Generic Associated Types Parsing & Name Resolution #45904
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -1293,9 +1293,9 @@ impl<'a> Parser<'a> { | |
| let lo = self.span; | ||
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| let (name, node, generics) = if self.eat_keyword(keywords::Type) { | ||
| let (generics, TyParam {ident, bounds, default, ..}) = | ||
| self.parse_trait_item_assoc_ty(vec![])?; | ||
| (ident, TraitItemKind::Type(bounds, default), generics) | ||
| } else if self.is_const_item() { | ||
| self.expect_keyword(keywords::Const)?; | ||
| let ident = self.parse_ident()?; | ||
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@@ -4442,6 +4442,39 @@ impl<'a> Parser<'a> { | |
| }) | ||
| } | ||
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| /// Parses the following grammar: | ||
| /// TraitItemAssocTy = Ident ["<"...">"] [":" [TyParamBounds]] ["where" ...] ["=" Ty] | ||
| fn parse_trait_item_assoc_ty(&mut self, preceding_attrs: Vec<Attribute>) | ||
| -> PResult<'a, (ast::Generics, TyParam)> { | ||
| let span = self.span; | ||
| let ident = self.parse_ident()?; | ||
| let mut generics = self.parse_generics()?; | ||
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| // Parse optional colon and param bounds. | ||
| let bounds = if self.eat(&token::Colon) { | ||
| self.parse_ty_param_bounds()? | ||
| } else { | ||
| Vec::new() | ||
| }; | ||
| generics.where_clause = self.parse_where_clause()?; | ||
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| let default = if self.eat(&token::Eq) { | ||
| Some(self.parse_ty()?) | ||
| } else { | ||
| None | ||
| }; | ||
| self.expect(&token::Semi)?; | ||
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| Ok((generics, TyParam { | ||
| attrs: preceding_attrs.into(), | ||
| ident, | ||
| id: ast::DUMMY_NODE_ID, | ||
| bounds, | ||
| default, | ||
| span, | ||
| })) | ||
| } | ||
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| /// Parses (possibly empty) list of lifetime and type parameters, possibly including | ||
| /// trailing comma and erroneous trailing attributes. | ||
| pub fn parse_generic_params(&mut self) -> PResult<'a, (Vec<LifetimeDef>, Vec<TyParam>)> { | ||
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@@ -4983,12 +5016,18 @@ impl<'a> Parser<'a> { | |
| let vis = self.parse_visibility(false)?; | ||
| let defaultness = self.parse_defaultness()?; | ||
| let (name, node, generics) = if self.eat_keyword(keywords::Type) { | ||
| // This parses the grammar: | ||
| // ImplItemAssocTy = Ident ["<"...">"] ["where" ...] "=" Ty ";" | ||
| let name = self.parse_ident()?; | ||
| let mut generics = self.parse_generics()?; | ||
| generics.where_clause = self.parse_where_clause()?; | ||
| self.expect(&token::Eq)?; | ||
| let typ = self.parse_ty()?; | ||
| self.expect(&token::Semi)?; | ||
| (name, ast::ImplItemKind::Type(typ), generics) | ||
| } else if self.is_const_item() { | ||
| // This parses the grammar: | ||
| // ImplItemConst = "const" Ident ":" Ty "=" Expr ";" | ||
|
There was a problem hiding this comment. This comment isn't relevant to what I'm adding, but I added it because @nikomatsakis mentioned that it's good to document the grammar in places like this |
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| self.expect_keyword(keywords::Const)?; | ||
| let name = self.parse_ident()?; | ||
| self.expect(&token::Colon)?; | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,28 @@ | ||
| // Copyright 2012 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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| use std::ops::Deref; | ||
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| trait PointerFamily<U> { | ||
| type Pointer<T>: Deref<Target = T>; | ||
| //~^ ERROR generic associated types are unstable | ||
| type Pointer2<T>: Deref<Target = T> where T: Clone, U: Clone; | ||
| //~^ ERROR generic associated types are unstable | ||
| } | ||
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| struct Foo; | ||
| impl PointerFamily<u32> for Foo { | ||
| type Pointer<usize> = Box<usize>; | ||
| //~^ ERROR generic associated types are unstable | ||
| type Pointer2<u32> = Box<u32>; | ||
| //~^ ERROR generic associated types are unstable | ||
| } | ||
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| fn main() {} |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,28 @@ | ||
| // Copyright 2012 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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| #![feature(generic_associated_types)] | ||
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| //FIXME(#44265): "undeclared lifetime" errors will be addressed in a follow-up PR | ||
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| trait Foo { | ||
| type Bar<'a, 'b>; | ||
| } | ||
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| trait Baz { | ||
| type Quux<'a>; | ||
| } | ||
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| impl<T> Baz for T where T: Foo { | ||
| type Quux<'a> = <T as Foo>::Bar<'a, 'static>; | ||
| //~^ ERROR undeclared lifetime | ||
| } | ||
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| fn main() {} |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,8 @@ | ||
| error[E0261]: use of undeclared lifetime name `'a` | ||
| --> $DIR/construct_with_other_type.rs:24:37 | ||
| | | ||
| 24 | type Quux<'a> = <T as Foo>::Bar<'a, 'static>; | ||
| | ^^ undeclared lifetime | ||
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| error: aborting due to previous error | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,18 @@ | ||
| // Copyright 2017 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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| #![feature(generic_associated_types)] | ||
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| trait Foo { | ||
| type Bar<,>; | ||
| //~^ ERROR expected one of `>`, identifier, or lifetime, found `,` | ||
| } | ||
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| fn main() {} |
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@nikomatsakis Is there a reason why
parse_trait_item_assoc_tydoesn't consume the semicolon? I think it really could given that it's only used in one place and it wouldn't make any sense to parse all of this without the semicolon at the end. The only invocation of this function immediately expects a semicolon right after it.(added this question again because GitHub removed it on the latest diff)
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It doesn't make a big difference either way. A lot of times it's good to leave separators and terminators out from functions like this, since it makes them more re-usable, but I think in this case the
;logically "belongs" to the trait item, so it would make sense for this function to consume it.There was a problem hiding this comment.
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In the latest code, the semicolon is consumed.