Rollup of 13 pull requests

compiler/rustc_borrowck/src/consumers.rs

@@ -14,16 +14,16 @@ pub use super::{
 };
 
 /// This function computes Polonius facts for the given body. It makes a copy of
-/// the body because it needs to regenerate the region identifiers.
+/// the body because it needs to regenerate the region identifiers. This function
+/// should never be invoked during a typical compilation session due to performance
+/// issues with Polonius.
 ///
 /// Note:
 /// *   This function will panic if the required body was already stolen. This
 ///     can, for example, happen when requesting a body of a `const` function
 ///     because they are evaluated during typechecking. The panic can be avoided
 ///     by overriding the `mir_borrowck` query. You can find a complete example
 ///     that shows how to do this at `src/test/run-make/obtain-borrowck/`.
-/// *   This function will also panic if computation of Polonius facts
-///     (`-Zpolonius` flag) is not enabled.
 ///
 /// *   Polonius is highly unstable, so expect regular changes in its signature or other details.
 pub fn get_body_with_borrowck_facts<'tcx>(

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -40,6 +40,7 @@ impl ConstraintDescription for ConstraintCategory {
             ConstraintCategory::CopyBound => "copying this value ",
             ConstraintCategory::OpaqueType => "opaque type ",
             ConstraintCategory::ClosureUpvar(_) => "closure capture ",
+            ConstraintCategory::Usage => "this usage ",
             ConstraintCategory::Boring
             | ConstraintCategory::BoringNoLocation
             | ConstraintCategory::Internal => "",

compiler/rustc_borrowck/src/lib.rs

@@ -154,11 +154,6 @@ fn do_mir_borrowck<'a, 'tcx>(
 
     debug!("do_mir_borrowck(def = {:?})", def);
 
-    assert!(
-        !return_body_with_facts || infcx.tcx.sess.opts.debugging_opts.polonius,
-        "borrowck facts can be requested only when Polonius is enabled"
-    );
-
     let tcx = infcx.tcx;
     let param_env = tcx.param_env(def.did);
     let id = tcx.hir().local_def_id_to_hir_id(def.did);
@@ -235,6 +230,8 @@ fn do_mir_borrowck<'a, 'tcx>(
     let borrow_set =
         Rc::new(BorrowSet::build(tcx, body, locals_are_invalidated_at_exit, &mdpe.move_data));
 
+    let use_polonius = return_body_with_facts || infcx.tcx.sess.opts.debugging_opts.polonius;
+
     // Compute non-lexical lifetimes.
     let nll::NllOutput {
         regioncx,
@@ -254,6 +251,7 @@ fn do_mir_borrowck<'a, 'tcx>(
         &mdpe.move_data,
         &borrow_set,
         &upvars,
+        use_polonius,
     );
 
     // Dump MIR results into a file, if that is enabled. This let us

compiler/rustc_borrowck/src/nll.rs

@@ -164,8 +164,10 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
     move_data: &MoveData<'tcx>,
     borrow_set: &BorrowSet<'tcx>,
     upvars: &[Upvar<'tcx>],
+    use_polonius: bool,
 ) -> NllOutput<'tcx> {
-    let mut all_facts = AllFacts::enabled(infcx.tcx).then_some(AllFacts::default());
+    let mut all_facts =
+        (use_polonius || AllFacts::enabled(infcx.tcx)).then_some(AllFacts::default());
 
     let universal_regions = Rc::new(universal_regions);
 
@@ -281,7 +283,7 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
             all_facts.write_to_dir(dir_path, location_table).unwrap();
         }
 
-        if infcx.tcx.sess.opts.debugging_opts.polonius {
+        if use_polonius {
             let algorithm =
                 env::var("POLONIUS_ALGORITHM").unwrap_or_else(|_| String::from("Hybrid"));
             let algorithm = Algorithm::from_str(&algorithm).unwrap();

