diff options
| -rw-r--r-- | compiler/rustc_parse/src/parser/ty.rs | 42 | ||||
| -rw-r--r-- | tests/ui/impl-trait/precise-capturing/parenthesized.rs | 8 | ||||
| -rw-r--r-- | tests/ui/impl-trait/precise-capturing/parenthesized.stderr | 14 |
3 files changed, 48 insertions, 16 deletions
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs index 0d479731e73..b02eeeb93a8 100644 --- a/compiler/rustc_parse/src/parser/ty.rs +++ b/compiler/rustc_parse/src/parser/ty.rs @@ -849,8 +849,9 @@ impl<'a> Parser<'a> { fn parse_precise_capturing_args( &mut self, - ) -> PResult<'a, (ThinVec<PreciseCapturingArg>, Span)> { - let lo = self.token.span; + lo: Span, + parens: ast::Parens, + ) -> PResult<'a, GenericBound> { self.expect_lt()?; let (args, _, _) = self.parse_seq_to_before_tokens( &[exp!(Gt)], @@ -876,7 +877,22 @@ impl<'a> Parser<'a> { }, )?; self.expect_gt()?; - Ok((args, lo.to(self.prev_token.span))) + + if let ast::Parens::Yes = parens { + self.expect(exp!(CloseParen))?; + let hi = self.prev_token.span; + let mut diag = self + .dcx() + .struct_span_err(lo.to(hi), "precise capturing lists may not be parenthesized"); + diag.multipart_suggestion( + "remove the parentheses", + vec![(lo, String::new()), (hi, String::new())], + Applicability::MachineApplicable, + ); + diag.emit(); + } + + Ok(GenericBound::Use(args, lo.to(self.prev_token.span))) } /// Is a `dyn B0 + ... + Bn` type allowed here? @@ -987,24 +1003,18 @@ impl<'a> Parser<'a> { /// BOUND = TY_BOUND | LT_BOUND /// ``` fn parse_generic_bound(&mut self) -> PResult<'a, GenericBound> { - let lo = self.token.span; let leading_token = self.prev_token; + let lo = self.token.span; + let parens = if self.eat(exp!(OpenParen)) { ast::Parens::Yes } else { ast::Parens::No }; - let bound = if self.token.is_lifetime() { - self.parse_generic_lt_bound(lo, parens)? + if self.token.is_lifetime() { + self.parse_generic_lt_bound(lo, parens) } else if self.eat_keyword(exp!(Use)) { - // parse precise captures, if any. This is `use<'lt, 'lt, P, P>`; a list of - // lifetimes and ident params (including SelfUpper). These are validated later - // for order, duplication, and whether they actually reference params. - let use_span = self.prev_token.span; - let (args, args_span) = self.parse_precise_capturing_args()?; - GenericBound::Use(args, use_span.to(args_span)) + self.parse_precise_capturing_args(lo, parens) } else { - self.parse_generic_ty_bound(lo, parens, &leading_token)? - }; - - Ok(bound) + self.parse_generic_ty_bound(lo, parens, &leading_token) + } } /// Parses a lifetime ("outlives") bound, e.g. `'a`, according to: diff --git a/tests/ui/impl-trait/precise-capturing/parenthesized.rs b/tests/ui/impl-trait/precise-capturing/parenthesized.rs new file mode 100644 index 00000000000..e3f80fc1d9f --- /dev/null +++ b/tests/ui/impl-trait/precise-capturing/parenthesized.rs @@ -0,0 +1,8 @@ +// Ensure that we forbid parenthesized use-bounds. In the future we might want +// to lift this restriction but for now they bear no use whatsoever. + +fn f() -> impl Sized + (use<>) {} +//~^ ERROR precise capturing lists may not be parenthesized +//~| HELP remove the parentheses + +fn main() {} diff --git a/tests/ui/impl-trait/precise-capturing/parenthesized.stderr b/tests/ui/impl-trait/precise-capturing/parenthesized.stderr new file mode 100644 index 00000000000..c97fa9972ef --- /dev/null +++ b/tests/ui/impl-trait/precise-capturing/parenthesized.stderr @@ -0,0 +1,14 @@ +error: precise capturing lists may not be parenthesized + --> $DIR/parenthesized.rs:4:24 + | +LL | fn f() -> impl Sized + (use<>) {} + | ^^^^^^^ + | +help: remove the parentheses + | +LL - fn f() -> impl Sized + (use<>) {} +LL + fn f() -> impl Sized + use<> {} + | + +error: aborting due to 1 previous error + |