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Rollup merge of #97420 - WaffleLapkin:no_oxford_casts_qqq, r=Mark-Simulacrum

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Be a little nicer with casts when formatting `fn` pointers

This removes a `fn(...) -> ...` -> `usize` -> `*const ()` -> `usize` cast. cc #95489.
This commit is contained in:
Dylan DPC 2022-06-02 15:26:57 +02:00 committed by GitHub
commit 0b2d48e5af
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2 changed files with 36 additions and 40 deletions
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22
library/core/src/fmt/mod.rs
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@ -2233,9 +2233,19 @@ impl Display for char {
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Pointer for *const T {
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
/// Since the formatting will be identical for all pointer types, use a non-monomorphized
/// implementation for the actual formatting to reduce the amount of codegen work needed
fn inner(ptr: *const (), f: &mut Formatter<'_>) -> Result {
// Cast is needed here because `.addr()` requires `T: Sized`.
pointer_fmt_inner((*self as *const ()).addr(), f)
}
}
/// Since the formatting will be identical for all pointer types, use a non-monomorphized
/// implementation for the actual formatting to reduce the amount of codegen work needed.
///
/// This uses `ptr_addr: usize` and not `ptr: *const ()` to be able to use this for
/// `fn(...) -> ...` without using [problematic] "Oxford Casts".
///
/// [problematic]: https://github.com/rust-lang/rust/issues/95489
pub(crate) fn pointer_fmt_inner(ptr_addr: usize, f: &mut Formatter<'_>) -> Result {
let old_width = f.width;
let old_flags = f.flags;
@ -2252,16 +2262,12 @@ impl<T: ?Sized> Pointer for *const T {
}
f.flags |= 1 << (FlagV1::Alternate as u32);
let ret = LowerHex::fmt(&(ptr.addr()), f);
let ret = LowerHex::fmt(&ptr_addr, f);
f.width = old_width;
f.flags = old_flags;
ret
}
inner(*self as *const (), f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]

14
library/core/src/ptr/mod.rs
View File

@ -1878,24 +1878,14 @@ macro_rules! fnptr_impls_safety_abi {
#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<Ret, $($Arg),*> fmt::Pointer for $FnTy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// HACK: The intermediate cast as usize is required for AVR
// so that the address space of the source function pointer
// is preserved in the final function pointer.
//
// https://github.com/avr-rust/rust/issues/143
fmt::Pointer::fmt(&(*self as usize as *const ()), f)
fmt::pointer_fmt_inner(*self as usize, f)
}
}
#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<Ret, $($Arg),*> fmt::Debug for $FnTy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// HACK: The intermediate cast as usize is required for AVR
// so that the address space of the source function pointer
// is preserved in the final function pointer.
//
// https://github.com/avr-rust/rust/issues/143
fmt::Pointer::fmt(&(*self as usize as *const ()), f)
fmt::pointer_fmt_inner(*self as usize, f)
}
}
}