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Merge pull request #281 from RalfJung/unsized

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fix size_of_val on unsized tuples
This commit is contained in:
Ralf Jung 2017-08-03 11:39:30 -07:00 • committed by GitHub
commit 5aed31812e
2 changed files with 19 additions and 4 deletions
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21
src/librustc_mir/interpret/eval_context.rs
View file

@ -277,6 +277,9 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
self.tcx.erase_regions(&value)
}
/// Return the size and aligment of the value at the given type.
/// Note that the value does not matter if the type is sized. For unsized types,
/// the value has to be a fat pointer, and we only care about the "extra" data in it.
pub fn size_and_align_of_dst(
&mut self,
ty: ty::Ty<'tcx>,
@ -286,7 +289,7 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
Ok((size as u64, self.type_align(ty)? as u64))
} else {
match ty.sty {
ty::TyAdt(def, substs) => {
ty::TyAdt(..) | ty::TyTuple(..) => {
// First get the size of all statically known fields.
// Don't use type_of::sizing_type_of because that expects t to be sized,
// and it also rounds up to alignment, which we want to avoid,
@ -309,9 +312,19 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
// Recurse to get the size of the dynamically sized field (must be
// the last field).
let last_field = def.struct_variant().fields.last().unwrap();
let field_ty = self.field_ty(substs, last_field);
let (unsized_size, unsized_align) = self.size_and_align_of_dst(field_ty, value)?;
let (unsized_size, unsized_align) = match ty.sty {
ty::TyAdt(def, substs) => {
let last_field = def.struct_variant().fields.last().unwrap();
let field_ty = self.field_ty(substs, last_field);
self.size_and_align_of_dst(field_ty, value)?
}
ty::TyTuple(ref types, _) => {
let field_ty = types.last().unwrap();
let field_ty = self.tcx.normalize_associated_type(field_ty);
self.size_and_align_of_dst(field_ty, value)?
}
_ => bug!("We already checked that we know this type"),
};
// FIXME (#26403, #27023): We should be adding padding
// to `sized_size` (to accommodate the `unsized_align`

2
tests/run-pass-fullmir/unsized-tuple-impls.rs
View file

@ -9,6 +9,7 @@
// except according to those terms.
#![feature(unsized_tuple_coercion)]
use std::mem;
fn main() {
let x : &(i32, i32, [i32]) = &(0, 1, [2, 3]);
@ -18,4 +19,5 @@ fn main() {
assert_eq!(a, [x, y]);
assert_eq!(&format!("{:?}", a), "[(0, 1, [2, 3]), (0, 1, [2, 3, 4])]");
assert_eq!(mem::size_of_val(x), 16);
}