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1388,11 +1388,24 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             ConstraintCategory::Return(ReturnConstraint::Normal)
                         }
                     }
+                    Some(l)
+                        if matches!(
+                            body.local_decls[l].local_info,
+                            Some(box LocalInfo::AggregateTemp)
+                        ) =>
+                    {
+                        ConstraintCategory::Usage
+                    }
                     Some(l) if !body.local_decls[l].is_user_variable() => {
                         ConstraintCategory::Boring
                     }
                     _ => ConstraintCategory::Assignment,
                 };
+                debug!(
+                    "assignment category: {:?} {:?}",
+                    category,
+                    place.as_local().map(|l| &body.local_decls[l])
+                );
 
                 let place_ty = place.ty(body, tcx).ty;
                 let place_ty = self.normalize(place_ty, location);

compiler/rustc_expand/src/mbe/quoted.rs

@@ -72,7 +72,7 @@ pub(super) fn parse(
                                             // this with just `span.edition()`. A
                                             // `SyntaxContext::root()` from the current crate will
                                             // have the edition of the current crate, and a
-                                            // `SyntaxxContext::root()` from a foreign crate will
+                                            // `SyntaxContext::root()` from a foreign crate will
                                             // have the edition of that crate (which we manually
                                             // retrieve via the `edition` parameter).
                                             if span.ctxt() == SyntaxContext::root() {

compiler/rustc_infer/src/traits/error_reporting/mod.rs

@@ -83,10 +83,6 @@ pub fn report_object_safety_error(
                     messages.push(msg.clone());
                 }
             }
-            if trait_span.is_some() {
-                // Only provide the help if its a local trait, otherwise it's not actionable.
-                violation.solution(&mut err);
-            }
         }
     }
     let has_multi_span = !multi_span.is_empty();
@@ -104,5 +100,13 @@ pub fn report_object_safety_error(
          to be resolvable dynamically; for more information visit \
          <https://doc.rust-lang.org/reference/items/traits.html#object-safety>",
     );
+    if trait_span.is_some() {
+        let mut reported_violations: Vec<_> = reported_violations.into_iter().collect();
+        reported_violations.sort();
+        for violation in reported_violations {
+            // Only provide the help if its a local trait, otherwise it's not actionable.
+            violation.solution(&mut err);
+        }
+    }
     err
 }

compiler/rustc_lint/src/types.rs

@@ -851,12 +851,18 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
         use FfiResult::*;
 
         if def.repr.transparent() {
-            // Can assume that only one field is not a ZST, so only check
+            // Can assume that at most one field is not a ZST, so only check
             // that field's type for FFI-safety.
             if let Some(field) = transparent_newtype_field(self.cx.tcx, variant) {
                 self.check_field_type_for_ffi(cache, field, substs)
             } else {
-                bug!("malformed transparent type");
+                // All fields are ZSTs; this means that the type should behave
+                // like (), which is FFI-unsafe
+                FfiUnsafe {
+                    ty,
+                    reason: "this struct contains only zero-sized fields".into(),
+                    help: None,
+                }
             }
         } else {
             // We can't completely trust repr(C) markings; make sure the fields are

compiler/rustc_middle/src/mir/mod.rs

@@ -992,6 +992,9 @@ pub enum LocalInfo<'tcx> {
     StaticRef { def_id: DefId, is_thread_local: bool },
     /// A temporary created that references the const with the given `DefId`
     ConstRef { def_id: DefId },
+    /// A temporary created during the creation of an aggregate
+    /// (e.g. a temporary for `foo` in `MyStruct { my_field: foo }`)
+    AggregateTemp,
 }
 
 impl<'tcx> LocalDecl<'tcx> {

compiler/rustc_middle/src/mir/query.rs

@@ -332,17 +332,15 @@ pub enum ConstraintCategory {
     CopyBound,
     SizedBound,
     Assignment,
+    /// A constraint that came from a usage of a variable (e.g. in an ADT expression
+    /// like `Foo { field: my_val }`)
+    Usage,
     OpaqueType,
     ClosureUpvar(hir::HirId),
 
     /// A "boring" constraint (caused by the given location) is one that
     /// the user probably doesn't want to see described in diagnostics,
     /// because it is kind of an artifact of the type system setup.
-    /// Example: `x = Foo { field: y }` technically creates
-    /// intermediate regions representing the "type of `Foo { field: y
-    /// }`", and data flows from `y` into those variables, but they
-    /// are not very interesting. The assignment into `x` on the other
-    /// hand might be.
     Boring,
     // Boring and applicable everywhere.
     BoringNoLocation,

compiler/rustc_middle/src/traits/mod.rs

@@ -730,7 +730,7 @@ pub struct ImplSourceTraitAliasData<'tcx, N> {
     pub nested: Vec<N>,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, HashStable)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, HashStable, PartialOrd, Ord)]
 pub enum ObjectSafetyViolation {
     /// `Self: Sized` declared on the trait.
     SizedSelf(SmallVec<[Span; 1]>),
@@ -879,7 +879,7 @@ impl ObjectSafetyViolation {
 }
 
