Prevent where < ident > from parsing. by withoutboats · Pull Request #38268 · rust-lang/rust

withoutboats · 2016-12-09T19:00:35Z

In order to be forward compatible with where<'a> syntax for higher
rank parameters, prevent potential conflicts with UFCS from parsing
correctly for the near term.

In order to be forward compatible with `where<'a>` syntax for higher rank parameters, prevent potential conflicts with UFCS from parsing correctly for the near term.

rust-highfive · 2016-12-09T19:00:49Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

withoutboats · 2016-12-09T19:02:26Z

This is my first PR to rustc! 🎉

I think this is correct, though I don't have any idea at all what error message to issue in this case.

See also rust-lang/rfcs#1598 for background on this change. cc @rust-lang/lang

r? @eddyb

petrochenkov · 2016-12-09T19:11:27Z

+ *t == token::Gt || *t == token::Comma || *t == token::Colon
+ });
+ if gt_comma_or_colon {
+ return Err(self.fatal("TODO How to even explain this error?"));


This is a recoverable error, no need to return Err.
self.err("syntax `where<T>` is reserved for future use"); would be more appropriate.

Should we consume tokens until the the next Gt in that case?

Nah, if it's indeed <A>::B: Tr (more likely), then it'll parse successfully without consuming extra tokens, otherwise (less likely) it doesn't matter.

But don't we want it to parse as ::B: Tr1? I suppose it doesn't matter much since it errors anyway.

eddyb · 2016-12-10T09:48:30Z

LGTM, I'll start a crater run.

eddyb · 2016-12-10T11:35:53Z

@brson Looks like crater is busted again, build completes successfully but then:

mv: cannot stat 'rust/dist/rustc-*-x86_64-unknown-linux-gnu.tar.gz': No such file or directory

withoutboats · 2016-12-15T23:54:11Z

Any update on crater?

This wants to land before the next beta is cut.

eddyb · 2016-12-16T00:04:47Z

@withoutboats If you rebase I could try again, but I didn't hear back from @brson on this.

withoutboats · 2016-12-16T00:05:40Z

Cool, I'll rebase when I get home tonight

brson · 2016-12-16T00:07:30Z

@eddyb This is because of the change to rustbuild. Also changes to cargo's release process broke crater. So crater can neither build custom rustc nor install the latest cargo nightlies atm. I can't get to it this week I'm afraid, but next.

brson · 2016-12-22T22:55:03Z

I'll crater.

withoutboats · 2016-12-22T22:59:58Z

oops i forgot to rebase this, let me know if thats a problem

brson · 2016-12-23T05:52:22Z

Crater says: https://gist.github.com/anonymous/4ad4a0abf91b713fa58d7771ad281de0

Looks like no regressions, 1 false positive.

withoutboats · 2016-12-23T22:47:07Z

Awesome, what are the steps to landing & backporting this to 1.15 beta?

aturon · 2016-12-23T22:49:42Z

Since @eddyb already reviewed, it's ready for bors! I'll also nominate for backport.

@bors r=eddyb

bors · 2016-12-23T22:49:43Z

📌 Commit 14e4b00 has been approved by eddyb

bors · 2016-12-24T00:21:54Z

⌛ Testing commit 14e4b00 with merge 8d65c8d...

…ddyb Prevent where < ident > from parsing. In order to be forward compatible with `where<'a>` syntax for higher rank parameters, prevent potential conflicts with UFCS from parsing correctly for the near term.

bors · 2016-12-24T03:11:06Z

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-cargotest, auto-linux-64-cross-freebsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-rustbuild, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-cargotest, auto-win-msvc-64-opt, auto-win-msvc-64-opt-rustbuild
Approved by: eddyb
Pushing 8d65c8d to master...

nikomatsakis · 2016-12-30T20:13:03Z

Why do we want this on 1.15 beta?

eddyb · 2016-12-30T20:27:59Z

Because in 1.15, one of my PRs made it so where <T>::Assoc: ... worked just as well as the form without <>, as HIR no longer distinguishes between the two - this information should've been in the description.

nikomatsakis · 2016-12-30T22:09:09Z

OK, marking as beta-accepted. cc @rust-lang/compiler

syntax: Rewrite parsing of impls Properly parse impls for the never type `!` Recover from missing `for` in `impl Trait for Type` Prohibit inherent default impls and default impls of auto traits (#37653 (comment), #37653 (comment)) Change wording in more diagnostics to use "auto traits" Fix some spans in diagnostics Some other minor code cleanups in the parser Disambiguate generics and qualified paths in impls (parse `impl <Type as Trait>::AssocTy { ... }`) Replace the future-compatibility hack from #38268 with actually parsing generic parameters Add a test for #46438

Prevent where < ident > from parsing.
90f6219
In order to be forward compatible with `where<'a>` syntax for higher rank parameters, prevent potential conflicts with UFCS from parsing correctly for the near term.

rust-highfive assigned nikomatsakis Dec 9, 2016

rust-highfive assigned eddyb and unassigned nikomatsakis Dec 9, 2016

petrochenkov reviewed Dec 9, 2016
View reviewed changes

withoutboats added 3 commits December 9, 2016 20:39

Improve error message.
ddae271

Add test.
e93e00f

Fix mistake.
14e4b00

eddyb added the T-lang Relevant to the language team label Dec 10, 2016

brson added the relnotes Marks issues that should be documented in the release notes of the next release. label Dec 23, 2016

aturon added the beta-nominated Nominated for backporting to the compiler in the beta channel. label Dec 23, 2016

bors mentioned this pull request Dec 24, 2016
Use DefIds instead of NodeIds for pub(restricted) visibilities #38490
Merged

bors merged commit 14e4b00 into rust-lang:masterDec 24, 2016

nikomatsakis added the beta-accepted Accepted for backporting to the compiler in the beta channel. label Dec 30, 2016

nikomatsakis mentioned this pull request Jan 6, 2017
Beta backports #38872
Merged
17 tasks

alexcrichton removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Jan 6, 2017

petrochenkov mentioned this pull request Dec 2, 2017
syntax: Rewrite parsing of impls #46455
Merged

Mark-Simulacrum mentioned this pull request Jun 7, 2018
Missing tokens in custom derive input generated by macro #51331
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