Merge `TraitItem` & `ImplItem into` AssocItem` #67131

Centril · 2019-12-07T23:28:35Z

In this PR we:

Merge {Trait,Impl}Item{Kind?} into AssocItem{Kind?} as discussed in an empty :vis doesn't work in trait declaration #65041 (comment).
- This is done by using the cover grammar of both forms.
- In particular, it requires that we syntactically allow (under #[cfg(FALSE)]):
  - defaultness on trait items,
  - impl items without a body / definition (const, type, and fn),
  - and associated types in impls with bounds, e.g., type Foo: Ord;.
- The syntactic restrictions are replaced by semantic ones in ast_validation.
Move syntactic restrictions around C-variadic parameters from the parser into ast_validation:
- fns in all contexts now syntactically allow ...,
- ... can occur anywhere in the list syntactically (fn foo(..., x: usize) {}),
- and ... can be the sole parameter (fn foo(...) {}.

r? @petrochenkov

petrochenkov · 2019-12-08T10:50:09Z

r=me on the implementation.

Not sure whether this needs an FCP from the lang team or the consensus in #65041 (comment) is enough.

Centril · 2019-12-08T10:51:30Z

👋 @rust-lang/lang :)

Centril · 2019-12-10T07:37:58Z

I'm gonna interpret the radio silence here + general feeling about semantic vs. syntactic errors expressed in the past as "I have nothing new to add atop the existing consensus in #65041 (comment)". :)

@bors r=petrochenkov

bors · 2019-12-10T07:38:00Z

📌 Commit bf521fb5300a194ffbd34cb70e6f4c8b8eb487eb has been approved by petrochenkov

bors · 2019-12-10T13:44:55Z

⌛ Testing commit bf521fb5300a194ffbd34cb70e6f4c8b8eb487eb with merge 0ecb374d13d500af84e0453ffde16d81cb97b52a...

eddyb · 2019-12-10T15:55:08Z

Could this PR allow the following (assuming delegate is some proc macro)?

struct Wrapper<T>(T);

#[delegate(self.0: T)]
impl<T> fmt::Debug for Wrapper<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result;
}

Which could expand into:

struct Wrapper<T>(T);

impl<T> fmt::Debug for Wrapper<T>
    where T: fmt::Debug
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&self.0, f)
    }
}

I guess you could do it before this PR too and just require an empty body or thereabouts, but being able to have an explicit ; seems slightly nicer.

nikomatsakis · 2019-12-10T22:37:23Z

@Centril

I'm gonna interpret the radio silence here + general feeling about semantic vs. syntactic errors expressed in the past as "I have nothing new to add atop the existing consensus in #65041 (comment)". :)

in my case, I just hadn't gotten to the notification -- but I am indeed fine with the "language implications" here.

I didn't look too closely at the PR itself, though from a quick look it seemed good.

Centril · 2019-12-11T09:01:11Z

Could this PR allow the following (assuming delegate is some proc macro)?

@eddyb Indeed, that would be allowed. :) Go forth and implement!

src/libsyntax/print/pprust.rs

Centril · 2019-12-11T10:15:39Z

The job i686-mingw-2 of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Might be spurious? I have no idea why this is happening at the moment so let's try again and see if it was.

@bors r=petrochenkov rollup=never

Also fix error the code description.

Centril · 2019-12-19T09:44:05Z

@bors r=petrochenkov

bors · 2019-12-19T09:44:08Z

📌 Commit 054458b has been approved by petrochenkov

@petrochenkov

Merge `TraitItem` & `ImplItem into `AssocItem` In this PR we: - Merge `{Trait,Impl}Item{Kind?}` into `AssocItem{Kind?}` as discussed in rust-lang#65041 (comment). - This is done by using the cover grammar of both forms. - In particular, it requires that we syntactically allow (under `#[cfg(FALSE)]`): - `default`ness on `trait` items, - `impl` items without a body / definition (`const`, `type`, and `fn`), - and associated `type`s in `impl`s with bounds, e.g., `type Foo: Ord;`. - The syntactic restrictions are replaced by semantic ones in `ast_validation`. - Move syntactic restrictions around C-variadic parameters from the parser into `ast_validation`: - `fn`s in all contexts now syntactically allow `...`, - `...` can occur anywhere in the list syntactically (`fn foo(..., x: usize) {}`), - and `...` can be the sole parameter (`fn foo(...) {}`. r? @petrochenkov

