Rollup merge of #89753 - jkugelman:must-use-from_value-conversions, r=joshtriplett

Add #[must_use] to from_value conversions

I added two methods to the list myself. Clippy did not flag them because they take `mut` args, but neither modifies their argument.

```rust
core::str           const unsafe fn from_utf8_unchecked_mut(v: &mut [u8]) -> &mut str;
std::ffi::CString   unsafe fn from_raw(ptr: *mut c_char) -> CString;
```

I put a custom note on `from_raw`:

```rust
#[must_use = "call `drop(from_raw(ptr))` if you intend to drop the `CString`"]
pub unsafe fn from_raw(ptr: *mut c_char) -> CString {
```

Parent issue: #89692

r? ``@joshtriplett``
This commit is contained in:
Guillaume Gomez
2021-10-11 14:11:45 +02:00
committed by GitHub
17 changed files with 50 additions and 1 deletions

View File

@@ -297,6 +297,7 @@ macro_rules! int_impl {
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_int_conversions", since = "1.32.0")]
#[must_use]
#[inline]
pub const fn from_be(x: Self) -> Self {
#[cfg(target_endian = "big")]
@@ -328,6 +329,7 @@ macro_rules! int_impl {
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_int_conversions", since = "1.32.0")]
#[must_use]
#[inline]
pub const fn from_le(x: Self) -> Self {
#[cfg(target_endian = "little")]
@@ -2671,6 +2673,7 @@ macro_rules! int_impl {
/// ```
#[stable(feature = "int_to_from_bytes", since = "1.32.0")]
#[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
#[must_use]
#[inline]
pub const fn from_be_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
Self::from_be(Self::from_ne_bytes(bytes))
@@ -2701,6 +2704,7 @@ macro_rules! int_impl {
/// ```
#[stable(feature = "int_to_from_bytes", since = "1.32.0")]
#[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
#[must_use]
#[inline]
pub const fn from_le_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
Self::from_le(Self::from_ne_bytes(bytes))
@@ -2742,6 +2746,7 @@ macro_rules! int_impl {
/// ```
#[stable(feature = "int_to_from_bytes", since = "1.32.0")]
#[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
#[must_use]
// SAFETY: const sound because integers are plain old datatypes so we can always
// transmute to them
#[inline]