Add managarm as a tier 3 target
This PR aims to introduce the `x86_64-unknown-managarm-mlibc` as a tier 3 target to Rust.
[managarm](https://github.com/managarm/managarm) is a microkernel with fully asynchronous I/O that also provides a POSIX server. Despite the differences, managarm provides good compatability with POSIX and Linux APIs. As a rule of thumb, barring OS-specific code, it should be mostly source-compatible with Linux.
We have been shipping a patched rust for over 25 releases now, and we would like to upstream our work. For a smoother process, this PR only adds the target to rustc and some documentation. `std` support will be added in a future PR.
## Addressing the tier 3 target policy
> A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
`@no92,` `@64` and `@Dennisbonke` will be target maintainers.
> Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
> - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
> - If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo.
`x86_64-unknown-managarm-mlibc` is what we use for LLVM as well.
> Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
> - The target must not introduce license incompatibilities.
> - Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
> - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
> - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
> - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
[managarm](https://github.com/managarm/managarm) is licensed as MIT. No dependencies were added.
> Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
> - This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.
Understood. None of the listed maintainers are on a Rust team.
> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
Support for `std` will be provided in a future PR. Only minor changes are required, however they depend on support in the `libc` crate which will be PRed in soon.
> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.
The steps needed to take are described in the documentation provided with this PR.
> Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
> - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
Understood.
> Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
> - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
We have no indication that anything breaks due to this PR.
> Tier 3 targets must be able to produce assembly using at least one of rustc's supported backends from any host target.
No problems here, as we target `x86_64`.
r? compiler-team
Avoid more rustc rebuilds in cross-compilation scenarios
This is a continuation of https://github.com/rust-lang/rust/pull/145874.
It adds a `compiler_for_std` function, which is a slimmed down version of `compiler_for`, which is much simpler, and designed to be used only for the standard library.
The build, dist and doc steps somtimes work with a stage2 std for a given target. That currently requires building a stage2 host compiler. However, if we uplift the stage1 libstd anyway, that is wasteful, in particular when we are cross-compiling.
The last two commits progressively make the stage 2 host rustc build avoidance more and more aggressive. I think that if we decide that it is fine to ship stage1 libstd everywhere, then it makes sense to go all the way.
When we ship stuff, we always build it with the stage 1 compiler (e.g. we ship stage 2 rustc which is built with stage 1 rustc). Libstd is the only component where stage N is built with the stage N compiler. So I think that shipping stage 1 libstd is "enough", and we could thus optimize what gets built on CI.
r? `@jieyouxu`
bootstrap: Explicitly mark the end of a failed test's captured output
While working on some compiletest stuff, I noticed that when bootstrap prints a failed test's captured output, there's no indication of where that output actually ends.
In addition to indicating where the captured output ends, this end marker also makes it easier to see the relevant test name when scrolling upwards in terminal output.
bootstrap: vendor `clippy_test_deps` too
This internal crate explicitly separates itself from the `rustc`
workspace, but it is needed for `./x test clippy` to work, including its
dependencies when building from a vendored `rustc-src` tarball.
Always build miri for the host in `x run miri`
Previously we were building Miri for the passed `--target`, which was wrong.
Fixes: https://github.com/rust-lang/rust/issues/145839
r? `@jieyouxu`
Make `x test distcheck` self-contained
Before, the checked components were extracted under the checked out source root, which caused us to test some weird combination of tarball + checkout sources/aritfacts/configuration.
Now `x test distcheck` works with an external temporary directory instead, which should make it self-contained. I also moved some config from the Dockerfile to the test itself, and fixed an issue in tidy that caused `x test tidy` to fail on tarball sources.
I also removed `.args(&builder.config.configure_args)`, because it was passing all kinds of crap from the CI config to the distcheck step, which was making it less reproducible.
Fixes: https://github.com/rust-lang/rust/issues/145183
r? ```@jieyouxu```
try-job: x86_64-gnu-distcheck
This internal crate explicitly separates itself from the `rustc`
workspace, but it is needed for `./x test clippy` to work, including its
dependencies when building from a vendored `rustc-src` tarball.
Create a dedicated enum to abstract the different ways compiler-builtins
can be configured.
This also relaxes build.optimized-compiler-builtins to accept the path
of a library to match the behavior of <target>.optimized-compiler-builtins
override.
Extend the <target>.optimized-compiler-builtins bootstrap option to accept a
path to a prebuilt compiler-rt builtins library, and update compiler-builtins
to enable optimized builtins without building compiler-rt builtins.
Enforce in bootstrap that dist and install must have stage at least 1
This is a continuation of my efforts to fix staging in bootstrap after the stage0 redesign. This PR gets rid of all `compiler_for` usages in the `dist` steps 🎉 The only remaining usages are in the `test` steps, which are my next goal, and which will be the final boss.. both because they are quite tricky, and because most of the the rest of the steps have been already fixed.
The changes are relatively straightforward, `x dist` defaults to stage 2, so in that case we want to use a stage 1 build compiler for everything (except stdlib, but we usually use it even there because of uplifting).
What I didn't fix yet are the docs steps, because they are *very* implicit right now, and fixing them deserves its own PR.
The first commit reverts the tests that I accidentally removed in https://github.com/rust-lang/rust/pull/145340🤦♂️ I did it in this PR to avoid further git conflicts..
Best reviewed commit-by-commit.
r? `@jieyouxu`
try-job: dist-i686-linux
try-job: dist-armhf-linux
try-job: dist-x86_64-linux
try-job: dist-x86_64-msvc
try-job: dist-apple-various
try-job: dist-x86_64-apple
try-job: x86_64-msvc-2
