Auto merge of rust-lang#2794 - RalfJung:rustup, r=RalfJung

Rustup

Cargo.lock

@@ -4180,6 +4180,7 @@ dependencies = [
  "rustc_hir_analysis",
  "rustc_hir_typeck",
  "rustc_incremental",
+ "rustc_index",
  "rustc_lint",
  "rustc_macros",
  "rustc_metadata",

compiler/rustc_ast_lowering/src/item.rs

@@ -13,7 +13,7 @@ use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
 use rustc_hir::PredicateOrigin;
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::ty::{DefIdTree, ResolverAstLowering, TyCtxt};
-use rustc_span::lev_distance::find_best_match_for_name;
+use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{Span, Symbol};

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -534,7 +534,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                     return PlaceTy::from_ty(self.tcx().ty_error());
                 }
             }
-            place_ty = self.sanitize_projection(place_ty, elem, place, location);
+            place_ty = self.sanitize_projection(place_ty, elem, place, location, context);
         }
 
         if let PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) = context {
@@ -630,12 +630,14 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn sanitize_projection(
         &mut self,
         base: PlaceTy<'tcx>,
         pi: PlaceElem<'tcx>,
         place: &Place<'tcx>,
         location: Location,
+        context: PlaceContext,
     ) -> PlaceTy<'tcx> {
         debug!("sanitize_projection: {:?} {:?} {:?}", base, pi, place);
         let tcx = self.tcx();
@@ -713,8 +715,11 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 match self.field_ty(place, base, field, location) {
                     Ok(ty) => {
                         let ty = self.cx.normalize(ty, location);
-                        if let Err(terr) = self.cx.eq_types(
+                        debug!(?fty, ?ty);
+
+                        if let Err(terr) = self.cx.relate_types(
                             ty,
+                            self.get_ambient_variance(context),
                             fty,
                             location.to_locations(),
                             ConstraintCategory::Boring,
@@ -743,9 +748,10 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 let ty = self.sanitize_type(place, ty);
                 let ty = self.cx.normalize(ty, location);
                 self.cx
-                    .eq_types(
-                        base.ty,
+                    .relate_types(
                         ty,
+                        self.get_ambient_variance(context),
+                        base.ty,
                         location.to_locations(),
                         ConstraintCategory::TypeAnnotation,
                     )
@@ -760,6 +766,21 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         self.tcx().ty_error()
     }
 
+    fn get_ambient_variance(&self, context: PlaceContext) -> ty::Variance {
+        use rustc_middle::mir::visit::NonMutatingUseContext::*;
+        use rustc_middle::mir::visit::NonUseContext::*;
+
+        match context {
+            PlaceContext::MutatingUse(_) => ty::Invariant,
+            PlaceContext::NonUse(StorageDead | StorageLive | VarDebugInfo) => ty::Invariant,
+            PlaceContext::NonMutatingUse(
+                Inspect | Copy | Move | SharedBorrow | ShallowBorrow | UniqueBorrow | AddressOf
+                | Projection,
+            ) => ty::Covariant,
+            PlaceContext::NonUse(AscribeUserTy) => ty::Covariant,
+        }
+    }
+
     fn field_ty(
         &mut self,
         parent: &dyn fmt::Debug,

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -33,6 +33,7 @@ use rustc_target::spec::{RelocModel, Target};
 /// <dt>dylib</dt>
 /// <dd>The metadata can be found in the `.rustc` section of the shared library.</dd>
 /// </dl>
+#[derive(Debug)]
 pub struct DefaultMetadataLoader;
 
