`mir_stats` mod has not been used since c1ff104.

Popping and pushing from the end of a linked list is constant time. This
documentation is already there for popping and pushing from the front.

@bors: r+ 38fe8d2 rollup

Also, provide a suggestion for the correct syntax.

Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This
was pointed out during code review. This commit adds a test to prevent
capacity of ZST vectors from accidentally changing to prevent that
from happening again.

This shrinks `Option<Symbol>` from 8 bytes to 4 bytes, which shrinks
`Token` from 24 bytes to 16 bytes. This reduces instruction counts by up
to 1% across a range of benchmarks.

…previously not in test suite.

…t-lang/libc#1057.

Part of issue rust-lang#55465

Requested in rust-lang/stdarch#322 this is hopefully the first
step!

gdb versions before 8.1 have a bug that prevents the BTreeSet and
BTreeMap pretty-printers from working.  This patch disables the test
on those versions, and also disables the pretty-printers there as
well.

Closes rust-lang#56730

This adds a new rustc target-configuration called 'x86_64-unknown_uefi'.
Furthermore, it adds a UEFI base-configuration to be used with other
targets supported by UEFI (e.g., i386, armv7hl, aarch64, itanium, ...).

UEFI systems provide a very basic operating-system environment, meant
to unify how systems are booted. It is tailored for simplicity and fast
setup, as it is only meant to bootstrap other systems. For instance, it
copies most of the ABI from Microsoft Windows, rather than inventing
anything on its own. Furthermore, any complex CPU features are
disabled. Only one CPU is allowed to be up, no interrupts other than
the timer-interrupt are allowed, no process-separation is performed,
page-tables are identity-mapped, ...

Nevertheless, UEFI has an application model. Its main purpose is to
allow operating-system vendors to write small UEFI applications that
load their kernel and terminate the UEFI system. However, many other
UEFI applications have emerged in the past, including network-boot,
debug-consoles, and more.

This UEFI target allows to compile rust code natively as UEFI
applications. No standard library support is added, but libcore can be
used out-of-the-box if a panic-handler is provided. Furthermore,
liballoc works as well, if a `GlobalAlloc` handler is provided. Both
have been tested with this target-configuration.

Note that full libstd support is unlikely to happen. While UEFI does
have standardized interfaces for networking and alike, none of these
are mandatory and they are unlikely to be shipped in common consumer
firmwares. Furthermore, several features like process-separation are
not available (or only in very limited fashion). Those parts of libstd
would have to be masked.

Co-Authored-By: estebank <estebank@users.noreply.github.com>

This is going to be required for binding a number of AVX-512 intrinsics
in the `stdsimd` repository, and this intrinsic is the same as
`simd_select` except that it takes a bitmask as the first argument
instead of a SIMD vector. This bitmask is then transmuted into a `<NN x
i8>` argument, depending on how many bits it is.

cc rust-lang/stdarch#310

Add lint for items deprecated in future

Resolves rust-lang#55892

…omatsakis

Remove not used mod

`mir_stats` mod has not been used since c1ff104.

Clearer error message for dead assign

I'm not that this is the right place for this (if it needs an RFC or not).

I had the problem where I misunderstood the compiler lint message rust-lang#56436 and other people seem to have had the same problem https://www.reddit.com/r/rust/comments/8cy9p4/value_assigned_to_is_never_read/.

I think this new wording might be slightly clearer (and help out beginners like me). I'm very new though, so there might be some nuance I'm missing that would make this more confusing or a bad idea for other reasons.

I thought I would create a PR to make it easy to change the code if the consensus was that it would make sense to make a change.

If this is the wrong place for this sort of thing I'll happily delete/move it.

…=alexcrichton

Add checked_add method to Instant time type

Appending functionality to the already opened topic of `checked_add` on time types over at rust-lang#55940.

Doing checked addition between an `Instant` and a `Duration` is important to reliably determine a future instant. We could use this in the `parking_lot` crate to compute an instant when in the future to wake a thread up without risking a panic.

…MatthewJasper

polonius tweaks

- bump polonius to 0.6.0
- fix 2-phase-borrow activations

r? @matthewjasper

bootstrap: fix edition

A byproduct of work on rust-lang#56595; done with `cargo fix --edition`.

…et-cpu-attr, r=alexcrichton

Unconditionally emit the target-cpu LLVM attribute.

