Account for unicode confusables on typoed identifiers

[estebank]

When a name can't be matched to any existing identifier, we look for
identifiers that have the same "skeleton" for possible suggestions,
instead of relying only on Levenshtein distance.

CC #55467

[rust-highfive]

r? @petrochenkov

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[rust-highfive]

The job x86_64-gnu-llvm-6.0 of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-11-28T20:20:18.8449914Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-11-28T20:20:19.6355285Z ##[command]git config gc.auto 0
2019-11-28T20:20:19.6359648Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-11-28T20:20:19.6362460Z ##[command]git config --get-all http.proxy
2019-11-28T20:20:19.6366105Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/66849/merge:refs/remotes/pull/66849/merge
---
2019-11-28T20:26:20.7713112Z Found 0 error codes with no tests
2019-11-28T20:26:20.7713161Z Done!
2019-11-28T20:26:20.7713186Z 
2019-11-28T20:26:20.7713208Z 
2019-11-28T20:26:20.7714386Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "--no-vendor"
2019-11-28T20:26:20.7714483Z 
2019-11-28T20:26:20.7714698Z 
2019-11-28T20:26:20.7720224Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
2019-11-28T20:26:20.7721071Z Build completed unsuccessfully in 0:01:26
2019-11-28T20:26:20.7721071Z Build completed unsuccessfully in 0:01:26
2019-11-28T20:26:20.7779100Z == clock drift check ==
2019-11-28T20:26:20.7790556Z   local time: Thu Nov 28 20:26:20 UTC 2019
2019-11-28T20:26:21.0557976Z   network time: Thu, 28 Nov 2019 20:26:21 GMT
2019-11-28T20:26:21.0562178Z == end clock drift check ==
2019-11-28T20:26:22.3577804Z 
2019-11-28T20:26:22.3692610Z ##[error]Bash exited with code '1'.
2019-11-28T20:26:22.3724553Z ##[section]Starting: Checkout
2019-11-28T20:26:22.3726804Z ==============================================================================
2019-11-28T20:26:22.3726862Z Task         : Get sources
2019-11-28T20:26:22.3726911Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[the8472]

Would it make sense to compute the distance over skeletons instead of looking either at the regular distance or the exact skeleton match?

[estebank]

@the8472 that's a good idea.

[petrochenkov]

Tidy fails because the new crates.io dependencies are not whitelisted.
Not sure what is the exact policy here, at minimum the license compatibility for the new crates need to be checked.

[petrochenkov]

Would it make sense to compute the distance over skeletons instead of looking either at the regular distance or the exact skeleton match?

+1

Also, it looks like it can be an implementation details of find_best_match_for_name not leaking to its users.

[bors]

☔ The latest upstream changes (presumably #66997) made this pull request unmergeable. Please resolve the merge conflicts.

[joelpalmer]

Ping from Triage: any updates @estebank?

[joelpalmer]

Ping from Triage: Closing due to inactivity. Please re-open with updates. Thanks! @estebank