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Auto merge of #49219 - eddyb:proc-macro-decouple, r=alexcrichton
Decouple proc_macro from the rest of the compiler.
This PR removes all dependencies of `proc_macro` on compiler crates and allows multiple copies of `proc_macro`, built even by different compilers (but from the same source), to interoperate.
Practically, it allows:
* running proc macro tests at stage1 (I moved most from `-fulldeps` to the regular suites)
* using proc macros in the compiler itself (may require some rustbuild trickery)
On the server (i.e. compiler front-end) side:
* `server::*` traits are implemented to provide the concrete types and methods
* the concrete types are completely separated from the `proc_macro` public API
* the only use of the type implementing `Server` is to be passed to `Client::run`
On the client (i.e. proc macro) side (potentially using a different `proc_macro` instance!):
* `client::Client` wraps around client-side (expansion) function pointers
* it encapsulates the `proc_macro` instance used by the client
* its `run` method can be called by a server, to execute the client-side function
* the client instance is bridged to the provided server, while it runs
* ~~currently a thread is spawned, could use process isolation in the future~~
(not the case anymore, see #56058)
* proc macro crates get a generated `static` holding a `&[ProcMacro]`
* this describes all derives/attr/bang proc macros, replacing the "registrar" function
* each variant of `ProcMacro` contains an appropriately typed `Client<fn(...) -> ...>`
`proc_macro` public APIs call into the server via an internal "bridge":
* only a currently running proc macro `Client` can interact with those APIs
* server code might not be able to (if it uses a different `proc_macro` instance)
* however, it can always create and `run` its own `Client`, but that may be inefficient
* the `bridge` uses serialization, C ABI and integer handles to avoid Rust ABI instability
* each invocation of a proc macro results in disjoint integers in its `proc_macro` handles
* this prevents using values of those types across invocations (if they even can be kept)
r? @alexcrichton cc @jseyfried @nikomatsakis @Zoxc @thepowersgang- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
|
|
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| //! Buffer management for same-process client<->server communication. | ||
|
|
||
| use std::io::{self, Write}; | ||
| use std::mem; | ||
| use std::ops::{Deref, DerefMut}; | ||
| use std::slice; | ||
|
|
||
| #[repr(C)] | ||
| struct Slice<'a, T: 'a> { | ||
| data: &'a [T; 0], | ||
| len: usize, | ||
| } | ||
|
|
||
| unsafe impl<'a, T: Sync> Sync for Slice<'a, T> {} | ||
| unsafe impl<'a, T: Sync> Send for Slice<'a, T> {} | ||
|
|
||
| impl<T> Copy for Slice<'a, T> {} | ||
| impl<T> Clone for Slice<'a, T> { | ||
| fn clone(&self) -> Self { | ||
| *self | ||
| } | ||
| } | ||
|
|
||
| impl<T> From<&'a [T]> for Slice<'a, T> { | ||
| fn from(xs: &'a [T]) -> Self { | ||
| Slice { | ||
| data: unsafe { &*(xs.as_ptr() as *const [T; 0]) }, | ||
| len: xs.len(), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl<T> Deref for Slice<'a, T> { | ||
| type Target = [T]; | ||
| fn deref(&self) -> &[T] { | ||
| unsafe { slice::from_raw_parts(self.data.as_ptr(), self.len) } | ||
| } | ||
| } | ||
|
|
||
| #[repr(C)] | ||
| pub struct Buffer<T: Copy> { | ||
| data: *mut T, | ||
| len: usize, | ||
| capacity: usize, | ||
| extend_from_slice: extern "C" fn(Buffer<T>, Slice<T>) -> Buffer<T>, | ||
| drop: extern "C" fn(Buffer<T>), | ||
| } | ||
|
|
||
| unsafe impl<T: Copy + Sync> Sync for Buffer<T> {} | ||
