Handle statics in MIR as const pointers
This is the first PR towards the goal of removing `PlaceBase::Static`. In this PR:
* Statics are lowered to dereferencing a const pointer.
* The temporaries holding such pointers are tracked in MIR, for the most part this is only used for diagnostics. There are two exceptions:
* The borrow checker has some checks for thread-locals that directly use this data.
* Const checking will suppress "cannot dereference raw pointer" diagnostics for pointers to `static mut`/`extern static`. This is to maintain the current behaviour (12 tests fail otherwise).
The following are left to future PRs (I think that @spastorino will be working on the first 3):
* Applying the same treatments to promoted statics.
* Removing `PlaceBase::Static`.
* Replacing `PlaceBase` with `Local`.
* Moving the ever growing collection of metadata that we have for diagnostics in MIR passes somewhere more appropriate.
r? @oli-obk
Remove pretty printing of specific nodes in AST
The ability to print a specific item as identified by NodeId or path
seems not particularly useful, and certainly carries quite a bit of
complexity with it.
This is intended to simplify our CLI parsing a bit and remove a
non-uncomplicated piece of it; I largely did this to remove the
dependency on NodeId from librustc/session but it's not really
necessary to do so in this invasive a way. The alternative is
moving it to librustc_interface or driver, probably.
*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.
Delay an `is_local_ever_initialized` call.
This commit moves the call after a `return` that almost always runs. It
speeds up the `unicode_normalization` benchmark by about 2%.
r? @spastorino
Support multiple revisions in `compiletest`
The `//[X]~` syntax filters errors for tests that are run across multiple cfgs with `// revisions:`. This commit extends that syntax to accept `//[X,Y]~`, which will match multiple cfgs to the same error annotation. This is functionally the same as writing two comments, `//[X]~` and `//[Y]~`, but can fit on a single line.
While refactoring `compiletest` to support this, I also uncovered a small bug that was causing an incremental test to always pass, despite no errors being emitted.
r? @Centril
[mir-opt] asking `?`s in a more optimized fashion
This PR works towards https://github.com/rust-lang/rust/issues/66234 by providing two optimization passes meant to run in sequence:
- `SimplifyArmIdentity` which transforms something like:
```rust
_LOCAL_TMP = ((_LOCAL_1 as Variant ).FIELD: TY );
((_LOCAL_0 as Variant).FIELD: TY) = move _LOCAL_TMP;
discriminant(_LOCAL_0) = VAR_IDX;
```
into:
```rust
_LOCAL_0 = move _LOCAL_1
```
- `SimplifyBranchSame` which transforms `SwitchInt`s to identical basic blocks into a `goto` to the first reachable target.
Together, these are meant to simplify the following into just `res`:
```rust
match res {
Ok(x) => Ok(x),
Err(x) => Err(x),
}
```
It should be noted however that the desugaring of `?` includes a function call and so the first pass in this PR relies on inlining to substitute that function call for identity on `x`. Inlining requires `mir-opt-level=2` so this might not have any effect in perf-bot but let's find out.
r? @oli-obk -- This is WIP, but I'd appreciate feedback. :)
This test does not actually emit any warnings, since
`#![allow(warnings)]` was specified. `compiletest` was erroneously
ignoring `//~` tests and looking only for `//[X]~` ones. As a result of
the changes in the previous commit, we now look for `//~` comments in
incremental tests and expect them to appear in *all* revisions.
The `//[X]~` syntax filters errors for tests that are run across
multiple cfgs with `// revisions:`. This commit extends that syntax to
accept `//[X,Y]~`, which will match multiple cfgs to the same error
annotation. This is functionally the same as writing two comments,
`//[X]~` and `//[Y]~`, but can fit on a single line.
Aggregation of drive-by cosmetic changes for trait-upcasting PR
Cherry-picked from #60900.
As requested by @Centril (and @nikomatsakis, I believe).
r? @Centril
This optimization depends on inlining for the identity
conversions introduced by the lowering of the `?`.
To take advantage of `SimplifyArmIdentity`, `-Z mir-opt-level=2`
is required because that triggers the inlining MIR optimization.
Rollup of 5 pull requests
Successful merges:
- #65355 (Stabilize `!` in Rust 1.41.0)
- #65730 (Suggest to add lifetime constraint at explicit ouput of functions)
- #66468 (Cleanup Miri SIMD intrinsics)
- #66515 (Reduce size of `hir::Expr` by boxing more of `hir::InlineAsm`)
- #66602 (Revert "Update Source Code Pro and include italics")
Failed merges:
r? @ghost
