From 2ea386424f1a9065947a5ac246043a6945e90def Mon Sep 17 00:00:00 2001 From: Matthew Jasper Date: Mon, 15 Jun 2020 18:04:43 +0100 Subject: [PATCH 1/2] Remove use of specialization from librustc_arena --- src/librustc_arena/lib.rs | 91 +++++++++++++++++--------------- src/librustc_ast_lowering/lib.rs | 2 - src/librustc_middle/lib.rs | 1 - 3 files changed, 48 insertions(+), 46 deletions(-) diff --git a/src/librustc_arena/lib.rs b/src/librustc_arena/lib.rs index 4a2a0de0e211f..7f154052538ac 100644 --- a/src/librustc_arena/lib.rs +++ b/src/librustc_arena/lib.rs @@ -602,7 +602,7 @@ macro_rules! which_arena_for_type { #[macro_export] macro_rules! declare_arena { - ([], [$($a:tt $name:ident: $ty:ty, $gen_ty:ty;)*], $tcx:lifetime) => { + ([], [$($a:tt $name:ident: $ty:ty, $_gen_ty:ty;)*], $tcx:lifetime) => { #[derive(Default)] pub struct Arena<$tcx> { pub dropless: $crate::DroplessArena, @@ -610,39 +610,56 @@ macro_rules! declare_arena { $($name: $crate::arena_for_type!($a[$ty]),)* } - #[marker] - pub trait ArenaAllocatable<'tcx> {} - - impl<'tcx, T: Copy> ArenaAllocatable<'tcx> for T {} - - unsafe trait ArenaField<'tcx>: Sized + ArenaAllocatable<'tcx> { - /// Returns a specific arena to allocate from. - /// If `None` is returned, the `DropArena` will be used. - fn arena<'a>(arena: &'a Arena<'tcx>) -> Option<&'a $crate::TypedArena>; + pub trait ArenaAllocatable<'tcx, T = Self>: Sized { + fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut Self; + fn allocate_from_iter<'a>( + arena: &'a Arena<'tcx>, + iter: impl ::std::iter::IntoIterator, + ) -> &'a mut [Self]; } - unsafe impl<'tcx, T: ArenaAllocatable<'tcx>> ArenaField<'tcx> for T { + impl<'tcx, T: Copy> ArenaAllocatable<'tcx, ()> for T { #[inline] - default fn arena<'a>(_: &'a Arena<'tcx>) -> Option<&'a $crate::TypedArena> { - panic!() + fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut Self { + arena.dropless.alloc(self) + } + #[inline] + fn allocate_from_iter<'a>( + arena: &'a Arena<'tcx>, + iter: impl ::std::iter::IntoIterator, + ) -> &'a mut [Self] { + arena.dropless.alloc_from_iter(iter) } - } + } $( - #[allow(unused_lifetimes)] - impl<$tcx> ArenaAllocatable<$tcx> for $ty {} - unsafe impl<$tcx, '_x, '_y, '_z, '_w> ArenaField<$tcx> for $gen_ty where Self: ArenaAllocatable<$tcx> { + impl<$tcx> ArenaAllocatable<$tcx, $ty> for $ty { #[inline] - fn arena<'a>(_arena: &'a Arena<$tcx>) -> Option<&'a $crate::TypedArena> { - // SAFETY: We only implement `ArenaAllocatable<$tcx>` for - // `$ty`, so `$ty` and Self are the same type - unsafe { - ::std::mem::transmute::< - Option<&'a $crate::TypedArena<$ty>>, - Option<&'a $crate::TypedArena>, - >( - $crate::which_arena_for_type!($a[&_arena.$name]) - ) + fn allocate_on<'a>(self, arena: &'a Arena<$tcx>) -> &'a mut Self { + if !::std::mem::needs_drop::() { + return arena.dropless.alloc(self); + } + match $crate::which_arena_for_type!($a[&arena.