Refactor InferenceFudger (née RegionFudger)

[varkor]

• Rename RegionFudger (and related methods) to InferenceFudger.
• Take integer and float inference variables into account.
• Refactor types_created_since_snapshot and vars_created_since_snapshot with the new version of ena.
• Some other refactoring in the area.

r? @eddyb

[eddyb]

r=me with comments addressed (or wait for @nikomatsakis' review)

[eddyb]

@bors r+

[bors]

📌 Commit 2b4171bb967bb709326a4255f4dc06f70addae0b has been approved by eddyb

[varkor]

@bors p=1
This is blocking #59008.

[bors]

🔒 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:

1. git checkout values_since_snapshot(switch to your branch)
2. git fetch upstream master(retrieve the latest master)
3. git rebase upstream/master -p(rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self values_since_snapshot --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

warning: Cannot merge binary files: Cargo.lock (HEAD vs. heads/homu-tmp)
Auto-merging src/librustc_typeck/check/mod.rs
Auto-merging Cargo.lock
CONFLICT (content): Merge conflict in Cargo.lock
Automatic merge failed; fix conflicts and then commit the result.

[varkor]

@bors r=eddyb

[bors]

📌 Commit 86d5a69 has been approved by eddyb

[bors]

⌛ Testing commit 86d5a69 with merge 33ef0ba...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: eddyb
Pushing 33ef0ba to master...