From c147805a6ab62ae52df7fb79067a05358d95fe72 Mon Sep 17 00:00:00 2001 From: Jubilee Young Date: Mon, 24 Jun 2024 13:57:06 -0700 Subject: [PATCH 1/2] library: outline VaList into ffi::va_list and reexport --- library/core/src/ffi/mod.rs | 414 ++------------------------------ library/core/src/ffi/va_list.rs | 407 +++++++++++++++++++++++++++++++ src/tools/tidy/src/pal.rs | 2 + 3 files changed, 423 insertions(+), 400 deletions(-) create mode 100644 library/core/src/ffi/va_list.rs diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs index 6d1f10f5211..88adc378477 100644 --- a/library/core/src/ffi/mod.rs +++ b/library/core/src/ffi/mod.rs @@ -10,8 +10,6 @@ #![allow(non_camel_case_types)] use crate::fmt; -use crate::marker::PhantomData; -use crate::ops::{Deref, DerefMut}; #[doc(no_inline)] #[stable(feature = "core_c_str", since = "1.64.0")] @@ -28,6 +26,20 @@ #[unstable(feature = "c_str_module", issue = "112134")] pub mod c_str; +#[unstable( + feature = "c_variadic", + issue = "44930", + reason = "the `c_variadic` feature has not been properly tested on all supported platforms" +)] +pub use self::va_list::{VaList, VaListImpl}; + +#[unstable( + feature = "c_variadic", + issue = "44930", + reason = "the `c_variadic` feature has not been properly tested on all supported platforms" +)] +pub mod va_list; + macro_rules! type_alias { { $Docfile:tt, $Alias:ident = $Real:ty; @@ -205,404 +217,6 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { } } -/// Basic implementation of a `va_list`. -// The name is WIP, using `VaListImpl` for now. -#[cfg(any( - all( - not(target_arch = "aarch64"), - not(target_arch = "powerpc"), - not(target_arch = "s390x"), - not(target_arch = "x86_64") - ), - all(target_arch = "aarch64", target_vendor = "apple"), - target_family = "wasm", - target_os = "uefi", - windows, -))] -#[cfg_attr(not(doc), repr(transparent))] // work around https://github.com/rust-lang/rust/issues/90435 -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -#[lang = "va_list"] -pub struct VaListImpl<'f> { - ptr: *mut c_void, - - // Invariant over `'f`, so each `VaListImpl<'f>` object is tied to - // the region of the function it's defined in - _marker: PhantomData<&'f mut &'f c_void>, -} - -#[cfg(any( - all( - not(target_arch = "aarch64"), - not(target_arch = "powerpc"), - not(target_arch = "s390x"), - not(target_arch = "x86_64") - ), - all(target_arch = "aarch64", target_vendor = "apple"), - target_family = "wasm", - target_os = "uefi", - windows, -))] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'f> fmt::Debug for VaListImpl<'f> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - write!(f, "va_list* {:p}", self.ptr) - } -} - -/// AArch64 ABI implementation of a `va_list`. See the -/// [AArch64 Procedure Call Standard] for more details. -/// -/// [AArch64 Procedure Call Standard]: -/// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf -#[cfg(all( - target_arch = "aarch64", - not(target_vendor = "apple"), - not(target_os = "uefi"), - not(windows), -))] -#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 -#[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -#[lang = "va_list"] -pub struct VaListImpl<'f> { - stack: *mut c_void, - gr_top: *mut c_void, - vr_top: *mut c_void, - gr_offs: i32, - vr_offs: i32, - _marker: PhantomData<&'f mut &'f c_void>, -} - -/// PowerPC ABI implementation of a `va_list`. -#[cfg(all(target_arch = "powerpc", not(target_os = "uefi"), not(windows)))] -#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 -#[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -#[lang = "va_list"] -pub struct VaListImpl<'f> { - gpr: u8, - fpr: u8, - reserved: u16, - overflow_arg_area: *mut c_void, - reg_save_area: *mut c_void, - _marker: PhantomData<&'f mut &'f c_void>, -} - -/// s390x ABI implementation of a `va_list`. -#[cfg(target_arch = "s390x")] -#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 -#[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -#[lang = "va_list"] -pub struct VaListImpl<'f> { - gpr: i64, - fpr: i64, - overflow_arg_area: *mut c_void, - reg_save_area: *mut c_void, - _marker: