Currently, it's very challenging to perform a sandboxed `opt-dist`
bootstrap because the tool requires `rustc-perf` to be present, but
there is no proper management/tracking of it. Instead, a specific commit
is hardcoded where it is needed, and a non-checksummed zip is fetched
ad-hoc. This happens in two places:
`src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile`:
```dockerfile
ENV PERF_COMMIT 4f313add609f43e928e98132358e8426ed3969ae
RUN curl -LS -o perf.zip https://ci-mirrors.rust-lang.org/rustc/rustc-perf-$PERF_COMMIT.zip && \
unzip perf.zip && \
mv rustc-perf-$PERF_COMMIT rustc-perf && \
rm perf.zip
```
`src/tools/opt-dist/src/main.rs`
```rust
// FIXME: add some mechanism for synchronization of this commit SHA with
// Linux (which builds rustc-perf in a Dockerfile)
// rustc-perf version from 2023-10-22
const PERF_COMMIT: &str = "4f313add609f43e928e98132358e8426ed3969ae";
let url = format!("https://ci-mirrors.rust-lang.org/rustc/rustc-perf-{PERF_COMMIT}.zip");
let client = reqwest::blocking::Client::builder()
.timeout(Duration::from_secs(60 * 2))
.connect_timeout(Duration::from_secs(60 * 2))
.build()?;
let response = retry_action(
|| Ok(client.get(&url).send()?.error_for_status()?.bytes()?.to_vec()),
"Download rustc-perf archive",
5,
)?;
```
This causes a few issues:
1. Maintainers need to be careful to bump PERF_COMMIT in both places
every time
2. In order to run `opt-dist` in a sandbox, you need to provide your own
`rustc-perf` (https://github.com/rust-lang/rust/pull/125125), but to
figure out which commit to provide you need to grep the Dockerfile
3. Even if you manage to provide the correct `rustc-perf`, its
dependencies are not included in the `vendor/` dir created during
`dist`, so it will fail to build from the published source tarballs
4. It is hard to provide any level of automation around updating the
`rustc-perf` in use, leading to staleness
Fundamentally, this means `rustc-src` tarballs no longer contain
everything you need to bootstrap Rust, and packagers hoping to leverage
`opt-dist` need to go out of their way to keep track of this "hidden"
dependency on `rustc-perf`.
This change adds rustc-perf as a git submodule, pinned to the current
`PERF_COMMIT` 4f313add609f43e928e98132358e8426ed3969ae. Subsequent
commits ensure the submodule is initialized when necessary, and make use
of it in `opt-dist`.
There were three issues previously:
* The self argument was pinned, despite Iterator::next taking an
unpinned mutable reference.
* A resume argument was passed, despite Iterator::next not having one.
* The return value was CoroutineState<Item, ()> rather than Option<Item>
While these things just so happened to work with the LLVM backend,
cg_clif does much stricter checks when trying to assign a value to a
place. In addition it can't handle the mismatch between the amount of
arguments specified by the FnAbi and the FnSig.
This enables programmers to use a safe alternative to the current
`extern "platform-intrinsics"` API for writing portable SIMD code.
This is `#![feature(portable_simd)]` as tracked in #86656
I need to have multiple `build` directories, such as `build`,
`build-fuchsia`, and `build-test`. But when I'm uploading a change, I
run `./x.py test tidy`, and if I have a `build-something` directory with
Rust sources, I git a bunch of formatting errors.
`rustfmt.toml` only ignores the directory named `build`.
This change extends the patterns to also ignore `build-*` and `*-build`.
As a rustc contributor, I not only build the rust compiler to develop
new features, but I also build alternative "distributions" (using
secondary `*-config.toml` files with different configurations),
including:
* To occasionally rebuild a version of the compiler that `rust-analyzer`
can use to `check` source (which fixes issues in the VS Code UI, so
changing and rebuilding the compiler does not break VS Code editing Rust
code).
* To build custom distributions for Fuchsia
* To build test distributions when working on changes to `bootstrap`
(e.g., when I recently added `rust-demangler` to distributions)
This commit is a proof-of-concept for switching the standard library's
backtrace symbolication mechanism on most platforms from libbacktrace to
gimli. The standard library's support for `RUST_BACKTRACE=1` requires
in-process parsing of object files and DWARF debug information to
interpret it and print the filename/line number of stack frames as part
of a backtrace.
Historically this support in the standard library has come from a
library called "libbacktrace". The libbacktrace library seems to have
been extracted from gcc at some point and is written in C. We've had a
lot of issues with libbacktrace over time, unfortunately, though. The
library does not appear to be actively maintained since we've had
patches sit for months-to-years without comments. We have discovered a
good number of soundness issues with the library itself, both when
parsing valid DWARF as well as invalid DWARF. This is enough of an issue
that the libs team has previously decided that we cannot feed untrusted
inputs to libbacktrace. This also doesn't take into account the
portability of libbacktrace which has been difficult to manage and
maintain over time. While possible there are lots of exceptions and it's
the main C dependency of the standard library right now.
