From patchwork Sat Jun 24 09:24:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Benno Lossin X-Patchwork-Id: 112439 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp6306538vqr; Sat, 24 Jun 2023 03:11:48 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5P7TYRMGdGipRcxL6aPc7Yi8ufCEcAiijY9/QDeMIXp06AkVxNDknFlQ85d1YlpsC1GT6o X-Received: by 2002:a05:622a:d:b0:3fd:dab5:942d with SMTP id x13-20020a05622a000d00b003fddab5942dmr29250533qtw.53.1687601507834; Sat, 24 Jun 2023 03:11:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1687601507; cv=none; d=google.com; s=arc-20160816; b=GIreFdb0dxVN82kbEUg7+J4qt+TaogGB5NR2+eh/YcDn0+N14FBIiq01N2fwJzq0nj hzzjz6q2FztuXtks/VeS7qWRe2vJnz5qxQzXGhZnNEN9rPws/u4aJR11IV8whILkUeq0 zd8OFSpmXV6b8nFkWv4QNrHhpsmPdA2xi2r6sGDvaNRLsMr6emPlHQtEJyI7c6wDVrEy UX/lfFipaFlMTGgTYS1Z0+iSwK9PFboQUK7xiHiWw9awPiKwxBa6zlEh5kNsRwEp+zRD kXhKGzjJ6s/yh1rqkY44X6PDsbHAMx5XB+wGJLxmuKUs8Jx7Dc3HAl4QQmu23bH8ZsDf wB9A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :feedback-id:message-id:subject:cc:from:to:dkim-signature:date; bh=59XOq8B2rCdfLJSTN1omKI9iBhysqGeBftTNdO85xB4=; fh=MjAOSe9N0TSmaKf+f9PeCP42XQuaAqCEgZCvUulmBUE=; b=na+SuGhGYnee+OGBlftSA4ZtMircwtwp8wBh2nHmyikNPhupQH5KUuCj+9ThCFue3o PxeOXbySA1Dht7ImmupLXmrJgxmVDN2JSjkdpo2+k4JJKD9zPaIzwvXA0mCXmWSQwmSj j7Wjut5a3WLt5Btw/W1KVA0DohS+wXjVqhKwNk2s+V9Kdw0zPWB0ZDgIZflwpBXNWbY0 +JdKRYS6koWD8r/PMH9x0UIEeeXMju77M084W5stw3WRQ2GG3+nPtI1Ye+3JLBc3TpZT rQ5rK9pstNuZpgR722ZXkVH4Hh0rN4aR2vsV+H/bnSIUJleSJjTXaW2Hb3sRwJSIAkrz M2ig== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@proton.me header.s=protonmail header.b=dNkEWve8; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=proton.me Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id d4-20020a056a0024c400b006590bb60328si1046195pfv.173.2023.06.24.03.11.34; Sat, 24 Jun 2023 03:11:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@proton.me header.s=protonmail header.b=dNkEWve8; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=proton.me Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232984AbjFXJZP (ORCPT + 99 others); Sat, 24 Jun 2023 05:25:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231514AbjFXJZM (ORCPT ); Sat, 24 Jun 2023 05:25:12 -0400 Received: from mail-40131.protonmail.ch (mail-40131.protonmail.ch [185.70.40.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F42010FD; Sat, 24 Jun 2023 02:25:06 -0700 (PDT) Date: Sat, 24 Jun 2023 09:24:55 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=proton.me; s=protonmail; t=1687598703; x=1687857903; bh=59XOq8B2rCdfLJSTN1omKI9iBhysqGeBftTNdO85xB4=; h=Date:To:From:Cc:Subject:Message-ID:Feedback-ID:From:To:Cc:Date: Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=dNkEWve8JU2Qz+j2G+Y3ujxGakQQHYRMlAmL07B3+9Ypdj7x0eg4YQm6bjH5oVL64 OpPrBE3Fjs6S3x/Zbp7OKy263ur9y9HVxeXs2eykwqpz2PNNcL2d4gLwFlol7/7UQE t5MpCQL5UB3BzLaVyRkb+AnZlnhpY1Q7Fyluibt/XBDsEY+ZwyXZOIyhMc1SBl0F8D SZYvoM8C5zDZSxZIyH112lSkGg8KurcGtC1fUz9UygG2HUSm5V//HBTuK97e4DZqU/ /a+Es9cPOy7aD/Kw0AhbjYpvXvt9g1jTBNxJ2iCyIsJ3TpOB18UHoIIH0jxzEaTDGa egBjOrk6IZebQ== To: Miguel Ojeda , Wedson Almeida Filho , Alex Gaynor From: Benno Lossin Cc: Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Alice Ryhl , Andreas Hindborg , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev Subject: [PATCH 1/7] rust: init: consolidate init macros Message-ID: <20230624092330.157338-1-benno.lossin@proton.me> Feedback-ID: 71780778:user:proton MIME-Version: 1.0 X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_PASS,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1769578438549564547?= X-GMAIL-MSGID: =?utf-8?q?1769578438549564547?= Merges the implementations of `try_init!` and `try_pin_init!`. These two macros are very similar, but use different traits. The new macro `__init_internal!