Centril · 2019-12-20T16:23:52Z

@bors rollup=maybe

@ghost

Rollup of 5 pull requests Successful merges: - #64588 (Add a raw "address of" operator) - #67031 (Update tokio crates to latest versions) - #67131 (Merge `TraitItem` & `ImplItem into `AssocItem`) - #67354 (Fix pointing at arg when cause is outside of call) - #67363 (Fix handling of wasm import modules and names) Failed merges: r? @ghost

@estebank

Refactor type & bounds parsing thoroughly PR is based on rust-lang#67131 with first one from this PR being ` extract parse_ty_tuple_or_parens`. Also fixes rust-lang#67146. r? @estebank

@estebank

Refactor type & bounds parsing thoroughly PR is based on rust-lang#67131 with first one from this PR being ` extract parse_ty_tuple_or_parens`. Also fixes rust-lang#67146. r? @estebank

@estebank

Refactor type & bounds parsing thoroughly PR is based on rust-lang#67131 with first one from this PR being ` extract parse_ty_tuple_or_parens`. Also fixes rust-lang#67146. r? @estebank

TraitItem/ImplItem were combined to `AssocItem`, along with their respecitve `*Kind`'s, the `Method` variant was also renamed to `Fn` in the new `AssocItemKind` rust-lang/rust#67131

@estebank

…enkov parse: merge `fn` syntax + cleanup item parsing Here we continue the work in rust-lang#67131 in particular to merge the grammars of `fn` items in various positions. A list of *language level* changes (as sanctioned by the language team in rust-lang#65041 (comment) and rust-lang#67131): - `self` parameters are now *syntactically* allowed as the first parameter irrespective of item context (and in function pointers). Instead, semantic validation (`ast_validation`) is used. - Syntactically, `fn` items in `extern { ... }` blocks can now have bodies (`fn foo() { ... }` as opposed to `fn foo();`). As above, we use semantic restrictions instead. - Syntactically, `fn` items in free contexts (directly in a file or a module) can now be without bodies (`fn foo();` as opposed to `fn foo() { ... }`. As above, we use semantic restrictions instead, including for non-ident parameter patterns. - `const extern fn` feature gating is now done post-expansion such that we do not have conditional compatibilities of function qualifiers *in parsing*. - The `FnFrontMatter` grammar becomes: ```rust Extern = "extern" StringLit ; FnQual = "const"? "async"? "unsafe"? Extern? ; FnFrontMatter = FnQual "fn" ; ``` That is, all item contexts now *syntactically* allow `const async unsafe extern "C" fn` and use semantic restrictions to rule out combinations previously prevented syntactically. The semantic restrictions include in particular: - `fn`s in `extern { ... }` can have no qualifiers. - `const` and `async` cannot be combined. - To fuse the list-of-items parsing in the 4 contexts that items are allowed, we now must permit inner attributes (`#![attr]`) inside `trait Foo { ... }` definitions. That is, we now allow e.g. `trait Foo { #![attr] }`. This was probably an oversight due to not using a uniform parsing mechanism, which we now do have (`fn parse_item_list`). The semantic support (including e.g. for linting) falls out directly from the attributes infrastructure. To ensure this, we include a test for lints. Put together, these grammar changes allow us to substantially reduce the complexity of item parsing and its grammar. There are however some other non-language improvements that allow the compression to take place. A list of *compiler-internal* changes (in particular noting the parser-external data-structure changes): - We use `enum AllowPlus/RecoverQPath/AllowCVariadic { Yes, No }` in `parser/ty.rs` instead of passing around 3 different `bool`s. I felt this was necessary as it was becoming mentally taxing to track which-is-which. - `fn visit_trait_item` and `fn visit_impl_item` are merged into `fn visit_assoc_item` which now is passed an `AssocCtxt` to check which one it is. - We change `FnKind` to: ```rust pub enum FnKind<'a> { Fn(FnCtxt, Ident, &'a FnSig, &'a Visibility, Option<&'a Block>), Closure(&'a FnDecl, &'a Expr), } ``` with: ```rust pub enum FnCtxt { Free, Foreign, Assoc(AssocCtxt), } ``` This is then taken advantage of in tweaking the various semantic restrictions as well as in pretty printing. - In `ItemKind::Fn`, we change `P<Block>` to `Option<P<Block>>`. - In `ForeignItemKind::Fn`, we change `P<FnDecl>` to `FnSig` and `P<Block>` to `Option<P<Block>>`. - We change `ast::{Unsafety, Spanned<Constness>}>` into `enum ast::{Unsafe, Const} { Yes(Span), No }` respectively. This change in formulation allow us to exclude `Span` in the case of `No`, which facilitates parsing. Moreover, we also add a `Span` to `IsAsync` which is renamed to `Async`. The new `Span`s in `Unsafety` and `Async` are then taken advantage of for better diagnostics. A reason this change was made is to have a more uniform and clear naming scheme. The HIR keeps the structures in AST (with those definitions moved into HIR) for now to avoid regressing perf. - Various cleanups, bug fixes, and diagnostics improvements are made along the way. It is probably best to understand those via the diffs. I would recommend reviewing this commit-by-commit with whitespace changes hidden. r? @estebank @petrochenkov