| unsafe impl<T: Copy + Send> Send for Buffer<T> {} | ||
|
|
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| impl<T: Copy> Default for Buffer<T> { | ||
| fn default() -> Self { | ||
| Self::from(vec![]) | ||
| } | ||
| } | ||
|
|
||
| impl<T: Copy> Deref for Buffer<T> { | ||
| type Target = [T]; | ||
| fn deref(&self) -> &[T] { | ||
| unsafe { slice::from_raw_parts(self.data as *const T, self.len) } | ||
| } | ||
| } | ||
|
|
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| impl<T: Copy> DerefMut for Buffer<T> { | ||
| fn deref_mut(&mut self) -> &mut [T] { | ||
| unsafe { slice::from_raw_parts_mut(self.data, self.len) } | ||
| } | ||
| } | ||
|
|
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| impl<T: Copy> Buffer<T> { | ||
| pub(super) fn new() -> Self { | ||
| Self::default() | ||
| } | ||
|
|
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| pub(super) fn clear(&mut self) { | ||
| self.len = 0; | ||
| } | ||
|
|
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| pub(super) fn take(&mut self) -> Self { | ||
| mem::replace(self, Self::default()) | ||
| } | ||
|
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| pub(super) fn extend_from_slice(&mut self, xs: &[T]) { | ||
| // Fast path to avoid going through an FFI call. | ||
| if let Some(final_len) = self.len.checked_add(xs.len()) { | ||
| if final_len <= self.capacity { | ||
| let dst = unsafe { slice::from_raw_parts_mut(self.data, self.capacity) }; | ||
| dst[self.len..][..xs.len()].copy_from_slice(xs); | ||
| self.len = final_len; | ||
| return; | ||
| } | ||
| } | ||
| let b = self.take(); | ||
| *self = (b.extend_from_slice)(b, Slice::from(xs)); | ||
| } | ||
| } | ||
|
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| impl Write for Buffer<u8> { | ||
| fn write(&mut self, xs: &[u8]) -> io::Result<usize> { | ||
| self.extend_from_slice(xs); | ||
| Ok(xs.len()) | ||
| } | ||
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| fn write_all(&mut self, xs: &[u8]) -> io::Result<()> { | ||
| self.extend_from_slice(xs); | ||
| Ok(()) | ||
| } | ||
|
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| fn flush(&mut self) -> io::Result<()> { | ||
| Ok(()) | ||
| } | ||
| } | ||
|
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| impl<T: Copy> Drop for Buffer<T> { | ||
| fn drop(&mut self) { | ||
| let b = self.take(); | ||
| (b.drop)(b); | ||
| } | ||
| } | ||
|
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| impl<T: Copy> From<Vec<T>> for Buffer<T> { | ||
| fn from(mut v: Vec<T>) -> Self { | ||
| let (data, len, capacity) = (v.as_mut_ptr(), v.len(), v.capacity()); | ||
| mem::forget(v); | ||
|
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| // This utility function is nested in here because it can *only* | ||
| // be safely called on `Buffer`s created by *this* `proc_macro`. | ||
| fn to_vec<T: Copy>(b: Buffer<T>) -> Vec<T> { | ||
| unsafe { | ||
| let Buffer { | ||
| data, | ||
| len, | ||
| capacity, | ||
| .. | ||
| } = b; | ||
| mem::forget(b); | ||
| Vec::from_raw_parts(data, len, capacity) | ||
| } | ||
| } | ||
|
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| extern "C" fn extend_from_slice<T: Copy>(b: Buffer<T>, xs: Slice<T>) -> Buffer<T> { | ||
| let mut v = to_vec(b); | ||
| v.extend_from_slice(&xs); | ||
| Buffer::from(v) | ||
| } | ||
|
|
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| extern "C" fn drop<T: Copy>(b: Buffer<T>) { | ||
| mem::drop(to_vec(b)); | ||
| } | ||
|
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| Buffer { | ||
| data, | ||
| len, | ||
| capacity, | ||
| extend_from_slice, | ||
| drop, | ||
| } | ||
| } | ||
| } |
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