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Improve generic arg–param mismatch errors #68437

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varkor opened this issue Jan 21, 2020 · 9 comments · Fixed by #72271
Closed

Improve generic arg–param mismatch errors #68437

varkor opened this issue Jan 21, 2020 · 9 comments · Fixed by #72271
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A-diagnostics Area: Messages for errors, warnings, and lints C-cleanup Category: PRs that clean code up or issues documenting cleanup. E-mentor Call for participation: This issue has a mentor. Use #t-compiler/help on Zulip for discussion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@varkor
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varkor commented Jan 21, 2020 •
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The current diagnostics are a little ad hoc and rely on counting the number of mismatches (e.g. they will only produce an error for the first mismatch). It would be nice to produce diagnostics like:

missing generic arguments for `T`, `const N: usize`, `U`

cc @eddyb

This issue has been assigned to @rakshith-ravi via this comment.
@varkor varkor added C-cleanup Category: PRs that clean code up or issues documenting cleanup. A-diagnostics Area: Messages for errors, warnings, and lints T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 21, 2020
@varkor
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varkor commented Jan 21, 2020

This is follow up work for #68434.

@contrun
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contrun commented Mar 13, 2020

Please give more context on this. I am not sure the error message of which test should be improved.

@eddyb
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eddyb commented Mar 13, 2020

@contrun This is more of the kind of issue opened to avoid forgetting about finishing some work, sorry for the confusion.

That is, this is @varkor leaving a TODO to themselves about improving the diagnostics from #68434.

@contrun
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contrun commented Mar 13, 2020

Ok. I see. Thanks for the explanation.

@eddyb
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eddyb commented Mar 13, 2020 •
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That said, if @varkor is too busy to work on this, you could talk to them on Discord or Zulip to see what their plans were, and maybe turn this into a mentored issue.

@varkor
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varkor commented Mar 14, 2020

The idea is essentially this. We currently emit errors telling the user that the generic arguments they provide are in the wrong order: https://github.com/rust-lang/rust/pull/68434/files#diff-5df0144261224cec2047029de05fa827R107
However, what we'd like to do is suggest reordering the parameters, and let rustfix automatically apply the suggestion.

I don't have the bandwidth to work on this at the moment, or any time soon, so if anyone is interested in tackling it, I'll be happy to mentor the issue.

@varkor varkor added the E-mentor Call for participation: This issue has a mentor. Use #t-compiler/help on Zulip for discussion. label Mar 14, 2020
@rakshith-ravi
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@varkor would you mind if I take this up?

@varkor
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varkor commented May 9, 2020

@rakshith-ravi: you're very welcome to! Let me know if you need any guidance in tackling this issue!

@rakshith-ravi
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@rustbot claim

@rustbot rustbot self-assigned this May 10, 2020
@rakshith-ravi rakshith-ravi mentioned this issue May 16, 2020
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Manishearth added a commit to Manishearth/rust that referenced this issue Jun 21, 2020
@Manishearth
Rollup merge of rust-lang#72271 - rakshith-ravi:master, r=varkor
005b222 
Improve compiler error message for wrong generic parameter order

- Added optional "help" parameter that shows a help message on the compiler error if required.
- Added a simple ordered parameter as a sample help.

@varkor will make more changes as required. Let me know if I'm heading in the right direction.

Fixes rust-lang#68437

r? @varkor
Manishearth added a commit to Manishearth/rust that referenced this issue Jun 21, 2020
@Manishearth
Rollup merge of rust-lang#72271 - rakshith-ravi:master, r=varkor
103b0e3 
Improve compiler error message for wrong generic parameter order

- Added optional "help" parameter that shows a help message on the compiler error if required.
- Added a simple ordered parameter as a sample help.

@varkor will make more changes as required. Let me know if I'm heading in the right direction.

Fixes rust-lang#68437

r? @varkor
Manishearth added a commit to Manishearth/rust that referenced this issue Jun 22, 2020
@Manishearth
Rollup merge of rust-lang#72271 - rakshith-ravi:master, r=varkor
f441819 
Improve compiler error message for wrong generic parameter order

- Added optional "help" parameter that shows a help message on the compiler error if required.
- Added a simple ordered parameter as a sample help.

@varkor will make more changes as required. Let me know if I'm heading in the right direction.

Fixes rust-lang#68437

r? @varkor
@bors bors closed this as completed in 59e87c0 Jun 23, 2020
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A-diagnostics Area: Messages for errors, warnings, and lints C-cleanup Category: PRs that clean code up or issues documenting cleanup. E-mentor Call for participation: This issue has a mentor. Use #t-compiler/help on Zulip for discussion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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Improve compiler error message for wrong generic parameter order rakshith-ravi/rust
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@eddyb @varkor @rakshith-ravi @contrun @rustbot