Improve Error Messaging for Unconstructed Structs and Enum Variants in Generic Contexts #92569

George-lewis · 2022-01-05T03:55:23Z

Improves error messaging for empty-tuple structs and enum variants in certain generic contexts. See new ui tests for examples.

Closes #87181

rust-highfive · 2022-01-05T03:55:27Z

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

Please see the contribution instructions for more information.

George-lewis · 2022-01-05T03:56:32Z

r? @estebank

George-lewis · 2022-01-05T03:57:22Z

compiler/rustc_typeck/src/check/method/suggest.rs

+                        if let Some(snippet) = snippet {
+                            if let ty::FnDef(def_id, _) = rcvr_ty.kind() {
+                                let hir_id =
+                                    tcx.hir().local_def_id_to_hir_id(def_id.expect_local());


Can we assume this won't fail here? Is it ok for it to fail?

compiler/rustc_typeck/src/astconv/mod.rs

compiler/rustc_typeck/src/check/method/suggest.rs

camelid · 2022-01-05T05:08:21Z

Please also add a UI test (src/test/ui/...).

compiler/rustc_typeck/src/check/method/suggest.rs

camelid · 2022-01-05T05:28:32Z

src/test/ui/typeck/issue-87181-empty-tuple-fields.stderr

+error[E0599]: no method named `foo` found for fn item `fn() -> Inner {Inner}` in the current scope
+  --> src/test/ui/typeck/issue-87181-empty-tuple-fields.rs:16:15


I think you need to run ./x.py test --bless src/test/ui/typeck/issue-87181-empty-tuple-fields.rs.

I think I might be missing something? I ran your command and it generated the stderr file, but the test still fails, and it's showing me some JSON.

Edit: I figured it out, I needed a //~^ ERROR in there

George-lewis · 2022-01-05T05:28:34Z

@camelid Did I pick an acceptable filename for the ui test? I couldn't find much guidance in the contribution guide

camelid · 2022-01-05T05:29:09Z

The name seems fine to me.

George-lewis · 2022-01-05T07:42:18Z

Proposal: Go beyond the scope of the ticket to improve error handling to support tuple-structs with elements, and also add the check to member access rather than just to method calls

For instance we can cover this case as so:

struct Bar<T> {
    bar: T
}

struct Foo(u8);
impl Foo {
    fn foo() { }
}

fn main() {
    let thing = Bar { bar: Foo };
    thing.bar.0;
}

error[E0609]: no field `0` on type `fn(u8) -> Foo {Foo}`
  --> test.rs:12:15
   |
12 |     thing.bar.0;
   |     --------- ^
   |     |
   |     help: call the constructor: `(thing.bar)(_)`
   |
   = help: placeholder

error: aborting due to previous error

For more information about this error, try `rustc --explain E0609`.

Also, if the original code has unnecessary brackets, like (thing.0).0, the current code will suggest a superfluous pair of brackets. Should we worry about that or just let the unnecessary-bracket lint pick it up for us?

George-lewis · 2022-01-05T21:03:18Z

I have expanded the scope a little in line with my proposal. Now, the same checks are applied to field accesses, and non-empty tuple constructors are handled. There are 2 new tests to cover these cases.

compiler/rustc_typeck/src/check/mod.rs

bors · 2022-04-26T15:59:40Z

💔 Test failed - checks-actions

George-lewis · 2022-04-26T16:13:19Z

curl: (6) Could not resolve host: ci-mirrors.rust-lang.org

It seems like there might have been a network error?

estebank · 2022-04-26T16:18:24Z

@bors retry

bors · 2022-04-26T18:48:49Z

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

git checkout 87181 (switch to your branch)
git fetch upstream master (retrieve the latest master)
git rebase upstream/master -p (rebase on top of it)
Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
git push self 87181 --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging compiler/rustc_typeck/src/check/method/suggest.rs
CONFLICT (content): Merge conflict in compiler/rustc_typeck/src/check/method/suggest.rs
Auto-merging compiler/rustc_typeck/src/check/expr.rs
Automatic merge failed; fix conflicts and then commit the result.

estebank · 2022-04-26T18:59:02Z

It seems like you'll have to rebase. You might want to squash all your commits into one before doing that to make it easier to resolve the merge conflicts.

