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Auto merge of #108080 - oli-obk:FnPtr-trait, r=lcnr
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Add a builtin `FnPtr` trait that is implemented for all function pointers

r? `@ghost`

Rebased version of rust-lang/rust#99531 (plus adjustments mentioned in the PR).

If perf is happy with this version, I would like to land it, even if the diagnostics fix in 9df8e1befb5031a5bf9d8dfe25170620642d3c59 only works for `FnPtr` specifically, and does not generally improve blanket impls.
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@bors
bors committed Mar 28, 2023
2 parents fac0b9b + 2e60a18 commit 25c5543
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15 changes: 15 additions & 0 deletions core/src/marker.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -922,3 +922,18 @@ mod copy_impls {
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Copy for &T {}
}

/// A common trait implemented by all function pointers.
#[unstable(
feature = "fn_ptr_trait",
issue = "none",
reason = "internal trait for implementing various traits for all function pointers"
)]
#[lang = "fn_ptr_trait"]
#[cfg(not(bootstrap))]
#[rustc_deny_explicit_impl]
pub trait FnPtr: Copy + Clone {
/// Returns the address of the function pointer.
#[lang = "fn_ptr_addr"]
fn addr(self) -> *const ();
}
267 changes: 161 additions & 106 deletions core/src/ptr/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1891,150 +1891,205 @@ pub fn hash<T: ?Sized, S: hash::Hasher>(hashee: *const T, into: &mut S) {
hashee.hash(into);
}

// If this is a unary fn pointer, it adds a doc comment.
// Otherwise, it hides the docs entirely.
macro_rules! maybe_fnptr_doc {
(@ #[$meta:meta] $item:item) => {
#[doc(hidden)]
#[$meta]
$item
};
($a:ident @ #[$meta:meta] $item:item) => {
#[doc(fake_variadic)]
#[doc = "This trait is implemented for function pointers with up to twelve arguments."]
#[$meta]
$item
};
($a:ident $($rest_a:ident)+ @ #[$meta:meta] $item:item) => {
#[doc(hidden)]
#[$meta]
$item
};
}
#[cfg(bootstrap)]
mod old_fn_ptr_impl {
use super::*;
// If this is a unary fn pointer, it adds a doc comment.
// Otherwise, it hides the docs entirely.
macro_rules! maybe_fnptr_doc {
(@ #[$meta:meta] $item:item) => {
#[doc(hidden)]
#[$meta]
$item
};
($a:ident @ #[$meta:meta] $item:item) => {
#[doc(fake_variadic)]
#[doc = "This trait is implemented for function pointers with up to twelve arguments."]
#[$meta]
$item
};
($a:ident $($rest_a:ident)+ @ #[$meta:meta] $item:item) => {
#[doc(hidden)]
#[$meta]
$item
};
}

// FIXME(strict_provenance_magic): function pointers have buggy codegen that
// necessitates casting to a usize to get the backend to do the right thing.
// for now I will break AVR to silence *a billion* lints. We should probably
// have a proper "opaque function pointer type" to handle this kind of thing.
// FIXME(strict_provenance_magic): function pointers have buggy codegen that
// necessitates casting to a usize to get the backend to do the right thing.
// for now I will break AVR to silence *a billion* lints. We should probably
// have a proper "opaque function pointer type" to handle this kind of thing.

// Impls for function pointers
macro_rules! fnptr_impls_safety_abi {
($FnTy: ty, $($Arg: ident),*) => {
// Impls for function pointers
macro_rules! fnptr_impls_safety_abi {
($FnTy: ty, $($Arg: ident),*) => {
fnptr_impls_safety_abi! { #[stable(feature = "fnptr_impls", since = "1.4.0")] $FnTy, $($Arg),* }
};
(@c_unwind $FnTy: ty, $($Arg: ident),*) => {
fnptr_impls_safety_abi! { #[unstable(feature = "c_unwind", issue = "74990")] $FnTy, $($Arg),* }
};
(#[$meta:meta] $FnTy: ty, $($Arg: ident),*) => {
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> PartialEq for $FnTy {
#[inline]
fn eq(&self, other: &Self) -> bool {
*self as usize == *other as usize
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> PartialEq for $FnTy {
#[inline]
fn eq(&self, other: &Self) -> bool {
*self as usize == *other as usize
}
}
}
}

maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> Eq for $FnTy {}
}
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> Eq for $FnTy {}
}

maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> PartialOrd for $FnTy {
#[inline]
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
(*self as usize).partial_cmp(&(*other as usize))
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> PartialOrd for $FnTy {
#[inline]
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
(*self as usize).partial_cmp(&(*other as usize))
}
}
}
}

maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> Ord for $FnTy {
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
(*self as usize).cmp(&(*other as usize))
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> Ord for $FnTy {
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
(*self as usize).cmp(&(*other as usize))
}
}
}
}

maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> hash::Hash for $FnTy {
fn hash<HH: hash::Hasher>(&self, state: &mut HH) {
state.write_usize(*self as usize)
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> hash::Hash for $FnTy {
fn hash<HH: hash::Hasher>(&self, state: &mut HH) {
state.write_usize(*self as usize)
}
}
}
}

maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> fmt::Pointer for $FnTy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::pointer_fmt_inner(*self as usize, f)
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> fmt::Pointer for $FnTy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::pointer_fmt_inner(*self as usize, f)
}
}
}
}

maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> fmt::Debug for $FnTy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::pointer_fmt_inner(*self as usize, f)
maybe_fnptr_doc! {
$($Arg)* @
#[$meta]
impl<Ret, $($Arg),*> fmt::Debug for $FnTy {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::pointer_fmt_inner(*self as usize, f)
}
}
}
}
}
}

macro_rules! fnptr_impls_args {
($($Arg: ident),+) => {
fnptr_impls_safety_abi! { extern "Rust" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { extern "C" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { extern "C" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
macro_rules! fnptr_impls_args {
($($Arg: ident),+) => {
fnptr_impls_safety_abi! { extern "Rust" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { extern "C" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { extern "C" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { @c_unwind extern "C-unwind" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { @c_unwind extern "C-unwind" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { unsafe extern "Rust" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { unsafe extern "Rust" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { @c_unwind unsafe extern "C-unwind" fn($($Arg),+) -> Ret, $($Arg),+ }
fnptr_impls_safety_abi! { @c_unwind unsafe extern "C-unwind" fn($($Arg),+ , ...) -> Ret, $($Arg),+ }
};
() => {
// No variadic functions with 0 parameters
fnptr_impls_safety_abi! { extern "Rust" fn() -> Ret, }
fnptr_impls_safety_abi! { extern "C" fn() -> Ret, }
};
() => {
// No variadic functions with 0 parameters
fnptr_impls_safety_abi! { extern "Rust" fn() -> Ret, }
fnptr_impls_safety_abi! { extern "C" fn() -> Ret, }
fnptr_impls_safety_abi! { @c_unwind extern "C-unwind" fn() -> Ret, }
fnptr_impls_safety_abi! { unsafe extern "Rust" fn() -> Ret, }
fnptr_impls_safety_abi! { unsafe extern "C" fn() -> Ret, }
fnptr_impls_safety_abi! { unsafe extern "Rust" fn() -> Ret, }
fnptr_impls_safety_abi! { unsafe extern "C" fn() -> Ret, }
fnptr_impls_safety_abi! { @c_unwind unsafe extern "C-unwind" fn() -> Ret, }
};
};
}

fnptr_impls_args! {}
fnptr_impls_args! { T }
fnptr_impls_args! { A, B }
fnptr_impls_args! { A, B, C }
fnptr_impls_args! { A, B, C, D }
fnptr_impls_args! { A, B, C, D, E }
fnptr_impls_args! { A, B, C, D, E, F }
fnptr_impls_args! { A, B, C, D, E, F, G }
fnptr_impls_args! { A, B, C, D, E, F, G, H }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K, L }
}

fnptr_impls_args! {}
fnptr_impls_args! { T }
fnptr_impls_args! { A, B }
fnptr_impls_args! { A, B, C }
fnptr_impls_args! { A, B, C, D }
fnptr_impls_args! { A, B, C, D, E }
fnptr_impls_args! { A, B, C, D, E, F }
fnptr_impls_args! { A, B, C, D, E, F, G }
fnptr_impls_args! { A, B, C, D, E, F, G, H }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K }
fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K, L }
#[cfg(not(bootstrap))]
mod new_fn_ptr_impl {
use super::*;
use crate::marker::FnPtr;

#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> PartialEq for F {
#[inline]
fn eq(&self, other: &Self) -> bool {
self.addr() == other.addr()
}
}
#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> Eq for F {}

#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> PartialOrd for F {
#[inline]
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
self.addr().partial_cmp(&other.addr())
}
}
#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> Ord for F {
#[inline]
fn cmp(&self, other: &Self) -> Ordering {
self.addr().cmp(&other.addr())
}
}

#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> hash::Hash for F {
fn hash<HH: hash::Hasher>(&self, state: &mut HH) {
state.write_usize(self.addr() as _)
}
}

#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> fmt::Pointer for F {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::pointer_fmt_inner(self.addr() as _, f)
}
}

#[stable(feature = "fnptr_impls", since = "1.4.0")]
impl<F: FnPtr> fmt::Debug for F {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::pointer_fmt_inner(self.addr() as _, f)
}
}
}
/// Create a `const` raw pointer to a place, without creating an intermediate reference.
///
/// Creating a reference with `&`/`&mut` is only allowed if the pointer is properly aligned
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