support revealing-uses in closures

Author: lcnr

compiler/rustc_borrowck/src/consumers.rs

@@ -15,7 +15,7 @@ pub use super::polonius::legacy::{
     RichLocation, RustcFacts,
 };
 pub use super::region_infer::RegionInferenceContext;
-use crate::{BorrowCheckRootCtxt, do_mir_borrowck};
+use crate::BorrowCheckRootCtxt;
 
 /// Options determining the output behavior of [`get_body_with_borrowck_facts`].
 ///
@@ -101,6 +101,6 @@ pub fn get_body_with_borrowck_facts(
     def_id: LocalDefId,
     options: ConsumerOptions,
 ) -> BodyWithBorrowckFacts<'_> {
-    let mut root_cx = BorrowCheckRootCtxt::new(tcx, def_id);
-    *do_mir_borrowck(&mut root_cx, def_id, Some(options)).1.unwrap()
+    let root_cx = BorrowCheckRootCtxt::new(tcx, def_id);
+    *root_cx.borrowck_root(Some(options)).1.unwrap()
 }

compiler/rustc_borrowck/src/lib.rs

@@ -22,6 +22,7 @@ use std::cell::RefCell;
 use std::marker::PhantomData;
 use std::ops::{ControlFlow, Deref};
 
+use nll::YieldComputeRegions;
 use root_cx::BorrowCheckRootCtxt;
 use rustc_abi::FieldIdx;
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -52,6 +53,7 @@ use rustc_session::lint::builtin::{TAIL_EXPR_DROP_ORDER, UNUSED_MUT};
 use rustc_span::{ErrorGuaranteed, Span, Symbol};
 use smallvec::SmallVec;
 use tracing::{debug, instrument};
+use type_check::Locations;
 
 use crate::borrow_set::{BorrowData, BorrowSet};
 use crate::consumers::{BodyWithBorrowckFacts, ConsumerOptions};
@@ -125,12 +127,8 @@ fn mir_borrowck(
         let opaque_types = ConcreteOpaqueTypes(Default::default());
         Ok(tcx.arena.alloc(opaque_types))
     } else {
-        let mut root_cx = BorrowCheckRootCtxt::new(tcx, def);
-        let PropagatedBorrowCheckResults { closure_requirements, used_mut_upvars } =
-            do_mir_borrowck(&mut root_cx, def, None).0;
-        debug_assert!(closure_requirements.is_none());
-        debug_assert!(used_mut_upvars.is_empty());
-        root_cx.finalize()
+        let root_cx = BorrowCheckRootCtxt::new(tcx, def);
+        root_cx.borrowck_root(None).0
     }
 }
 
@@ -142,6 +140,8 @@ struct PropagatedBorrowCheckResults<'tcx> {
     used_mut_upvars: SmallVec<[FieldIdx; 8]>,
 }
 
+type DeferredClosureRequirements<'tcx> = Vec<(LocalDefId, ty::GenericArgsRef<'tcx>, Locations)>;
+
 /// After we borrow check a closure, we are left with various
 /// requirements that we have inferred between the free regions that
 /// appear in the closure's signature or on its field types. These
@@ -280,6 +280,17 @@ impl<'tcx> ClosureOutlivesSubjectTy<'tcx> {
     }
 }
 
+struct YieldDoMirBorrowck<'tcx> {
+    infcx: BorrowckInferCtxt<'tcx>,
+    body_owned: Body<'tcx>,
+    promoted: IndexVec<Promoted, Body<'tcx>>,
+    move_data: MoveData<'tcx>,
+    locals_are_invalidated_at_exit: bool,
+    borrow_set: BorrowSet<'tcx>,
+    location_table: PoloniusLocationTable,
+    yield_compute_regions: YieldComputeRegions<'tcx>,
+}
+
 /// Perform the actual borrow checking.
 ///
 /// Use `consumer_options: None` for the default behavior of returning
@@ -288,11 +299,11 @@ impl<'tcx> ClosureOutlivesSubjectTy<'tcx> {
 ///
 /// For nested bodies this should only be called through `root_cx.get_or_insert_nested`.
 #[instrument(skip(root_cx), level = "debug")]
-fn do_mir_borrowck<'tcx>(
+fn start_do_mir_borrowck<'tcx>(
     root_cx: &mut BorrowCheckRootCtxt<'tcx>,
     def: LocalDefId,
     consumer_options: Option<ConsumerOptions>,
-) -> (PropagatedBorrowCheckResults<'tcx>, Option<Box<BodyWithBorrowckFacts<'tcx>>>) {
+) -> YieldDoMirBorrowck<'tcx> {
     let tcx = root_cx.tcx;
     let infcx = BorrowckInferCtxt::new(tcx, def);
     let (input_body, promoted) = tcx.mir_promoted(def);
@@ -303,33 +314,13 @@ fn do_mir_borrowck<'tcx>(
         root_cx.set_tainted_by_errors(e);
     }
 
