Report I/O errors from rmeta encoding with emit_fatal
https://github.com/rust-lang/rust/issues/119456 reminded me that I never did systematic testing to provoke the out-of-disk ICEs so I grepped through a recent crater run (https://github.com/rust-lang/rust/pull/119440#issuecomment-1873393963) for more out-of-disk ICEs on current master and yep there's 2 in there.
So I finally cooked up a way to provoke for these crashes. I wrote a little `cdylib` crate that has a `#[no_mangle] pub extern "C" fn write` which occasionally reports `ENOSPC`, and prints a backtrace when it does.
<details><summary><strong>code for the dylib</strong></summary>
<p>
```rust
// cargo add libc rand backtrace
use rand::Rng;
#[no_mangle]
pub extern "C" fn write(
fd: libc::c_int,
buf: *const libc::c_void,
count: libc::size_t,
) -> libc::ssize_t {
if fd > 2 && rand::thread_rng().gen::<u8>() == 0 {
let mut count = 0;
backtrace::trace(|frame| {
backtrace::resolve_frame(frame, |symbol| {
if let Some(name) = symbol.name() {
if count > 3 {
eprintln!("{}", name);
}
}
count += 1;
});
true
});
unsafe {
*libc::__errno_location() = libc::ENOSPC;
}
return -1;
} else {
unsafe {
let res =
libc::syscall(libc::SYS_write, fd as usize, buf as usize, count as usize) as isize;
if res < 0 {
*libc::__errno_location() = -res as i32;
-1
} else {
res
}
}
}
}
```
</p>
</details>
Then `LD_PRELOAD` that dylib and repeatedly build a big project until it ICEs, such as with this:
```bash
while true; do
cargo clean
LD_PRELOAD=/home/ben/evil/target/release/libevil.so cargo +stage1 check 2> errors
if grep "thread 'rustc' panicked" errors; then
break
fi
done
```
My "big project" for testing was an otherwise-empty project with `cargo add axum`.
Before this PR, the above procedure finds a crash in between 1 and 15 minutes. With this PR, I have not found a crash in 30 minutes, and I'll be leaving this to run overnight (starting now). (A night has now passed, no crashes were found)
I believe the problem is that even though since https://github.com/rust-lang/rust/pull/117301 we correctly check `FileEncoder` for errors on all paths, we use `emit_err`, so there is a window of time between the call to `emit_err` and the full error reporting where rustc believes it has emitted a valid rmeta file and will permit Cargo to launch a build for a dependent crate. Changing these calls to `emit_fatal` closes that window.
I think there are a number of other cases where `emit_err` has been used instead of the more-correct `emit_fatal` such as e51e98dde6/compiler/rustc_codegen_ssa/src/back/write.rs (L542) but unlike rmeta encoding I am not aware of those cases of those causing problems.
r? ``@WaffleLapkin``
Update books
## rust-lang/reference
1 commits in f9f5b5babd95515e7028c32d6ca4d9790f64c146..3565c7978cfc9662f5963b135690ff9cbbfa0318
2023-12-29 21:01:19 UTC to 2023-12-29 21:01:19 UTC
- Use proper footnote for number literals `_` separator note (rust-lang/reference#1444)
## rust-lang/rust-by-example
1 commits in 4c2b24ff9d9cf19f2fcff799a3a49b9a2c50ae8e..c0be6299e52e4164c30ba6f41bd0ad0aaee64972
2023-12-21 15:22:11 UTC to 2023-12-21 15:22:11 UTC
- point to raw indentifiers, talking about fields (rust-lang/rust-by-example#1789)
## rust-lang/rustc-dev-guide
5 commits in 0610665a8687b1b0aa037917a1598b9f2a21e3ef..d13e85152a977cd0bcaf583cf5f49e86225697de
2023-12-30 09:58:25 UTC to 2023-12-19 10:02:34 UTC
- Prominently mention `profiler = true` on the coverage page (rust-lang/rustc-dev-guide#1844)
- Add a description of `unpretty=hir` to the HIR docs (rust-lang/rustc-dev-guide#1842)
- Fix typo in unsize docs (rust-lang/rustc-dev-guide#1843)
- Suggest `gcc_multi` to make `mir_opts` run on nixos (rust-lang/rustc-dev-guide#1841)
- bootstrapping: Clarify that stage0 std code is not executed to produce stage1 compiler (rust-lang/rustc-dev-guide#1840)
Update tracking issue of naked_functions
The original tracking issue #32408 was superseded by the new one #90957 (constrainted naked functions) and therefore is closed.
rc: Take *const T in is_dangling
It is not important which one is used since `is_dangling` does not access memory, but `*const` removes the needs of `*const T` -> `*mut T` casts in `from_raw_in`.
Document that File does not buffer reads/writes
...and refer to `BufReader`/`BufWriter`.
This is a common source of efficiency issues in Rust programs written naively. Including this information with the `File` docs, and adding a link to the wrapper types, will help discoverability.
Query panic!() to useful diagnostic
Changes some more ICEs from bare panic!()s
Adds an `expect_job()` helper method as that is a moral equivalent of what was happening at the uses.
re:#118955
rustc_lint: Enforce `rustc::potential_query_instability` lint
Stop allowing `rustc::potential_query_instability` on all of `rustc_lint` and instead allow it on a case-by-case basis if it is safe to do so. In this particular crate, all lints were safe to allow.
Part of https://github.com/rust-lang/rust/issues/84447 which is E-help-wanted.
Stop allowing `rustc::potential_query_instability` on all of
`rustc_lint` and instead allow it on a case-by-case basis if it is safe
to do so. In this particular crate, all lints were safe to allow.
Simplify bootstrap `--check-cfg` arguments
This PR simplifies the generated check-cfg arguments generated for the no-values case.
For the `bootstrap` cfg:
```diff
- --check-cfg=cfg(bootstrap,values())
+ --check-cfg=cfg(bootstrap)
```
Those are equivalent, so there isn't any semantic difference; but the invocation is short and less distracting.
`@rustbot` label +F-check-cfg
Fix `<BoundConstness as Display>`
There was infinite recursion, which is not very good. I'm not sure what the best way to implement this is, I just did something that felt right.
r? `@fmease`
