Remove a const-if-hack in RawVec

[mark-i-m]

r? @ecstatic-morse

cc @Centril

[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.

2019-11-26T00:15:43.1337860Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-11-26T00:15:43.9915876Z ##[command]git config gc.auto 0
2019-11-26T00:15:43.9922014Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-11-26T00:15:43.9925200Z ##[command]git config --get-all http.proxy
2019-11-26T00:15:43.9930226Z ##[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/66755/merge:refs/remotes/pull/66755/merge
---
2019-11-26T00:43:57.3116729Z    Compiling rustc-demangle v0.1.16
2019-11-26T00:43:58.4026097Z error[E0599]: no associated item named `MAX` found for type `usize` in the current scope
2019-11-26T00:43:58.4027191Z   --> src/liballoc/raw_vec.rs:57:52
2019-11-26T00:43:58.4027493Z    |
2019-11-26T00:43:58.4027872Z 57 |             { if mem::size_of::<T>() == 0 { usize::MAX } else { 0 } }
2019-11-26T00:43:58.4028620Z    |                                                    ^^^ associated item not found in `usize`
2019-11-26T00:43:58.6799215Z error: aborting due to previous error
2019-11-26T00:43:58.6799422Z 
2019-11-26T00:43:58.6804073Z For more information about this error, try `rustc --explain E0599`.
2019-11-26T00:43:58.7008780Z error: could not compile `alloc`.
---
2019-11-26T00:43:58.9141867Z   local time: Tue Nov 26 00:43:58 UTC 2019
2019-11-26T00:43:59.1931606Z   network time: Tue, 26 Nov 2019 00:43:59 GMT
2019-11-26T00:43:59.1931719Z == end clock drift check ==
2019-11-26T00:44:01.9441504Z 
2019-11-26T00:44:01.9559051Z ##[error]Bash exited with code '1'.
2019-11-26T00:44:01.9635292Z ##[section]Starting: Checkout
2019-11-26T00:44:01.9638827Z ==============================================================================
2019-11-26T00:44:01.9638890Z Task         : Get sources
2019-11-26T00:44:01.9639274Z 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)

[ecstatic-morse]

@mark-i-m the beta will branch in mid-December. If you want to wait until then to merge this, that would be fine. I don't think there's any codegen benefits to the if version.

Otherwise r=me.

[mark-i-m]

Let's wait then. It's only a couple more weeks.

[mati865]

FYI beta has been branched.

[mark-i-m]

I rebased, but I think we still have to wait for this to merge: #67402

[rust-highfive]

The job mingw-check 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.

2019-12-18T18:05:42.3486264Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-12-18T18:05:43.0102717Z ##[command]git config gc.auto 0
2019-12-18T18:05:43.0108182Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-12-18T18:05:43.0113801Z ##[command]git config --get-all http.proxy
2019-12-18T18:05:43.0118983Z ##[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/66755/merge:refs/remotes/pull/66755/merge
---
2019-12-18T18:10:59.4597524Z     Checking backtrace v0.3.40
2019-12-18T18:11:00.9063860Z error[E0019]: constant function contains unimplemented expression type
2019-12-18T18:11:00.9065020Z   --> src/liballoc/raw_vec.rs:55:22
2019-12-18T18:11:00.9065565Z    |
2019-12-18T18:11:00.9066087Z 55 |         let cap = if mem::size_of::<T>() == 0 { core::usize::MAX } else { 0 };
2019-12-18T18:11:00.9067439Z 
2019-12-18T18:11:00.9067958Z error[E0019]: constant function contains unimplemented expression type
2019-12-18T18:11:00.9068453Z   --> src/liballoc/raw_vec.rs:55:19
2019-12-18T18:11:00.9068856Z    |
2019-12-18T18:11:00.9068856Z    |
2019-12-18T18:11:00.9069359Z 55 |         let cap = if mem::size_of::<T>() == 0 { core::usize::MAX } else { 0 };
2019-12-18T18:11:00.9070632Z 
2019-12-18T18:11:01.1512245Z error: aborting due to 2 previous errors
2019-12-18T18:11:01.1512950Z 
2019-12-18T18:11:01.1513467Z For more information about this error, try `rustc --explain E0019`.
---
2019-12-18T18:11:01.1893303Z   local time: Wed Dec 18 18:11:01 UTC 2019
2019-12-18T18:11:01.4795283Z   network time: Wed, 18 Dec 2019 18:11:01 GMT
2019-12-18T18:11:01.4802555Z == end clock drift check ==
2019-12-18T18:11:09.2134208Z 
2019-12-18T18:11:09.2244246Z ##[error]Bash exited with code '1'.
2019-12-18T18:11:09.2286036Z ##[section]Starting: Checkout
2019-12-18T18:11:09.2288136Z ==============================================================================
2019-12-18T18:11:09.2288190Z Task         : Get sources
2019-12-18T18:11:09.2288238Z 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)

[mark-i-m]

@ecstatic-morse Should be ready now. I rebased over the new master after bootstrapping was changed over.

[ecstatic-morse]

@bors r+

[bors]

📌 Commit 7d26811 has been approved by ecstatic-morse

[bors]

🌲 The tree is currently closed for pull requests below priority 100, this pull request will be tested once the tree is reopened