Auto merge of #78027 - lcnr:lift-by-value, r=varkor

Lift: take self by value seems small enough to not warrant an MCP 🤷
rust-lang · Oct 21, 2020 · c4fe25d · c4fe25d
2 parents 1eaadeb + 17825c9
commit c4fe25d
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Showing 15 changed files with 139 additions and 167 deletions.
diff --git a/compiler/rustc_infer/src/infer/free_regions.rs b/compiler/rustc_infer/src/infer/free_regions.rs
@@ -157,7 +157,7 @@ impl<'tcx> FreeRegionRelations<'tcx> for FreeRegionMap<'tcx> {
 
 impl<'a, 'tcx> Lift<'tcx> for FreeRegionMap<'a> {
     type Lifted = FreeRegionMap<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<FreeRegionMap<'tcx>> {
-        self.relation.maybe_map(|&fr| tcx.lift(&fr)).map(|relation| FreeRegionMap { relation })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<FreeRegionMap<'tcx>> {
+        self.relation.maybe_map(|&fr| tcx.lift(fr)).map(|relation| FreeRegionMap { relation })
     }
 }
diff --git a/compiler/rustc_macros/src/lift.rs b/compiler/rustc_macros/src/lift.rs
@@ -3,6 +3,7 @@ use syn::{self, parse_quote};
 
 pub fn lift_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     s.add_bounds(synstructure::AddBounds::Generics);
+    s.bind_with(|_| synstructure::BindStyle::Move);
 
     let tcx: syn::Lifetime = parse_quote!('tcx);
     let newtcx: syn::GenericParam = parse_quote!('__lifted);
@@ -43,8 +44,8 @@ pub fn lift_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStre
         quote! {
             type Lifted = #lifted;
 
-            fn lift_to_tcx(&self, __tcx: ::rustc_middle::ty::TyCtxt<'__lifted>) -> Option<#lifted> {
-                Some(match *self { #body })
+            fn lift_to_tcx(self, __tcx: ::rustc_middle::ty::TyCtxt<'__lifted>) -> Option<#lifted> {
+                Some(match self { #body })
             }
         },
     )

diff --git a/compiler/rustc_middle/src/macros.rs b/compiler/rustc_middle/src/macros.rs
@@ -29,8 +29,8 @@ macro_rules! CloneLiftImpls {
         $(
             impl<$tcx> $crate::ty::Lift<$tcx> for $ty {
                 type Lifted = Self;
-                fn lift_to_tcx(&self, _: $crate::ty::TyCtxt<$tcx>) -> Option<Self> {
-                    Some(Clone::clone(self))
+                fn lift_to_tcx(self, _: $crate::ty::TyCtxt<$tcx>) -> Option<Self> {
+                    Some(self)
                 }
             }
         )+

diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
@@ -2210,7 +2210,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
 
                         let name = ty::tls::with(|tcx| {
                             let mut name = String::new();
-                            let substs = tcx.lift(&substs).expect("could not lift for printing");
+                            let substs = tcx.lift(substs).expect("could not lift for printing");
                             FmtPrinter::new(tcx, &mut name, Namespace::ValueNS)
                                 .print_def_path(variant_def.def_id, substs)?;
                             Ok(name)
@@ -2233,7 +2233,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                         if let Some(def_id) = def_id.as_local() {
                             let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
                             let name = if tcx.sess.opts.debugging_opts.span_free_formats {
-                                let substs = tcx.lift(&substs).unwrap();
+                                let substs = tcx.lift(substs).unwrap();
                                 format!(
                                     "[closure@{}]",
                                     tcx.def_path_str_with_substs(def_id.to_def_id(), substs),
@@ -2527,7 +2527,7 @@ fn pretty_print_const(
 ) -> fmt::Result {
     use crate::ty::print::PrettyPrinter;
     ty::tls::with(|tcx| {
-        let literal = tcx.lift(&c).unwrap();
+        let literal = tcx.lift(c).unwrap();
         let mut cx = FmtPrinter::new(tcx, fmt, Namespace::ValueNS);
         cx.print_alloc_ids = true;
         cx.pretty_print_const(literal, print_types)?;

diff --git a/compiler/rustc_middle/src/mir/terminator.rs b/compiler/rustc_middle/src/mir/terminator.rs
@@ -535,7 +535,7 @@ impl<'tcx> TerminatorKind<'tcx> {
             Goto { .. } => vec!["".into()],
             SwitchInt { ref targets, switch_ty, .. } => ty::tls::with(|tcx| {
                 let param_env = ty::ParamEnv::empty();
-                let switch_ty = tcx.lift(&switch_ty).unwrap();
+                let switch_ty = tcx.lift(switch_ty).unwrap();
                 let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size;
                 targets
                     .values

