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update fixmes

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This commit is contained in:
DPC 2020-08-30 14:43:52 +02:00
parent ea800d529a
commit b3d7b7bdcb
3 changed files with 13 additions and 14 deletions
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16
library/core/src/fmt/float.rs
View File

@ -14,11 +14,11 @@ fn float_to_decimal_common_exact<T>(
where
T: flt2dec::DecodableFloat,
{
// SAFETY: Possible undefined behavior, see FIXME(#53491)
// SAFETY: Possible undefined behavior, see FIXME(#76092)
unsafe {
let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 4]>::uninit();
// FIXME(#53491): This is calling `get_mut` on an uninitialized
// FIXME(#76092): This is calling `assume_init_mut` on an uninitialized
// `MaybeUninit` (here and elsewhere in this file). Revisit this once
// we decided whether that is valid or not.
// We can do this only because we are libstd and coupled to the compiler.
@ -47,12 +47,12 @@ fn float_to_decimal_common_shortest<T>(
where
T: flt2dec::DecodableFloat,
{
// SAFETY: Possible undefined behavior, see FIXME(#53491)
// SAFETY: Possible undefined behavior, see FIXME(#76092)
unsafe {
// enough for f32 and f64
let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninit();
let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 4]>::uninit();
// FIXME(#53491)
// FIXME(#76092)
let formatted = flt2dec::to_shortest_str(
flt2dec::strategy::grisu::format_shortest,
*num,
@ -103,11 +103,11 @@ fn float_to_exponential_common_exact<T>(
where
T: flt2dec::DecodableFloat,
{
// SAFETY: Possible undefined behavior, see FIXME(#53491)
// SAFETY: Possible undefined behavior, see FIXME(#76092)
unsafe {
let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 6]>::uninit();
// FIXME(#53491)
// FIXME(#76092)
let formatted = flt2dec::to_exact_exp_str(
flt2dec::strategy::grisu::format_exact,
*num,
@ -133,12 +133,12 @@ fn float_to_exponential_common_shortest<T>(
where
T: flt2dec::DecodableFloat,
{
// SAFETY: Possible undefined behavior, see FIXME(#53491)
// SAFETY: Possible undefined behavior, see FIXME(#76092)
unsafe {
// enough for f32 and f64
let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninit();
let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 6]>::uninit();
// FIXME(#53491)
// FIXME(#76092)
let formatted = flt2dec::to_shortest_exp_str(
flt2dec::strategy::grisu::format_shortest,
*num,

9
library/core/src/mem/maybe_uninit.rs
View File

@ -167,8 +167,7 @@ use crate::mem::ManuallyDrop;
///
/// // For each item in the array, drop if we allocated it.
/// for elem in &mut data[0..data_len] {
/// unsafe { ptr::drop_in_place(elem.
/// ptr()); }
/// unsafe { ptr::drop_in_place(elem.ptr()); }
/// }
/// ```
///
@ -718,7 +717,7 @@ impl<T> MaybeUninit<T> {
/// {
/// let mut buffer = MaybeUninit::<[u8; 64]>::uninit();
/// reader.read_exact(unsafe { buffer.assume_init_mut() })?;
/// // ^^^^^^^^^^^^^^^^
/// // ^^^^^^^^^^^^^^^^^^^^^^^^
/// // (mutable) reference to uninitialized memory!
/// // This is undefined behavior.
/// Ok(unsafe { buffer.assume_init() })
@ -739,11 +738,11 @@ impl<T> MaybeUninit<T> {
/// let foo: Foo = unsafe {
/// let mut foo = MaybeUninit::<Foo>::uninit();
/// ptr::write(&mut foo.assume_init_mut().a as *mut u32, 1337);
/// // ^^^^^^^^^^^^^
/// // ^^^^^^^^^^^^^^^^^^^^^
/// // (mutable) reference to uninitialized memory!
/// // This is undefined behavior.
/// ptr::write(&mut foo.assume_init_mut().b as *mut u8, 42);
/// // ^^^^^^^^^^^^^
/// // ^^^^^^^^^^^^^^^^^^^^^
/// // (mutable) reference to uninitialized memory!
/// // This is undefined behavior.
/// foo.assume_init()

2
library/std/src/io/util.rs
View File

@ -49,7 +49,7 @@ where
W: Write,
{
let mut buf = MaybeUninit::<[u8; super::DEFAULT_BUF_SIZE]>::uninit();
// FIXME(#53491): This is calling `get_mut` and `get_ref` on an uninitialized
// FIXME(#76092): This is calling `get_mut` and `get_ref` on an uninitialized
// `MaybeUninit`. Revisit this once we decided whether that is valid or not.
// This is still technically undefined behavior due to creating a reference
// to uninitialized data, but within libstd we can rely on more guarantees