Auto merge of #45503 - thombles:tk/i44339-v5, r=petrochenkov
Improve diagnostics when list of tokens has incorrect separators Make `parse_seq_to_before_tokens` more resilient to error conditions. Where possible it is better if it can consume up to the final bracket before returning. This change improves the diagnostics in a couple of situations: ``` struct S(pub () ()); // omitted separator use std::{foo. bar}; // used a similar but wrong separator ``` Fixes #44339 r? @petrochenkov
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commit
c1a0b6d9eb
7 changed files with 55 additions and 4 deletions
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@ -1033,7 +1033,23 @@ impl<'a> Parser<'a> {
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} else {
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if let Err(e) = self.expect(t) {
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fe(e);
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break;
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// Attempt to keep parsing if it was a similar separator
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if let Some(ref tokens) = t.similar_tokens() {
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if tokens.contains(&self.token) {
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self.bump();
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}
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}
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// Attempt to keep parsing if it was an omitted separator
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match f(self) {
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Ok(t) => {
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v.push(t);
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continue;
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},
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Err(mut e) => {
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e.cancel();
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break;
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}
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}
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}
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}
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}
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@ -433,6 +433,16 @@ impl Token {
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})
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}
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/// Returns tokens that are likely to be typed accidentally instead of the current token.
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/// Enables better error recovery when the wrong token is found.
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pub fn similar_tokens(&self) -> Option<Vec<Token>> {
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match *self {
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Comma => Some(vec![Dot, Lt]),
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Semi => Some(vec![Colon]),
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_ => None
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}
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}
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/// Returns `true` if the token is either a special identifier or a keyword.
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pub fn is_reserved_ident(&self) -> bool {
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self.is_special_ident() || self.is_used_keyword() || self.is_unused_keyword()
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@ -13,5 +13,5 @@ mod foo {
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struct S1(pub(in foo) (), pub(T), pub(crate) (), pub(((), T)));
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struct S2(pub((foo)) ());
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//~^ ERROR expected `,`, found `(`
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//~| ERROR expected one of `;` or `where`, found `(`
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//~| ERROR cannot find type `foo` in this scope
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}
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@ -14,7 +14,6 @@ macro_rules! define_struct {
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struct S2(pub (in foo) ());
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struct S3(pub $t ());
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//~^ ERROR expected `,`, found `(`
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//~| ERROR expected one of `;` or `where`, found `(`
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}
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}
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@ -14,7 +14,6 @@ macro_rules! define_struct {
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struct S2(pub (in foo) ());
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struct S3(pub($t) ());
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//~^ ERROR expected `,`, found `(`
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//~| ERROR expected one of `;` or `where`, found `(`
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}
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}
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19
src/test/ui/similar-tokens.rs
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19
src/test/ui/similar-tokens.rs
Normal file
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@ -0,0 +1,19 @@
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// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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mod x {
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pub struct A;
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pub struct B;
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}
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// `.` is similar to `,` so list parsing should continue to closing `}`
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use x::{A. B};
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fn main() {}
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8
src/test/ui/similar-tokens.stderr
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8
src/test/ui/similar-tokens.stderr
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@ -0,0 +1,8 @@
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error: expected one of `,` or `as`, found `.`
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--> $DIR/similar-tokens.rs:17:10
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17 | use x::{A. B};
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| ^ expected one of `,` or `as` here
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error: aborting due to previous error
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