Fix abort-on-eprintln during process shutdown
This commit fixes an issue where if `eprintln!` is used in a TLS
destructor it can accidentally cause the process to abort. TLS
destructors are executed after `main` returns on the main thread, and at
this point we've also deinitialized global `Lazy` values like those
which store the `Stderr` and `Stdout` internals. This means that despite
handling TLS not being accessible in `eprintln!`, we will fail due to
not being able to call `stderr()`. This means that we'll double-panic
quickly because panicking also attempt to write to stderr.
The fix here is to reimplement the global stderr handle to avoid the
need for destruction. This avoids the need for `Lazy` as well as the
hidden panic inside of the `stderr` function.
Overall this should improve the robustness of printing errors and/or
panics in weird situations, since the `stderr` accessor should be
infallible in more situations.
add #[rustc_layout(debug)]
@eddyb recently told me about the `#[rustc_layout]` attribute, and I think it would be very useful if it could be used to print all the layout information Rust has about a type. When working with layouts (e.g. in Miri), it is often not clear how certain surface language features get represented internally. I have some awful hacks locally to be able to dump this debug information; with this attribute I could get it on the playground which is so much better. :)
can_begin_literal_maybe_minus: `true` on `"-"? lit` NTs.
Make `can_begin_literal_or_bool` (renamed to `can_begin_literal_maybe_minus`) accept `NtLiteral(e) | NtExpr(e)` where `e` is either a literal or a negated literal.
Fixes https://github.com/rust-lang/rust/issues/70050.
r? @petrochenkov
Use generator resume arguments in the async/await lowering
This removes the TLS requirement from async/await and enables it in `#![no_std]` crates.
Closes https://github.com/rust-lang/rust/issues/56974
I'm not confident the HIR lowering is completely correct, there seem to be quite a few undocumented invariants in there. The `async-std` and tokio test suites are passing with these changes though.
This commit fixes an issue where if `eprintln!` is used in a TLS
destructor it can accidentally cause the process to abort. TLS
destructors are executed after `main` returns on the main thread, and at
this point we've also deinitialized global `Lazy` values like those
which store the `Stderr` and `Stdout` internals. This means that despite
handling TLS not being accessible in `eprintln!`, we will fail due to
not being able to call `stderr()`. This means that we'll double-panic
quickly because panicking also attempt to write to stderr.
The fix here is to reimplement the global stderr handle to avoid the
need for destruction. This avoids the need for `Lazy` as well as the
hidden panic inside of the `stderr` function.
Overall this should improve the robustness of printing errors and/or
panics in weird situations, since the `stderr` accessor should be
infallible in more situations.
Add regression test for TAIT lifetime inference (issue #55099)
Fixes#55099
The minimized reproducer in issue #55099 now compiles successfully.
This commit adds a regression test for it.
std: Don't abort process when printing panics in tests
This commit fixes an issue when using `set_print` and friends, notably
used by libtest, to avoid aborting the process if printing panics. This
previously panicked due to borrowing a mutable `RefCell` twice, and this
is worked around by borrowing these cells for less time, instead
taking out and removing contents temporarily.
Closes#69558
Previously, metadata encoding used DUMMY_SP to represent any spans that
referenced an 'imported' SourceFile - e.g. a SourceFile from an upstream
dependency. These leads to sub-optimal error messages in certain cases
(see the included test).
This PR changes how we encode and decode spans in crate metadata. We
encode spans in one of two ways:
* 'Local' spans, which reference non-imported SourceFiles, are encoded
exactly as before.
* 'Foreign' spans, which reference imported SourceFiles, are encoded
with the CrateNum of their 'originating' crate. Additionally, their
'lo' and 'high' values are rebased on top of the 'originating' crate,
which allows them to be used with the SourceMap data encoded for that
crate.
The `ExternalSource` enum is renamed to `ExternalSourceKind`. There is
now a struct called `ExternalSource`, which holds an
`ExternalSourceKind` along with the original line number information for
the file. This is used during `Span` serialization to rebase spans onto
their 'owning' crate.
Expansion-driven outline module parsing
After this PR, the parser will not do any conditional compilation or loading of external module files when `mod foo;` is encountered. Instead, the parser only leaves `mod foo;` in place in the AST, with no items filled in. Expansion later kicks in and will load the actual files and do the parsing. This entails that the following is now valid:
```rust
#[cfg(FALSE)]
mod foo {
mod bar {
mod baz; // `foo/bar/baz.rs` doesn't exist, but no error!
}
}
```
Fixes https://github.com/rust-lang/rust/issues/64197.
r? @petrochenkov
Use smaller discriminants for generators
Closes https://github.com/rust-lang/rust/issues/69815
I'm not yet sure about the runtime performance impact of this, so I'll try running this on some benchmarks (if I can find any). (Update: No impact on the benchmarks I've measured on)
* [x] Add test with a generator that has exactly 256 total states
* [x] Add test with a generator that has more than 256 states so that it needs to use a u16 discriminant
* [x] Add tests for the size of `Option<[generator]>`
* [x] Add tests for the `discriminant_value` intrinsic in all cases
Erase regions in writeback
Regions in `TypeckTables` (except canonicalized user annotations) are now erased. Further, we no longer do lexical region solving on item bodies with `-Zborrowck=mir`.
cc #68261
r? @nikomatsakis
