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Rollup merge of #65704 - RalfJung:exact-size, r=oli-obk

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relax ExactSizeIterator bound on write_bytes

Too many iterators don't have that bound. Instead we do run-time checks.

r? @oli-obk
This commit is contained in:
Mazdak Farrokhzad 2019-10-23 22:19:24 +02:00 committed by GitHub
commit 3cd7a17406
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2 changed files with 9 additions and 5 deletions
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7
src/librustc/mir/interpret/allocation.rs
View File

@ -353,11 +353,14 @@ impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> {
&mut self,
cx: &impl HasDataLayout,
ptr: Pointer<Tag>,
src: impl IntoIterator<Item=u8, IntoIter: iter::ExactSizeIterator>,
src: impl IntoIterator<Item=u8>,
) -> InterpResult<'tcx>
{
let mut src = src.into_iter();
let bytes = self.get_bytes_mut(cx, ptr, Size::from_bytes(src.len() as u64))?;
let (lower, upper) = src.size_hint();
let len = upper.expect("can only write bounded iterators");
assert_eq!(lower, len, "can only write iterators with a precise length");
let bytes = self.get_bytes_mut(cx, ptr, Size::from_bytes(len as u64))?;
// `zip` would stop when the first iterator ends; we want to definitely
// cover all of `bytes`.
for dest in bytes {

7
src/librustc_mir/interpret/memory.rs
View File

@ -7,7 +7,7 @@
//! short-circuiting the empty case!
use std::collections::VecDeque;
use std::{ptr, iter};
use std::ptr;
use std::borrow::Cow;
use rustc::ty::{self, Instance, ParamEnv, query::TyCtxtAt};
@ -791,11 +791,12 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
pub fn write_bytes(
&mut self,
ptr: Scalar<M::PointerTag>,
src: impl IntoIterator<Item=u8, IntoIter: iter::ExactSizeIterator>,
src: impl IntoIterator<Item=u8>,
) -> InterpResult<'tcx>
{
let src = src.into_iter();
let size = Size::from_bytes(src.len() as u64);
let size = Size::from_bytes(src.size_hint().0 as u64);
// `write_bytes` checks that this lower bound matches the upper bound matches reality.
let ptr = match self.check_ptr_access(ptr, size, Align::from_bytes(1).unwrap())? {
Some(ptr) => ptr,
None => return Ok(()), // zero-sized access