` that is now the implementation for both takes these traits as parameters. This change does not affect any users, as no public API has been changed, but it should simplify maintaining the init macros. Signed-off-by: Benno Lossin Reviewed-by: Björn Roy Baron --- rust/kernel/init.rs | 388 +++---------------------------------- rust/kernel/init/macros.rs | 237 +++++++++++++++++++++- 2 files changed, 259 insertions(+), 366 deletions(-) base-commit: d2e3115d717197cb2bc020dd1f06b06538474ac3 -- 2.41.0 diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index b4332a4ec1f4..d9a91950cba2 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -540,11 +540,14 @@ macro_rules! pin_init { ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }) => { - $crate::try_pin_init!( + $crate::__init_internal!( @this($($this)?), @typ($t $(::<$($generics),*>)?), @fields($($fields)*), @error(::core::convert::Infallible), + @data(PinData, use_data), + @has_data(HasPinData, __pin_data), + @construct_closure(pin_init_from_closure), ) }; } @@ -593,205 +596,29 @@ macro_rules! try_pin_init { ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }) => { - $crate::try_pin_init!( + $crate::__init_internal!( @this($($this)?), @typ($t $(::<$($generics),*>)? ), @fields($($fields)*), @error($crate::error::Error), + @data(PinData, use_data), + @has_data(HasPinData, __pin_data), + @construct_closure(pin_init_from_closure), ) }; ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }? $err:ty) => { - $crate::try_pin_init!( + $crate::__init_internal!( @this($($this)?), @typ($t $(::<$($generics),*>)? ), @fields($($fields)*), @error($err), + @data(PinData, use_data), + @has_data(HasPinData, __pin_data), + @construct_closure(pin_init_from_closure), ) }; - ( - @this($($this:ident)?), - @typ($t:ident $(::<$($generics:ty),*>)?), - @fields($($fields:tt)*), - @error($err:ty), - ) => {{ - // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return - // type and shadow it later when we insert the arbitrary user code. That way there will be - // no possibility of returning without `unsafe`. - struct __InitOk; - // Get the pin data from the supplied type. - let data = unsafe { - use $crate::init::__internal::HasPinData; - $t$(::<$($generics),*>)?::__pin_data() - }; - // Ensure that `data` really is of type `PinData` and help with type inference: - let init = $crate::init::__internal::PinData::make_closure::<_, __InitOk, $err>( - data, - move |slot| { - { - // Shadow the structure so it cannot be used to return early. - struct __InitOk; - // Create the `this` so it can be referenced by the user inside of the - // expressions creating the individual fields. - $(let $this = unsafe { ::core::ptr::NonNull::new_unchecked(slot) };)? - // Initialize every field. - $crate::try_pin_init!(init_slot: - @data(data), - @slot(slot), - @munch_fields($($fields)*,), - ); - // We use unreachable code to ensure that all fields have been mentioned exactly - // once, this struct initializer will still be type-checked and complain with a - // very natural error message if a field is forgotten/mentioned more than once. - #[allow(unreachable_code, clippy::diverging_sub_expression)] - if false { - $crate::try_pin_init!(make_initializer: - @slot(slot), - @type_name($t), - @munch_fields($($fields)*,), - @acc(), - ); - } - // Forget all guards, since initialization was a success. - $crate::try_pin_init!(forget_guards: - @munch_fields($($fields)*,), - ); - } - Ok(__InitOk) - } - ); - let init = move |slot| -> ::core::result::Result<(), $err> { - init(slot).map(|__InitOk| ()) - }; - let init = unsafe { $crate::init::pin_init_from_closure::<_, $err>(init) }; - init - }}; - (init_slot: - @data($data:ident), - @slot($slot:ident), - @munch_fields($(,)?), - ) => { - // Endpoint of munching, no fields are left. - }; - (init_slot: - @data($data:ident), - @slot($slot:ident), - // In-place initialization syntax. - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - ) => { - let $field = $val; - // Call the initializer. - // - // SAFETY: `slot` is valid, because we are inside of an initializer closure, we - // return when an error/panic occurs. - // We also use the `data` to require the correct trait (`Init` or `PinInit`) for `$field`. - unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), $field)? }; - // Create the drop guard. - // - // We only give access to `&DropGuard`, so it cannot be forgotten via safe code. - // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; - - $crate::try_pin_init!