`Decoder` has two impls:
- opaque: this impl is already partly infallible, i.e. in some places it
currently panics on failure (e.g. if the input is too short, or on a
bad `Result` discriminant), and in some places it returns an error
(e.g. on a bad `Option` discriminant). The number of places where
either happens is surprisingly small, just because the binary
representation has very little redundancy and a lot of input reading
can occur even on malformed data.
- json: this impl is fully fallible, but it's only used (a) for the
`.rlink` file production, and there's a `FIXME` comment suggesting it
should change to a binary format, and (b) in a few tests in
non-fundamental ways. Indeed #85993 is open to remove it entirely.
And the top-level places in the compiler that call into decoding just
abort on error anyway. So the fallibility is providing little value, and
getting rid of it leads to some non-trivial performance improvements.
Much of this commit is pretty boring and mechanical. Some notes about
a few interesting parts:
- The commit removes `Decoder::{Error,error}`.
- `InternIteratorElement::intern_with`: the impl for `T` now has the same
optimization for small counts that the impl for `Result<T, E>` has,
because it's now much hotter.
- Decodable impls for SmallVec, LinkedList, VecDeque now all use
`collect`, which is nice; the one for `Vec` uses unsafe code, because
that gave better perf on some benchmarks.
Stabilize `-Z print-link-args` as `--print link-args`
We have stable options for adding linker arguments; we should have a
stable option to help debug linker arguments.
Add documentation for the new option. In the documentation, make it clear that
the *exact* format of the output is not a stable guarantee.
Exit nonzero on rustc -Wall
Previously `rustc -Wall /dev/null` would print a paragraph explaining that `-Wall` is not a thing in Rust, but would then exit 0. I believe exiting 0 is not the right behavior. For something like `rustc --version` or `rustc --help` or `rustc -C help` the user is requesting rustc to print some information; rustc prints that information and exits 0 because what the user requested has been accomplished. In the case of `rustc -Wall path/to/main.rs`, I don't find it correct to conceptualize this as "the user requested rustc to print information about the fact that Wall doesn't exist". The user requested a particular thing, and despite rustc knowing what they probably meant and informing them about that, the thing they requested has *not* been accomplished. Thus a nonzero exit code is needed.
LLVM has built-in heuristics for adding stack canaries to functions. These
heuristics can be selected with LLVM function attributes. This patch adds a
rustc option `-Z stack-protector={none,basic,strong,all}` which controls the use
of these attributes. This gives rustc the same stack smash protection support as
clang offers through options `-fno-stack-protector`, `-fstack-protector`,
`-fstack-protector-strong`, and `-fstack-protector-all`. The protection this can
offer is demonstrated in test/ui/abi/stack-protector.rs. This fills a gap in the
current list of rustc exploit
mitigations (https://doc.rust-lang.org/rustc/exploit-mitigations.html),
originally discussed in #15179.
Stack smash protection adds runtime overhead and is therefore still off by
default, but now users have the option to trade performance for security as they
see fit. An example use case is adding Rust code in an existing C/C++ code base
compiled with stack smash protection. Without the ability to add stack smash
protection to the Rust code, the code base artifacts could be exploitable in
ways not possible if the code base remained pure C/C++.
Stack smash protection support is present in LLVM for almost all the current
tier 1/tier 2 targets: see
test/assembly/stack-protector/stack-protector-target-support.rs. The one
exception is nvptx64-nvidia-cuda. This patch follows clang's example, and adds a
warning message printed if stack smash protection is used with this target (see
test/ui/stack-protector/warn-stack-protector-unsupported.rs). Support for tier 3
targets has not been checked.
Since the heuristics are applied at the LLVM level, the heuristics are expected
to add stack smash protection to a fraction of functions comparable to C/C++.
Some experiments demonstrating how Rust code is affected by the different
heuristics can be found in
test/assembly/stack-protector/stack-protector-heuristics-effect.rs. There is
potential for better heuristics using Rust-specific safety information. For
example it might be reasonable to skip stack smash protection in functions which
transitively only use safe Rust code, or which uses only a subset of functions
the user declares safe (such as anything under `std.*`). Such alternative
heuristics could be added at a later point.