For years it's been the desire to switch over to a Rust-based solution
for symbolicating backtraces. It's been assumed that we'll be using the
Gimli family of crates for this purpose, which are targeted at safely
and efficiently parsing DWARF debug information. I've been working
recently to shore up the Gimli support in the `backtrace` crate. As of a
few weeks ago the `backtrace` crate, by default, uses Gimli when loaded
from crates.io. This transition has gone well enough that I figured it
was time to start talking seriously about this change to the standard
library.
This commit is a preview of what's probably the best way to integrate
the `backtrace` crate into the standard library with the Gimli feature
turned on. While today it's used as a crates.io dependency, this commit
switches the `backtrace` crate to a submodule of this repository which
will need to be updated manually. This is not done lightly, but is
thought to be the best solution. The primary reason for this is that the
`backtrace` crate needs to do some pretty nontrivial filesystem
interactions to locate debug information. Working without `std::fs` is
not an option, and while it might be possible to do some sort of
trait-based solution when prototyped it was found to be too unergonomic.
Using a submodule allows the `backtrace` crate to build as a submodule
of the `std` crate itself, enabling it to use `std::fs` and such.
Otherwise this adds new dependencies to the standard library. This step
requires extra attention because this means that these crates are now
going to be included with all Rust programs by default. It's important
to note, however, that we're already shipping libbacktrace with all Rust
programs by default and it has a bunch of C code implementing all of
this internally anyway, so we're basically already switching
already-shipping functionality to Rust from C.
* `object` - this crate is used to parse object file headers and
contents. Very low-level support is used from this crate and almost
all of it is disabled. Largely we're just using struct definitions as
well as convenience methods internally to read bytes and such.
* `addr2line` - this is the main meat of the implementation for
symbolication. This crate depends on `gimli` for DWARF parsing and
then provides interfaces needed by the `backtrace` crate to turn an
address into a filename / line number. This crate is actually pretty
small (fits in a single file almost!) and mirrors most of what
`dwarf.c` does for libbacktrace.
* `miniz_oxide` - the libbacktrace crate transparently handles
compressed debug information which is compressed with zlib. This crate
is used to decompress compressed debug sections.
* `gimli` - not actually used directly, but a dependency of `addr2line`.
* `adler32`- not used directly either, but a dependency of
`miniz_oxide`.
The goal of this change is to improve the safety of backtrace
symbolication in the standard library, especially in the face of
possibly malformed DWARF debug information. Even to this day we're still
seeing segfaults in libbacktrace which could possibly become security
vulnerabilities. This change should almost entirely eliminate this
possibility whilc also paving the way forward to adding more features
like split debug information.
Some references for those interested are:
* Original addition of libbacktrace - #12602
* OOM with libbacktrace - #24231
* Backtrace failure due to use of uninitialized value - #28447
* Possibility to feed untrusted data to libbacktrace - #21889
* Soundness fix for libbacktrace - #33729
* Crash in libbacktrace - #39468
* Support for macOS, never merged - ianlancetaylor/libbacktrace#2
* Performance issues with libbacktrace - #29293, #37477
* Update procedure is quite complicated due to how many patches we
need to carry - #50955
* Libbacktrace doesn't work on MinGW with dynamic libs - #71060
* Segfault in libbacktrace on macOS - #71397
Switching to Rust will not make us immune to all of these issues. The
crashes are expected to go away, but correctness and performance may
still have bugs arise. The gimli and `backtrace` crates, however, are
actively maintained unlike libbacktrace, so this should enable us to at
least efficiently apply fixes as situations come up.
This commit is a proof-of-concept for switching the standard library's
backtrace symbolication mechanism on most platforms from libbacktrace to
gimli. The standard library's support for `RUST_BACKTRACE=1` requires
in-process parsing of object files and DWARF debug information to
interpret it and print the filename/line number of stack frames as part
of a backtrace.
Historically this support in the standard library has come from a
library called "libbacktrace". The libbacktrace library seems to have
been extracted from gcc at some point and is written in C. We've had a
lot of issues with libbacktrace over time, unfortunately, though. The
library does not appear to be actively maintained since we've had
patches sit for months-to-years without comments. We have discovered a
good number of soundness issues with the library itself, both when
parsing valid DWARF as well as invalid DWARF. This is enough of an issue
that the libs team has previously decided that we cannot feed untrusted
inputs to libbacktrace. This also doesn't take into account the
portability of libbacktrace which has been difficult to manage and
maintain over time. While possible there are lots of exceptions and it's
the main C dependency of the standard library right now.