PhantomData<&'f mut &'f c_void>, -} - -/// x86_64 ABI implementation of a `va_list`. -#[cfg(all(target_arch = "x86_64", not(target_os = "uefi"), not(windows)))] -#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 -#[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -#[lang = "va_list"] -pub struct VaListImpl<'f> { - gp_offset: i32, - fp_offset: i32, - overflow_arg_area: *mut c_void, - reg_save_area: *mut c_void, - _marker: PhantomData<&'f mut &'f c_void>, -} - -/// A wrapper for a `va_list` -#[cfg_attr(not(doc), repr(transparent))] // work around https://github.com/rust-lang/rust/issues/90435 -#[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -pub struct VaList<'a, 'f: 'a> { - #[cfg(any( - all( - not(target_arch = "aarch64"), - not(target_arch = "powerpc"), - not(target_arch = "s390x"), - not(target_arch = "x86_64") - ), - all(target_arch = "aarch64", target_vendor = "apple"), - target_family = "wasm", - target_os = "uefi", - windows, - ))] - inner: VaListImpl<'f>, - - #[cfg(all( - any( - target_arch = "aarch64", - target_arch = "powerpc", - target_arch = "s390x", - target_arch = "x86_64" - ), - any(not(target_arch = "aarch64"), not(target_vendor = "apple")), - not(target_family = "wasm"), - not(target_os = "uefi"), - not(windows), - ))] - inner: &'a mut VaListImpl<'f>, - - _marker: PhantomData<&'a mut VaListImpl<'f>>, -} - -#[cfg(any( - all( - not(target_arch = "aarch64"), - not(target_arch = "powerpc"), - not(target_arch = "s390x"), - not(target_arch = "x86_64") - ), - all(target_arch = "aarch64", target_vendor = "apple"), - target_family = "wasm", - target_os = "uefi", - windows, -))] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'f> VaListImpl<'f> { - /// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`. - #[inline] - pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> { - VaList { inner: VaListImpl { ..*self }, _marker: PhantomData } - } -} - -#[cfg(all( - any( - target_arch = "aarch64", - target_arch = "powerpc", - target_arch = "s390x", - target_arch = "x86_64" - ), - any(not(target_arch = "aarch64"), not(target_vendor = "apple")), - not(target_family = "wasm"), - not(target_os = "uefi"), - not(windows), -))] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'f> VaListImpl<'f> { - /// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`. - #[inline] - pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> { - VaList { inner: self, _marker: PhantomData } - } -} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'a, 'f: 'a> Deref for VaList<'a, 'f> { - type Target = VaListImpl<'f>; - - #[inline] - fn deref(&self) -> &VaListImpl<'f> { - &self.inner - } -} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'a, 'f: 'a> DerefMut for VaList<'a, 'f> { - #[inline] - fn deref_mut(&mut self) -> &mut VaListImpl<'f> { - &mut self.inner - } -} - -// The VaArgSafe trait needs to be used in public interfaces, however, the trait -// itself must not be allowed to be used outside this module. Allowing users to -// implement the trait for a new type (thereby allowing the va_arg intrinsic to -// be used on a new type) is likely to cause undefined behavior. -// -// FIXME(dlrobertson): In order to use the VaArgSafe trait in a public interface -// but also ensure it cannot be used elsewhere, the trait needs to be public -// within a private module. Once RFC 2145 has been implemented look into -// improving this. -mod sealed_trait { - /// Trait which permits the allowed types to be used with [super::VaListImpl::arg]. - #[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" - )] - pub unsafe trait VaArgSafe {} -} - -macro_rules! impl_va_arg_safe { - ($($t:ty),+) => { - $( - #[unstable(feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930")] - unsafe impl sealed_trait::VaArgSafe for $t {} - )+ - } -} - -impl_va_arg_safe! {i8, i16, i32, i64, usize} -impl_va_arg_safe! {u8, u16, u32, u64, isize} -impl_va_arg_safe! {f64} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -unsafe impl sealed_trait::VaArgSafe for *mut T {} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -unsafe impl sealed_trait::VaArgSafe for *const T {} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'f> VaListImpl<'f> { - /// Advance to the next arg. - #[inline] - pub unsafe fn arg(&mut self) -> T { - // SAFETY: the caller must uphold the safety contract for `va_arg`. - unsafe { va_arg(self) } - } - - /// Copies the `va_list` at the current location. - pub unsafe fn with_copy(&self, f: F) -> R - where - F: for<'copy> FnOnce(VaList<'copy, 'f>) -> R, - { - let mut ap = self.clone(); - let ret = f(ap.as_va_list()); - // SAFETY: the caller must uphold the safety contract for `va_end`. - unsafe { - va_end(&mut ap); - } - ret - } -} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'f> Clone for VaListImpl<'f> { - #[inline] - fn clone(&self) -> Self { - let mut dest = crate::mem::MaybeUninit::uninit(); - // SAFETY: we write to the `MaybeUninit`, thus it is initialized and `assume_init` is legal - unsafe { - va_copy(dest.as_mut_ptr(), self); - dest.assume_init() - } - } -} - -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] -impl<'f> Drop for VaListImpl<'f> { - fn drop(&mut self) { - // FIXME: this should call `va_end`, but there's no clean way to - // guarantee that `drop` always gets inlined into its caller, - // so the `va_end` would get directly called from the same function as - // the corresponding `va_copy`. `man va_end` states that C requires this, - // and LLVM basically follows the C semantics, so we need to make sure - // that `va_end` is always called from the same function as `va_copy`. - // For more details, see https://github.com/rust-lang/rust/pull/59625 - // and https://llvm.org/docs/LangRef.html#llvm-va-end-intrinsic. - // - // This works for now, since `va_end` is a no-op on all current LLVM targets. - } -} - -extern "rust-intrinsic" { - /// Destroy the arglist `ap` after initialization with `va_start` or - /// `va_copy`. - #[rustc_nounwind] - fn va_end(ap: &mut VaListImpl<'_>); - - /// Copies the current location of arglist `src` to the arglist `dst`. - #[rustc_nounwind] - fn va_copy<'f>(dest: *mut VaListImpl<'f>, src: &VaListImpl<'f>); - - /// Loads an argument of type `T` from the `va_list` `ap` and increment the - /// argument `ap` points to. - #[rustc_nounwind] - fn va_arg(ap: &mut VaListImpl<'_>) -> T; -} - // Link the MSVC default lib #[cfg(all(windows, target_env = "msvc"))] #[link( diff --git a/library/core/src/ffi/va_list.rs b/library/core/src/ffi/va_list.rs new file mode 100644 index 00000000000..88c5909b113 --- /dev/null +++ b/library/core/src/ffi/va_list.rs @@ -0,0 +1,407 @@ +//! C's "variable arguments" +//! +//! Better known as "varargs". + +use crate::ffi::c_void; + +#[allow(unused_imports)] +use crate::fmt; +use crate::marker::PhantomData; +use crate::ops::{Deref, DerefMut}; + +/// Basic implementation of a `va_list`. +// The name is WIP, using `VaListImpl` for now. +#[cfg(any( + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), + all(target_arch = "aarch64", target_vendor = "apple"), + target_family = "wasm", + target_os = "uefi", + windows, +))] +#[cfg_attr(not(doc), repr(transparent))] // work around https://github.com/rust-lang/rust/issues/90435 +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + ptr: *mut c_void, + + // Invariant over `'f`, so each `VaListImpl<'f>` object is tied to + // the region of the function it's defined in + _marker: PhantomData<&'f mut &'f c_void>, +} + +#[cfg(any( + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), + all(target_arch = "aarch64", target_vendor = "apple"), + target_family = "wasm", + target_os = "uefi", + windows, +))] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'f> fmt::Debug for VaListImpl<'f> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "va_list* {:p}", self.ptr) + } +} + +/// AArch64 ABI implementation of a `va_list`. See the +/// [AArch64 Procedure Call Standard] for more details. +/// +/// [AArch64 Procedure Call Standard]: +/// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf +#[cfg(all( + target_arch = "aarch64", + not(target_vendor = "apple"), + not(target_os = "uefi"), + not(windows), +))] +#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + