mir borrowck: cleanup late-bound region handling
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lcnr
parent
e491caec14
commit
99657aa338
7 changed files with 33 additions and 47 deletions
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@ -34,7 +34,6 @@ pub(crate) enum RegionCtxt {
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Location(Location),
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TyContext(TyContext),
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Free(Symbol),
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Bound(Symbol),
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LateBound(Symbol),
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Existential(Option<Symbol>),
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Placeholder(Symbol),
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@ -467,15 +467,13 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
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self.infcx.tcx.local_parent(self.mir_def),
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|r| {
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debug!(?r);
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if !indices.indices.contains_key(&r) {
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let region_vid = {
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let name = r.get_name_or_anon();
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self.infcx.next_nll_region_var(FR, || RegionCtxt::LateBound(name))
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};
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let region_vid = {
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let name = r.get_name_or_anon();
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self.infcx.next_nll_region_var(FR, || RegionCtxt::LateBound(name))
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};
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debug!(?region_vid);
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indices.insert_late_bound_region(r, region_vid.as_var());
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}
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debug!(?region_vid);
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indices.insert_late_bound_region(r, region_vid.as_var());
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},
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);
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@ -484,21 +482,17 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
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self.infcx.num_region_vars()
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};
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// "Liberate" the late-bound regions. These correspond to
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// "local" free regions.
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// Converse of above, if this is a function/closure then the late-bound regions declared
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// on its signature are local.
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//
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// We manually loop over `bound_inputs_and_output` instead of using
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// `for_each_late_bound_region_in_item` as we may need to add the otherwise
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// implicit `ClosureEnv` region.
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let bound_inputs_and_output = self.compute_inputs_and_output(&indices, defining_ty);
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let inputs_and_output = self.infcx.replace_bound_regions_with_nll_infer_vars(
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FR,
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self.mir_def,
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bound_inputs_and_output,
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&mut indices,
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);
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// Converse of above, if this is a function/closure then the late-bound regions declared on its
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// signature are local.
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for_each_late_bound_region_in_item(self.infcx.tcx, self.mir_def, |r| {
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debug!(?r);
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if !indices.indices.contains_key(&r) {
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for (idx, bound_var) in bound_inputs_and_output.bound_vars().iter().enumerate() {
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if let ty::BoundVariableKind::Region(kind) = bound_var {
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let kind = ty::LateParamRegionKind::from_bound(ty::BoundVar::from_usize(idx), kind);
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let r = ty::Region::new_late_param(self.infcx.tcx, self.mir_def.to_def_id(), kind);
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let region_vid = {
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let name = r.get_name_or_anon();
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self.infcx.next_nll_region_var(FR, || RegionCtxt::LateBound(name))
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@ -507,7 +501,12 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
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debug!(?region_vid);
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indices.insert_late_bound_region(r, region_vid.as_var());
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}
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});
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}
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let inputs_and_output = self.infcx.replace_bound_regions_with_nll_infer_vars(
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self.mir_def,
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bound_inputs_and_output,
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&indices,
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);
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let (unnormalized_output_ty, mut unnormalized_input_tys) =
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inputs_and_output.split_last().unwrap();
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@ -832,10 +831,9 @@ impl<'tcx> BorrowckInferCtxt<'tcx> {
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#[instrument(level = "debug", skip(self, indices))]
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fn replace_bound_regions_with_nll_infer_vars<T>(
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&self,
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origin: NllRegionVariableOrigin,
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all_outlive_scope: LocalDefId,
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value: ty::Binder<'tcx, T>,
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indices: &mut UniversalRegionIndices<'tcx>,
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indices: &UniversalRegionIndices<'tcx>,
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) -> T
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where
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T: TypeFoldable<TyCtxt<'tcx>>,
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@ -845,18 +843,7 @@ impl<'tcx> BorrowckInferCtxt<'tcx> {
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let kind = ty::LateParamRegionKind::from_bound(br.var, br.kind);
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let liberated_region =
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ty::Region::new_late_param(self.tcx, all_outlive_scope.to_def_id(), kind);
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let region_vid = {
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let name = match br.kind.get_name() {
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Some(name) => name,
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_ => sym::anon,
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};
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self.next_nll_region_var(origin, || RegionCtxt::Bound(name))
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};
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indices.insert_late_bound_region(liberated_region, region_vid.as_var());
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debug!(?liberated_region, ?region_vid);
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region_vid
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ty::Region::new_var(self.tcx, indices.to_region_vid(liberated_region))
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});
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value
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}
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@ -870,7 +857,7 @@ impl<'tcx> UniversalRegionIndices<'tcx> {
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/// well. These are used for error reporting.
