From f57ea7cb3daf186bcd181f9add9e56cc45ff8380 Mon Sep 17 00:00:00 2001 From: Vadim Petrochenkov Date: Sat, 27 Jan 2018 22:37:17 +0300 Subject: Make `+` in `impl/dyn Trait` non-associative --- src/libsyntax/parse/parser.rs | 22 ++++++- src/test/parse-fail/impl-trait-plus-priority.rs | 47 --------------- src/test/ui/impl-trait/impl-trait-plus-priority.rs | 59 +++++++++++++++++++ .../ui/impl-trait/impl-trait-plus-priority.stderr | 68 ++++++++++++++++++++++ 4 files changed, 146 insertions(+), 50 deletions(-) delete mode 100644 src/test/parse-fail/impl-trait-plus-priority.rs create mode 100644 src/test/ui/impl-trait/impl-trait-plus-priority.rs create mode 100644 src/test/ui/impl-trait/impl-trait-plus-priority.stderr diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index 0430be101b0..0b57d781412 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -1528,6 +1528,7 @@ impl<'a> Parser<'a> { maybe_whole!(self, NtTy, |x| x); let lo = self.span; + let mut impl_dyn_multi = false; let node = if self.eat(&token::OpenDelim(token::Paren)) { // `(TYPE)` is a parenthesized type. // `(TYPE,)` is a tuple with a single field of type TYPE. @@ -1614,12 +1615,17 @@ impl<'a> Parser<'a> { self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)? } } else if self.eat_keyword(keywords::Impl) { - TyKind::ImplTrait(self.parse_ty_param_bounds_common(allow_plus)?) + // Always parse bounds greedily for better error recovery. + let bounds = self.parse_ty_param_bounds()?; + impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus; + TyKind::ImplTrait(bounds) } else if self.check_keyword(keywords::Dyn) && self.look_ahead(1, |t| t.can_begin_bound() && !can_continue_type_after_ident(t)) { self.bump(); // `dyn` - TyKind::TraitObject(self.parse_ty_param_bounds_common(allow_plus)?, - TraitObjectSyntax::Dyn) + // Always parse bounds greedily for better error recovery. + let bounds = self.parse_ty_param_bounds()?; + impl_dyn_multi = bounds.len() > 1 || self.prev_token_kind == PrevTokenKind::Plus; + TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn) } else if self.check(&token::Question) || self.check_lifetime() && self.look_ahead(1, |t| t == &token::BinOp(token::Plus)) { // Bound list (trait object type) @@ -1655,6 +1661,7 @@ impl<'a> Parser<'a> { let ty = Ty { node, span, id: ast::DUMMY_NODE_ID }; // Try to recover from use of `+` with incorrect priority. + self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty); self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?; let ty = self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)?; @@ -1672,6 +1679,15 @@ impl<'a> Parser<'a> { Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None)) } + fn maybe_report_ambiguous_plus(&mut self, allow_plus: bool, impl_dyn_multi: bool, ty: &Ty) { + if !allow_plus && impl_dyn_multi { + let sum_with_parens = format!("({})", pprust::ty_to_string(&ty)); + self.struct_span_err(ty.span, "ambiguous `+` in a type") + .span_suggestion(ty.span, "use parentheses to disambiguate", sum_with_parens) + .emit(); + } + } + fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> { // Do not add `+` to expected tokens. if !allow_plus || self.token != token::BinOp(token::Plus) { diff --git a/src/test/parse-fail/impl-trait-plus-priority.rs b/src/test/parse-fail/impl-trait-plus-priority.rs deleted file mode 100644 index 6d12a68cf3d..00000000000 --- a/src/test/parse-fail/impl-trait-plus-priority.rs +++ /dev/null @@ -1,47 +0,0 @@ -// 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 or the MIT license -// , at your -// option. This file may not be copied, modified, or distributed -// except according to those terms. - -// compile-flags: -Z parse-only -Z continue-parse-after-error - -fn f() -> impl A + B {} // OK -fn f() -> dyn A + B {} // OK -fn f() -> A + B {} // OK - -impl S { - fn f(self) -> impl A + B { // OK - let _ = |a, b| -> impl A + B {}; // OK - } - fn f(self) -> dyn A + B { // OK - let _ = |a, b| -> dyn A + B {}; // OK - } - fn f(self) -> A + B { // OK - let _ = |a, b| -> A + B {}; // OK - } -} - -type A = fn() -> impl A + B; -//~^ ERROR expected a path on the left-hand side of `+`, not `fn() -> impl A` -type A = fn() -> dyn A + B; -//~^ ERROR expected a path on the left-hand side of `+`, not `fn() -> dyn A` -type A = fn() -> A + B; -//~^ ERROR expected a path on the left-hand side of `+`, not `fn() -> A` - -type A = Fn() -> impl A + B; // OK, interpreted as `(Fn() -> impl A) + B` -type A = Fn() -> dyn A + B; // OK, interpreted as `(Fn() -> dyn A) + B` -type A = Fn() -> A + B; // OK, interpreted as `(Fn() -> A) + B` - -type A = &impl A + B; -//~^ ERROR expected a path on the left-hand side of `+`, not `&impl A` -type A = &dyn A + B; -//~^ ERROR expected a path on the left-hand side of `+`, not `&dyn A` -type A = &A + B; -//~^ ERROR expected a path on the left-hand side of `+`, not `&A` - -fn main() {} diff --git a/src/test/ui/impl-trait/impl-trait-plus-priority.rs b/src/test/ui/impl-trait/impl-trait-plus-priority.rs new file mode 100644 index 00000000000..f451123ca27 --- /dev/null +++ b/src/test/ui/impl-trait/impl-trait-plus-priority.rs @@ -0,0 +1,59 @@ +// 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// compile-flags: -Z parse-only -Z continue-parse-after-error + +fn f() -> impl A + {} // OK +fn f() -> impl A + B {} // OK +fn f() -> dyn A + B {} // OK +fn f() -> A + B {} // OK + +impl S { + fn f(self) -> impl A + { // OK + let _ = |a, b| -> impl A + {}; // OK + } + fn f(self) -> impl A + B { // OK + let _ = |a, b| -> impl A + B {}; // OK + } + fn f(self) -> dyn A + B { // OK + let _ = |a, b| -> dyn A + B {}; // OK + } + fn f(self) -> A + B { // OK + let _ = |a, b| -> A + B {}; // OK + } +} + +type A = fn() -> impl A +; +//~^ ERROR ambiguous `+` in a type +type A = fn() -> impl A + B; +//~^ ERROR ambiguous `+` in a type +type A = fn() -> dyn A + B; +//~^ ERROR ambiguous `+` in a type +type A = fn() -> A + B; +//~^ ERROR expected a path on the left-hand side of `+`, not `fn() -> A` + +type A = Fn() -> impl A +; +//~^ ERROR ambiguous `+` in a type +type A = Fn() -> impl A + B; +//~^ ERROR ambiguous `+` in a type +type A = Fn() -> dyn A + B; +//~^ ERROR ambiguous `+` in a type +type A = Fn() -> A + B; // OK, interpreted as `(Fn() -> A) + B` for compatibility + +type A = &impl A +; +//~^ ERROR ambiguous `+` in a type +type A = &impl A + B; +//~^ ERROR ambiguous `+` in a type +type A = &dyn A + B; +//~^ ERROR ambiguous `+` in a type +type A = &A + B; +//~^ ERROR expected a path on the left-hand side of `+`, not `&A` + +fn main() {} diff --git a/src/test/ui/impl-trait/impl-trait-plus-priority.stderr b/src/test/ui/impl-trait/impl-trait-plus-priority.stderr new file mode 100644 index 00000000000..885c3941971 --- /dev/null +++ b/src/test/ui/impl-trait/impl-trait-plus-priority.stderr @@ -0,0 +1,68 @@ +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:33:18 + | +33 | type A = fn() -> impl A +; + | ^^^^^^^^ help: use parentheses to disambiguate: `(impl A)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:35:18 + | +35 | type A = fn() -> impl A + B; + | ^^^^^^^^^^ help: use parentheses to disambiguate: `(impl A + B)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:37:18 + | +37 | type A = fn() -> dyn A + B; + | ^^^^^^^^^ help: use parentheses to disambiguate: `(dyn A + B)` + +error[E0178]: expected a path on the left-hand side of `+`, not `fn() -> A` + --> $DIR/impl-trait-plus-priority.rs:39:10 + | +39 | type A = fn() -> A + B; + | ^^^^^^^^^^^^^ perhaps you forgot parentheses? + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:42:18 + | +42 | type A = Fn() -> impl A +; + | ^^^^^^^^ help: use parentheses to disambiguate: `(impl A)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:44:18 + | +44 | type A = Fn() -> impl A + B; + | ^^^^^^^^^^ help: use parentheses to disambiguate: `(impl A + B)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:46:18 + | +46 | type A = Fn() -> dyn A + B; + | ^^^^^^^^^ help: use parentheses to disambiguate: `(dyn A + B)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:50:11 + | +50 | type A = &impl A +; + | ^^^^^^^^ help: use parentheses to disambiguate: `(impl A)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:52:11 + | +52 | type A = &impl A + B; + | ^^^^^^^^^^ help: use parentheses to disambiguate: `(impl A + B)` + +error: ambiguous `+` in a type + --> $DIR/impl-trait-plus-priority.rs:54:11 + | +54 | type A = &dyn A + B; + | ^^^^^^^^^ help: use parentheses to disambiguate: `(dyn A + B)` + +error[E0178]: expected a path on the left-hand side of `+`, not `&A` + --> $DIR/impl-trait-plus-priority.rs:56:10 + | +56 | type A = &A + B; + | ^^^^^^ help: try adding parentheses: `&(A + B)` + +error: aborting due to 11 previous errors + -- cgit 1.4.1-3-g733a5