$name]) { + ::std::option::Option::<&$crate::TypedArena>::Some(ty_arena) => { + ty_arena.alloc(self) + } + ::std::option::Option::None => unsafe { arena.drop.alloc(self) }, + } + } + + #[inline] + fn allocate_from_iter<'a>( + arena: &'a Arena<$tcx>, + iter: impl ::std::iter::IntoIterator, + ) -> &'a mut [Self] { + if !::std::mem::needs_drop::() { + return arena.dropless.alloc_from_iter(iter); + } + match $crate::which_arena_for_type!($a[&arena.$name]) { + ::std::option::Option::<&$crate::TypedArena>::Some(ty_arena) => { + ty_arena.alloc_from_iter(iter) + } + ::std::option::Option::None => unsafe { arena.drop.alloc_from_iter(iter) }, } } } @@ -650,14 +667,8 @@ macro_rules! declare_arena { impl<'tcx> Arena<'tcx> { #[inline] - pub fn alloc>(&self, value: T) -> &mut T { - if !::std::mem::needs_drop::() { - return self.dropless.alloc(value); - } - match >::arena(self) { - ::std::option::Option::Some(arena) => arena.alloc(value), - ::std::option::Option::None => unsafe { self.drop.alloc(value) }, - } + pub fn alloc, U>(&self, value: T) -> &mut T { + value.allocate_on(self) } #[inline] @@ -668,17 +679,11 @@ macro_rules! declare_arena { self.dropless.alloc_slice(value) } - pub fn alloc_from_iter<'a, T: ArenaAllocatable<'tcx>>( + pub fn alloc_from_iter<'a, T: ArenaAllocatable<'tcx, U>, U>( &'a self, iter: impl ::std::iter::IntoIterator, ) -> &'a mut [T] { - if !::std::mem::needs_drop::() { - return self.dropless.alloc_from_iter(iter); - } - match >::arena(self) { - ::std::option::Option::Some(arena) => arena.alloc_from_iter(iter), - ::std::option::Option::None => unsafe { self.drop.alloc_from_iter(iter) }, - } + T::allocate_from_iter(self, iter) } } } diff --git a/src/librustc_ast_lowering/lib.rs b/src/librustc_ast_lowering/lib.rs index a722a88a7a102..af1e33a049bfb 100644 --- a/src/librustc_ast_lowering/lib.rs +++ b/src/librustc_ast_lowering/lib.rs @@ -32,8 +32,6 @@ #![feature(array_value_iter)] #![feature(crate_visibility_modifier)] -#![feature(marker_trait_attr)] -#![feature(min_specialization)] #![feature(or_patterns)] #![recursion_limit = "256"] diff --git a/src/librustc_middle/lib.rs b/src/librustc_middle/lib.rs index 62c92e988ba60..2e27ab514d80b 100644 --- a/src/librustc_middle/lib.rs +++ b/src/librustc_middle/lib.rs @@ -36,7 +36,6 @@ #![feature(drain_filter)] #![feature(never_type)] #![feature(exhaustive_patterns)] -#![feature(marker_trait_attr)] #![feature(extern_types)] #![feature(nll)] #![feature(option_expect_none)] From 1b92d592b5c7f8a3d399e5b9005f4b316b316ef1 Mon Sep 17 00:00:00 2001 From: Matthew Jasper Date: Tue, 16 Jun 2020 19:29:53 +0100 Subject: [PATCH 2/2] Explain unused macro param --- src/librustc_arena/lib.rs | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/librustc_arena/lib.rs b/src/librustc_arena/lib.rs index 7f154052538ac..a21d30bf817e3 100644 --- a/src/librustc_arena/lib.rs +++ b/src/librustc_arena/lib.rs @@ -602,6 +602,10 @@ macro_rules! which_arena_for_type { #[macro_export] macro_rules! declare_arena { + // This macro has to take the same input as + // `impl_arena_allocatable_decoders` which requires a second version of + // each type. We ignore that type until we can fix + // `impl_arena_allocatable_decoders`. ([], [$($a:tt $name:ident: $ty:ty, $_gen_ty:ty;)*], $tcx:lifetime) => { #[derive(Default)] pub struct Arena<$tcx> {