tcx, parent);

src/librustc/ty/outlives.rs

@@ -73,7 +73,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         // projection).
         match ty.sty {
             ty::Closure(def_id, ref substs) => {
-
                 for upvar_ty in substs.upvar_tys(def_id, *self) {
                     self.compute_components(upvar_ty, out);
                 }
@@ -183,9 +182,5 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 }
 
 fn push_region_constraints<'tcx>(out: &mut Vec<Component<'tcx>>, regions: Vec<ty::Region<'tcx>>) {
-    for r in regions {
-        if !r.is_late_bound() {
-            out.push(Component::Region(r));
-        }
-    }
+    out.extend(regions.iter().filter(|&r| !r.is_late_bound()).map(|r| Component::Region(r)));
 }