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address nits by mattewjasper

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This commit is contained in:
Niko Matsakis 2019-06-17 09:26:48 -04:00
parent 0b15a66a80
commit adba6a8f90
7 changed files with 13 additions and 64 deletions
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32
src/librustc/infer/lexical_region_resolve/mod.rs
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@ -197,26 +197,8 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
}
}
/// Enforce constraints of the form:
///
/// ```
/// 'r0 in ['o1...'oN]
/// ```
///
/// such a constraint simply means that `'r0` must be equal to one
/// of the regions `'o1...'oN`. This is an annoying constraint to
/// integrate into our inference, which generally works by
/// iteratively growing regions until we find a match -- that's
/// not an option here.
///
/// What we currently do:
///
/// - Search forward in the graph from `'r0` to find each region `'b`
/// where `'r0 <= 'b` must hold.
/// - Try to rule out some of the `'o1..'oN` options:
/// - if `'o[i] <= 'b` is false, then `'o[i]` is not an option
///
/// Hopefully this narrows it down to just one option.
/// Enforce all pick constraints and return true if anything
/// changed. See `enforce_pick_constraint` for more details.
fn enforce_pick_constraints(
&self,
graph: &RegionGraph<'tcx>,
@ -237,15 +219,17 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
/// pick 'r from ['o...]
/// ```
///
/// We look to see if there is a unique option `'o` from the list of options
/// that:
/// We look for all option regions from the list `'o...` that:
///
/// (a) is greater than the current value of `'r` (which is a lower bound)
/// (a) are greater than the current value of `'r` (which is a lower bound)
///
/// and
///
/// (b) is compatible with the upper bounds of `'r` that we can
/// (b) are compatible with the upper bounds of `'r` that we can
/// find by traversing the graph.
///
/// From that list, we look for a *minimal* option `'o_min`. If we
/// find one, then we can enforce that `'r: 'o_min`.
fn enforce_pick_constraint(
&self,
graph: &RegionGraph<'tcx>,

2
src/librustc/infer/mod.rs
View File

@ -915,7 +915,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
region: ty::Region<'tcx>,
in_regions: &Rc<Vec<ty::Region<'tcx>>>,
) {
debug!("sub_regions({:?} <: {:?})", region, in_regions);
debug!("pick_constraint({:?} <: {:?})", region, in_regions);
self.borrow_region_constraints()
.pick_constraint(opaque_type_def_id, definition_span, hidden_ty, region, in_regions);
}

7
src/librustc/infer/opaque_types/mod.rs
View File

@ -271,8 +271,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
/// is an inference variable). If we generated a constraint that
/// `Tc: 'a`, then this would incorrectly require that `T: 'a` --
/// but this is not necessary, because the existential type we
/// create will be allowed to reference `T`. So instead we just
/// generate a constraint that `'0: 'a`.
/// create will be allowed to reference `T`. So we only generate a
/// constraint that `'0: 'a`.
///
/// # The `free_region_relations` parameter
///
@ -563,8 +563,7 @@ pub fn unexpected_hidden_region_diagnostic(
// ```
//
// Here the captured lifetime is the intersection of `'a` and
// `'b`, which we can't quite express. This prticulararticular
// is kind of an unfortunate error anyway.
// `'b`, which we can't quite express.
if let Some(region_scope_tree) = region_scope_tree {
// If the `region_scope_tree` is available, this is being

1
src/librustc_data_structures/graph/vec_graph/mod.rs
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@ -1,6 +1,7 @@
use crate::indexed_vec::{Idx, IndexVec};
use crate::graph::{DirectedGraph, WithNumNodes, WithNumEdges, WithSuccessors, GraphSuccessors};
#[cfg(test)]
mod test;
pub struct VecGraph<N: Idx> {

2
src/librustc_data_structures/graph/vec_graph/test.rs
View File

@ -1,5 +1,3 @@
#![cfg(test)]
use super::*;
fn create_graph() -> VecGraph<usize> {

22
src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-original.stderr
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@ -1,22 +0,0 @@
warning[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
--> $DIR/ordinary-bounds-pick-original.rs:10:50
|
LL | fn upper_bounds<'a, 'b>(a: &'a u8, b: &'b u8) -> impl Trait<'a, 'b> {
| ^^^^^^^^^^^^^^^^^^
|
= note: hidden type `(&u8, &u8)` captures lifetime '_#6r
= warning: this error has been downgraded to a warning for backwards compatibility with previous releases
= warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future
= note: for more information, try `rustc --explain E0729`
warning[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
--> $DIR/ordinary-bounds-pick-original.rs:10:50
|
LL | fn upper_bounds<'a, 'b>(a: &'a u8, b: &'b u8) -> impl Trait<'a, 'b> {
| ^^^^^^^^^^^^^^^^^^
|
= note: hidden type `(&u8, &u8)` captures lifetime '_#7r
= warning: this error has been downgraded to a warning for backwards compatibility with previous releases
= warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future
= note: for more information, try `rustc --explain E0729`

11
src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-other.stderr
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@ -1,11 +0,0 @@
warning[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
--> $DIR/ordinary-bounds-pick-other.rs:17:74
|
LL | fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e>
| ^^^^^^^^^^^^^^^^^^
|
= note: hidden type `Ordinary<'_>` captures lifetime '_#8r
= warning: this error has been downgraded to a warning for backwards compatibility with previous releases
= warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future
= note: for more information, try `rustc --explain E0729`