For years it's been the desire to switch over to a Rust-based solution
for symbolicating backtraces. It's been assumed that we'll be using the
Gimli family of crates for this purpose, which are targeted at safely
and efficiently parsing DWARF debug information. I've been working
recently to shore up the Gimli support in the `backtrace` crate. As of a
few weeks ago the `backtrace` crate, by default, uses Gimli when loaded
from crates.io. This transition has gone well enough that I figured it
was time to start talking seriously about this change to the standard
library.
This commit is a preview of what's probably the best way to integrate
the `backtrace` crate into the standard library with the Gimli feature
turned on. While today it's used as a crates.io dependency, this commit
switches the `backtrace` crate to a submodule of this repository which
will need to be updated manually. This is not done lightly, but is
thought to be the best solution. The primary reason for this is that the
`backtrace` crate needs to do some pretty nontrivial filesystem
interactions to locate debug information. Working without `std::fs` is
not an option, and while it might be possible to do some sort of
trait-based solution when prototyped it was found to be too unergonomic.
Using a submodule allows the `backtrace` crate to build as a submodule
of the `std` crate itself, enabling it to use `std::fs` and such.
Otherwise this adds new dependencies to the standard library. This step
requires extra attention because this means that these crates are now
going to be included with all Rust programs by default. It's important
to note, however, that we're already shipping libbacktrace with all Rust
programs by default and it has a bunch of C code implementing all of
this internally anyway, so we're basically already switching
already-shipping functionality to Rust from C.
* `object` - this crate is used to parse object file headers and
contents. Very low-level support is used from this crate and almost
all of it is disabled. Largely we're just using struct definitions as
well as convenience methods internally to read bytes and such.
* `addr2line` - this is the main meat of the implementation for
symbolication. This crate depends on `gimli` for DWARF parsing and
then provides interfaces needed by the `backtrace` crate to turn an
address into a filename / line number. This crate is actually pretty
small (fits in a single file almost!) and mirrors most of what
`dwarf.c` does for libbacktrace.
* `miniz_oxide` - the libbacktrace crate transparently handles
compressed debug information which is compressed with zlib. This crate
is used to decompress compressed debug sections.
* `gimli` - not actually used directly, but a dependency of `addr2line`.
* `adler32`- not used directly either, but a dependency of
`miniz_oxide`.
The goal of this change is to improve the safety of backtrace
symbolication in the standard library, especially in the face of
possibly malformed DWARF debug information. Even to this day we're still
seeing segfaults in libbacktrace which could possibly become security
vulnerabilities. This change should almost entirely eliminate this
possibility whilc also paving the way forward to adding more features
like split debug information.
Some references for those interested are:
* Original addition of libbacktrace - #12602
* OOM with libbacktrace - #24231
* Backtrace failure due to use of uninitialized value - #28447
* Possibility to feed untrusted data to libbacktrace - #21889
* Soundness fix for libbacktrace - #33729
* Crash in libbacktrace - #39468
* Support for macOS, never merged - ianlancetaylor/libbacktrace#2
* Performance issues with libbacktrace - #29293, #37477
* Update procedure is quite complicated due to how many patches we
need to carry - #50955
* Libbacktrace doesn't work on MinGW with dynamic libs - #71060
* Segfault in libbacktrace on macOS - #71397
Switching to Rust will not make us immune to all of these issues. The
crashes are expected to go away, but correctness and performance may
still have bugs arise. The gimli and `backtrace` crates, however, are
actively maintained unlike libbacktrace, so this should enable us to at
least efficiently apply fixes as situations come up.
The current plan is that submodule tracks the `release` branch of
rust-analyzer, which is updated once a week.
rust-analyzer is a workspace (with a virtual manifest), the actual
binary is provide by `crates/rust-analyzer` package.
Note that we intentionally don't add rust-analyzer to `Kind::Test`,
for two reasons.
*First*, at the moment rust-analyzer's test suite does a couple of
things which might not work in the context of rust repository. For
example, it shells out directly to `rustup` and `rustfmt`. So, making
this work requires non-trivial efforts.
*Second*, it seems unlikely that running tests in rust-lang/rust repo
would provide any additional guarantees. rust-analyzer builds with
stable and does not depend on the specifics of the compiler, so
changes to compiler can't break ra, unless they break stability
guarantee. Additionally, rust-analyzer itself is gated on bors, so we
are pretty confident that test suite passes.
This replaces cargo-fmt with rustfmt with --skip-children which should
allow us to format code without running into rust-lang/rustfmt#3930.
This also bumps up the version of rustfmt used to a more recent one.
This commit adds an rustfmt.toml for using for **new** code.
Old code should continut to use old style, until we put automated
style checks in place.
See
https://internals.rust-lang.org/t/running-rustfmt-on-rust-lang-rust-and-other-rust-lang-repositories/8732/81
for the reason why we deviate from the default formatting. The TL;DR
is that currently compiler uses a pretty condensed style of code, and
default settings both create a huge diff and inflate the number of
lines. use_small_heuristics=Max fixes that.
version=Two is required for bug-fixes, which technically can't be made
to the stable first version
