Add str::strip_prefix and str::strip_suffix

[SOF3]

Introduces a counterpart for Path::strip_prefix on str.

This was also discussed in https://internals.rust-lang.org/t/pre-pr-path-strip-prefix-counterpart-in-str/11364/.

[rust-highfive]

r? @withoutboats

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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.

2019-11-26T09:43:47.1613552Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-11-26T09:43:47.7506578Z ##[command]git config gc.auto 0
2019-11-26T09:43:47.7512043Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-11-26T09:43:47.7515935Z ##[command]git config --get-all http.proxy
2019-11-26T09:43:47.7521296Z ##[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/66735/merge:refs/remotes/pull/66735/merge
---
2019-11-26T09:49:48.6184500Z    Compiling serde_json v1.0.40
2019-11-26T09:49:50.3584964Z    Compiling tidy v0.1.0 (/checkout/src/tools/tidy)
2019-11-26T09:50:01.1653588Z     Finished release [optimized] target(s) in 1m 29s
2019-11-26T09:50:01.1756885Z tidy check
2019-11-26T09:50:02.0755650Z tidy error: /checkout/src/libcore/str/mod.rs:3817: line longer than 100 chars
2019-11-26T09:50:02.0756400Z tidy error: /checkout/src/libcore/str/mod.rs:3853: line longer than 100 chars
2019-11-26T09:50:04.0115782Z Found 486 error codes
2019-11-26T09:50:04.0115983Z Found 0 error codes with no tests
2019-11-26T09:50:04.0116049Z Done!
2019-11-26T09:50:04.0116091Z some tidy checks failed
2019-11-26T09:50:04.0116091Z some tidy checks failed
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2019-11-26T09:50:04.0117104Z 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"
2019-11-26T09:50:04.0117215Z 
2019-11-26T09:50:04.0117241Z 
2019-11-26T09:50:04.0121473Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
2019-11-26T09:50:04.0121548Z Build completed unsuccessfully in 0:01:33
2019-11-26T09:50:04.0121548Z Build completed unsuccessfully in 0:01:33
2019-11-26T09:50:04.0173203Z == clock drift check ==
2019-11-26T09:50:04.0183789Z   local time: Tue Nov 26 09:50:04 UTC 2019
2019-11-26T09:50:04.1675317Z   network time: Tue, 26 Nov 2019 09:50:04 GMT
2019-11-26T09:50:04.1675505Z == end clock drift check ==
2019-11-26T09:50:05.5137396Z 
2019-11-26T09:50:05.5210336Z ##[error]Bash exited with code '1'.
2019-11-26T09:50:05.5239511Z ##[section]Starting: Checkout
2019-11-26T09:50:05.5241761Z ==============================================================================
2019-11-26T09:50:05.5241818Z Task         : Get sources
2019-11-26T09:50:05.5241881Z 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)

[Alexendoo]

Ping from triage, any updates? @withoutboats

[Dylan-DPC-zz]

r? @KodrAus

[KodrAus]

Naming wise it looks like we've got a few schemes going here: trim vs strip and start/end vs prefix/suffix.

Personally, I think strip_prefix and strip_suffix are nicely discoverable names, and this API is distinct enough from the trim ones in the way it operates that it doesn't seem necessary to me to make them consistent. They can sit out as distinct so users don't have to try compare signatures to see what makes them different.

So this looks good to me! I'll open up a tracking issue and circle back, but r=me if anybody beats me to it 🙂

[Dylan-DPC-zz]

@KodrAus can I merge this?

[JohnCSimon]

Ping from triage - @KodrAus , see Dylan-DPC's comment

[CAD97]

This still needs the tracking issue created and to be linked up to, then r=@KodrAus.

[Dylan-DPC-zz]

Yes. But I don't want to keep the Pr hanging on an issue creation which can happen at a later stage as well

[Dylan-DPC-zz]

I've created the tracking issue (#67302)

@bors r+ rollup

[bors]

📌 Commit 4718e20 has been approved by Dylan-DPC

[dtolnay]

Yes. But I don't want to keep the Pr hanging on an issue creation which can happen at a later stage as well

The PR can't land before tracking issue creation because the issue number needs to go inside the #[unstable(...)] attribute. We shouldn't be merging unstable methods with issue = "0".

@bors r-

[Dylan-DPC-zz]

Ah right, my bad 😆

[KodrAus]

Whoops! Looks like I preempted my own dropping of the ball here. Thanks for opening the tracking issue @Dylan-DPC.

@bors r+

[bors]

📌 Commit 6176051 has been approved by KodrAus

[bors]

🌲 The tree is currently closed for pull requests below priority 1000, this pull request will be tested once the tree is reopened