 fn load_metadata_with(

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -312,6 +312,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
+    /// `src` is a *pointer to* a `source_ty`, and in `dest` we should store a pointer to th same
+    /// data at type `cast_ty`.
     fn unsize_into_ptr(
         &mut self,
         src: &OpTy<'tcx, M::Provenance>,
@@ -335,7 +337,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 );
                 self.write_immediate(val, dest)
             }
-            (ty::Dynamic(data_a, ..), ty::Dynamic(data_b, ..)) => {
+            (ty::Dynamic(data_a, _, ty::Dyn), ty::Dynamic(data_b, _, ty::Dyn)) => {
                 let val = self.read_immediate(src)?;
                 if data_a.principal() == data_b.principal() {
                     // A NOP cast that doesn't actually change anything, should be allowed even with mismatching vtables.
@@ -359,7 +361,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             _ => {
-                span_bug!(self.cur_span(), "invalid unsizing {:?} -> {:?}", src.layout.ty, cast_ty)
+                span_bug!(
+                    self.cur_span(),
+                    "invalid pointer unsizing {:?} -> {:?}",
+                    src.layout.ty,
+                    cast_ty
+                )
             }
         }
     }

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -632,7 +632,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 }
                 Ok(Some((size, align)))
             }
-            ty::Dynamic(..) => {
+            ty::Dynamic(_, _, ty::Dyn) => {
                 let vtable = metadata.unwrap_meta().to_pointer(self)?;
                 // Read size and align from vtable (already checks size).
                 Ok(Some(self.get_vtable_size_and_align(vtable)?))

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -242,7 +242,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
             let mplace = self.ecx.ref_to_mplace(&value)?;
             assert_eq!(mplace.layout.ty, referenced_ty);
             // Handle trait object vtables.
-            if let ty::Dynamic(..) =
+            if let ty::Dynamic(_, _, ty::Dyn) =
                 tcx.struct_tail_erasing_lifetimes(referenced_ty, self.ecx.param_env).kind()
             {
                 let ptr = mplace.meta.unwrap_meta().to_pointer(&tcx)?;

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -255,7 +255,22 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> {
         }
     }
 
-    pub fn offset_with_meta(
+    /// Replace the layout of this operand. There's basically no sanity check that this makes sense,
+    /// you better know what you are doing! If this is an immediate, applying the wrong layout can
+    /// not just lead to invalid data, it can actually *shift the data around* since the offsets of
+    /// a ScalarPair are entirely determined by the layout, not the data.
+    pub fn transmute(&self, layout: TyAndLayout<'tcx>) -> Self {
+        assert_eq!(
+            self.layout.size, layout.size,
+            "transmuting with a size change, that doesn't seem right"
+        );
+        OpTy { layout, ..*self }
+    }
+
+    /// Offset the operand in memory (if possible) and change its metadata.
+    ///
+    /// This can go wrong very easily if you give the wrong layout for the new place!
+    pub(super) fn offset_with_meta(
         &self,
         offset: Size,
         meta: MemPlaceMeta<Prov>,
@@ -276,6 +291,9 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> {
         }
     }
 
+    /// Offset the operand in memory (if possible).
+    ///
+    /// This can go wrong very easily if you give the wrong layout for the new place!
     pub fn offset(
         &self,
         offset: Size,

compiler/rustc_const_eval/src/interpret/place.rs

@@ -26,6 +26,7 @@ pub enum MemPlaceMeta<Prov: Provenance = AllocId> {
 }
 
 impl<Prov: Provenance> MemPlaceMeta<Prov> {
+    #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn unwrap_meta(self) -> Scalar<Prov> {
         match self {
             Self::Meta(s) => s,
@@ -147,12 +148,16 @@ impl<Prov: Provenance> MemPlace<Prov> {
     }
 
     #[inline]
-    pub fn offset_with_meta<'tcx>(
+    pub(super) fn offset_with_meta<'tcx>(
         self,
         offset: Size,
         meta: MemPlaceMeta<Prov>,
         cx: &impl HasDataLayout,
     ) -> InterpResult<'tcx, Self> {
+        debug_assert!(
+            !meta.has_meta() || self.meta.has_meta(),
+            "cannot use `offset_with_meta` to add metadata to a place"
+        );
         Ok(MemPlace { ptr: self.ptr.offset(offset, cx)?, meta })
     }
 }
@@ -182,8 +187,11 @@ impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> {
         MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None }, layout, align }
     }
 