This PR makes `rustc` always emit the `target-cpu` LLVM attribute for functions. The goal is to allow for cross-language inlining of functions defined in `libstd`. So far `libstd` functions were the only function without a `target-cpu` attribute, so in whole-crate-graph cross-lang LTO scenarios they were not eligible for inlining into foreign code.

r? @alexcrichton

…r=petrochenkov

Add non-panicking `maybe_new_parser_from_file` variant

Add (seemingly?) missing `maybe_new_parser_from_file` constructor variant.

Disclaimer: I'm not certain this is the correct approach - just found out we don't have this when working on a Rustfmt PR to catch/prevent more Rust parser panics: rust-lang/rustfmt#3240 and tried to make it work somehow.

Document time of back operations of a Linked List

Popping and pushing from the end of a linked list is constant time. This
documentation is already there for popping and pushing from the front.

@bors: r+ 38fe8d2 rollup

#[must_use] on traits in stdlib

Based on rust-lang#55506.

Adds `#[must_use]` attribute to traits in the stdlib:
- `Iterator`
- `Future`
- `FnOnce`
- `Fn`
- `FnMut`

There may be other traits that should have the attribute, but I couldn't find/think of any.

overhaul external doc attribute diagnostics

This PR improves the error handling and spans for the external doc attribute. Many cases that silently failed before now emit errors, spans are tightened, and the errors have help and suggestions.

I tried to address all the cases that users ran into in the tracking issue.

cc rust-lang#44732

r? @QuietMisdreavus

…k, r=jonas-schievink

fix install broken link

solves rust-lang#56690

…bank

Fix irrefutable matches on integer ranges

Fixes rust-lang#56659.

Use a `newtype_index!` within `Symbol`.

This shrinks `Option<Symbol>` from 8 bytes to 4 bytes, which shrinks
`Token` from 24 bytes to 16 bytes. This reduces instruction counts by up
to 1% across a range of benchmarks.

r? @oli-obk

…r=michaelwoerister

[self-profiler] Add column for percent of total time

Example output:

```
Self profiling results:

| Phase            | Time (ms)      | Time (%) | Queries        | Hits (%)
| ---------------- | -------------- | -------- | -------------- | --------
| Parsing          | 3              | 0.52     |                |
| Expansion        | 64             | 11.27    |                |
| TypeChecking     | 13             | 2.36     | 35208          | 90.77
| BorrowChecking   | 0              | 0.10     | 68             | 50.00
| Codegen          | 22             | 3.82     | 7362           | 75.12
| Linking          | 252            | 43.81    | 458            | 68.56
| Other            | 219            | 38.12    | 47372          | 56.84

Optimization level: No
Incremental: off

```

cc @michaelwoerister

…, r=alexcrichton

Remove some unnecessary feature gates

fixes rust-lang#56585

cc @jethrogb

… r=QuietMisdreavus

Remove unneeded extra chars to reduce search-index size

Before:

```
2013782 Dec 11 10:16 build/x86_64-unknown-linux-gnu/doc/search-index.js
```

After:

```
1736597 Dec 11 10:50 build/x86_64-unknown-linux-gnu/doc/search-index.js
```

No changes in the output of the search.

r? @QuietMisdreavus

…alexcrichton

Always set the RDRAND and RDSEED features on SGX

Not sure if this is 100% correct.

This [Intel article](https://software.intel.com/en-us/articles/intel-software-guard-extensions-tutorial-part-5-enclave-development) goes in great depth regarding using (untrusted) CPUID to see whether RDRAND/RDSEED is supported, and explains what happens to the enclave if the CPUID result is faked.

I'd say that an implementation of SGX that doesn't make RDRAND available to the enclave is so severely limited/broken that it's ok if you get #UD in that case. The case is less clear for RDSEED, but it so far every processor released by Intel with SGX support also has RDSEED (including Gemini Lake).

cc @briansmith

Test capacity of ZST vector

Initially, rust-lang#50233 accidentally changed the capacity of empty ZST. This was pointed out during code review. This commit adds a test to prevent capacity of ZST vectors from accidentally changing to prevent that from happening again.

… r=alexcrichton

Use libbacktrace pretty-printing

r? @alexcrichton

fix rust-lang/rust issue rust-lang#50583

Rationale for the fix is in rust-lang#50583.  I've verified that before the fix /musl-armhf/lib/libc.a is riddled with the illegal variant of vmov.f64 and after the fix the version built doesn't contain any of these illegal instructions.