 /// Reasons a method might not be object-safe.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, PartialOrd, Ord)]
 pub enum MethodViolationCode {
     /// e.g., `fn foo()`
     StaticMethod(Option<(&'static str, Span)>, Span, bool /* has args */),

compiler/rustc_mir_build/src/build/expr/as_operand.rs

@@ -20,7 +20,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         expr: &Expr<'tcx>,
     ) -> BlockAnd<Operand<'tcx>> {
         let local_scope = self.local_scope();
-        self.as_operand(block, Some(local_scope), expr)
+        self.as_operand(block, Some(local_scope), expr, None)
     }
 
     /// Returns an operand suitable for use until the end of the current scope expression and
@@ -85,6 +85,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// temporary `tmp = x`, so that we capture the value of `x` at
     /// this time.
     ///
+    /// If we end up needing to create a temporary, then we will use
+    /// `local_info` as its `LocalInfo`, unless `as_temporary`
+    /// has already assigned it a non-`None` `LocalInfo`.
+    /// Normally, you should use `None` for `local_info`
+    ///
     /// The operand is known to be live until the end of `scope`.
     ///
     /// Like `as_local_call_operand`, except that the argument will
@@ -94,15 +99,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         mut block: BasicBlock,
         scope: Option<region::Scope>,
         expr: &Expr<'tcx>,
+        local_info: Option<Box<LocalInfo<'tcx>>>,
     ) -> BlockAnd<Operand<'tcx>> {
-        debug!("as_operand(block={:?}, expr={:?})", block, expr);
+        debug!("as_operand(block={:?}, expr={:?} local_info={:?})", block, expr, local_info);
         let this = self;
 
         if let ExprKind::Scope { region_scope, lint_level, value } = expr.kind {
             let source_info = this.source_info(expr.span);
             let region_scope = (region_scope, source_info);
             return this.in_scope(region_scope, lint_level, |this| {
-                this.as_operand(block, scope, &this.thir[value])
+                this.as_operand(block, scope, &this.thir[value], local_info)
             });
         }
 
@@ -115,6 +121,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
             Category::Place | Category::Rvalue(..) => {
                 let operand = unpack!(block = this.as_temp(block, scope, expr, Mutability::Mut));
+                if this.local_decls[operand].local_info.is_none() {
+                    this.local_decls[operand].local_info = local_info;
+                }
                 block.and(Operand::Move(Place::from(operand)))
             }
         }
@@ -167,6 +176,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
         }
 
-        this.as_operand(block, scope, expr)
+        this.as_operand(block, scope, expr, None)
     }
 }

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

@@ -52,16 +52,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
             ExprKind::Repeat { value, count } => {
                 let value_operand =
-                    unpack!(block = this.as_operand(block, scope, &this.thir[value]));
+                    unpack!(block = this.as_operand(block, scope, &this.thir[value], None));
                 block.and(Rvalue::Repeat(value_operand, count))
             }
             ExprKind::Binary { op, lhs, rhs } => {
-                let lhs = unpack!(block = this.as_operand(block, scope, &this.thir[lhs]));
-                let rhs = unpack!(block = this.as_operand(block, scope, &this.thir[rhs]));
+                let lhs = unpack!(block = this.as_operand(block, scope, &this.thir[lhs], None));
+                let rhs = unpack!(block = this.as_operand(block, scope, &this.thir[rhs], None));
                 this.build_binary_op(block, op, expr_span, expr.ty, lhs, rhs)
             }
             ExprKind::Unary { op, arg } => {
-                let arg = unpack!(block = this.as_operand(block, scope, &this.thir[arg]));
+                let arg = unpack!(block = this.as_operand(block, scope, &this.thir[arg], None));
                 // Check for -MIN on signed integers
                 if this.check_overflow && op == UnOp::Neg && expr.ty.is_signed() {
                     let bool_ty = this.tcx.types.bool;
@@ -116,11 +116,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 block.and(Rvalue::Use(Operand::Move(Place::from(result))))
             }
             ExprKind::Cast { source } => {
-                let source = unpack!(block = this.as_operand(block, scope, &this.thir[source]));
+                let source =
+                    unpack!(block = this.as_operand(block, scope, &this.thir[source], None));
                 block.and(Rvalue::Cast(CastKind::Misc, source, expr.ty))
             }
             ExprKind::Pointer { cast, source } => {
-                let source = unpack!(block = this.as_operand(block, scope, &this.thir[source]));
+                let source =
+                    unpack!(block = this.as_operand(block, scope, &this.thir[source], None));
                 block.and(Rvalue::Cast(CastKind::Pointer(cast), source, expr.ty))
             }
             ExprKind::Array { ref fields } => {
@@ -155,7 +157,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let fields: Vec<_> = fields
                     .into_iter()
                     .copied()
-                    .map(|f| unpack!(block = this.as_operand(block, scope, &this.thir[f])))
+                    .map(|f| unpack!(block = this.as_operand(block, scope, &this.thir[f], None)))
                     .collect();
 