(init_slot: - @data($data), - @slot($slot), - @munch_fields($($rest)*), - ); - }; - (init_slot: - @data($data:ident), - @slot($slot:ident), - // Direct value init, this is safe for every field. - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - ) => { - $(let $field = $val;)? - // Initialize the field. - // - // SAFETY: The memory at `slot` is uninitialized. - unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; - // Create the drop guard: - // - // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. - // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; - - $crate::try_pin_init!(init_slot: - @data($data), - @slot($slot), - @munch_fields($($rest)*), - ); - }; - (make_initializer: - @slot($slot:ident), - @type_name($t:ident), - @munch_fields($(,)?), - @acc($($acc:tt)*), - ) => { - // Endpoint, nothing more to munch, create the initializer. - // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to - // get the correct type inference here: - unsafe { - ::core::ptr::write($slot, $t { - $($acc)* - }); - } - }; - (make_initializer: - @slot($slot:ident), - @type_name($t:ident), - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - @acc($($acc:tt)*), - ) => { - $crate::try_pin_init!(make_initializer: - @slot($slot), - @type_name($t), - @munch_fields($($rest)*), - @acc($($acc)* $field: ::core::panic!(),), - ); - }; - (make_initializer: - @slot($slot:ident), - @type_name($t:ident), - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - @acc($($acc:tt)*), - ) => { - $crate::try_pin_init!(make_initializer: - @slot($slot), - @type_name($t), - @munch_fields($($rest)*), - @acc($($acc)* $field: ::core::panic!(),), - ); - }; - (forget_guards: - @munch_fields($(,)?), - ) => { - // Munching finished. - }; - (forget_guards: - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - ) => { - unsafe { $crate::init::__internal::DropGuard::forget($field) }; - - $crate::try_pin_init!(forget_guards: - @munch_fields($($rest)*), - ); - }; - (forget_guards: - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - ) => { - unsafe { $crate::init::__internal::DropGuard::forget($field) }; - - $crate::try_pin_init!(forget_guards: - @munch_fields($($rest)*), - ); - }; } /// Construct an in-place initializer for `struct`s. @@ -816,11 +643,14 @@ macro_rules! init { ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }) => { - $crate::try_init!( + $crate::__init_internal!( @this($($this)?), @typ($t $(::<$($generics),*>)?), @fields($($fields)*), @error(::core::convert::Infallible), + @data(InitData, /*no use_data*/), + @has_data(HasInitData, __init_data), + @construct_closure(init_from_closure), ) } } @@ -863,199 +693,29 @@ macro_rules! try_init { ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }) => { - $crate::try_init!( + $crate::__init_internal!( @this($($this)?), @typ($t $(::<$($generics),*>)?), @fields($($fields)*), @error($crate::error::Error), + @data(InitData, /*no use_data*/), + @has_data(HasInitData, __init_data), + @construct_closure(init_from_closure), ) }; ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }? $err:ty) => { - $crate::try_init!( + $crate::__init_internal!