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Improve parser diagnostics #95211

Merged
merged 1 commit into from
Jun 14, 2022
Merged

Improve parser diagnostics #95211

merged 1 commit into from
Jun 14, 2022

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terrarier2111
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@terrarier2111 terrarier2111 commented Mar 22, 2022 •
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This pr fixes #93867 and contains a couple of diagnostics related changes to the parser.
Here is a short list with some of the changes:

  • don't suggest the same thing that is the current token
  • suggest removing the current token if the following token is one of the suggestions (maybe incorrect)
  • tell the user to put a type or lifetime after where if there is none (as a warning)
  • reduce the amount of tokens suggested (via the new eat_noexpect and check_noexpect methods)

If any of these changes are undesirable, i can remove them, thanks!

@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Mar 22, 2022
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r? @matthewjasper

(rust-highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 22, 2022
@terrarier2111 terrarier2111 force-pushed the improve-parser branch 2 times, most recently from aa01a0b to 3f8fdb7 Compare March 22, 2022 16:32
@terrarier2111 terrarier2111 changed the title Improves parser diagnostics, fixes #93867 Improve parser diagnostics Mar 22, 2022
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r? @compiler-errors

could you take a look at this cuz i took some inspiration from your comments and you seemed to be interested in smth like this as well?

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I cannot r+ this (and hence high-five bot didn't assign me), but I will certainly take a look!

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lol, nvm, highfive-bot does not care about bors permissions apparently. anywho, I cannot approve this for you, so I will reassign this to someone who can. I will try to give it a review though!

r? rust-lang/compiler

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@bors delegate=compiler-errors

@compiler-errors if you want to review this, go for it (I'll try to look at this regardless later today)

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bors commented Mar 22, 2022

✌️ @compiler-errors can now approve this pull request

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compiler-errors requested changes Mar 22, 2022
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I am concerned with a regression in parsing fn foo() where {}. Also left a few other comments.

src/test/ui/generic-associated-types/issue-93341.rs Outdated Show resolved Hide resolved
src/test/ui/moves/use_of_moved_value_copy_suggestions.rs Outdated Show resolved Hide resolved
src/test/ui/parser/doc-comment-in-stmt.stderr Outdated
@@ -19,6 +24,11 @@ LL | false
LL | /*! bar */
| ^^^^^^^^^^ unexpected token
|
help: Consider removing this token
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It is somewhat misleading to call this a "token"

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What name would you suggest, i am willing to adjust this

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@compiler-errors compiler-errors Mar 22, 2022 •
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Can you special-case this for certain tokens?

Also, not sure if the suggestion to remove a comment is useful here, since comments are usually intentionally placed. This one might be better fixed with a separate suggestion.

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@terrarier2111 terrarier2111 Mar 22, 2022 •
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Can you special-case this for certain tokens?

Also, not sure if the suggestion to remove a comment is useful here, since comments are usually intentionally placed. This one might be better fixed with a separate suggestion.

Oh, yea i can special case different token kinds and i can ignore comments i think

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Okay, so i made it vary based on the kind of token

src/test/ui/parser/float-field-interpolated.stderr Outdated Show resolved Hide resolved
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I am concerned with a regression in parsing fn foo() where {}. Also left a few other comments.

I fixed this regression by downgrading the diagnostic from an error to a warning

@terrarier2111 terrarier2111 force-pushed the improve-parser branch 2 times, most recently from e57b61b to 0839c08 Compare March 22, 2022 18:59
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@terrarier2111, is it too much work to split this up into several commits? We might want to land some of these diagnostics separately, possibly so it's easier to git-bisect later on, and because they are varying levels of opinionated. Or at least, several commits might be easier to review. For example, I could see the _noexpect changes landing immediately, but the remove token help might need some refining.

compiler-errors
compiler-errors reviewed Mar 22, 2022
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compiler/rustc_parse/src/parser/diagnostics.rs Outdated Show resolved Hide resolved
compiler/rustc_parse/src/parser/diagnostics.rs Outdated
Comment on lines 334 to 432
if !ignore
&& self.look_ahead(1, |next| {
is_ident_eq_keyword(next.kind.clone(), token.clone())
})
{
suggest_removing = true;
}
if let TokenType::Token(kind) = token.clone() {
if !ignore && self.look_ahead(1, |next| kind == next.kind) {
suggest_removing = true;
}
if kind == self.token.kind {
None
} else {
Some(token)
}
} else {
Some(token)
}
}
} else {
None
}
})
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Do you mind leaving comments explaining what this logic is checking for? Also, perhaps using return might help tighten some of the if-else blocks.