                 block.and(Rvalue::Aggregate(Box::new(AggregateKind::Array(el_ty)), fields))
@@ -166,7 +168,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let fields: Vec<_> = fields
                     .into_iter()
                     .copied()
-                    .map(|f| unpack!(block = this.as_operand(block, scope, &this.thir[f])))
+                    .map(|f| unpack!(block = this.as_operand(block, scope, &this.thir[f], None)))
                     .collect();
 
                 block.and(Rvalue::Aggregate(Box::new(AggregateKind::Tuple), fields))
@@ -242,7 +244,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                             &this.thir[arg],
                                         )
                                     ),
-                                    _ => unpack!(block = this.as_operand(block, scope, upvar)),
+                                    _ => {
+                                        unpack!(block = this.as_operand(block, scope, upvar, None))
+                                    }
                                 }
                             }
                         }
@@ -304,7 +308,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     Category::of(&expr.kind),
                     Some(Category::Rvalue(RvalueFunc::AsRvalue))
                 ));
-                let operand = unpack!(block = this.as_operand(block, scope, expr));
+                let operand = unpack!(block = this.as_operand(block, scope, expr, None));
                 block.and(Rvalue::Use(operand))
             }
         }

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -326,10 +326,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let fields_map: FxHashMap<_, _> = fields
                     .into_iter()
                     .map(|f| {
+                        let local_info = Box::new(LocalInfo::AggregateTemp);
                         (
                             f.name,
                             unpack!(
-                                block = this.as_operand(block, Some(scope), &this.thir[f.expr])
+                                block = this.as_operand(
+                                    block,
+                                    Some(scope),
+                                    &this.thir[f.expr],
+                                    Some(local_info)
+                                )
                             ),
                         )
                     })
@@ -508,7 +514,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             ExprKind::Yield { value } => {
                 let scope = this.local_scope();
-                let value = unpack!(block = this.as_operand(block, Some(scope), &this.thir[value]));
+                let value =
+                    unpack!(block = this.as_operand(block, Some(scope), &this.thir[value], None));
                 let resume = this.cfg.start_new_block();
                 this.cfg.terminate(
                     block,

compiler/rustc_mir_dataflow/src/lib.rs

@@ -28,8 +28,8 @@ pub use self::drop_flag_effects::{
     on_lookup_result_bits,
 };
 pub use self::framework::{
-    fmt, lattice, visit_results, Analysis, AnalysisDomain, Backward, Direction, Engine, Forward,
-    GenKill, GenKillAnalysis, JoinSemiLattice, Results, ResultsCursor, ResultsRefCursor,
+    fmt, graphviz, lattice, visit_results, Analysis, AnalysisDomain, Backward, Direction, Engine,
+    Forward, GenKill, GenKillAnalysis, JoinSemiLattice, Results, ResultsCursor, ResultsRefCursor,
     ResultsVisitable, ResultsVisitor,
 };
 

compiler/rustc_mir_transform/src/lib.rs

@@ -76,7 +76,7 @@ mod unreachable_prop;
 use rustc_const_eval::transform::check_consts;
 use rustc_const_eval::transform::promote_consts;
 use rustc_const_eval::transform::validate;
-use rustc_const_eval::transform::MirPass;
+pub use rustc_const_eval::transform::MirPass;
 use rustc_mir_dataflow::rustc_peek;
 
 pub fn provide(providers: &mut Providers) {

compiler/rustc_span/src/symbol.rs

@@ -934,7 +934,6 @@ symbols! {
         panic_unwind,
         panicking,
         param_attrs,
-        parent_trait,
         partial_cmp,
         partial_ord,
         passes,