( @this($($this)?), @typ($t $(::<$($generics),*>)?), @fields($($fields)*), @error($err), + @data(InitData, /*no use_data*/), + @has_data(HasInitData, __init_data), + @construct_closure(init_from_closure), ) }; - ( - @this($($this:ident)?), - @typ($t:ident $(::<$($generics:ty),*>)?), - @fields($($fields:tt)*), - @error($err:ty), - ) => {{ - // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return - // type and shadow it later when we insert the arbitrary user code. That way there will be - // no possibility of returning without `unsafe`. - struct __InitOk; - // Get the init data from the supplied type. - let data = unsafe { - use $crate::init::__internal::HasInitData; - $t$(::<$($generics),*>)?::__init_data() - }; - // Ensure that `data` really is of type `InitData` and help with type inference: - let init = $crate::init::__internal::InitData::make_closure::<_, __InitOk, $err>( - data, - move |slot| { - { - // Shadow the structure so it cannot be used to return early. - struct __InitOk; - // Create the `this` so it can be referenced by the user inside of the - // expressions creating the individual fields. - $(let $this = unsafe { ::core::ptr::NonNull::new_unchecked(slot) };)? - // Initialize every field. - $crate::try_init!(init_slot: - @slot(slot), - @munch_fields($($fields)*,), - ); - // We use unreachable code to ensure that all fields have been mentioned exactly - // once, this struct initializer will still be type-checked and complain with a - // very natural error message if a field is forgotten/mentioned more than once. - #[allow(unreachable_code, clippy::diverging_sub_expression)] - if false { - $crate::try_init!(make_initializer: - @slot(slot), - @type_name($t), - @munch_fields($($fields)*,), - @acc(), - ); - } - // Forget all guards, since initialization was a success. - $crate::try_init!(forget_guards: - @munch_fields($($fields)*,), - ); - } - Ok(__InitOk) - } - ); - let init = move |slot| -> ::core::result::Result<(), $err> { - init(slot).map(|__InitOk| ()) - }; - let init = unsafe { $crate::init::init_from_closure::<_, $err>(init) }; - init - }}; - (init_slot: - @slot($slot:ident), - @munch_fields( $(,)?), - ) => { - // Endpoint of munching, no fields are left. - }; - (init_slot: - @slot($slot:ident), - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - ) => { - let $field = $val; - // Call the initializer. - // - // SAFETY: `slot` is valid, because we are inside of an initializer closure, we - // return when an error/panic occurs. - unsafe { - $crate::init::Init::__init($field, ::core::ptr::addr_of_mut!((*$slot).$field))?; - } - // Create the drop guard. - // - // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. - // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; - - $crate::try_init!(init_slot: - @slot($slot), - @munch_fields($($rest)*), - ); - }; - (init_slot: - @slot($slot:ident), - // Direct value init. - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - ) => { - $(let $field = $val;)? - // Call the initializer. - // - // SAFETY: The memory at `slot` is uninitialized. - unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; - // Create the drop guard. - // - // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. - // - // SAFETY: We forget the guard later when initialization has succeeded. - let $field = &unsafe { - $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) - }; - - $crate::try_init!(init_slot: - @slot($slot), - @munch_fields($($rest)*), - ); - }; - (make_initializer: - @slot($slot:ident), - @type_name($t:ident), - @munch_fields( $(,)?), - @acc($($acc:tt)*), - ) => { - // Endpoint, nothing more to munch, create the initializer. - // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to - // get the correct type inference here: - unsafe { - ::core::ptr::write($slot, $t { - $($acc)* - }); - } - }; - (make_initializer: - @slot($slot:ident), - @type_name($t:ident), - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - @acc($($acc:tt)*), - ) => { - $crate::try_init!(make_initializer: - @slot($slot), - @type_name($t), - @munch_fields($($rest)*), - @acc($($acc)*$field: ::core::panic!(),), - ); - }; - (make_initializer: - @slot($slot:ident), - @type_name($t:ident), - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - @acc($($acc:tt)*), - ) => { - $crate::try_init!