typeck: limit number of candidates shown for a single error

[birkenfeld]

No idea if 10/11 is a good limit. Are there any other such limits in rustc currently?

Fixes: #25356

[rust-highfive]

r? @Aatch

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[Manishearth]

good idea

[Manishearth]

good idea

[Manishearth]

LGTM. I'd like someone else (@jonathandturner?) to rubber-stamp the number 10 as well, though 😄

[sophiajt]

How difficult would it be to show an elision?

Something like:

src\main.rs:206:9: 206:35 error: multiple applicable methods in scope [E0034]
src\main.rs:206     0.0.max(normal.dot(light_dir)) * res
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~
src\main.rs:206:9: 206:35 note: candidate #1 is defined in an impl of the trait `core::iter::Iterator` for the type `std::ascii::EscapeDefault`
src\main.rs:206     0.0.max(normal.dot(light_dir)) * res
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~
src\main.rs:206:9: 206:35 note: candidate #2 is defined in an impl of the trait `core::iter::Iterator` for the type `std::collections::hash::table::RawBuckets<'_, _, _>`
src\main.rs:206     0.0.max(normal.dot(light_dir)) * res
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~
src\main.rs:206:9: 206:35 note: additional candidates elided.

FWIW, I'm fine stopping at 10, but I think it'd be good to let the user know there were others, they just aren't shown.

[birkenfeld]

@jonathandturner it should already say "N more candidates not shown" at the end.

I just found another example in

rust/src/librustc/traits/error_reporting.rs

Line 209 in 90318b8

fn report_similar_impl_candidates(span: Span,

- it stops at 4 and says "and N others" at the end. I could adapt to this.

[sophiajt]

Great, I missed that. If it has the message, I'm fine stopping even sooner than 10. 4 sounds good.

[Manishearth]

sgtm either way. I'd like to switch to "and N others" though, let's keep things uniform.

@bors delegate+

[bors]

✌️ @birkenfeld can now approve this pull request

[birkenfeld]

@bors r=Manishearth

[bors]

📌 Commit 9508180 has been approved by Manishearth

[bors]

⌛ Testing commit 9508180 with merge db2531f...

[Manishearth]

@bors clean force

[Manishearth]

@bors r- clean force

(something's wrong with the queue)

[Manishearth]

@bors r+ clean

[bors]

📌 Commit 9508180 has been approved by Manishearth

[alexcrichton]

@bors: retry force clean

[steveklabnik]

Is the travis failure here legitimate?

[birkenfeld]

Yes; the diagnostics API changed on master. I'll fix it soon.

[bors]

☔ The latest upstream changes (presumably #33425) made this pull request unmergeable. Please resolve the merge conflicts.

[birkenfeld]

Rebased.

[jseyfried]

@bors r+

[bors]

📌 Commit 6ab93d7 has been approved by jseyfried

[bors]

⌛ Testing commit 6ab93d7 with merge e88defe...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-32cross-opt, auto-linux-64-cargotest, auto-linux-64-cross-armhf, auto-linux-64-cross-armsf, auto-linux-64-cross-freebsd, auto-linux-64-cross-netbsd, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-opt-mir, 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-nopt-t, auto-mac-64-opt, auto-mac-64-opt-rustbuild, auto-mac-cross-ios-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-32-opt-rustbuild, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-cross-opt, auto-win-msvc-32-opt, auto-win-msvc-64-cargotest, auto-win-msvc-64-opt, auto-win-msvc-64-opt-mir, auto-win-msvc-64-opt-rustbuild