I originally thought that the arm-linux-gnueabi version also needed fixing - to add a -mfloat-abi-soft but that's unnecessary as it's compiled with the gnueabi (not hf) compiler (I've some a quick check that the libc.a produced doesn't include VFP instructions).

r? @alexcrichton

Add missing urls in ffi module docs

r? @QuietMisdreavus

…s-message, r=zackmdavis

Fix private_no_mangle_fns message grammar

Simply changes "an warning" to "a warning" in the `private_no_mangle_fns` warning. I started getting this in some code after upgrading to 1.31.0.

…=oli-obk

infer: remove Box from a returned Iterator

…wjasper

specialize: remove Boxes used by Children::insert

…osure-using-region-from-containing-fn, r=nikomatsakis

Add test of current behavior (infer free region within closure body)

This behavior was previously not encoded in our test suite.

it is pretty important that we test this behavior. In particular, in rust-lang#56537  I had proposed expanding the lifetime elision rules so that they would apply to some of the cases encoded in this test, which would cause them to start failing to compile successfully (because the lifetime attached to the return type would start being treated as connected to the lifetime on the input parameter to the lambda expression, which is explicitly *not* what the code wants in this particular case).

In other words, I am trying to ensure that anyone who tries such experiments with lifetime elision in the future quickly finds out why we don't support lifetime elision on lambda expressions (at least not in the naive manner described on rust-lang#56537).

…ckmdavis

target: remove Box returned by get_targets

x86: Add the `adx` target feature to whitelist

Requested in rust-lang/stdarch#322 this is hopefully the first
step!

Allow ptr::hash to accept fat pointers

Fat pointers implement Hash since rust-lang#45483.  This is a follow-up to rust-lang#56250.

…ertj

Account for `impl Trait` when suggesting lifetime

Fix rust-lang#56745

…er, r=alexcrichton

Disable btree pretty-printers on older gdbs

gdb versions before 8.1 have a bug that prevents the BTreeSet and
BTreeMap pretty-printers from working.  This patch disables the test
on those versions, and also disables the pretty-printers there as
well.

Closes rust-lang#56730

… r=kennytm

Add short emoji status to toolstate updates

I get a lot of these emails and it's good to know which ones I should be paying closer attention to -- i.e. the ones where clippy breaks. This adds a short emoji status report to the first line of the commit message, which shows up in notifications directly

I haven't been able to test it, and the actual emoji are just suggestions.

r? @kennytm

cc @rust-lang/infra @rust-lang/devtools

Deduplicate unsatisfied trait bounds

Fix rust-lang#35677.

Add x86_64-unknown-uefi target

This adds a new rustc target-configuration called 'x86_64-unknown_uefi'.
Furthermore, it adds a UEFI base-configuration to be used with other
targets supported by UEFI (e.g., i386, armv7hl, aarch64, itanium, ...).

UEFI systems provide a very basic operating-system environment, meant
to unify how systems are booted. It is tailored for simplicity and fast
setup, as it is only meant to bootstrap other systems. For instance, it
copies most of the ABI from Microsoft Windows, rather than inventing
anything on its own. Furthermore, any complex CPU features are
disabled. Only one CPU is allowed to be up, no interrupts other than
the timer-interrupt are allowed, no process-separation is performed,
page-tables are identity-mapped, ...

Nevertheless, UEFI has an application model. Its main purpose is to
allow operating-system vendors to write small UEFI applications that
load their kernel and terminate the UEFI system. However, many other
UEFI applications have emerged in the past, including network-boot,
debug-consoles, and more.

This UEFI target allows to compile rust code natively as UEFI
applications. No standard library support is added, but libcore can be
used out-of-the-box if a panic-handler is provided. Furthermore,
liballoc works as well, if a `GlobalAlloc` handler is provided. Both
have been tested with this target-configuration.

Note that full libstd support is unlikely to happen. While UEFI does
have standardized interfaces for networking and alike, none of these
are mandatory and they are unlikely to be shipped in common consumer
firmwares. Furthermore, several features like process-separation are
not available (or only in very limited fashion). Those parts of libstd
would have to be masked.

…=rkruppe

rustc: Add an unstable `simd_select_bitmask` intrinsic

This is going to be required for binding a number of AVX-512 intrinsics
in the `stdsimd` repository, and this intrinsic is the same as
`simd_select` except that it takes a bitmask as the first argument
instead of a SIMD vector. This bitmask is then transmuted into a `<NN x
i8>` argument, depending on how many bits it is.

cc rust-lang/stdarch#310

…rsion, r=alexcrichton

Update libc version required by rustc

This is meant to be an easy-to-backport fix for rust-lang#55465