AST/HIR: Introduce `ExprKind::Err` for better error recovery in the front-end
This way we can avoid aborting compilation if expansion produces errors and generate `ExprKind::Err`s instead.
Implement the new-style trait solver
Final PR of what I believe to be a minimally working implementation of the new-style trait solver.
The new trait solver can be used by providing the `-Z chalk` command line flag. It is currently used everywhere in `rustc_typeck`, and for everything relying on `rustc::infer::canonical::query_response::enter_canonical_trait_query`.
The trait solver is invoked in rustc by using the `evaluate_goal` canonical query. This is not optimal because each call to `evaluate_goal` creates a new `chalk_engine::Forest`, hence rustc cannot use answers to intermediate goals produced by the root goal. We'll need to change that but I guess that's ok for now.
Some next steps, I think, are:
* handle region constraints: region constraints are computed but are completely ignored for now, I think we may need additional support from `chalk_engine` (as a side effect, types or trait references with outlive requirements cannot be proved well-formed)
* deactivate eager normalization in the presence of `-Z chalk` in order to leverage the lazy normalization strategy of the new-style trait solver
* add the remaining built-in impls (only `Sized` is supported currently)
* transition the compiler to using generic goals instead of predicates that still refer to named type parameters etc
I added a few very simple tests to check that the new solver has the right behavior, they won't be needed anymore once it is mature enough. Additionally it shows off that we get [implied bounds](https://github.com/rust-lang/rust/issues/44491) for free.
r? @nikomatsakis
Call poly_project_and_unify_type on types that contain inference types
Commit f57247c48c (Ensure that Rusdoc discovers all necessary auto
trait bounds) added a check to ensure that we only attempt to unify a
projection predicatre with inference variables. However, the check it
added was too strict - instead of checking that a type *contains* an
inference variable (e.g. '&_', 'MyType<_>'), it required the type to
*be* an inference variable (i.e. only '_' would match).
This commit relaxes the check to use 'ty.has_infer_types', ensuring that
we perform unification wherever possible.
Fixes#56822
Add `io` and `arch` modules to `std::os::fortanix_sgx`
This PR adds two more (unstable) modules to `std::os::fortanix_sgx` for the `x86_64-fortanix-unknown-sgx` target.
### io
`io` allows conversion between raw file descriptors and Rust types, similar to `std::os::unix::io`.
### arch
`arch` exposes the `ENCLU[EREPORT]` and `ENCLU[EGETKEY]` instructions. The current functions are very likely not going to be the final form of these functions (see also https://github.com/fortanix/rust-sgx/issues/15), but this should be sufficient to enable experimentation in libraries. I tried using the actual types (from the [`sgx-isa` crate](https://crates.io/crates/sgx-isa)) instead of byte arrays, but that would make `std` dependent on the `bitflags` crate which I didn't want to do at this time.
When a format string has escaped whitespace characters format
arguments were shifted by one per each escaped character. Account
for these escaped characters when synthesizing the spans.
Fix#55155.
Various changes to string format diagnostics
- Point at opening mismatched formatting brace
- Account for differences between raw and regular strings
- Account for differences between the code snippet and `InternedString`
- Add more tests
```
error: invalid format string: expected `'}'`, found `'t'`
--> $DIR/ifmt-bad-arg.rs:85:1
|
LL | ninth number: {
| - because of this opening brace
LL | tenth number: {}",
| ^ expected `}` in format string
|
= note: if you intended to print `{`, you can escape it using `{{`
```
Fix#53837.
- Point at opening mismatched formatting brace
- Account for differences between raw and regular strings
- Account for differences between the code snippet and `InternedString`
- Add more tests
