Provide suggestion for missing `>` in a type parameter list #94495

estebank · 2022-03-01T19:41:36Z

When encountering an inproperly terminated type parameter list, provide
a suggestion to close it after the last non-constraint type parameter
that was successfully parsed.

Fix #94058.

rust-highfive · 2022-03-01T19:41:39Z

r? @jackh726

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compiler-errors · 2022-03-01T20:10:16Z

I am somewhat concerned about the ratio of misleading to useful "add >" suggestions here

... though I'm not sure how much additional effort it would take to improve this to e.g. not suggest adding > when there are already more > tokens downstream, or e.g. not suggest changing <a; b> into <a>; b> when the user uses an incorrect delimiter in a comma-separated list.

For example:

   |
help: you might have meant to end the type parameters here
   |
LL |     fn f1<'a>(arg : Box<dyn X<X::Y> = u32>>) {}
   |                                   +

   |
help: you might have meant to end the type parameters here
   |
LL | fn foo<'a, 'b>(x: &mut Foo<'a>; 'b>) {}
   |                              +

estebank · 2022-03-01T22:44:34Z

Those two cases in particular could/should be handled, one by explicitly accepting <type param> = <type> and rejecting it with an explicit error and by detecting , -> ; substitution, as we do elsewhere in the parser, but at the same time I feel that should be handled on its own targeted PR. From what I've seen most other tests that are changing seem to be caused by weird enough errors that the suggestion isn't entirely detrimental. What is problematic is the redundant label that I hadn't noticed saying "maybe try to close unmatched angle bracket".

estebank · 2022-03-27T02:49:11Z

@JohnCSimon I'm gonna revert the labels back here because I'm waiting on further review 😅

I feel like the fallout is acceptable as is for merging, but can understand if the reviewers disagree.

When encountering an inproperly terminated type parameter list, provide a suggestion to close it after the last non-constraint type parameter that was successfully parsed. Fix rust-lang#94058.

jackh726

I think it's hard to say anything about the "very wrong syntax" cases. But, I think this is worth it from the new tests, which more likely represent what a user would normally run into.

One nit, but r=me with/without.

jackh726 · 2022-03-27T02:59:09Z

compiler/rustc_parse/src/parser/path.rs

+                                arg.span().shrink_to_hi(),
+                                "you might have meant to end the type parameters here",
+                                ">".to_string(),
+                                Applicability::MaybeIncorrect,


I don't know if MaybeIncorrect is the right choice here. A lot of the suggestions in tests don't result in valid code (namely when we later have a closing >. But 🤷‍♀️

I think it's the best of the available Applicabilitys we have available today :)

estebank · 2022-03-27T06:06:52Z

Added one more check for ,/; typo in type params.

jackh726 · 2022-03-27T14:27:48Z

@bors r+

bors · 2022-03-27T14:27:49Z

📌 Commit 157c67b has been approved by jackh726

bors · 2022-03-27T14:27:57Z

⌛ Testing commit 157c67b with merge 6a755d790d12f0ba5a1234f613f147f19725be76...

bors · 2022-03-27T15:03:07Z

💔 Test failed - checks-actions

rust-log-analyzer · 2022-03-27T15:03:45Z

The job x86_64-gnu-tools failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

To only update this specific test, also pass `--test-args concurrency/libc_pthread_cond.rs`

error: 1 errors occurred comparing output.
status: exit status: 101
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools-bin/miri" "tests/run-pass/concurrency/libc_pthread_cond.rs" "-L" "/tmp/compiletestMD29BU" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-C" "prefer-dynamic" "-o" "/tmp/compiletestMD29BU/concurrency/libc_pthread_cond.stage-id" "-A" "unused" "--edition" "2018" "-Astable-features" "--sysroot" "/home/user/.cache/miri/HOST" "-Zmiri-disable-isolation" "-Zmiri-check-number-validity" "-L" "/tmp/compiletestMD29BU/concurrency/libc_pthread_cond.stage-id.aux"
------------------------------------------

------------------------------------------
stderr:
---
To only update this specific test, also pass `--test-args concurrency/sync.rs`

error: 2 errors occurred comparing output.
status: exit status: 101
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools-bin/miri" "tests/run-pass/concurrency/sync.rs" "-L" "/tmp/compiletestMD29BU" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-C" "prefer-dynamic" "-o" "/tmp/compiletestMD29BU/concurrency/sync.stage-id" "-A" "unused" "--edition" "2018" "-Astable-features" "--sysroot" "/home/user/.cache/miri/HOST" "-Zmiri-disable-isolation" "-Zmiri-check-number-validity" "-L" "/tmp/compiletestMD29BU/concurrency/sync.stage-id.aux"
------------------------------------------

