Cleanup BodyCache

[Nashenas88]

After this PR:

• BodyCache is renamed to BodyAndCache
• ReadOnlyBodyCache is renamed to ReadOnlyBodyAndCache
• ReadOnlyBodyAndCache::body fn is removed and all calls to it are replaced by a deref (possible due to fix of its Deref imp in rustc: split FnAbi's into definitions/direct calls ("of_instance") and indirect calls ("of_fn_ptr"). #65947)

cc @eddyb @oli-obk

[rust-highfive]

r? @davidtwco

(rust_highfive has picked a reviewer for you, use r? to override)

[Nashenas88]

r? @eddyb

[Nashenas88]

This should address @eddyb 's comments here #64736 (comment) (and the comments below in that link).

[Nashenas88]

@eddyb Thank you so much for pointing on the &'a in the Deref impl. That was the only reason this fn was left around, and it helped clean up a lot of code. CC @oli-obk

[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.

2019-12-03T16:57:39.4219675Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-12-03T16:57:40.3051365Z ##[command]git config gc.auto 0
2019-12-03T16:57:40.3058413Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-12-03T16:57:40.3064201Z ##[command]git config --get-all http.proxy
2019-12-03T16:57:40.3069056Z ##[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/66991/merge:refs/remotes/pull/66991/merge
---
2019-12-03T17:03:35.2079995Z    Compiling serde_json v1.0.40
2019-12-03T17:03:36.8525170Z    Compiling tidy v0.1.0 (/checkout/src/tools/tidy)
2019-12-03T17:03:47.5697799Z     Finished release [optimized] target(s) in 1m 25s
2019-12-03T17:03:47.5796719Z tidy check
2019-12-03T17:03:48.2323409Z tidy error: /checkout/src/librustc_mir/util/def_use.rs:3: line longer than 100 chars
2019-12-03T17:03:48.2767910Z tidy error: /checkout/src/librustc_mir/shim.rs:322: line longer than 100 chars
2019-12-03T17:03:50.2831618Z some tidy checks failed
2019-12-03T17:03:50.2833957Z Found 486 error codes
2019-12-03T17:03:50.2834652Z Found 0 error codes with no tests
2019-12-03T17:03:50.2834751Z Done!
2019-12-03T17:03:50.2834751Z Done!
2019-12-03T17:03:50.2834854Z 
2019-12-03T17:03:50.2839001Z 
2019-12-03T17:03:50.2840118Z 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"
2019-12-03T17:03:50.2840554Z 
2019-12-03T17:03:50.2840685Z 
2019-12-03T17:03:50.2849872Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
2019-12-03T17:03:50.2850203Z Build completed unsuccessfully in 0:01:29
2019-12-03T17:03:50.2850203Z Build completed unsuccessfully in 0:01:29
2019-12-03T17:03:50.2906645Z == clock drift check ==
2019-12-03T17:03:50.2918001Z   local time: Tue Dec  3 17:03:50 UTC 2019
2019-12-03T17:03:50.4479048Z   network time: Tue, 03 Dec 2019 17:03:50 GMT
2019-12-03T17:03:50.4482466Z == end clock drift check ==
2019-12-03T17:03:51.7940227Z 
2019-12-03T17:03:51.8012439Z ##[error]Bash exited with code '1'.
2019-12-03T17:03:51.8041518Z ##[section]Starting: Checkout
2019-12-03T17:03:51.8043904Z ==============================================================================
2019-12-03T17:03:51.8043987Z Task         : Get sources
2019-12-03T17:03:51.8044041Z 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)

[eddyb]

Btw as I mentioned on the original PR, I've made this change in #65947, so I'd prefer landing that first.

[Nashenas88]

I saw that. I didn't plan to merge this until that one was merged first. I just wanted to make that change in this branch too so I could verify that the other changes wouldn't cause any issues. I'll update the main detail of the PR to make note of that.

[bors]

☔ The latest upstream changes (presumably #65947) made this pull request unmergeable. Please resolve the merge conflicts.

[Nashenas88]

@eddyb I rebased the PR and updated the main comment to reflect the minimized changes. Let me know if this still makes sense to move forward, otherwise I can just close this PR.

[bors]

☔ The latest upstream changes (presumably #66815) made this pull request unmergeable. Please resolve the merge conflicts.

[eddyb]

r=me after rebase

[oli-obk]

@bors r=eddyb

[bors]

📌 Commit a5e144b has been approved by eddyb