-    let mut local_names = IndexVec::from_elem(None, &input_body.local_decls);
-    for var_debug_info in &input_body.var_debug_info {
-        if let VarDebugInfoContents::Place(place) = var_debug_info.value {
-            if let Some(local) = place.as_local() {
-                if let Some(prev_name) = local_names[local]
-                    && var_debug_info.name != prev_name
-                {
-                    span_bug!(
-                        var_debug_info.source_info.span,
-                        "local {:?} has many names (`{}` vs `{}`)",
-                        local,
-                        prev_name,
-                        var_debug_info.name
-                    );
-                }
-                local_names[local] = Some(var_debug_info.name);
-            }
-        }
-    }
-
     // Replace all regions with fresh inference variables. This
     // requires first making our own copy of the MIR. This copy will
     // be modified (in place) to contain non-lexical lifetimes. It
     // will have a lifetime tied to the inference context.
     let mut body_owned = input_body.clone();
     let mut promoted = input_promoted.to_owned();
-    let free_regions = nll::replace_regions_in_mir(&infcx, &mut body_owned, &mut promoted);
+    let universal_regions = nll::replace_regions_in_mir(&infcx, &mut body_owned, &mut promoted);
     let body = &body_owned; // no further changes
 
     let location_table = PoloniusLocationTable::new(body);
@@ -343,6 +334,50 @@ fn do_mir_borrowck<'tcx>(
     let locals_are_invalidated_at_exit = tcx.hir_body_owner_kind(def).is_fn_or_closure();
     let borrow_set = BorrowSet::build(tcx, body, locals_are_invalidated_at_exit, &move_data);
 
+    let yield_compute_regions = nll::compute_regions(
+        root_cx,
+        &infcx,
+        universal_regions,
+        body,
+        &promoted,
+        &location_table,
+        flow_inits,
+        &move_data,
+        &borrow_set,
+        consumer_options,
+    );
+
+    YieldDoMirBorrowck {
+        infcx,
+        body_owned,
+        promoted,
+        move_data,
+        locals_are_invalidated_at_exit,
+        borrow_set,
+        location_table,
+        yield_compute_regions,
+    }
+}
+
+fn resume_do_mir_borrowck<'tcx>(
+    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    def: LocalDefId,
+    consumer_options: Option<ConsumerOptions>,
+    YieldDoMirBorrowck {
+        infcx,
+        body_owned,
+        promoted,
+        move_data,
+        locals_are_invalidated_at_exit,
+        borrow_set,
+        location_table,
+        yield_compute_regions,
+    }: YieldDoMirBorrowck<'tcx>,
+) -> (PropagatedBorrowCheckResults<'tcx>, Option<Box<BodyWithBorrowckFacts<'tcx>>>) {
+    assert!(!infcx.has_opaque_types_in_storage());
+    let tcx = infcx.tcx;
+    let body = &body_owned;
+
     // Compute non-lexical lifetimes.
     let nll::NllOutput {
         regioncx,
@@ -351,17 +386,15 @@ fn do_mir_borrowck<'tcx>(
         opt_closure_req,
         nll_errors,
         polonius_diagnostics,
-    } = nll::compute_regions(
+    } = nll::resume_compute_regions(
         root_cx,
         &infcx,
-        free_regions,
         body,
-        &promoted,
         &location_table,
-        flow_inits,
         &move_data,
         &borrow_set,
         consumer_options,
+        yield_compute_regions,
     );
 
     // Dump MIR results into a file, if that is enabled. This lets us
@@ -376,14 +409,14 @@ fn do_mir_borrowck<'tcx>(
     let movable_coroutine =
     // The first argument is the coroutine type passed by value
     if let Some(local) = body.local_decls.raw.get(1)
-    // Get the interior types and args which typeck computed
-    && let ty::Coroutine(def_id, _) = *local.ty.kind()
-    && tcx.coroutine_movability(def_id) == hir::Movability::Movable
-{
-    true
-} else {
-    false
-};
+        // Get the interior types and args which typeck computed
+        && let ty::Coroutine(def_id, _) = *local.ty.kind()
+        && tcx.coroutine_movability(def_id) == hir::Movability::Movable
+    {
+        true
+    } else {
+        false
+    };
 
     // While promoteds should mostly be correct by construction, we need to check them for
     // invalid moves to detect moving out of arrays:`struct S; fn main() { &([S][0]); }`.
@@ -434,6 +467,26 @@ fn do_mir_borrowck<'tcx>(
         promoted_mbcx.report_move_errors();
     }
 
+    let mut local_names = IndexVec::from_elem(None, &body.local_decls);
+    for var_debug_info in &body.var_debug_info {
+        if let VarDebugInfoContents::Place(place) = var_debug_info.value {
+            if let Some(local) = place.as_local() {
+                if let Some(prev_name) = local_names[local]
+                    && var_debug_info.name != prev_name
+                {
+                    span_bug!(
+                        var_debug_info.source_info.span,
+                        "local {:?} has many names (`{}` vs `{}`)",
+                        local,
+                        prev_name,
+                        var_debug_info.name
+                    );
+                }
+                local_names[local] = Some(var_debug_info.name);
+            }
+        }
+    }
+
     let mut mbcx = MirBorrowckCtxt {
         root_cx,
         infcx: &infcx,