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parse: allow type Foo: Ord syntactically.

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This commit is contained in:
Mazdak Farrokhzad 2020-02-21 23:00:27 +01:00
parent 14442e0ebb
commit 9f3dfd29a2
18 changed files with 160 additions and 61 deletions
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32
src/librustc_parse/parser/item.rs
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@ -156,8 +156,7 @@ impl<'a> Parser<'a> {
self.parse_item_mod(attrs)?
} else if self.eat_keyword(kw::Type) {
// TYPE ITEM
let (ident, ty, generics) = self.parse_type_alias()?;
(ident, ItemKind::TyAlias(ty, generics))
self.parse_type_alias()?
} else if self.eat_keyword(kw::Enum) {
// ENUM ITEM
self.parse_item_enum()?
@ -676,7 +675,10 @@ impl<'a> Parser<'a> {
vis: &Visibility,
) -> PResult<'a, (Ident, AssocItemKind)> {
if self.eat_keyword(kw::Type) {
self.parse_assoc_ty()
match self.parse_type_alias()? {
(ident, ItemKind::TyAlias(a, b, c)) => Ok((ident, AssocItemKind::TyAlias(a, b, c))),
_ => unreachable!(),
}
} else if self.check_fn_front_matter() {
let (ident, sig, generics, body) = self.parse_fn(at_end, attrs, req_name)?;
Ok((ident, AssocItemKind::Fn(sig, generics, body)))
@ -700,10 +702,12 @@ impl<'a> Parser<'a> {
}
}
/// Parses the following grammar:
///
/// AssocTy = Ident ["<"...">"] [":" [GenericBounds]] ["where" ...] ["=" Ty]
fn parse_assoc_ty(&mut self) -> PResult<'a, (Ident, AssocItemKind)> {
/// Parses a `type` alias with the following grammar:
/// ```
/// TypeAlias = "type" Ident Generics {":" GenericBounds}? {"=" Ty}? ";" ;
/// ```
/// The `"type"` has already been eaten.
fn parse_type_alias(&mut self) -> PResult<'a, (Ident, ItemKind)> {
let ident = self.parse_ident()?;
let mut generics = self.parse_generics()?;
@ -715,7 +719,7 @@ impl<'a> Parser<'a> {
let default = if self.eat(&token::Eq) { Some(self.parse_ty()?) } else { None };
self.expect_semi()?;
Ok((ident, AssocItemKind::TyAlias(generics, bounds, default)))
Ok((ident, ItemKind::TyAlias(generics, bounds, default)))
}
/// Parses a `UseTree`.
@ -989,18 +993,6 @@ impl<'a> Parser<'a> {
P(Ty { kind: TyKind::Infer, span: id.span, id: ast::DUMMY_NODE_ID })
}
/// Parses the grammar:
/// Ident ["<"...">"] ["where" ...] ("=" | ":") Ty ";"
fn parse_type_alias(&mut self) -> PResult<'a, (Ident, P<Ty>, Generics)> {
let ident = self.parse_ident()?;
let mut tps = self.parse_generics()?;
tps.where_clause = self.parse_where_clause()?;
self.expect(&token::Eq)?;
let ty = self.parse_ty()?;
self.expect_semi()?;
Ok((ident, ty, tps))
}
/// Parses an enum declaration.
fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
let id = self.parse_ident()?;