LLVM also offers a "safestack" sanitizer as an alternative way to guard against
stack smashing (see #26612). This could possibly also be included as a
stack-protection heuristic. An alternative is to add it as a sanitizer (#39699).
This is what clang does: safestack is exposed with option
`-fsanitize=safe-stack`.
The options are only supported by the LLVM backend, but as with other codegen
options it is visible in the main codegen option help menu. The heuristic names
"basic", "strong", and "all" are hopefully sufficiently generic to be usable in
other backends as well.
Reviewed-by: Nikita Popov <nikic@php.net>
Extra commits during review:
- [address-review] make the stack-protector option unstable
- [address-review] reduce detail level of stack-protector option help text
- [address-review] correct grammar in comment
- [address-review] use compiler flag to avoid merging functions in test
- [address-review] specify min LLVM version in fortanix stack-protector test
Only for Fortanix test, since this target specifically requests the
`--x86-experimental-lvi-inline-asm-hardening` flag.
- [address-review] specify required LLVM components in stack-protector tests
- move stack protector option enum closer to other similar option enums
- rustc_interface/tests: sort debug option list in tracking hash test
- add an explicit `none` stack-protector option
Revert "set LLVM requirements for all stack protector support test revisions"
This reverts commit a49b74f92a4e7d701d6f6cf63d207a8aff2e0f68.
Index and hash HIR as part of lowering
Part of https://github.com/rust-lang/rust/pull/88186
~Based on https://github.com/rust-lang/rust/pull/88880 (see merge commit).~
Once HIR is lowered, it is later indexed by the `index_hir` query and hashed for `crate_hash`. This PR moves those post-processing steps to lowering itself. As a side objective, the HIR crate data structure is refactored as an `IndexVec<LocalDefId, Option<OwnerInfo<'hir>>>` where `OwnerInfo` stores all the relevant information for an HIR owner.
r? `@michaelwoerister`
cc `@petrochenkov`
Rustc was incorrectly reading the value of `RUSTC_LOG` as the
environment vairable with the logging configuration, rather than the
logging configuration itself.
This commit changes the `tracing_subscriber` initialization in
`rustc_driver` so that the `WARN` verbosity level is enabled by default
when the `RUSTC_LOG` env variable is empty. If the `RUSTC_LOG` env
variable is set, the filter string in the environment variable is
honored, instead.
Fixes#76824Closes#89623
cc @eddyb, @oli-obk
Consistently use 'supertrait'.
A subset of places referred to 'super-trait', so this changes them
to all use 'supertrait'. This matches 'supertype' and some other
usages. An exception is 'auto-trait' which is consistently used
in that manner.
Fix clippy lints
I'm currently working on allowing clippy to run on librustdoc after a discussion I had with `@Mark-Simulacrum.` So in the meantime, I fixed a few lints on the compiler crates.
A subset of places referred to 'super-trait', so this changes them
to all use 'supertrait'. This matches 'supertype' and some other
usages. An exception is 'auto-trait' which is consistently used
in that manner.
Couple of changes to FileSearch and SearchPath
* Turn a couple of regular comments into doc comments
* Move `get_tools_search_paths` from `FileSearch` to `Session`
* Use Lrc instead of Option to avoid duplication of a `SearchPath`
rfc3052 followup: Remove authors field from Cargo manifests
Since RFC 3052 soft deprecated the authors field, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information for contributors, we may as well
remove it from crates in this repo.
Since RFC 3052 soft deprecated the authors field anyway, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information, we should remove it from
crates in this repo.
Implement printing of stack traces on LLVM segfaults and aborts
Implement #79153
Based on discussion, try to extend the rust_backtrace=1 feature to handle segfault or aborts in the llvm backend
Remove unused dependencies from compiler crates
Various compiler crates have dependencies that they don't appear to use. I used some scripting to detect such dependencies, filtered them based on some manual review, and removed those that do indeed appear to be entirely unused.
