compiler/rustc_infer/src/infer/opaque_types/table.rs

   1 use rustc_data_structures::undo_log::UndoLogs;
   2 use rustc_hir::OpaqueTyOrigin;
   3 use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, Ty};
   4 use rustc_span::DUMMY_SP;
   5
   6 use crate::infer::{InferCtxtUndoLogs, UndoLog};
   7
   8 use super::{OpaqueTypeDecl, OpaqueTypeMap};
   9
  10 #[derive(Default, Debug, Clone)]
  11 pub struct OpaqueTypeStorage<'tcx> {
  12     // Opaque types found in explicit return types and their
  13     // associated fresh inference variable. Writeback resolves these
  14     // variables to get the concrete type, which can be used to
  15     // 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
  16     pub opaque_types: OpaqueTypeMap<'tcx>,
  17 }
  18
  19 impl<'tcx> OpaqueTypeStorage<'tcx> {
  20     #[instrument(level = "debug")]
  21     pub(crate) fn remove(&mut self, key: OpaqueTypeKey<'tcx>, idx: Option<OpaqueHiddenType<'tcx>>) {
  22         if let Some(idx) = idx {
  23             self.opaque_types.get_mut(&key).unwrap().hidden_type = idx;
  24         } else {
  25             match self.opaque_types.remove(&key) {
  26                 None => bug!("reverted opaque type inference that was never registered: {:?}", key),
  27                 Some(_) => {}
  28             }
  29         }
  30     }
  31
  32     #[instrument(level = "debug", ret)]
  33     pub fn take_opaque_types(&mut self) -> OpaqueTypeMap<'tcx> {
  34         std::mem::take(&mut self.opaque_types)
  35     }
  36
  37     #[inline]
  38     pub(crate) fn with_log<'a>(
  39         &'a mut self,
  40         undo_log: &'a mut InferCtxtUndoLogs<'tcx>,
  41     ) -> OpaqueTypeTable<'a, 'tcx> {
  42         OpaqueTypeTable { storage: self, undo_log }
  43     }
  44 }
  45
  46 impl<'tcx> Drop for OpaqueTypeStorage<'tcx> {
  47     fn drop(&mut self) {
  48         if !self.opaque_types.is_empty() {
  49             ty::tls::with(|tcx| {
  50                 tcx.sess.delay_span_bug(DUMMY_SP, &format!("{:?}", self.opaque_types))
  51             });
  52         }
  53     }
  54 }
  55
  56 pub struct OpaqueTypeTable<'a, 'tcx> {
  57     storage: &'a mut OpaqueTypeStorage<'tcx>,
  58
  59     undo_log: &'a mut InferCtxtUndoLogs<'tcx>,
  60 }
  61
  62 impl<'a, 'tcx> OpaqueTypeTable<'a, 'tcx> {
  63     #[instrument(skip(self), level = "debug")]
  64     pub(crate) fn register(
  65         &mut self,
  66         key: OpaqueTypeKey<'tcx>,
  67         hidden_type: OpaqueHiddenType<'tcx>,
  68         origin: OpaqueTyOrigin,
  69     ) -> Option<Ty<'tcx>> {
  70         if let Some(decl) = self.storage.opaque_types.get_mut(&key) {
  71             let prev = std::mem::replace(&mut decl.hidden_type, hidden_type);
  72             self.undo_log.push(UndoLog::OpaqueTypes(key, Some(prev)));
  73             return Some(prev.ty);
  74         }
  75         let decl = OpaqueTypeDecl { hidden_type, origin };
  76         self.storage.opaque_types.insert(key, decl);
  77         self.undo_log.push(UndoLog::OpaqueTypes(key, None));
  78         None
  79     }
  80 }