Auto merge of #160980 - JonathanBrouwer:rollup-MX1XSgM, r=JonathanBrouwer

Rollup of 6 pull requests

Successful merges:

 - #160966 (bootstrap: Avoid some unnecessary imports from the crate root)
 - #159987 (trait solver: Track canonical response universe assumptions)
 - #160886 (Trim `GoalStalledOn::Certainty`)
 - #160925 (Add `TypeId::is_signed` method)
 - #160926 (sve: add addl. passing test for field projection)
 - #160977 (Remove `MutatingUseContext::Retag`)

Author: bors

compiler/rustc_borrowck/src/def_use.rs

@@ -59,8 +59,7 @@ pub(crate) fn categorize(context: PlaceContext) -> Option<DefUse> {
         PlaceContext::NonMutatingUse(NonMutatingUseContext::RawBorrow) |
         PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect) |
         PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) |
-        PlaceContext::NonMutatingUse(NonMutatingUseContext::Move) |
-        PlaceContext::MutatingUse(MutatingUseContext::Retag) => Some(DefUse::Use),
+        PlaceContext::NonMutatingUse(NonMutatingUseContext::Move) => Some(DefUse::Use),
 
         ///////////////////////////////////////////////////////////////////////////
         // DROP USES

compiler/rustc_codegen_ssa/src/mir/analyze.rs

@@ -211,8 +211,7 @@ impl<'a, 'b, 'tcx, Bx: BuilderMethods<'b, 'tcx>> Visitor<'tcx> for LocalAnalyzer
             }
 
             PlaceContext::NonUse(_)
-            | PlaceContext::NonMutatingUse(NonMutatingUseContext::PlaceMention)
-            | PlaceContext::MutatingUse(MutatingUseContext::Retag) => {}
+            | PlaceContext::NonMutatingUse(NonMutatingUseContext::PlaceMention) => {}
 
             PlaceContext::NonMutatingUse(
                 NonMutatingUseContext::Copy

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -606,6 +606,11 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
                 ecx.write_type_info(ty, dest)?;
             }
 
+            sym::type_id_is_signed => {
+                let ty = ecx.read_type_id(&args[0])?;
+                ecx.write_scalar(Scalar::from_bool(ty.is_signed()), dest)?;
+            }
+
             sym::size_of_type_id => {
                 let ty = ecx.read_type_id(&args[0])?;
                 let layout = ecx.layout_of(ty)?;

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -221,6 +221,7 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
         | sym::type_id_field_representing_type
         | sym::type_id_fields
         | sym::type_id_generics
+        | sym::type_id_is_signed
         | sym::type_id_variants
         | sym::type_id_vtable
         | sym::type_name
@@ -332,6 +333,7 @@ pub(crate) fn check_intrinsic_type(
             (0, 0, vec![type_id_ty(), tcx.types.usize, tcx.types.usize], type_id_ty())
         }
         sym::type_id_fields => (0, 0, vec![type_id_ty(), tcx.types.usize], tcx.types.usize),
+        sym::type_id_is_signed => (0, 0, vec![type_id_ty()], tcx.types.bool),
         sym::type_id_variants => (0, 0, vec![type_id_ty()], tcx.types.usize),
         sym::type_id_vtable => {
             let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, span);

compiler/rustc_middle/src/mir/visit.rs

@@ -1354,8 +1354,6 @@ pub enum MutatingUseContext {
     /// f(&mut x.y);
     /// ```
     Projection,
-    /// Retagging, a "Stacked Borrows" shadow state operation
-    Retag,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]

compiler/rustc_mir_dataflow/src/impls/liveness.rs

@@ -180,8 +180,7 @@ impl DefUse {
             PlaceContext::MutatingUse(
                 MutatingUseContext::RawBorrow
                 | MutatingUseContext::Borrow
-                | MutatingUseContext::Drop
-                | MutatingUseContext::Retag,
+                | MutatingUseContext::Drop,
             )
             | PlaceContext::NonMutatingUse(
                 NonMutatingUseContext::RawBorrow

compiler/rustc_mir_transform/src/deduce_param_attrs.rs

@@ -74,8 +74,7 @@ impl<'tcx> Visitor<'tcx> for DeduceParamAttrs {
                   MutatingUseContext::Store
                 | MutatingUseContext::SetDiscriminant
                 | MutatingUseContext::AsmOutput
-                | MutatingUseContext::Projection
-                | MutatingUseContext::Retag) => {
+                | MutatingUseContext::Projection) => {
                 self.usage[i] |= UsageSummary::MUTATE;
             }
             | PlaceContext::NonMutatingUse(NonMutatingUseContext::RawBorrow) => {

compiler/rustc_mir_transform/src/known_panics_lint.rs

@@ -975,7 +975,6 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
             // whether they'd be fine right now.
             MutatingUse(MutatingUseContext::Yield)
             | MutatingUse(MutatingUseContext::Drop)
-            | MutatingUse(MutatingUseContext::Retag)
             // These can't ever be propagated under any scheme, as we can't reason about indirect
             // mutation.
             | NonMutatingUse(NonMutatingUseContext::SharedBorrow)

compiler/rustc_mir_transform/src/liveness.rs

@@ -1548,8 +1548,7 @@ impl DefUse {
             PlaceContext::MutatingUse(
                 MutatingUseContext::RawBorrow
                 | MutatingUseContext::Borrow
-                | MutatingUseContext::Drop
-                | MutatingUseContext::Retag,
+                | MutatingUseContext::Drop,
             )
             | PlaceContext::NonMutatingUse(
                 NonMutatingUseContext::RawBorrow

compiler/rustc_next_trait_solver/src/canonical/mod.rs

@@ -162,7 +162,20 @@ where
     let prev_universe = delegate.universe();
     let universes_created_in_query = response.max_universe.index();
     for _ in 0..universes_created_in_query {
-        delegate.create_next_universe();
+        let new_universe = delegate.create_next_universe();
+        if delegate.cx().assumptions_on_binders() {
+            // FIXME(-Zassumptions-on-binders): Remove this temporary workaround once
+            // opaque types no longer escape query responses with query-created placeholders.
+            // Region constraints involving query-created placeholders were handled inside
+            // the query. However, the placeholders can still escape in other response
+            // fields, such as opaque type constraints. To avoid triggering
+            // assertions, we explicitly insert empty assumptions for the
+            // recreated universes here.
+            delegate.insert_placeholder_assumptions(
+                new_universe,
+                Some(rustc_type_ir::region_constraint::Assumptions::empty()),
+            );
+        }
     }
 
     compute_query_response_instantiation_values_in_universe(