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handle arrays and slices uniformly in valtree creation

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This commit is contained in:
b-naber 2022-04-14 21:56:27 +02:00
parent 4b126b805b
commit d8205cd3fe
1 changed files with 13 additions and 31 deletions
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44
compiler/rustc_const_eval/src/const_eval/mod.rs
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@ -3,6 +3,7 @@
use std::convert::TryFrom;
use rustc_hir::Mutability;
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{
mir::{self, interpret::ConstAlloc},
@ -74,7 +75,7 @@ fn branches<'tcx>(
let field = ecx.mplace_field(&place, i).unwrap();
const_to_valtree_inner(ecx, &field)
});
// For enums, we preped their variant index before the variant's fields so we can figure out
// For enums, we prepend their variant index before the variant's fields so we can figure out
// the variant again when just seeing a valtree.
let branches = variant.into_iter().chain(fields);
Some(ty::ValTree::Branch(ecx.tcx.arena.alloc_from_iter(branches.collect::<Option<Vec<_>>>()?)))
@ -83,17 +84,13 @@ fn branches<'tcx>(
fn slice_branches<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
n: u64,
) -> Option<ty::ValTree<'tcx>> {
let elems = (0..n).map(|i| {
let n = place.len(&ecx.tcx()).expect(&format!("expected to use len of place {:?}", place));
let branches = (0..n).map(|i| {
let place_elem = ecx.mplace_index(place, i).unwrap();
const_to_valtree_inner(ecx, &place_elem)
});
// Need `len` for the ValTree -> ConstValue conversion
let len = Some(Some(ty::ValTree::Leaf(ScalarInt::from(n))));
let branches = len.into_iter().chain(elems);
Some(ty::ValTree::Branch(ecx.tcx.arena.alloc_from_iter(branches.collect::<Option<Vec<_>>>()?)))
}
@ -116,33 +113,19 @@ fn const_to_valtree_inner<'tcx>(
// agree with runtime equality tests.
ty::FnPtr(_) | ty::RawPtr(_) => None,
ty::Ref(_, inner_ty, _) => {
match inner_ty.kind() {
ty::Slice(_) | ty::Str => {
let derefd = ecx.deref_operand(&place.into()).unwrap();
debug!(?derefd);
let len = derefd.len(&ecx.tcx.tcx).unwrap();
let valtree = slice_branches(ecx, &derefd, len);
debug!(?valtree);
ty::Ref(_, _, _) => {
let derefd_place = ecx.deref_operand(&place.into()).unwrap_or_else(|e| bug!("couldn't deref {:?}, error: {:?}", place, e));
debug!(?derefd_place);
valtree
}
_ => {
let derefd_place = ecx.deref_operand(&place.into()).unwrap_or_else(|e| bug!("couldn't deref {:?}, error: {:?}", place, e));
debug!(?derefd_place);
const_to_valtree_inner(ecx, &derefd_place)
}
}
const_to_valtree_inner(ecx, &derefd_place)
}
ty::Str => {
bug!("ty::Str should have been handled in ty::Ref branch that uses raw bytes");
}
ty::Slice(_) => {
bug!("should have been handled in the Ref arm");
}
ty::Str | ty::Slice(_) | ty::Array(_, _) => {
let valtree = slice_branches(ecx, place);
debug!(?valtree);
valtree
}
// Trait objects are not allowed in type level constants, as we have no concept for
// resolving their backing type, even if we can do that at const eval time. We may
// hypothetically be able to allow `dyn StructuralEq` trait objects in the future,
@ -150,7 +133,6 @@ fn const_to_valtree_inner<'tcx>(
ty::Dynamic(..) => None,
ty::Tuple(substs) => branches(ecx, place, substs.len(), None),
ty::Array(_, len) => branches(ecx, place, usize::try_from(len.eval_usize(ecx.tcx.tcx, ecx.param_env)).unwrap(), None),
ty::Adt(def, _) => {
if def.variants().is_empty() {