user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

turn casts-to-raw into a proper raw-reborrow; that is just cleaner

Browse source
This commit is contained in:
Ralf Jung 2018-10-18 11:59:56 +02:00
parent c885d8b41e
commit 5dd0375ae0
1 changed files with 12 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

26
src/librustc_mir/interpret/cast.rs
View file

@ -37,7 +37,6 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
kind: CastKind,
dest: PlaceTy<'tcx, M::PointerTag>,
) -> EvalResult<'tcx> {
let src_layout = src.layout;
use rustc::mir::CastKind::*;
match kind {
Unsize => {
@ -45,29 +44,28 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
}
Misc => {
let src_layout = src.layout;
let src = self.read_value(src)?;
if M::ENABLE_PTR_TRACKING_HOOKS &&
src.layout.ty.is_region_ptr() && dest.layout.ty.is_unsafe_ptr()
{
let src = if M::ENABLE_PTR_TRACKING_HOOKS && src_layout.ty.is_region_ptr() {
// The only `Misc` casts on references are those creating raw pointers.
assert!(dest.layout.ty.is_unsafe_ptr());
// For the purpose of the "ptr tag hooks", treat this as creating
// a new, raw reference.
let place = self.ref_to_mplace(src)?;
let _val = self.create_ref(place, None)?;
// FIXME: The blog post said we should now also erase the tag.
// That would amount to using `_val` instead of `src` from here on.
// However, do we really want to do that? `transmute` doesn't
// do it either and we have to support that, somehow.
}
self.create_ref(place, None)?
} else {
*src
};
if self.type_is_fat_ptr(src.layout.ty) {
match (*src, self.type_is_fat_ptr(dest.layout.ty)) {
if self.type_is_fat_ptr(src_layout.ty) {
match (src, self.type_is_fat_ptr(dest.layout.ty)) {
// pointers to extern types
(Value::Scalar(_),_) |
// slices and trait objects to other slices/trait objects
(Value::ScalarPair(..), true) => {
// No change to value
self.write_value(*src, dest)?;
self.write_value(src, dest)?;
}
// slices and trait objects to thin pointers (dropping the metadata)
(Value::ScalarPair(data, _), false) => {
@ -79,7 +77,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
layout::Variants::Single { index } => {
if let Some(def) = src_layout.ty.ty_adt_def() {
// Cast from a univariant enum
assert!(src.layout.is_zst());
assert!(src_layout.is_zst());
let discr_val = def
.discriminant_for_variant(*self.tcx, index)
.val;