Use proc-macro to derive HashStable everywhere
Hello,
A second proc-macro is added to derive HashStable for crates librustc depends on.
This proc-macro `HashStable_Generic` (to bikeshed) allows to decouple code and strip much of librustc's boilerplate.
Still, two implementations `Span` and `TokenKind` require to be placed in librustc.
The latter only depends on the `bug` macro. Advise welcome on how to sever that link.
A trait `StableHasingContextLike` has been introduced at each crate root,
in order to handle those implementations which require librustc's very `StableHashingContext`.
This overall effort allowed to remove the `impl_stable_hash_for` macro.
Each commit passes the `x.py check`.
I still have to double check there was no change in the implementation.
Ast address-of
This is the parts of #64588 that don't affect MIR. If an address-of expression makes it to MIR lowering we error and lower to the best currently expressible approximation to limit further errors.
r? @Centril
Enable `if` and `match` in constants behind a feature flag
This PR is an initial implementation of #49146. It introduces a `const_if_match` feature flag and does the following if it is enabled:
- Allows `Downcast` projections, `SwitchInt` terminators and `FakeRead`s for matched places through the MIR const-checker.
- Allows `if` and `match` expressions through the HIR const-checker.
- Stops converting `&&` to `&` and `||` to `|` in `const` and `static` items.
As a result, the following operations are now allowed in a const context behind the feature flag:
- `if` and `match`
- short circuiting logic operators (`&&` and `||`)
- the `assert` and `debug_assert` macros (if the `const_panic` feature flag is also enabled)
However, the following operations remain forbidden:
- `while`, `loop` and `for` (see #52000)
- the `?` operator (calls `From::from` on its error variant)
- the `assert_eq` and `assert_ne` macros, along with their `debug` variants (calls `fmt::Debug`)
This PR is possible now that we use dataflow for const qualification (see #64470 and #66385).
r? @oli-obk
cc @rust-lang/wg-const-eval @eddyb
*Syntactically* permit visibilities on trait items & enum variants
Fixes#65041
Suppose we have `$vis trait_item` or `$vis enum_variant` and `$vis` is a `:vis` macro fragment. Before this PR, this would fail to parse. This is now instead allowed as per language team consensus in https://github.com/rust-lang/rust/issues/65041#issuecomment-538105286. (See added tests for elaboration.)
Moreover, we now also permit visibility modifiers on trait items & enum variants *syntactically* but reject them with semantic checks (in `ast_validation`):
```rust
#[cfg(FALSE)]
trait Foo { pub fn bar(); } // OK
#[cfg(FALSE)]
enum E { pub U } // OK
```
Add a proc-macro to derive HashStable in librustc dependencies
A second proc-macro is added to derive HashStable for crates librustc depends on.
This proc-macro HashStable_Generic (to bikeshed) allows to decouple code and some librustc's boilerplate.
Not everything is migrated, because `Span` and `TokenKind` require to be placed inside librustc.
Types using them stay there too.
Split out of #66279
r? @Zoxc
Move process_configure_mod to rustc_parse
This removes the hack in favor of perhaps a less principled, but less painful, approach.
This also supports my work to decouple `Session` from librustc, as `ParseSess` currently has `Attribute` as "part" of it but after this PR will no longer do so.
Making ICEs and test them in incremental
This adds:
- A way to make the compiler ICE
- A way to check for ICE in `cfail` tests with `should-ice`
- A regression test for issue #65401
I am not sure the attribute added `should-ice` is the best for this job
Suggest `#[repr(C)]` instead of `#[repr(C, packed, ...)]`
The code was previously suggesting `#[repr(C, packed, ...)]` for incorrect uses of `repr` (e.g. `#[repr = "C"]`). This change suggests the usage of `#[repr(C)]` instead.
r? @estebank
Ref: #61286.
Move the JSON error emitter to librustc_errors
This is done both as a cleanup (it makes little sense for this emitter to be in libsyntax), but also as part of broader work to decouple Session from librustc itself.
Along the way, this also moves SourceMap to syntax_pos, which is also nice for the above reasons, as well as allowing dropping the SourceMapper trait from code. This had the unfortunate side-effect of moving `FatalError` to rustc_data_structures (it's needed in syntax_pos, due to SourceMap, but putting it there feels somehow worse).
SourceMap is now in the root of all rustc-specific crates, syntax_pos,
so there's no need for the trait object to decouple the dependencies
between librustc_errors and libsyntax as was needed previously.
Push `ast::{ItemKind, ImplItemKind}::OpaqueTy` hack down into lowering
We currently have a hack in the form of `ast::{ItemKind, ImplItemKind}::OpaqueTy` which is constructed literally when you write `type Alias = impl Trait;` but not e.g. `type Alias = Vec<impl Trait>;`. Per https://github.com/rust-lang/rfcs/pull/2515, this needs to change to allow `impl Trait` in nested positions. This PR achieves this change for the syntactic aspect but not the semantic one, which will require changes in lowering and def collection. In the interim, `TyKind::opaque_top_hack` is introduced to avoid knock-on changes in lowering, collection, and resolve. These hacks can then be removed and fixed one by one until the desired semantics are supported.
r? @varkor
This does not update the use sites or delete the now unnecessary
SourceMapper trait, to allow git to interpret the file move as a rename
rather than a new file.
support issue = "none" in unstable attributes
This works towards fixing #41260.
This PR allows the use of `issue = "none"` in unstable attributes and makes changes to internally store the issue number as an `Option<NonZeroU32>`. For example:
```rust
#[unstable(feature = "unstable_test_feature", issue = "none")]
fn unstable_issue_none() {}
```
It was not made optional because feedback seen here #60860 suggested that people might forget the issue field if it was optional.
I could not remove the current uses of `issue = "0"` (of which there are a lot) because the stage 0 compiler expects the old syntax. Once this is available in the stage 0 compiler we can replace all uses of `"0"` with `"none"` and no longer allow `"0"`. This is my first time contributing, so I'm not sure what the protocol is with two-part things like this, so some guidance would be appreciated.
r? @varkor
Merge repeated definitions
Step forward on #66149
I may need further context to understand the need for a separate crate.
Also, please tell me if you think of other definitions to merge.