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fn insert_late_bound_region(&mut self, r: ty::Region<'tcx>, vid: ty::RegionVid) {
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debug!("insert_late_bound_region({:?}, {:?})", r, vid);
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self.indices.insert(r, vid);
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assert_eq!(self.indices.insert(r, vid), None);
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}
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/// Converts `r` into a local inference variable: `r` can either
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@ -9,7 +9,7 @@ LL | for<'a> || -> () { for<'c> |_: &'a ()| -> () {}; };
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extern "rust-call" fn((&(),)),
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(),
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]
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= note: late-bound region is '?4
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= note: late-bound region is '?3
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= note: late-bound region is '?2
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= note: number of external vids: 3
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= note: where '?1: '?2
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@ -26,7 +26,7 @@ LL | for<'a> || -> () { for<'c> |_: &'a ()| -> () {}; };
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extern "rust-call" fn(()),
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(),
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]
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= note: late-bound region is '?2
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= note: late-bound region is '?1
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note: no external requirements
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--> $DIR/nested-closures-regions.rs:7:1
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@ -17,7 +17,7 @@ LL | let mut closure = expect_sig(|p, y| *p = y);
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| - - ^^^^^^ assignment requires that `'1` must outlive `'2`
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| | |
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| | has type `&'1 i32`
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| has type `&'?2 mut &'2 i32`
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| has type `&'?1 mut &'2 i32`
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note: no external requirements
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--> $DIR/escape-argument-callee.rs:20:1
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@ -20,7 +20,7 @@ LL | foo(cell, |cell_a, cell_x| {
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LL | cell_a.set(cell_x.get()); // forces 'x: 'a, error in closure
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| ^^^^^^^^^^^^^^^^^^^^^^^^ `cell_x` escapes the closure body here
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= note: requirement occurs because of the type `Cell<&'?8 u32>`, which makes the generic argument `&'?8 u32` invariant
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= note: requirement occurs because of the type `Cell<&'?9 u32>`, which makes the generic argument `&'?9 u32` invariant
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= note: the struct `Cell<T>` is invariant over the parameter `T`
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= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
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@ -16,9 +16,9 @@ error: lifetime may not live long enough
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--> $DIR/propagate-fail-to-approximate-longer-no-bounds.rs:37:9
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LL | establish_relationships(&cell_a, &cell_b, |_outlives, x, y| {
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| --------- - has type `&'?7 Cell<&'1 u32>`
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| --------- - has type `&'?6 Cell<&'1 u32>`
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| |
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| has type `&'?5 Cell<&'2 &'?1 u32>`
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| has type `&'?4 Cell<&'2 &'?1 u32>`
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LL | // Only works if 'x: 'y:
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LL | demand_y(x, y, x.get())
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| ^^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'1` must outlive `'2`
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@ -16,9 +16,9 @@ error: lifetime may not live long enough
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--> $DIR/propagate-fail-to-approximate-longer-wrong-bounds.rs:41:9
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LL | establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| {
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| ---------- ---------- has type `&'?8 Cell<&'2 &'?2 u32>`
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| ---------- ---------- has type `&'?7 Cell<&'2 &'?2 u32>`
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| |
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| has type `&'?6 Cell<&'1 &'?1 u32>`
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| has type `&'?5 Cell<&'1 &'?1 u32>`
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LL | // Only works if 'x: 'y:
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LL | demand_y(x, y, x.get())
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| ^^^^^^^^^^^^^^^^^^^^^^^ argument requires that `'1` must outlive `'2`
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