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rework region flags: 'static can be erased too

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The existing flags did not consider `'static` to be "free". This then
fed into what was "erasable" -- but `'static` is most certainly
erasable.
This commit is contained in:
Niko Matsakis 2017-12-04 05:11:36 -05:00
parent 02e65250e4
commit 154cd94197
3 changed files with 35 additions and 9 deletions
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17
src/librustc/ty/fold.rs
View file

@ -97,14 +97,19 @@ pub trait TypeFoldable<'tcx>: fmt::Debug + Clone {
fn has_closure_types(&self) -> bool {
self.has_type_flags(TypeFlags::HAS_TY_CLOSURE)
}
fn has_erasable_regions(&self) -> bool {
self.has_type_flags(TypeFlags::HAS_RE_EARLY_BOUND |
TypeFlags::HAS_RE_INFER |
TypeFlags::HAS_FREE_REGIONS)
/// "Free" regions in this context means that it has any region
/// that is not (a) erased or (b) late-bound.
fn has_free_regions(&self) -> bool {
self.has_type_flags(TypeFlags::HAS_FREE_REGIONS)
}
/// True if there any any un-erased free regions.
fn has_erasable_regions(&self) -> bool {
self.has_type_flags(TypeFlags::HAS_FREE_REGIONS)
}
fn is_normalized_for_trans(&self) -> bool {
!self.has_type_flags(TypeFlags::HAS_RE_EARLY_BOUND |
TypeFlags::HAS_RE_INFER |
!self.has_type_flags(TypeFlags::HAS_RE_INFER |
TypeFlags::HAS_FREE_REGIONS |
TypeFlags::HAS_TY_INFER |
TypeFlags::HAS_PARAMS |

10
src/librustc/ty/mod.rs
View file

@ -421,8 +421,18 @@ bitflags! {
const HAS_TY_INFER = 1 << 2;
const HAS_RE_INFER = 1 << 3;
const HAS_RE_SKOL = 1 << 4;
/// Does this have any `ReEarlyBound` regions? Used to
/// determine whether substitition is required, since those
/// represent regions that are bound in a `ty::Generics` and
/// hence may be substituted.
const HAS_RE_EARLY_BOUND = 1 << 5;
/// Does this have any region that "appears free" in the type?
/// Basically anything but `ReLateBound` and `ReErased`.
const HAS_FREE_REGIONS = 1 << 6;
/// Is an error type reachable?
const HAS_TY_ERR = 1 << 7;
const HAS_PROJECTION = 1 << 8;

17
src/librustc/ty/sty.rs
View file

@ -1184,18 +1184,29 @@ impl RegionKind {
match *self {
ty::ReVar(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_RE_INFER;
flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
}
ty::ReSkolemized(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_RE_INFER;
flags = flags | TypeFlags::HAS_RE_SKOL;
flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
}
ty::ReLateBound(..) => { }
ty::ReEarlyBound(..) => { flags = flags | TypeFlags::HAS_RE_EARLY_BOUND; }
ty::ReStatic | ty::ReErased => { }
_ => { flags = flags | TypeFlags::HAS_FREE_REGIONS; }
ty::ReEarlyBound(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
}
ty::ReEmpty |
ty::ReStatic |
ty::ReFree { .. } |
ty::ReScope { .. } => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
}
ty::ReErased => {
}
}
match *self {