(make_initializer: - @slot($slot), - @type_name($t), - @munch_fields($($rest)*), - @acc($($acc)*$field: ::core::panic!(),), - ); - }; - (forget_guards: - @munch_fields($(,)?), - ) => { - // Munching finished. - }; - (forget_guards: - @munch_fields($field:ident <- $val:expr, $($rest:tt)*), - ) => { - unsafe { $crate::init::__internal::DropGuard::forget($field) }; - - $crate::try_init!(forget_guards: - @munch_fields($($rest)*), - ); - }; - (forget_guards: - @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), - ) => { - unsafe { $crate::init::__internal::DropGuard::forget($field) }; - - $crate::try_init!(forget_guards: - @munch_fields($($rest)*), - ); - }; } /// A pin-initializer for the type `T`. diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs index 00aa4e956c0a..fbaebd34f218 100644 --- a/rust/kernel/init/macros.rs +++ b/rust/kernel/init/macros.rs @@ -1,10 +1,12 @@ // SPDX-License-Identifier: Apache-2.0 OR MIT //! This module provides the macros that actually implement the proc-macros `pin_data` and -//! `pinned_drop`. +//! `pinned_drop`. It also contains `__init_internal` the implementation of the `{try_}{pin_}init!` +//! macros. //! //! These macros should never be called directly, since they expect their input to be -//! in a certain format which is internal. Use the proc-macros instead. +//! in a certain format which is internal. If used incorrectly, these macros can lead to UB even in +//! safe code! Use the public facing macros instead. //! //! This architecture has been chosen because the kernel does not yet have access to `syn` which //! would make matters a lot easier for implementing these as proc-macros. @@ -980,3 +982,234 @@ impl<$($impl_generics)*> $pin_data<$($ty_generics)*> } }; } + +/// The internal init macro. Do not call manually! +/// +/// This is called by the `{try_}{pin_}init!` macros with various inputs. +/// +/// This macro has multiple internal call configurations, these are always the very first ident: +/// - nothing: this is the base case and called by the `{try_}{pin_}init!` macros. +/// - `init_slot`: recursively creates the code that initializes all fields in `slot`. +/// - `make_initializer`: recursively create the struct initializer that guarantees that every +/// field has been initialized exactly once. +/// - `forget_guards`: recursively forget the drop guards for every field. +#[doc(hidden)] +#[macro_export] +macro_rules! __init_internal { + ( + @this($($this:ident)?), + @typ($t:ident $(::<$($generics:ty),*>)?), + @fields($($fields:tt)*), + @error($err:ty), + // Either `PinData` or `InitData`, `$use_data` should only be present in the `PinData` + // case. + @data($data:ident, $($use_data:ident)?), + // `HasPinData` or `HasInitData`. + @has_data($has_data:ident, $get_data:ident), + // `pin_init_from_closure` or `init_from_closure`. + @construct_closure($construct_closure:ident), + ) => {{ + // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return + // type and shadow it later when we insert the arbitrary user code. That way there will be + // no possibility of returning without `unsafe`. + struct __InitOk; + // Get the data about fields from the supplied type. + let data = unsafe { + use $crate::init::__internal::$has_data; + $t$(::<$($generics),*>)?::$get_data() + }; + // Ensure that `data` really is of type `$data` and help with type inference: + let init = $crate::init::__internal::$data::make_closure::<_, __InitOk, $err>( + data, + move |slot| { + { + // Shadow the structure so it cannot be used to return early. + struct __InitOk; + // Create the `this` so it can be referenced by the user inside of the + // expressions creating the individual fields. + $(let $this = unsafe { ::core::ptr::NonNull::new_unchecked(slot) };)? + // Initialize every field. + $crate::__init_internal!