+    /// Offset the place in memory and change its metadata.
+    ///
+    /// This can go wrong very easily if you give the wrong layout for the new place!
     #[inline]
-    pub fn offset_with_meta(
+    pub(crate) fn offset_with_meta(
         &self,
         offset: Size,
         meta: MemPlaceMeta<Prov>,
@@ -197,6 +205,9 @@ impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> {
         })
     }
 
+    /// Offset the place in memory.
+    ///
+    /// This can go wrong very easily if you give the wrong layout for the new place!
     pub fn offset(
         &self,
         offset: Size,
@@ -241,14 +252,6 @@ impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> {
             }
         }
     }
-
-    #[inline]
-    pub(super) fn vtable(&self) -> Scalar<Prov> {
-        match self.layout.ty.kind() {
-            ty::Dynamic(..) => self.mplace.meta.unwrap_meta(),
-            _ => bug!("vtable not supported on type {:?}", self.layout.ty),
-        }
-    }
 }
 
 // These are defined here because they produce a place.
@@ -266,7 +269,12 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> {
     #[inline(always)]
     #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn assert_mem_place(&self) -> MPlaceTy<'tcx, Prov> {
-        self.as_mplace_or_imm().left().unwrap()
+        self.as_mplace_or_imm().left().unwrap_or_else(|| {
+            bug!(
+                "OpTy of type {} was immediate when it was expected to be an MPlace",
+                self.layout.ty
+            )
+        })
     }
 }
 
@@ -283,7 +291,12 @@ impl<'tcx, Prov: Provenance> PlaceTy<'tcx, Prov> {
     #[inline(always)]
     #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn assert_mem_place(&self) -> MPlaceTy<'tcx, Prov> {
-        self.as_mplace_or_local().left().unwrap()
+        self.as_mplace_or_local().left().unwrap_or_else(|| {
+            bug!(
+                "PlaceTy of type {} was a local when it was expected to be an MPlace",
+                self.layout.ty
+            )
+        })
     }
 }
 
@@ -807,11 +820,16 @@ where
     }
 
     /// Turn a place with a `dyn Trait` type into a place with the actual dynamic type.
+    /// Aso returns the vtable.
     pub(super) fn unpack_dyn_trait(
         &self,
         mplace: &MPlaceTy<'tcx, M::Provenance>,
-    ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
-        let vtable = mplace.vtable().to_pointer(self)?; // also sanity checks the type
+    ) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, Pointer<Option<M::Provenance>>)> {
+        assert!(
+            matches!(mplace.layout.ty.kind(), ty::Dynamic(_, _, ty::Dyn)),
+            "`unpack_dyn_trait` only makes sense on `dyn*` types"
+        );
+        let vtable = mplace.meta.unwrap_meta().to_pointer(self)?;
         let (ty, _) = self.get_ptr_vtable(vtable)?;
         let layout = self.layout_of(ty)?;
 
@@ -820,7 +838,26 @@ where
             layout,
             align: layout.align.abi,
         };
-        Ok(mplace)
+        Ok((mplace, vtable))
+    }
+
+    /// Turn an operand with a `dyn* Trait` type into an operand with the actual dynamic type.
+    /// Aso returns the vtable.
+    pub(super) fn unpack_dyn_star(
+        &self,
+        op: &OpTy<'tcx, M::Provenance>,
+    ) -> InterpResult<'tcx, (OpTy<'tcx, M::Provenance>, Pointer<Option<M::Provenance>>)> {
+        assert!(
+            matches!(op.layout.ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
+            "`unpack_dyn_star` only makes sense on `dyn*` types"
+        );
+        let data = self.operand_field(&op, 0)?;
+        let vtable = self.operand_field(&op, 1)?;
+        let vtable = self.read_pointer(&vtable)?;
+        let (ty, _) = self.get_ptr_vtable(vtable)?;
+        let layout = self.layout_of(ty)?;
+        let data = data.transmute(layout);
+        Ok((data, vtable))
     }
 }