Version 1.42.0 (2020-03-12) ========================== Language -------- - [You can now use the slice pattern syntax with subslices.][67712] e.g. ```rust fn foo(words: &[&str]) { match words { ["Hello", "World", "!", ..] => println!("Hello World!"), ["Foo", "Bar", ..] => println!("Baz"), rest => println!("{:?}", rest), } } ``` - [You can now use `#[repr(transparent)]` on univariant `enum`s.][68122] Meaning that you can create an enum that has the exact layout and ABI of the type it contains. - [There are some *syntax-only* changes:][67131] - `default` is syntactically allowed before items in `trait` definitions. - Items in `impl`s (i.e. `const`s, `type`s, and `fn`s) may syntactically leave out their bodies in favor of `;`. - Bounds on associated types in `impl`s are now syntactically allowed (e.g. `type Foo: Ord;`). - `...` (the C-variadic type) may occur syntactically directly as the type of any function parameter. These are still rejected *semantically*, so you will likely receive an error but these changes can be seen and parsed by procedural macros and conditional compilation. Compiler -------- - [Added tier 2* support for `armv7a-none-eabi`.][68253] - [Added tier 2 support for `riscv64gc-unknown-linux-gnu`.][68339] - [`Option::{expect,unwrap}` and `Result::{expect, expect_err, unwrap, unwrap_err}` now produce panic messages pointing to the location where they were called, rather than `core`'s internals. ][67887] * Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`iter::Empty<T>` now implements `Send` and `Sync` for any `T`.][68348] - [`Pin::{map_unchecked, map_unchecked_mut}` no longer require the return type to implement `Sized`.][67935] - [`io::Cursor` now derives `PartialEq` and `Eq`.][67233] - [`Layout::new` is now `const`.][66254] - [Added Standard Library support for `riscv64gc-unknown-linux-gnu`.][66899] Stabilized APIs --------------- - [`CondVar::wait_while`] - [`CondVar::wait_timeout_while`] - [`DebugMap::key`] - [`DebugMap::value`] - [`ManuallyDrop::take`] - [`matches!`] - [`ptr::slice_from_raw_parts_mut`] - [`ptr::slice_from_raw_parts`] Cargo ----- - [You no longer need to include `extern crate proc_macro;` to be able to `use proc_macro;` in the `2018` edition.][cargo/7700] Compatibility Notes ------------------- - [`Error::description` has been deprecated, and its use will now produce a warning.][66919] It's recommended to use `Display`/`to_string` instead. - [`use $crate;` inside macros is now a hard error.][37390] The compiler emitted forward compatibility warnings since Rust 1.14.0. - [As previously announced, this release reduces the level of support for 32-bit Apple targets to tier 3.][apple-32bit-drop]. This means that the source code is still available to build, but the targets are no longer tested and no release binary is distributed by the Rust project. Please refer to the linked blog post for more information. [37390]: rust-lang/rust#37390 [68253]: rust-lang/rust#68253 [68348]: rust-lang/rust#68348 [67935]: rust-lang/rust#67935 [68339]: rust-lang/rust#68339 [68122]: rust-lang/rust#68122 [67712]: rust-lang/rust#67712 [67887]: rust-lang/rust#67887 [67131]: rust-lang/rust#67131 [67233]: rust-lang/rust#67233 [66899]: rust-lang/rust#66899 [66919]: rust-lang/rust#66919 [66254]: rust-lang/rust#66254 [cargo/7700]: rust-lang/cargo#7700 [`DebugMap::key`]: https://doc.rust-lang.org/stable/std/fmt/struct.DebugMap.html#method.key [`DebugMap::value`]: https://doc.rust-lang.org/stable/std/fmt/struct.DebugMap.html#method.value [`ManuallyDrop::take`]: https://doc.rust-lang.org/stable/std/mem/struct.ManuallyDrop.html#method.take [`matches!`]: https://doc.rust-lang.org/stable/std/macro.matches.html [`ptr::slice_from_raw_parts_mut`]: https://doc.rust-lang.org/stable/std/ptr/fn.slice_from_raw_parts_mut.html [`ptr::slice_from_raw_parts`]: https://doc.rust-lang.org/stable/std/ptr/fn.slice_from_raw_parts.html [`CondVar::wait_while`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.wait_while [`CondVar::wait_timeout_while`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.wait_timeout_while