------------------------------------------
stderr:
---



The actual stderr differed from the expected stderr.
Actual stderr saved to /tmp/compiletestMD29BU/vec.stage-id.stderr
To only update this specific test, also pass `--test-args vec.rs`

error: 1 errors occurred comparing output.
status: exit status: 101
status: exit status: 101
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools-bin/miri" "tests/run-pass/vec.rs" "-L" "/tmp/compiletestMD29BU" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-C" "prefer-dynamic" "-o" "/tmp/compiletestMD29BU/vec.stage-id" "-A" "unused" "--edition" "2018" "-Astable-features" "--sysroot" "/home/user/.cache/miri/HOST" "-Zmiri-tag-raw-pointers" "-Zmiri-check-number-validity" "-L" "/tmp/compiletestMD29BU/vec.stage-id.aux"
------------------------------------------

------------------------------------------
stderr:
---
.......... (60/61)
          (61/61)


/checkout/src/test/rustdoc-gui/search-tab-selection-if-current-is-empty.goml search-tab-selection-if-current-is-empty... FAILED
[ERROR] (line 6) TimeoutError: waiting for selector "#titles" failed: timeout 30000ms exceeded: for command `wait-for: "#titles"`
Build completed unsuccessfully in 0:00:46

estebank · 2022-03-27T17:06:07Z

Looks like a timeout error?

/checkout/src/test/rustdoc-gui/search-tab-selection-if-current-is-empty.goml search-tab-selection-if-current-is-empty... FAILED
Error:  (line 6) TimeoutError: waiting for selector "#titles" failed: timeout 30000ms exceeded: for command `wait-for: "#titles"`

Build completed unsuccessfully in 0:00:46
== clock drift check ==
  local time: Sun Mar 27 15:02:11 UTC 2022
  network time: Sun, 27 Mar 2022 15:02:11 GMT
== end clock drift check ==
F
Error: Process completed with exit code 1.

@bors retry

bors · 2022-03-27T18:56:01Z

⌛ Testing commit 157c67b with merge ab0c2e1...

bors · 2022-03-27T21:36:36Z

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing ab0c2e1 to master...

rust-timer · 2022-03-28T07:55:10Z

Finished benchmarking commit (ab0c2e1): comparison url.

Summary: This benchmark run did not return any relevant results. 7 results were found to be statistically significant but too small to be relevant.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

rust-highfive assigned jackh726 Mar 1, 2022

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Mar 1, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 1, 2022

JohnCSimon 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 Mar 20, 2022

estebank added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 27, 2022

Provide suggestion for missing > in a type parameter list

6874bd2

When encountering an inproperly terminated type parameter list, provide a suggestion to close it after the last non-constraint type parameter that was successfully parsed. Fix rust-lang#94058.

jackh726 approved these changes Mar 27, 2022

View reviewed changes

Handle , to ; substitution in arg params

157c67b

estebank force-pushed the missing-closing-gt branch from 9cc0897 to 157c67b Compare March 27, 2022 06:05

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-review Status: Awaiting review from the assignee but also interested parties. labels Mar 27, 2022

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 27, 2022

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-review Status: Awaiting review from the assignee but also interested parties. labels Mar 27, 2022

bors added the merged-by-bors This PR was explicitly merged by bors. label Mar 27, 2022

bors merged commit ab0c2e1 into rust-lang:master Mar 27, 2022

rustbot added this to the 1.61.0 milestone Mar 27, 2022

bors mentioned this pull request Mar 27, 2022

Improve parser diagnostics #95211

Merged

estebank deleted the missing-closing-gt branch November 9, 2023 05:14

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Provide suggestion for missing `>` in a type parameter list #94495

Provide suggestion for missing `>` in a type parameter list #94495

estebank commented Mar 1, 2022

rust-highfive commented Mar 1, 2022

compiler-errors commented Mar 1, 2022

estebank commented Mar 1, 2022

estebank commented Mar 27, 2022

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jackh726 Mar 27, 2022

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bors commented Mar 27, 2022

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rust-log-analyzer commented Mar 27, 2022

estebank commented Mar 27, 2022

bors commented Mar 27, 2022

bors commented Mar 27, 2022

rust-timer commented Mar 28, 2022

Provide suggestion for missing > in a type parameter list #94495

Provide suggestion for missing > in a type parameter list #94495

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rust-timer commented Mar 28, 2022

Provide suggestion for missing `>` in a type parameter list #94495

Provide suggestion for missing `>` in a type parameter list #94495