(init_slot($($use_data)?): + @data(data), + @slot(slot), + @munch_fields($($fields)*,), + ); + // We use unreachable code to ensure that all fields have been mentioned exactly + // once, this struct initializer will still be type-checked and complain with a + // very natural error message if a field is forgotten/mentioned more than once. + #[allow(unreachable_code, clippy::diverging_sub_expression)] + if false { + $crate::__init_internal!(make_initializer: + @slot(slot), + @type_name($t), + @munch_fields($($fields)*,), + @acc(), + ); + } + // Forget all guards, since initialization was a success. + $crate::__init_internal!(forget_guards: + @munch_fields($($fields)*,), + ); + } + Ok(__InitOk) + } + ); + let init = move |slot| -> ::core::result::Result<(), $err> { + init(slot).map(|__InitOk| ()) + }; + let init = unsafe { $crate::init::$construct_closure::<_, $err>(init) }; + init + }}; + (init_slot($($use_data:ident)?): + @data($data:ident), + @slot($slot:ident), + @munch_fields($(,)?), + ) => { + // Endpoint of munching, no fields are left. + }; + (init_slot($use_data:ident): // use_data is present, so we use the `data` to init fields. + @data($data:ident), + @slot($slot:ident), + // In-place initialization syntax. + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + let $field = $val; + // Call the initializer. + // + // SAFETY: `slot` is valid, because we are inside of an initializer closure, we + // return when an error/panic occurs. + // We also use the `data` to require the correct trait (`Init` or `PinInit`) for `$field`. + unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), $field)? }; + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be forgotten via safe code. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::__init_internal!(init_slot($use_data): + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (init_slot(): // no use_data, so we use `Init::__init` directly. + @data($data:ident), + @slot($slot:ident), + // In-place initialization syntax. + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + let $field = $val; + // Call the initializer. + // + // SAFETY: `slot` is valid, because we are inside of an initializer closure, we + // return when an error/panic occurs. + unsafe { $crate::init::Init::__init($field, ::core::ptr::addr_of_mut!((*$slot).$field))? }; + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be forgotten via safe code. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::__init_internal!(init_slot(): + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (init_slot($($use_data:ident)?): + @data($data:ident), + @slot($slot:ident), + // Init by-value. + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + $(let $field = $val;)? + // Initialize the field. + // + // SAFETY: The memory at `slot` is uninitialized. + unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; + // Create the drop guard: + // + // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::__init_internal!(init_slot($($use_data)?): + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($(,)?), + @acc($($acc:tt)*), + ) => { + // Endpoint, nothing more to munch, create the initializer. + // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to + // get the correct type inference here: + unsafe { + ::core::ptr::write($slot, $t { + $($acc)* + }); + } + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + $crate::__init_internal!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)* $field: ::core::panic!(),), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + $crate::__init_internal!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)* $field: ::core::panic!(),), + ); + }; + (forget_guards: + @munch_fields($(,)?), + ) => { + // Munching finished. + }; + (forget_guards: + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::__init_internal!(forget_guards: + @munch_fields($($rest)*), + ); + }; + (forget_guards: + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::__init_internal!(forget_guards: + @munch_fields($($rest)*), + ); + }; +}