rustc_borrowck/
root_cx.rs

1use rustc_abi::FieldIdx;
2use rustc_data_structures::fx::FxHashMap;
3use rustc_hir::def_id::LocalDefId;
4use rustc_middle::bug;
5use rustc_middle::ty::{OpaqueHiddenType, Ty, TyCtxt, TypeVisitableExt};
6use rustc_span::ErrorGuaranteed;
7use smallvec::SmallVec;
8
9use crate::{ClosureRegionRequirements, ConcreteOpaqueTypes, PropagatedBorrowCheckResults};
10
11/// The shared context used by both the root as well as all its nested
12/// items.
13pub(super) struct BorrowCheckRootCtxt<'tcx> {
14    pub tcx: TyCtxt<'tcx>,
15    root_def_id: LocalDefId,
16    concrete_opaque_types: ConcreteOpaqueTypes<'tcx>,
17    nested_bodies: FxHashMap<LocalDefId, PropagatedBorrowCheckResults<'tcx>>,
18    tainted_by_errors: Option<ErrorGuaranteed>,
19}
20
21impl<'tcx> BorrowCheckRootCtxt<'tcx> {
22    pub(super) fn new(tcx: TyCtxt<'tcx>, root_def_id: LocalDefId) -> BorrowCheckRootCtxt<'tcx> {
23        BorrowCheckRootCtxt {
24            tcx,
25            root_def_id,
26            concrete_opaque_types: Default::default(),
27            nested_bodies: Default::default(),
28            tainted_by_errors: None,
29        }
30    }
31
32    /// Collect all defining uses of opaque types inside of this typeck root. This
33    /// expects the hidden type to be mapped to the definition parameters of the opaque
34    /// and errors if we end up with distinct hidden types.
35    pub(super) fn add_concrete_opaque_type(
36        &mut self,
37        def_id: LocalDefId,
38        hidden_ty: OpaqueHiddenType<'tcx>,
39    ) {
40        // Sometimes two opaque types are the same only after we remap the generic parameters
41        // back to the opaque type definition. E.g. we may have `OpaqueType<X, Y>` mapped to
42        // `(X, Y)` and `OpaqueType<Y, X>` mapped to `(Y, X)`, and those are the same, but we
43        // only know that once we convert the generic parameters to those of the opaque type.
44        if let Some(prev) = self.concrete_opaque_types.0.get_mut(&def_id) {
45            if prev.ty != hidden_ty.ty {
46                let guar = hidden_ty.ty.error_reported().err().unwrap_or_else(|| {
47                    let (Ok(e) | Err(e)) =
48                        prev.build_mismatch_error(&hidden_ty, self.tcx).map(|d| d.emit());
49                    e
50                });
51                prev.ty = Ty::new_error(self.tcx, guar);
52            }
53            // Pick a better span if there is one.
54            // FIXME(oli-obk): collect multiple spans for better diagnostics down the road.
55            prev.span = prev.span.substitute_dummy(hidden_ty.span);
56        } else {
57            self.concrete_opaque_types.0.insert(def_id, hidden_ty);
58        }
59    }
60
61    pub(super) fn set_tainted_by_errors(&mut self, guar: ErrorGuaranteed) {
62        self.tainted_by_errors = Some(guar);
63    }
64
65    pub(super) fn get_or_insert_nested(
66        &mut self,
67        def_id: LocalDefId,
68    ) -> &PropagatedBorrowCheckResults<'tcx> {
69        debug_assert_eq!(
70            self.tcx.typeck_root_def_id(def_id.to_def_id()),
71            self.root_def_id.to_def_id()
72        );
73        if !self.nested_bodies.contains_key(&def_id) {
74            let result = super::do_mir_borrowck(self, def_id, None).0;
75            if let Some(prev) = self.nested_bodies.insert(def_id, result) {
76                bug!("unexpected previous nested body: {prev:?}");
77            }
78        }
79
80        self.nested_bodies.get(&def_id).unwrap()
81    }
82
83    pub(super) fn closure_requirements(
84        &mut self,
85        nested_body_def_id: LocalDefId,
86    ) -> &Option<ClosureRegionRequirements<'tcx>> {
87        &self.get_or_insert_nested(nested_body_def_id).closure_requirements
88    }
89
90    pub(super) fn used_mut_upvars(
91        &mut self,
92        nested_body_def_id: LocalDefId,
93    ) -> &SmallVec<[FieldIdx; 8]> {
94        &self.get_or_insert_nested(nested_body_def_id).used_mut_upvars
95    }
96
97    pub(super) fn finalize(self) -> Result<&'tcx ConcreteOpaqueTypes<'tcx>, ErrorGuaranteed> {
98        if let Some(guar) = self.tainted_by_errors {
99            Err(guar)
100        } else {
101            Ok(self.tcx.arena.alloc(self.concrete_opaque_types))
102        }
103    }
104}
rustc_borrowck/root_cx.rs

rustc_borrowck/
root_cx.rs