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@terrarier2111 terrarier2111 Mar 26, 2022 •
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I left some comments there and used returns, do the comments suffice?

compiler/rustc_parse/src/parser/diagnostics.rs Outdated Show resolved Hide resolved
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@terrarier2111, is it too much work to split this up into several commits? We might want to land some of these diagnostics separately, possibly so it's easier to git-bisect later on, and because they are varying levels of opinionated. Or at least, several commits might be easier to review. For example, I could see the _noexpect changes landing immediately, but the remove token help might need some refining.

Do you mean splitting these commits in different prs or just having multiple commits in this pr?

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bors commented Mar 27, 2022

☔ The latest upstream changes (presumably #94495) made this pull request unmergeable. Please resolve the merge conflicts.

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Sorry for taking some time to get back to this. I have a couple of comments.

compiler/rustc_parse/src/parser/diagnostics.rs Outdated Show resolved Hide resolved
compiler/rustc_parse/src/parser/expr.rs Show resolved Hide resolved
compiler-errors
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compiler/rustc_parse/src/parser/mod.rs
@@ -548,6 +548,22 @@ impl<'a> Parser<'a> {
is_present
}

fn check_noexpect(&self, tok: &TokenKind) -> bool {
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can you double check if the parser has other self.token == use cases that can be turned into check_noexpect?

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I don't think that i am able to do that as from what I was able to see that would require a decent amount of work and I just wanted to finish up the changes in this pr.

@compiler-errors compiler-errors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 6, 2022
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@terrarier2111, heads up that PRs should not include merge commits: https://rustc-dev-guide.rust-lang.org/git.html#no-merge-policy

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terrarier2111 commented Jun 6, 2022 •
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@compiler-errors Yea, i know i wanted to finish this later

@terrarier2111 terrarier2111 force-pushed the improve-parser branch 2 times, most recently from 7a47722 to 70589ba Compare June 6, 2022 19:37
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Heads up that you messed up the commit log I think: https://github.com/rust-lang/rust/pull/95211/commits

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Heads up that you messed up the commit log I think: https://github.com/rust-lang/rust/pull/95211/commits

Oh.. yea how could I solve this problem?

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perhaps git pull --rebase origin master (where origin is whatever remote you've set up for rust-lang/rust, not your personal fork) -- please also make sure the changes you've made in cf7e08607c580bd130a27adc0a7700e333f3e92b didn't get lost as well.

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Okay, well so i tried fixing it and actually made it worse :c
I think the issue is that i did "git push origin +MY_BRANCH" instead of "git push origin +master" because the master version didn't work for some reason

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I'm not sure if I can help -- I'm not familiar with the git push +branch syntax. Perhaps reset your branch and cherry-pick your specific commits? No idea.

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@compiler-errors do I have to do anything else for this to be good to go?

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This looks fine enough to merge now. Maybe we actually don't need the noexpect methods, but those are easy to remove.

@bors r+

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bors commented Jun 13, 2022

📌 Commit 21fdd54 has been approved by compiler-errors

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 13, 2022
@JohnTitor JohnTitor mentioned this pull request Jun 13, 2022
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bors added a commit to rust-lang-ci/rust that referenced this pull request Jun 13, 2022
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Auto merge of rust-lang#98075 - JohnTitor:rollup-nqwodnk, r=JohnTitor
3bdec3c 
Rollup of 4 pull requests

Successful merges:

 - rust-lang#95211 (Improve parser diagnostics)
 - rust-lang#95243 (Add Apple WatchOS compile targets)
 - rust-lang#97385 (Add WIP stable MIR crate)
 - rust-lang#97508 (Harden bad placeholder checks on statics/consts)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit e3a3c00 into rust-lang:master Jun 14, 2022
@rustbot rustbot added this to the 1.63.0 milestone Jun 14, 2022
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Misleading diagnostic on missing comma
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@terrarier2111 @rust-highfive @compiler-errors @jackh726 @bors @rust-log-analyzer @notriddle @klensy @matthewjasper @rustbot