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Revert "Revert "Rollup merge of #98582 - oli-obk:unconstrained_opaque_type, r=estebank""

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This reverts commit 4a742a691e.
This commit is contained in:
Oli Scherer 2022-07-27 11:58:34 +00:00
parent 5d664f7a8f
commit 40e2de8c41
30 changed files with 250 additions and 37 deletions
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17
compiler/rustc_mir_build/src/build/expr/as_place.rs
View file

@ -102,6 +102,8 @@ fn convert_to_hir_projections_and_truncate_for_capture<'tcx>(
variant = Some(*idx);
continue;
}
// These do not affect anything, they just make sure we know the right type.
ProjectionElem::OpaqueCast(_) => continue,
ProjectionElem::Index(..)
| ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. } => {
@ -168,7 +170,7 @@ fn find_capture_matching_projections<'a, 'tcx>(
/// `PlaceBuilder` now starts from `PlaceBase::Local`.
///
/// Returns a Result with the error being the PlaceBuilder (`from_builder`) that was not found.
#[instrument(level = "trace", skip(cx))]
#[instrument(level = "trace", skip(cx), ret)]
fn to_upvars_resolved_place_builder<'tcx>(
from_builder: PlaceBuilder<'tcx>,
cx: &Builder<'_, 'tcx>,
@ -213,7 +215,6 @@ fn to_upvars_resolved_place_builder<'tcx>(
&capture.captured_place.place.projections,
);
upvar_resolved_place_builder.projection.extend(remaining_projections);
trace!(?upvar_resolved_place_builder);
Ok(upvar_resolved_place_builder)
}
@ -232,16 +233,21 @@ fn strip_prefix<'tcx>(
prefix_projections: &[HirProjection<'tcx>],
) -> impl Iterator<Item = PlaceElem<'tcx>> {
let mut iter = projections.into_iter();
let mut next = || match iter.next()? {
// Filter out opaque casts, they are unnecessary in the prefix.
ProjectionElem::OpaqueCast(..) => iter.next(),
other => Some(other),
};
for projection in prefix_projections {
match projection.kind {
HirProjectionKind::Deref => {
assert!(matches!(iter.next(), Some(ProjectionElem::Deref)));
assert!(matches!(next(), Some(ProjectionElem::Deref)));
}
HirProjectionKind::Field(..) => {
if base_ty.is_enum() {
assert!(matches!(iter.next(), Some(ProjectionElem::Downcast(..))));
assert!(matches!(next(), Some(ProjectionElem::Downcast(..))));
}
assert!(matches!(iter.next(), Some(ProjectionElem::Field(..))));
assert!(matches!(next(), Some(ProjectionElem::Field(..))));
}
HirProjectionKind::Index | HirProjectionKind::Subslice => {
bug!("unexpected projection kind: {:?}", projection);
@ -711,6 +717,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
ProjectionElem::Field(..)
| ProjectionElem::Downcast(..)
| ProjectionElem::OpaqueCast(..)
| ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. } => (),
}

7
compiler/rustc_mir_build/src/build/matches/util.rs
View file

@ -95,9 +95,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
impl<'pat, 'tcx> MatchPair<'pat, 'tcx> {
pub(in crate::build) fn new(
place: PlaceBuilder<'tcx>,
mut place: PlaceBuilder<'tcx>,
pattern: &'pat Pat<'tcx>,
) -> MatchPair<'pat, 'tcx> {
// Force the place type to the pattern's type.
// FIXME(oli-obk): can we use this to simplify slice/array pattern hacks?
// FIXME(oli-obk): only add this projection if `place` actually had an opaque
// type before the projection.
place = place.project(ProjectionElem::OpaqueCast(pattern.ty));
MatchPair { place, pattern }
}
}

10
compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
View file

@ -842,7 +842,15 @@ fn is_useful<'p, 'tcx>(
}
}
} else {
let ty = v.head().ty();
let mut ty = v.head().ty();
// Opaque types can't get destructured/split, but the patterns can
// actually hint at hidden types, so we use the patterns' types instead.
if let ty::Opaque(..) = ty.kind() {
if let Some(row) = rows.first() {
ty = row.head().ty();
}
}
let is_non_exhaustive = cx.is_foreign_non_exhaustive_enum(ty);
debug!("v.head: {:?}, v.span: {:?}", v.head(), v.head().span());
let pcx = &PatCtxt { cx, ty, span: v.head().span(), is_top_level, is_non_exhaustive };