Rollup merge of #82579 - osa1:issue82566, r=estebank

Fix turbofish recovery with multiple generic args

This consists of two commits, each can be individually reviewed.

- First commit fixes the issue in [this comment](https://github.com/rust-lang/rust/issues/82566#issuecomment-786924466).
- Second commit fixes #82566

---

r? ````@estebank````
This commit is contained in:
Yuki Okushi 2021-03-02 21:23:17 +09:00 committed by GitHub
commit 906e535205
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7 changed files with 134 additions and 4 deletions

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@ -662,7 +662,7 @@ impl<'a> Parser<'a> {
let x = self.parse_seq_to_before_end(
&token::Gt,
SeqSep::trailing_allowed(token::Comma),
|p| p.parse_ty(),
|p| p.parse_generic_arg(),
);
match x {
Ok((_, _, false)) => {

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@ -545,7 +545,7 @@ impl<'a> Parser<'a> {
/// Parse a generic argument in a path segment.
/// This does not include constraints, e.g., `Item = u8`, which is handled in `parse_angle_arg`.
fn parse_generic_arg(&mut self) -> PResult<'a, Option<GenericArg>> {
pub(super) fn parse_generic_arg(&mut self) -> PResult<'a, Option<GenericArg>> {
let start = self.token.span;
let arg = if self.check_lifetime() && self.look_ahead(1, |t| !t.is_like_plus()) {
// Parse lifetime argument.

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@ -360,12 +360,20 @@ impl<'a> Parser<'a> {
}
Err(err) => return Err(err),
};
let ty = if self.eat(&token::Semi) {
TyKind::Array(elt_ty, self.parse_anon_const_expr()?)
let mut length = self.parse_anon_const_expr()?;
if let Err(e) = self.expect(&token::CloseDelim(token::Bracket)) {
// Try to recover from `X<Y, ...>` when `X::<Y, ...>` works
self.check_mistyped_turbofish_with_multiple_type_params(e, &mut length.value)?;
self.expect(&token::CloseDelim(token::Bracket))?;
}
TyKind::Array(elt_ty, length)
} else {
self.expect(&token::CloseDelim(token::Bracket))?;
TyKind::Slice(elt_ty)
};
self.expect(&token::CloseDelim(token::Bracket))?;
Ok(ty)
}

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@ -0,0 +1,21 @@
struct T1<const X1: usize>;
struct T2<const X1: usize, const X2: usize>;
struct T3<const X1: usize, const X2: usize, const X3: usize>;
impl T1<1> {
const C: () = ();
}
impl T2<1, 2> {
const C: () = ();
}
impl T3<1, 2, 3> {
const C: () = ();
}
fn main() {
T1<1>::C; //~ ERROR: comparison operators cannot be chained
T2<1, 2>::C; //~ ERROR: expected one of `.`, `;`, `?`, `}`, or an operator, found `,`
T3<1, 2, 3>::C; //~ ERROR: expected one of `.`, `;`, `?`, `}`, or an operator, found `,`
}

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@ -0,0 +1,35 @@
error: comparison operators cannot be chained
--> $DIR/issue-82566-1.rs:18:7
|
LL | T1<1>::C;
| ^ ^
|
help: use `::<...>` instead of `<...>` to specify type or const arguments
|
LL | T1::<1>::C;
| ^^
error: expected one of `.`, `;`, `?`, `}`, or an operator, found `,`
--> $DIR/issue-82566-1.rs:19:9
|
LL | T2<1, 2>::C;
| ^ expected one of `.`, `;`, `?`, `}`, or an operator
|
help: use `::<...>` instead of `<...>` to specify type or const arguments
|
LL | T2::<1, 2>::C;
| ^^
error: expected one of `.`, `;`, `?`, `}`, or an operator, found `,`
--> $DIR/issue-82566-1.rs:20:9
|
LL | T3<1, 2, 3>::C;
| ^ expected one of `.`, `;`, `?`, `}`, or an operator
|
help: use `::<...>` instead of `<...>` to specify type or const arguments
|
LL | T3::<1, 2, 3>::C;
| ^^
error: aborting due to 3 previous errors

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@ -0,0 +1,31 @@
struct Foo1<const N1: usize>;
struct Foo2<const N1: usize, const N2: usize>;
struct Foo3<const N1: usize, const N2: usize, const N3: usize>;
impl<const N1: usize> Foo1<N1> {
const SUM: usize = N1;
}
impl<const N1: usize, const N2: usize> Foo2<N1, N2> {
const SUM: usize = N1 + N2;
}
impl<const N1: usize, const N2: usize, const N3: usize> Foo3<N1, N2, N3> {
const SUM: usize = N1 + N2 + N3;
}
fn foo1() -> [(); Foo1<10>::SUM] { //~ ERROR: comparison operators cannot be chained
todo!()
}
fn foo2() -> [(); Foo2<10, 20>::SUM] {
//~^ ERROR: expected one of `.`, `?`, `]`, or an operator, found `,`
todo!()
}
fn foo3() -> [(); Foo3<10, 20, 30>::SUM] {
//~^ ERROR: expected one of `.`, `?`, `]`, or an operator, found `,`
todo!()
}
fn main() {}

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@ -0,0 +1,35 @@
error: comparison operators cannot be chained
--> $DIR/issue-82566-2.rs:17:23
|
LL | fn foo1() -> [(); Foo1<10>::SUM] {
| ^ ^
|
help: use `::<...>` instead of `<...>` to specify type or const arguments
|
LL | fn foo1() -> [(); Foo1::<10>::SUM] {
| ^^
error: expected one of `.`, `?`, `]`, or an operator, found `,`
--> $DIR/issue-82566-2.rs:21:26
|
LL | fn foo2() -> [(); Foo2<10, 20>::SUM] {
| ^ expected one of `.`, `?`, `]`, or an operator
|
help: use `::<...>` instead of `<...>` to specify type or const arguments
|
LL | fn foo2() -> [(); Foo2::<10, 20>::SUM] {
| ^^
error: expected one of `.`, `?`, `]`, or an operator, found `,`
--> $DIR/issue-82566-2.rs:26:26
|
LL | fn foo3() -> [(); Foo3<10, 20, 30>::SUM] {
| ^ expected one of `.`, `?`, `]`, or an operator
|
help: use `::<...>` instead of `<...>` to specify type or const arguments
|
LL | fn foo3() -> [(); Foo3::<10, 20, 30>::SUM] {
| ^^
error: aborting due to 3 previous errors