CTFE: simplify ConstValue by not checking for alignment
I hope the test suite actually covers the problematic cases here?
r? @oli-obk
Fixes https://github.com/rust-lang/rust/issues/61952
Move special treatment of `derive(Copy, PartialEq, Eq)` from expansion infrastructure to elsewhere
As described in https://github.com/rust-lang/rust/pull/62086#issuecomment-515195477.
Reminder:
- `derive(PartialEq, Eq)` makes the type it applied to a "structural match" type, so constants of this type can be used in patterns (and const generics in the future).
- `derive(Copy)` notifies other derives that the type it applied to implements `Copy`, so `derive(Clone)` can generate optimized code and other derives can generate code working with `packed` types and types with `rustc_layout_scalar_valid_range` attributes.
First, the special behavior is now enabled after properly resolving the derives, rather than after textually comparing them with `"Copy"`, `"PartialEq"` and `"Eq"` in `fn add_derived_markers`.
The markers are no longer kept as attributes in AST since derives cannot modify items and previously did it through hacks in the expansion infra.
Instead, the markers are now kept in a "global context" available from all the necessary places, namely - resolver.
For `derive(PartialEq, Eq)` the markers are created by the derive macros themselves and then consumed during HIR lowering to add the `#[structural_match]` attribute in HIR.
This is still a hack, but now it's a hack local to two specific macros rather than affecting the whole expansion infra.
Ideally we should find the way to put `#[structural_match]` on the impls rather than on the original item, and then consume it in `rustc_mir`, then no hacks in expansion and lowering will be required.
(I'll make an issue about this for someone else to solve, after this PR lands.)
The marker for `derive(Copy)` cannot be emitted by the `Copy` macro itself because we need to know it *before* the `Copy` macro is expanded for expanding other macros.
So we have to do it in resolve and block expansion of any derives in a `derive(...)` container until we know for sure whether this container has `Copy` in it or not.
Nasty stuff.
r? @eddyb or @matthewjasper
More Miri error tweaks
* Add `err_` version of the `_format!` macros
* Add `UbExperimental` variant so that Miri can mark some UB as experimental (e.g. Stacked Borrows)
r? @oli-obk
Rename `ItemKind::Ty` to `ItemKind::TyAlias`
The current name is not entirely clear without context and `TyAlias` is consistent with `ItemKind::TraitAlias`.
Use doc comments from 'pub use' statements
Split off from #62855
Currently, rustdoc ignores any doc comments found on 'pub use'
statements. As described in issue #58700, this makes it impossible to
properly document procedural macros. Any doc comments must be written on
the procedural macro definition, which must occur in a dedicated
proc-macro crate. This means that any doc comments or doc tests cannot
reference items defined in re-exporting crate, despite the fact that
such items may be required to use the procedural macro.
To solve this issue, this commit allows doc comments to be written on
'pub use' statements. For consistency, this applies to *all* 'pub use'
statements, not just those importing procedural macros.
When inlining documentation, documentation on 'pub use' statements will
be prepended to the documentation of the inlined item. For example,
the following items:
```rust
mod other_mod {
/// Doc comment from definition
pub struct MyStruct;
}
/// Doc comment from 'pub use'
///
pub use other_mod::MyStruct;
```
will caues the documentation for the re-export of 'MyStruct' to be
rendered as:
```
Doc comment from 'pub use'
Doc comment from definition
```
Note the empty line in the 'pub use' doc comments - because doc comments
are concatenated as-is, this ensure that the doc comments on the
definition start on a new line.
