Perform name resolution before and during ast->hir lowering
This PR performs name resolution before and during ast->hir lowering instead of in phase 3.
r? @nrc
rustc: Implement custom panic runtimes
This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.
[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md
Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.
With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.
Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).
Closes#32837
Add integer atomic types
Tracking issue: #32976
RFC: rust-lang/rfcs#1543
The changes to AtomicBool in the RFC are not included, they are in a separate PR (#32365).
This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.
[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md
Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.
With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.
Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).
degrade gracefully with empty spans
In https://github.com/rust-lang/rust/pull/32756, we solved the final test failure, but digging more into it the handling of that scenario could be better. The error was caused by an empty span supplied by the parser representing EOF. This patch checks that we cope more gracefully with such spans:
r? @jonathandturner
Implement constant support in MIR.
All of the intended features in `trans::consts` are now supported by `mir::constant`.
The implementation is considered a temporary measure until `miri` replaces it.
A `-Z orbit` bootstrap build will only translate LLVM IR from AST for `#[rustc_no_mir]` functions.
Furthermore, almost all checks of constant expressions have been moved to MIR.
In non-`const` functions, trees of temporaries are promoted, as per RFC 1414 (rvalue promotion).
Promotion before MIR borrowck would allow reasoning about promoted values' lifetimes.
The improved checking comes at the cost of four `[breaking-change]`s:
* repeat counts must contain a constant expression, e.g.:
`let arr = [0; { println!("foo"); 5 }];` used to be allowed (it behaved like `let arr = [0; 5];`)
* dereference of a reference to a `static` cannot be used in another `static`, e.g.:
`static X: [u8; 1] = [1]; static Y: u8 = (&X)[0];` was unintentionally allowed before
* the type of a `static` *must* be `Sync`, irrespective of the initializer, e.g.
`static FOO: *const T = &BAR;` worked as `&T` is `Sync`, but it shouldn't because `*const T` isn't
* a `static` cannot wrap `UnsafeCell` around a type that *may* need drop, e.g.
`static X: MakeSync<UnsafeCell<Option<String>>> = MakeSync(UnsafeCell::new(None));`
was previously allowed based on the fact `None` alone doesn't need drop, but in `UnsafeCell`
it can be later changed to `Some(String)` which *does* need dropping
The drop restrictions are relaxed by RFC 1440 (#33156), which is implemented, but feature-gated.
However, creating `UnsafeCell` from constants is unstable, so users can just enable the feature gate.
parser: do not try to continue with `unsafe` on foreign fns
The changed line makes it look like `unsafe` is allowed, but the first statement of `parse_item_foreign_fn` is:
```
self.expect_keyword(keywords::Fn)?;
```
So we get the strange "expected one of `fn`, `pub`, `static`, or `unsafe`, found `unsafe`".
Fixes: #27361
parser: fix suppression of syntax errors in range RHS
Invalid expressions on the RHS were just swallowed without generating an error. The new version more closely mirrors the code for parsing `..x` in the `parse_prefix_range_expr` method below, where no cancel is done either.
Fixes#33262.
Add more aliases for Unicode confusable chars
Building upon #29837, this PR:
* added aliases for space characters,
* distinguished square brackets from parens, and
* added common CJK punctuation characters as aliases.
This will especially help CJK users who may have forgotten to switch off IME when coding.
parser: change warning into an error on `T<A=B, C>`
part of #32214
This seems to be the obvious fix, and the error message is consistent with all the other parser errors ("expected x, found y").
lexer: do not display char confusingly in error message
Current code leads to messages like `... use a \xHH escape: \u{e4}` which is confusing.
The printed span already points to the offending character, which should be enough to identify the non-ASCII problem.
Fixes: #29088
There is now a CoreEmitter that everything desugars to, but without
losing any information. Also remove RenderSpan::FileLine. This lets the
rustc_driver tests build.
The extra filename and line was mainly there to keep the indentation
relative to the main snippet; now that this doesn't include
filename/line-number as a prefix, it is distracted.
Major changes:
- Remove old snippet rendering code and use the new stuff.
- Introduce `span_label` method to add a label
- Remove EndSpan mode and replace with a fn to get the last
character of a span.
- Stop using `Option<MultiSpan>` and just use an empty `MultiSpan`
- and probably a bunch of other stuff :)
Jonathan Turner