Mir tycheck aggregate rvalues

src/librustc/mir/mod.rs

@@ -1376,10 +1376,14 @@ pub enum AggregateKind<'tcx> {
     /// The type is of the element
     Array(Ty<'tcx>),
     Tuple,
-    /// The second field is variant number (discriminant), it's equal to 0
-    /// for struct and union expressions. The fourth field is active field
-    /// number and is present only for union expressions.
+
+    /// The second field is variant number (discriminant), it's equal
+    /// to 0 for struct and union expressions. The fourth field is
+    /// active field number and is present only for union expressions
+    /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
+    /// active field index would identity the field `c`
     Adt(&'tcx AdtDef, usize, &'tcx Substs<'tcx>, Option<usize>),
+
     Closure(DefId, ClosureSubsts<'tcx>),
     Generator(DefId, ClosureSubsts<'tcx>, GeneratorInterior<'tcx>),
 }

src/librustc_mir/transform/nll/mod.rs

@@ -46,7 +46,7 @@ pub fn compute_regions<'a, 'gcx, 'tcx>(
 
     // Run the MIR type-checker.
     let body_id = source.item_id();
-    let constraint_sets = &type_check::type_check(infcx, body_id, param_env, mir);
+    let constraint_sets = &type_check::type_check(infcx, body_id, param_env, mir, source);
 
     // Create the region inference context, taking ownership of the region inference
     // data that was contained in `infcx`.

src/librustc_mir/transform/type_check.rs

@@ -11,6 +11,7 @@
 //! This pass type-checks the MIR to ensure it is not broken.
 #![allow(unreachable_code)]
 
+use rustc::hir::map::DefPathData;
 use rustc::infer::{InferCtxt, InferOk, InferResult, LateBoundRegionConversionTime, UnitResult};
 use rustc::infer::region_constraints::RegionConstraintData;
 use rustc::traits::{self, FulfillmentContext};
@@ -41,8 +42,9 @@ pub fn type_check<'a, 'gcx, 'tcx>(
     body_id: ast::NodeId,
     param_env: ty::ParamEnv<'gcx>,
     mir: &Mir<'tcx>,
+    mir_source: MirSource,
 ) -> MirTypeckRegionConstraints<'tcx> {
-    let mut checker = TypeChecker::new(infcx, body_id, param_env);
+    let mut checker = TypeChecker::new(infcx, body_id, param_env, mir_source);
     let errors_reported = {
         let mut verifier = TypeVerifier::new(&mut checker, mir);
         verifier.visit_mir(mir);
@@ -408,6 +410,11 @@ pub struct TypeChecker<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
     body_id: ast::NodeId,
     reported_errors: FxHashSet<(Ty<'tcx>, Span)>,
     constraints: MirTypeckRegionConstraints<'tcx>,
+
+    // FIXME(#45940) - True if this is a MIR shim or ADT constructor
+    // (e.g., for a tuple struct.) In that case, the internal types of
+    // operands and things require normalization.
+    is_adt_constructor: bool,
 }
 
 /// A collection of region constraints that must be satisfied for the
@@ -459,14 +466,23 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
         body_id: ast::NodeId,
         param_env: ty::ParamEnv<'gcx>,
+        mir_source: MirSource,
     ) -> Self {
+        let mir_def_id = infcx.tcx.hir.local_def_id(mir_source.item_id());
+        let def_key = infcx.tcx.def_key(mir_def_id);
+        let is_adt_constructor = match def_key.disambiguated_data.data {
+            DefPathData::StructCtor => true,
+            _ => false,
+        };
+
         TypeChecker {
             infcx,
             last_span: DUMMY_SP,
             body_id,
             param_env,
             reported_errors: FxHashSet(),
             constraints: MirTypeckRegionConstraints::default(),
+            is_adt_constructor,
         }
     }
 
@@ -549,6 +565,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                         terr
                     );
                 }
+                self.check_rvalue(mir, rv, location);
             }
             StatementKind::SetDiscriminant {
                 ref lvalue,
@@ -1008,6 +1025,121 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
         }
     }
 