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Centril force-pushed the item-merge branch from 37d459d to bf521fb Compare December 8, 2019 05:33

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Refactor type & bounds parsing thoroughly #67148

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Centril added relnotes Marks issues that should be documented in the release notes of the next release. T-lang Relevant to the language team, which will review and decide on the PR/issue. labels Dec 11, 2019

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Centril force-pushed the item-merge branch from bf521fb to 9cc2acd Compare December 11, 2019 10:14

Centril commented Dec 11, 2019

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src/libsyntax/print/pprust.rs Show resolved Hide resolved

Centril added 4 commits December 12, 2019 18:05

Remove ast::{Impl,Trait}{Item,ItemKind}.

abf2e7a

AssocImplKind::{Method -> Fn}.

e52f902

De-fatalize ... parsing.

74d4fbc

Also fix error the code description.

make visitor uses more robust

054458b

Centril force-pushed the item-merge branch from 9cc2acd to 054458b Compare December 12, 2019 17:06

Centril mentioned this pull request Dec 16, 2019

Shrink Nonterminal #67340

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Centril modified the milestones: 1.41, 1.42 Dec 19, 2019

Centril mentioned this pull request Dec 20, 2019

Rollup of 5 pull requests #67455

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bors merged commit 054458b into rust-lang:master Dec 20, 2019

Centril deleted the item-merge branch December 20, 2019 21:02

Centril mentioned this pull request Jan 17, 2020

Specialization should allow for delegation to default trait method implementation #68309

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Centril mentioned this pull request Feb 1, 2020

parse: merge fn syntax + cleanup item parsing #68728

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ehuss mentioned this pull request Feb 9, 2020

Update grammar for parser unification rust-lang/reference#750

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lnicola mentioned this pull request Mar 13, 2020

Parser updates for #67131 rust-lang/rust-analyzer#3578

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Centril mentioned this pull request Mar 30, 2020

Update for new stable and unstable features, and fix a few mistakes. rust-lang/wg-grammar#68

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ehuss mentioned this pull request Jan 11, 2021

Update grammar for parser unification. rust-lang/reference#927

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Merge `TraitItem` & `ImplItem into` AssocItem` #67131

Merge `TraitItem` & `ImplItem into` AssocItem` #67131

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Merge TraitItem & ImplItem into AssocItem` #67131

Merge TraitItem & ImplItem into AssocItem` #67131

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Merge `TraitItem` & `ImplItem into` AssocItem` #67131

Merge `TraitItem` & `ImplItem into` AssocItem` #67131