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
@@ -1060,7 +1060,7 @@ impl<'tcx> TyCtxt<'tcx> {
         )
     }
 
-    pub fn lift<T: ?Sized + Lift<'tcx>>(self, value: &T) -> Option<T::Lifted> {
+    pub fn lift<T: Lift<'tcx>>(self, value: T) -> Option<T::Lifted> {
         value.lift_to_tcx(self)
     }
 
@@ -1569,16 +1569,16 @@ impl<'tcx> TyCtxt<'tcx> {
 /// e.g., `()` or `u8`, was interned in a different context.
 pub trait Lift<'tcx>: fmt::Debug {
     type Lifted: fmt::Debug + 'tcx;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>;
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>;
 }
 
 macro_rules! nop_lift {
     ($set:ident; $ty:ty => $lifted:ty) => {
         impl<'a, 'tcx> Lift<'tcx> for $ty {
             type Lifted = $lifted;
-            fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-                if tcx.interners.$set.contains_pointer_to(&Interned(*self)) {
-                    Some(unsafe { mem::transmute(*self) })
+            fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+                if tcx.interners.$set.contains_pointer_to(&Interned(self)) {
+                    Some(unsafe { mem::transmute(self) })
                 } else {
                     None
                 }
@@ -1591,12 +1591,12 @@ macro_rules! nop_list_lift {
     ($set:ident; $ty:ty => $lifted:ty) => {
         impl<'a, 'tcx> Lift<'tcx> for &'a List<$ty> {
             type Lifted = &'tcx List<$lifted>;
-            fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+            fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
                 if self.is_empty() {
                     return Some(List::empty());
                 }
-                if tcx.interners.$set.contains_pointer_to(&Interned(*self)) {
-                    Some(unsafe { mem::transmute(*self) })
+                if tcx.interners.$set.contains_pointer_to(&Interned(self)) {
+                    Some(unsafe { mem::transmute(self) })
                 } else {
                     None
                 }

diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
@@ -229,7 +229,7 @@ impl<'tcx> ty::TyS<'tcx> {
             ty::Adt(def, _) => format!("{} `{}`", def.descr(), tcx.def_path_str(def.did)).into(),
             ty::Foreign(def_id) => format!("extern type `{}`", tcx.def_path_str(def_id)).into(),
             ty::Array(t, n) => {
-                let n = tcx.lift(&n).unwrap();
+                let n = tcx.lift(n).unwrap();
                 match n.try_eval_usize(tcx, ty::ParamEnv::empty()) {
                     _ if t.is_simple_ty() => format!("array `{}`", self).into(),
                     Some(n) => format!("array of {} element{}", n, pluralize!(n)).into(),

diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
@@ -258,7 +258,7 @@ impl<'tcx> InstanceDef<'tcx> {
 impl<'tcx> fmt::Display for Instance<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         ty::tls::with(|tcx| {
-            let substs = tcx.lift(&self.substs).expect("could not lift for printing");
+            let substs = tcx.lift(self.substs).expect("could not lift for printing");
             FmtPrinter::new(tcx, &mut *f, Namespace::ValueNS)
                 .print_def_path(self.def_id(), substs)?;
             Ok(())

diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1848,7 +1848,7 @@ macro_rules! forward_display_to_print {
         $(impl fmt::Display for $ty {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 ty::tls::with(|tcx| {
-                    tcx.lift(self)
+                    tcx.lift(*self)
                         .expect("could not lift for printing")
                         .print(FmtPrinter::new(tcx, f, Namespace::TypeNS))?;
                     Ok(())