+    fn aggregate_field_ty(
+        &mut self,
+        ak: &Box<AggregateKind<'tcx>>,
+        field_index: usize,
+        location: Location,
+    ) -> Result<Ty<'tcx>, FieldAccessError> {
+        let tcx = self.tcx();
+
+        match **ak {
+            AggregateKind::Adt(def, variant_index, substs, active_field_index) => {
+                let variant = &def.variants[variant_index];
+                let adj_field_index = active_field_index.unwrap_or(field_index);
+                if let Some(field) = variant.fields.get(adj_field_index) {
+                    Ok(self.normalize(&field.ty(tcx, substs), location))
+                } else {
+                    Err(FieldAccessError::OutOfRange {
+                        field_count: variant.fields.len(),
+                    })
+                }
+            }
+            AggregateKind::Closure(def_id, substs) => {
+                match substs.upvar_tys(def_id, tcx).nth(field_index) {
+                    Some(ty) => Ok(ty),
+                    None => Err(FieldAccessError::OutOfRange {
+                        field_count: substs.upvar_tys(def_id, tcx).count(),
+                    }),
+                }
+            }
+            AggregateKind::Generator(def_id, substs, _) => {
+                if let Some(ty) = substs.upvar_tys(def_id, tcx).nth(field_index) {
+                    Ok(ty)
+                } else {
+                    match substs.field_tys(def_id, tcx).nth(field_index) {
+                        Some(ty) => Ok(ty),
+                        None => Err(FieldAccessError::OutOfRange {
+                            field_count: substs.field_tys(def_id, tcx).count() + 1,
+                        }),
+                    }
+                }
+            }
+            AggregateKind::Array(ty) => {
+                Ok(ty)
+            }
+            AggregateKind::Tuple => {
+                unreachable!("This should have been covered in check_rvalues");
+            }
+        }
+    }
+
+    fn check_rvalue(&mut self, mir: &Mir<'tcx>, rv: &Rvalue<'tcx>, location: Location) {
+        let tcx = self.tcx();
+        match rv {
+            Rvalue::Aggregate(ak, ops) => {
+                match **ak {
+                    // tuple rvalue field type is always the type of the op. Nothing to check here.
+                    AggregateKind::Tuple => {}
+                    _ => {
+                        for (i, op) in ops.iter().enumerate() {
+                            let field_ty = match self.aggregate_field_ty(ak, i, location) {
+                                Ok(field_ty) => field_ty,
+                                Err(FieldAccessError::OutOfRange { field_count }) => {
+                                    span_mirbug!(
+                                        self,
+                                        rv,
+                                        "accessed field #{} but variant only has {}",
+                                        i,
+                                        field_count
+                                    );
+                                    continue;
+                                }
+                            };
+                            let op_ty = match op {
+                                Operand::Consume(lv) => {
+                                    let lv_ty = lv.ty(mir, tcx).to_ty(tcx);
+                                    if self.is_adt_constructor {
+                                        self.normalize(&lv_ty, location)
+                                    } else {
+                                        lv_ty
+                                    }
+                                }
+                                Operand::Constant(c) => c.ty,
+                            };
+                            if let Err(terr) = self.sub_types(
+                                op_ty,
+                                field_ty,
+                                location.at_successor_within_block(),
+                            )
+                                {
+                                    span_mirbug!(
+                                    self,
+                                    rv,
+                                    "{:?} is not a subtype of {:?}: {:?}",
+                                    op_ty,
+                                    field_ty,
+                                    terr
+                                );
+                                }
+                        }
+                    }
+                }
+            }
+            // FIXME: These other cases have to be implemented in future PRs
+            Rvalue::Use(..) |
+            Rvalue::Repeat(..) |
+            Rvalue::Ref(..) |
+            Rvalue::Len(..) |
+            Rvalue::Cast(..) |
+            Rvalue::BinaryOp(..) |
+            Rvalue::CheckedBinaryOp(..) |
+            Rvalue::UnaryOp(..) |
+            Rvalue::Discriminant(..) |
+            Rvalue::NullaryOp(..) => {}
+        }
+    }
+
     fn typeck_mir(&mut self, mir: &Mir<'tcx>) {
         self.last_span = mir.span;
         debug!("run_on_mir: {:?}", mir.span);
@@ -1063,7 +1195,7 @@ impl MirPass for TypeckMir {
         }
         let param_env = tcx.param_env(def_id);
         tcx.infer_ctxt().enter(|infcx| {
-            let _region_constraint_sets = type_check(&infcx, item_id, param_env, mir);
+            let _region_constraint_sets = type_check(&infcx, item_id, param_env, mir, src);
 
             // For verification purposes, we just ignore the resulting
             // region constraint sets. Not our problem. =)

src/test/compile-fail/nll/reference-carried-through-struct-field.rs

@@ -0,0 +1,27 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//revisions: ast mir
+//[mir] compile-flags: -Z emit-end-regions -Z borrowck-mir -Z nll
+
+#![allow(unused_assignments)]
+
+struct Wrap<'a> { w: &'a mut u32 }
+
+fn foo() {
+    let mut x = 22;
+    let wrapper = Wrap { w: &mut x };
+    x += 1; //[ast]~ ERROR cannot assign to `x` because it is borrowed [E0506]
+    //[mir]~^ ERROR cannot assign to `x` because it is borrowed (Ast) [E0506]
+    //[mir]~^^ ERROR cannot assign to `x` because it is borrowed (Mir) [E0506]
+    //[mir]~^^^ ERROR cannot use `x` because it was mutably borrowed (Mir) [E0503]
+    *wrapper.w += 1;
+}
+
+fn main() { }