rust/src/libcore/cmp.rs, branch 1.41.0

Revert "Stabilize the `never_type`, written `!`."

2019-12-14T14:01:09+00:00

This reverts commit 15c30ddd69d6cc3fffe6d304c6dc968a5ed046f1.

Rollup merge of #66881 - krishna-veerareddy:issue-66780-bool-ord-optimization, r=sfackler

2019-12-11T09:10:41+00:00

Optimize Ord trait implementation for bool Casting the booleans to `i8`s and converting their difference into `Ordering` generates better assembly than casting them to `u8`s and comparing them. Fixes #66780 #### Comparison([Godbolt link](https://rust.godbolt.org/z/PjBpvF)) ##### Old assembly: ```asm example::boolean_cmp: mov ecx, edi xor ecx, esi test esi, esi mov eax, 255 cmove eax, ecx test edi, edi cmovne eax, ecx ret ``` ##### New assembly: ```asm example::boolean_cmp: mov eax, edi sub al, sil ret ``` ##### Old LLVM-MCA statistics: ``` Iterations: 100 Instructions: 800 Total Cycles: 234 Total uOps: 1000 Dispatch Width: 6 uOps Per Cycle: 4.27 IPC: 3.42 Block RThroughput: 1.7 ``` ##### New LLVM-MCA statistics: ``` Iterations: 100 Instructions: 300 Total Cycles: 110 Total uOps: 500 Dispatch Width: 6 uOps Per Cycle: 4.55 IPC: 2.73 Block RThroughput: 1.0 ```

Add better documentation for unsafe block

2019-12-10T21:30:06+00:00

Document usage of unsafe block

2019-12-02T15:45:35+00:00

Remove ord lang item

2019-12-01T21:09:07+00:00

Optimize Ord trait implementation for bool

2019-11-29T22:22:44+00:00

Casting the booleans to `i8`s and converting their difference into `Ordering` generates better assembly than casting them to `u8`s and comparing them.

follow the same function order in the trait

2019-11-26T14:55:38+00:00

This removes several warnings in IDE.

Rollup merge of #66566 - robamler:issue-66476, r=rkruppe

2019-11-22T18:57:46+00:00

Document pitfall with `impl PartialEq for A` Fixes #66476 by turning the violating example into an explicit counterexample.

Document pitfall with `impl PartialEq for A`

2019-11-22T07:16:44+00:00
Fixes #66476 by turning the violating example into an explicit counterexample.

Stabilize the `never_type`, written `!`.

2019-11-21T13:55:32+00:00