George-lewis · 2022-04-26T19:02:26Z

It does seem that way. I'm looking at it now and it looks like some new diagnostics were implemented, so I'll have to figure out what it does so I can integrate it with my diagnostics 🤔

bors · 2022-04-26T19:02:40Z

☔ The latest upstream changes (presumably #96428) made this pull request unmergeable. Please resolve the merge conflicts.

George-lewis · 2022-04-26T20:11:57Z

Oh God

George-lewis · 2022-04-26T20:12:31Z

I think I messed up the rebase. At this point I just want to make a new branch

Edit: I'm in the process of making a new branch now. ~~I guess I'll open a new PR when it's ready~~

George-lewis · 2022-04-26T21:14:05Z

Unfortunately I had to force push, but I think it should be ok now

estebank · 2022-04-26T21:32:46Z

@bors r+

bors · 2022-04-26T21:32:48Z

📌 Commit a6b570b has been approved by estebank

Rollup of 6 pull requests Successful merges: - rust-lang#92569 (Improve Error Messaging for Unconstructed Structs and Enum Variants in Generic Contexts) - rust-lang#96370 (Cleanup `report_method_error` a bit) - rust-lang#96383 (Fix erased region escaping into wfcheck due to rust-lang#95395) - rust-lang#96385 (Recover most `impl Trait` and `dyn Trait` lifetime bound suggestions under NLL) - rust-lang#96410 (rustdoc: do not write `{{root}}` in `pub use ::foo` docs) - rust-lang#96430 (Fix handling of `!` in rustdoc search) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

bors · 2022-04-27T03:42:45Z

⌛ Testing commit a6b570b with merge 99b70ee...

rust-highfive assigned davidtwco Jan 5, 2022

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jan 5, 2022

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rust-highfive assigned estebank and unassigned davidtwco Jan 5, 2022

George-lewis commented Jan 5, 2022

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camelid changed the title ~~Improve Error Messaging for Unconstructed Empty-Tuple Members~~ Improve Error Messaging for Unconstructed Empty-Tuple Fields Jan 5, 2022

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George-lewis changed the title ~~Improve Error Messaging for Unconstructed Empty-Tuple Fields~~ Improve Error Messaging for Unconstructed Structs and Enum Variants in Generic Contexts Jan 5, 2022

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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 Apr 26, 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 Apr 26, 2022

bors 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 26, 2022

George-lewis added 2 commits April 26, 2022 17:04

Add new diagnostic

14a127b

Tidy

a6b570b

George-lewis force-pushed the 87181 branch from 443bee2 to a6b570b Compare April 26, 2022 21:13

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 Apr 26, 2022

Dylan-DPC mentioned this pull request Apr 27, 2022

Rollup of 6 pull requests #96459

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bors merged commit ac46e17 into rust-lang:master Apr 27, 2022

rustbot added this to the 1.62.0 milestone Apr 27, 2022

SNCPlay42 mentioned this pull request May 5, 2022

Compiler crashes on syntax error when trying to call a function from a dependency #96738

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Improve Error Messaging for Unconstructed Structs and Enum Variants in Generic Contexts #92569

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		error[E0599]: no method named `foo` found for fn item `fn() -> Inner {Inner}` in the current scope
		--> src/test/ui/typeck/issue-87181-empty-tuple-fields.rs:16:15

Improve Error Messaging for Unconstructed Structs and Enum Variants in Generic Contexts #92569

Improve Error Messaging for Unconstructed Structs and Enum Variants in Generic Contexts #92569

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