stack: *mut c_void, + gr_top: *mut c_void, + vr_top: *mut c_void, + gr_offs: i32, + vr_offs: i32, + _marker: PhantomData<&'f mut &'f c_void>, +} + +/// PowerPC ABI implementation of a `va_list`. +#[cfg(all(target_arch = "powerpc", not(target_os = "uefi"), not(windows)))] +#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + gpr: u8, + fpr: u8, + reserved: u16, + overflow_arg_area: *mut c_void, + reg_save_area: *mut c_void, + _marker: PhantomData<&'f mut &'f c_void>, +} + +/// s390x ABI implementation of a `va_list`. +#[cfg(target_arch = "s390x")] +#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + gpr: i64, + fpr: i64, + overflow_arg_area: *mut c_void, + reg_save_area: *mut c_void, + _marker: PhantomData<&'f mut &'f c_void>, +} + +/// x86_64 ABI implementation of a `va_list`. +#[cfg(all(target_arch = "x86_64", not(target_os = "uefi"), not(windows)))] +#[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + gp_offset: i32, + fp_offset: i32, + overflow_arg_area: *mut c_void, + reg_save_area: *mut c_void, + _marker: PhantomData<&'f mut &'f c_void>, +} + +/// A wrapper for a `va_list` +#[cfg_attr(not(doc), repr(transparent))] // work around https://github.com/rust-lang/rust/issues/90435 +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +pub struct VaList<'a, 'f: 'a> { + #[cfg(any( + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), + all(target_arch = "aarch64", target_vendor = "apple"), + target_family = "wasm", + target_os = "uefi", + windows, + ))] + inner: VaListImpl<'f>, + + #[cfg(all( + any( + target_arch = "aarch64", + target_arch = "powerpc", + target_arch = "s390x", + target_arch = "x86_64" + ), + any(not(target_arch = "aarch64"), not(target_vendor = "apple")), + not(target_family = "wasm"), + not(target_os = "uefi"), + not(windows), + ))] + inner: &'a mut VaListImpl<'f>, + + _marker: PhantomData<&'a mut VaListImpl<'f>>, +} + +#[cfg(any( + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), + all(target_arch = "aarch64", target_vendor = "apple"), + target_family = "wasm", + target_os = "uefi", + windows, +))] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'f> VaListImpl<'f> { + /// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`. + #[inline] + pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> { + VaList { inner: VaListImpl { ..*self }, _marker: PhantomData } + } +} + +#[cfg(all( + any( + target_arch = "aarch64", + target_arch = "powerpc", + target_arch = "s390x", + target_arch = "x86_64" + ), + any(not(target_arch = "aarch64"), not(target_vendor = "apple")), + not(target_family = "wasm"), + not(target_os = "uefi"), + not(windows), +))] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'f> VaListImpl<'f> { + /// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`. + #[inline] + pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> { + VaList { inner: self, _marker: PhantomData } + } +} + +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'a, 'f: 'a> Deref for VaList<'a, 'f> { + type Target = VaListImpl<'f>; + + #[inline] + fn deref(&self) -> &VaListImpl<'f> { + &self.inner + } +} + +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'a, 'f: 'a> DerefMut for VaList<'a, 'f> { + #[inline] + fn deref_mut(&mut self) -> &mut VaListImpl<'f> { + &mut self.inner + } +} + +// The VaArgSafe trait needs to be used in public interfaces, however, the trait +// itself must not be allowed to be used outside this module. Allowing users to +// implement the trait for a new type (thereby allowing the va_arg intrinsic to +// be used on a new type) is likely to cause undefined behavior. +// +// FIXME(dlrobertson): In order to use the VaArgSafe trait in a public interface +// but also ensure it cannot be used elsewhere, the trait needs to be public +// within a private module. Once RFC 2145 has been implemented look into +// improving this. +mod sealed_trait { + /// Trait which permits the allowed types to be used with [super::VaListImpl::arg]. + #[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" + )] + pub unsafe trait VaArgSafe {} +} + +macro_rules! impl_va_arg_safe { + ($($t:ty),+) => { + $( + #[unstable(feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930")] + unsafe impl sealed_trait::VaArgSafe for $t {} + )+ + } +} + +impl_va_arg_safe! {i8, i16, i32, i64, usize} +impl_va_arg_safe! {u8, u16, u32, u64, isize} +impl_va_arg_safe! {f64} + +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +unsafe impl sealed_trait::VaArgSafe for *mut T {} +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +unsafe impl sealed_trait::VaArgSafe for *const T {} + +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'f> VaListImpl<'f> { + /// Advance to the next arg. + #[inline] + pub unsafe fn arg(&mut self) -> T { + // SAFETY: the caller must uphold the safety contract for `va_arg`. + unsafe { va_arg(self) } + } + + /// Copies the `va_list` at the current location. + pub unsafe fn with_copy(&self, f: F) -> R + where + F: for<'copy> FnOnce(VaList<'copy, 'f>) -> R, + { + let mut ap = self.clone(); + let ret = f(ap.as_va_list()); + // SAFETY: the caller must uphold the safety contract for `va_end`. + unsafe { + va_end(&mut ap); + } + ret + } +} + +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'f> Clone for VaListImpl<'f> { + #[inline] + fn clone(&self) -> Self { + let mut dest = crate::mem::MaybeUninit::uninit(); + // SAFETY: we write to the `MaybeUninit`, thus it is initialized and `assume_init` is legal + unsafe { + va_copy(dest.as_mut_ptr(), self); + dest.assume_init() + } + } +} + +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +impl<'f> Drop for VaListImpl<'f> { + fn drop(&mut self) { + // FIXME: this should call `va_end`, but there's no clean way to + // guarantee that `drop` always gets inlined into its caller, + // so the `va_end` would get directly called from the same function as + // the corresponding `va_copy`. `man va_end` states that C requires this, + // and LLVM basically follows the C semantics, so we need to make sure + // that `va_end` is always called from the same function as `va_copy`. + // For more details, see https://github.com/rust-lang/rust/pull/59625 + // and https://llvm.org/docs/LangRef.html#llvm-va-end-intrinsic. + // + // This works for now, since `va_end` is a no-op on all current LLVM targets. + } +} + +extern "rust-intrinsic" { + /// Destroy the arglist `ap` after initialization with `va_start` or + /// `va_copy`. + #[rustc_nounwind] + fn va_end(ap: &mut VaListImpl<'_>); + + /// Copies the current location of arglist `src` to the arglist `dst`. + #[rustc_nounwind] + fn va_copy<'f>(dest: *mut VaListImpl<'f>, src: &VaListImpl<'f>); + + /// Loads an argument of type `T` from the `va_list` `ap` and increment the + /// argument `ap` points to. + #[rustc_nounwind] + fn va_arg(ap: &mut VaListImpl<'_>) -> T; +} diff --git a/src/tools/tidy/src/pal.rs b/src/tools/tidy/src/pal.rs index 7e5656926ab..2f8abc77566 100644 --- a/src/tools/tidy/src/pal.rs +++ b/src/tools/tidy/src/pal.rs @@ -45,6 +45,8 @@ // pointer regardless of the target architecture. As a result, // we must use `#[cfg(windows)]` to conditionally compile the // correct `VaList` structure for windows. + "library/core/src/ffi/va_list.rs", + // We placed a linkage against Windows libraries here "library/core/src/ffi/mod.rs", "library/std/src/sys", // Platform-specific code for std lives here. "library/std/src/os", // Platform-specific public interfaces From c1a29b30d157689caafa34238e87313cda0fccc5 Mon Sep 17 00:00:00 2001 From: Jubilee Young Date: Mon, 24 Jun 2024 14:09:30 -0700 Subject: [PATCH 2/2] core: erase redundant stability attrs in va_list Now that VaList, et al. have a module, they only need one `#[unstable]`. --- library/core/src/ffi/va_list.rs | 106 -------------------------------- 1 file changed, 106 deletions(-) diff --git a/library/core/src/ffi/va_list.rs b/library/core/src/ffi/va_list.rs index 88c5909b113..6a2e8b67d0c 100644 --- a/library/core/src/ffi/va_list.rs +++ b/library/core/src/ffi/va_list.rs @@ -24,12 +24,6 @@ windows, ))] #[cfg_attr(not(doc), repr(transparent))] // work around https://github.com/rust-lang/rust/issues/90435 -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] #[lang = "va_list"] pub struct VaListImpl<'f> { ptr: *mut c_void, @@ -51,12 +45,6 @@ pub struct VaListImpl<'f> { target_os = "uefi", windows, ))] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'f> fmt::Debug for VaListImpl<'f> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "va_list* {:p}", self.ptr) @@ -76,12 +64,6 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { ))] #[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 #[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] #[lang = "va_list"] pub struct VaListImpl<'f> { stack: *mut c_void, @@ -96,12 +78,6 @@ pub struct VaListImpl<'f> { #[cfg(all(target_arch = "powerpc", not(target_os = "uefi"), not(windows)))] #[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 #[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] #[lang = "va_list"] pub struct VaListImpl<'f> { gpr: u8, @@ -116,12 +92,6 @@ pub struct VaListImpl<'f> { #[cfg(target_arch = "s390x")] #[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 #[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] #[lang = "va_list"] pub struct VaListImpl<'f> { gpr: i64, @@ -135,12 +105,6 @@ pub struct VaListImpl<'f> { #[cfg(all(target_arch = "x86_64", not(target_os = "uefi"), not(windows)))] #[cfg_attr(not(doc), repr(C))] // work around https://github.com/rust-lang/rust/issues/66401 #[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] #[lang = "va_list"] pub struct VaListImpl<'f> { gp_offset: i32, @@ -153,12 +117,6 @@ pub struct VaListImpl<'f> { /// A wrapper for a `va_list` #[cfg_attr(not(doc), repr(transparent))] // work around https://github.com/rust-lang/rust/issues/90435 #[derive(Debug)] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] pub struct VaList<'a, 'f: 'a> { #[cfg(any( all( @@ -203,12 +161,6 @@ pub struct VaList<'a, 'f: 'a> { target_os = "uefi", windows, ))] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'f> VaListImpl<'f> { /// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`. #[inline] @@ -229,12 +181,6 @@ pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> { not(target_os = "uefi"), not(windows), ))] -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'f> VaListImpl<'f> { /// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`. #[inline] @@ -243,12 +189,6 @@ pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> { } } -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'a, 'f: 'a> Deref for VaList<'a, 'f> { type Target = VaListImpl<'f>; @@ -258,12 +198,6 @@ fn deref(&self) -> &VaListImpl<'f> { } } -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'a, 'f: 'a> DerefMut for VaList<'a, 'f> { #[inline] fn deref_mut(&mut self) -> &mut VaListImpl<'f> { @@ -282,22 +216,12 @@ fn deref_mut(&mut self) -> &mut VaListImpl<'f> { // improving this. mod sealed_trait { /// Trait which permits the allowed types to be used with [super::VaListImpl::arg]. - #[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" - )] pub unsafe trait VaArgSafe {} } macro_rules! impl_va_arg_safe { ($($t:ty),+) => { $( - #[unstable(feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930")] unsafe impl sealed_trait::VaArgSafe for $t {} )+ } @@ -307,27 +231,9 @@ unsafe impl sealed_trait::VaArgSafe for $t {} impl_va_arg_safe! {u8, u16, u32, u64, isize} impl_va_arg_safe! {f64} -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] unsafe impl sealed_trait::VaArgSafe for *mut T {} -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] unsafe impl sealed_trait::VaArgSafe for *const T {} -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'f> VaListImpl<'f> { /// Advance to the next arg. #[inline] @@ -351,12 +257,6 @@ pub unsafe fn with_copy(&self, f: F) -> R } } -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'f> Clone for VaListImpl<'f> { #[inline] fn clone(&self) -> Self { @@ -369,12 +269,6 @@ fn clone(&self) -> Self { } } -#[unstable( - feature = "c_variadic", - reason = "the `c_variadic` feature has not been properly tested on \ - all supported platforms", - issue = "44930" -)] impl<'f> Drop for VaListImpl<'f> { fn drop(&mut self) { // FIXME: this should call `va_end`, but there's no clean way to