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HAIR lowering: improve code quality for slices

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This commit is contained in:
Mazdak Farrokhzad 2019-12-19 18:19:14 +01:00
parent 0de96d37fb
commit 3a93a0e860
1 changed files with 18 additions and 27 deletions
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45
src/librustc_mir/hair/pattern/mod.rs
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@ -557,14 +557,13 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
ty::Slice(..) |
ty::Array(..) =>
self.slice_or_array_pattern(pat.span, ty, prefix, slice, suffix),
ty::Error => { // Avoid ICE
return Pat { span: pat.span, ty, kind: Box::new(PatKind::Wild) };
}
_ =>
span_bug!(
pat.span,
"unexpanded type for vector pattern: {:?}",
ty),
// Avoid ICE
ty::Error => return Pat { span: pat.span, ty, kind: Box::new(PatKind::Wild) },
_ => span_bug!(
pat.span,
"unexpanded type for vector pattern: {:?}",
ty
),
}
}
@ -698,9 +697,8 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
&mut self,
prefix: Vec<Pat<'tcx>>,
slice: Option<Pat<'tcx>>,
suffix: Vec<Pat<'tcx>>)
-> (Vec<Pat<'tcx>>, Option<Pat<'tcx>>, Vec<Pat<'tcx>>)
{
suffix: Vec<Pat<'tcx>>,
) -> (Vec<Pat<'tcx>>, Option<Pat<'tcx>>, Vec<Pat<'tcx>>) {
let orig_slice = match slice {
Some(orig_slice) => orig_slice,
None => return (prefix, slice, suffix)
@ -734,31 +732,24 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
ty: Ty<'tcx>,
prefix: &'tcx [P<hir::Pat>],
slice: &'tcx Option<P<hir::Pat>>,
suffix: &'tcx [P<hir::Pat>])
-> PatKind<'tcx>
{
suffix: &'tcx [P<hir::Pat>],
) -> PatKind<'tcx> {
let prefix = self.lower_patterns(prefix);
let slice = self.lower_opt_pattern(slice);
let suffix = self.lower_patterns(suffix);
let (prefix, slice, suffix) =
self.flatten_nested_slice_patterns(prefix, slice, suffix);
let (prefix, slice, suffix) = self.flatten_nested_slice_patterns(prefix, slice, suffix);
// Some validation:
match ty.kind {
ty::Slice(..) => {
// matching a slice or fixed-length array
PatKind::Slice { prefix: prefix, slice: slice, suffix: suffix }
}
// Matching a slice, `[T]`.
ty::Slice(..) => PatKind::Slice { prefix, slice, suffix },
// Fixed-length array, `[T; len]`.
ty::Array(_, len) => {
// fixed-length array
let len = len.eval_usize(self.tcx, self.param_env);
assert!(len >= prefix.len() as u64 + suffix.len() as u64);
PatKind::Array { prefix: prefix, slice: slice, suffix: suffix }
}
_ => {
span_bug!(span, "bad slice pattern type {:?}", ty);
PatKind::Array { prefix, slice, suffix }
}
_ => span_bug!(span, "bad slice pattern type {:?}", ty),
}
}