Make integer exponentiation methods unstably const
cc #53718
This makes the following inherent methods on integer primitives into unstable `const fn`:
- `pow`
- `checked_pow`
- `wrapping_pow`
- `overflowing_pow`
- `saturating_pow`
- `next_power_of_two`
- `checked_next_power_of_two`
- `wrapping_next_power_of_two`
Only two changes were made to the implementation of these methods. First, I had to switch from the `?` operator, which is not yet implemented in a const context, to a `try_opt` macro. Second, `next_power_of_two` was using `ops::Add::add` (see the first commit) to "get overflow checks", so I switched to `#[rustc_inherit_overflow_checks]`. I'm not quite sure why the attribute wasn't used in the first place.
Allow trait methods to be called on concrete types in a const context
This partially implements [RFC 2632](https://github.com/rust-lang/rfcs/pull/2632) by const-checking methods inside an `impl const` block and allowing those methods to be called on concrete types. Calling trait methods on type parameters in a const context is not yet allowed. Implementing this will require much more work. Since we are only concerned with methods on concrete types, we are able to take advantage of the machinery in `Instance::resolve`, which is doing most of the work.
This also propagates `#[rustc_const_unstable]` from parent items to child items, making that attribute behave like `#[stable]` and `#[unstable]` do. This allows trait methods to be marked as unstably const.
cc #67792#57563
cc @rust-lang/wg-const-eval
r? @oli-obk
Remove special case for `simd_shuffle` arg promotion
After rust-lang/stdarch#825, these intrinsics are now defined with `#[rustc_args_required_const(2)]`, so the special-case is no longer necessary.
Combine `HaveBeenBorrowedLocals` and `IndirectlyMutableLocals` into one dataflow analysis
This PR began as an attempt to port `HaveBeenBorrowedLocals` to the new dataflow framework (see #68241 for prior art). Along the way, I noticed that it could share most of its code with `IndirectlyMutableLocals` and then found a few bugs in the two analyses:
- Neither one marked locals as borrowed after an `Rvalue::AddressOf`.
- `IndirectlyMutableLocals` was missing a minor fix that `HaveBeenBorrowedLocals` got in #61069. This is not a problem today since it is only used during const-checking, where custom drop glue is forbidden. However, this may change some day.
I decided to combine the two analyses so that they wouldn't diverge in the future while ensuring that they remain distinct types (called `MaybeBorrowedLocals` and `MaybeMutBorrowedLocals` to be consistent with the `Maybe{Un,}InitializedPlaces` naming scheme). I fixed the bugs and switched to exhaustive matching where possible to make them less likely in the future. Finally, I added comments explaining some of the finer points of the transfer function for these analyses (see #61069 and #65006).
Revert "Remove `checked_add` in `Layout::repeat`"
This fixes a a segfault in safe code, a stable regression. Reported in #69225.
This reverts commit a983e0590a.
This fixes a a segfault in safe code, a stable regression. Reported in
\#69225.
This reverts commit a983e0590a.
Also adds a test for the expected behaviour.
parse: recover `mut (x @ y)` as `(mut x @ mut y)`.
Follow up to https://github.com/rust-lang/rust/pull/68992#discussion_r376829749 and https://github.com/rust-lang/rust/pull/63945.
Specifically, when given `let mut (x @ y)` we recover with `let (mut x @ mut y)` as the suggestion:
```rust
error: `mut` must be attached to each individual binding
--> $DIR/mut-patterns.rs:12:9
|
LL | let mut (x @ y) = 0;
| ^^^^^^^^^^^ help: add `mut` to each binding: `(mut x @ mut y)`
|
= note: `mut` may be followed by `variable` and `variable @ pattern`
```
r? @matthewjasper @estebank
Do not emit note suggesting to implement operation trait to foreign type
When a binary operation isn't valid, you will get a lint proposing to add a trait implementation to make the operation possible. However, this cannot be done for foreign types, such as types from `core` or `std`.
For example:
```
= note: an implementation of `std::ops::Add` might be missing for `std::option::Option<i8>`
```
As mentioned in https://github.com/rust-lang/rust/issues/60497#issuecomment-562665539:
> The note suggesting implementing Add<i8> should only be emitted if Option<i8> were local to the current crate, which it isn't, so in this case it shouldn't be emitted.
(I will use the CI to check tests for me, or my computer will just burn... and running IDEs is not possible on a pile of ashes)
r? @estebank
parser: Simplify treatment of macro variables in `Parser::bump`
Follow-up to https://github.com/rust-lang/rust/pull/69006.
Token normalization for `$ident` and `$lifetime` is merged directly into `bump`.
Special "unknown macro variable" diagnostic for unexpected `$`s is removed as preventing legal code from compiling (as a result `bump` also doesn't call itself recursively anymore and can't make `prev_token` inconsistent).
r? @Centril
parse: fuse associated and extern items up to defaultness
Language changes:
- The grammar of extern `type` aliases is unified with associated ones, and becomes:
```rust
TypeItem = "type" ident generics {":" bounds}? where_clause {"=" type}? ";" ;
```
Semantic restrictions (`ast_validation`) are added to forbid any parameters in `generics`, any bounds in `bounds`, and any predicates in `where_clause`, as well as the presence of a type expression (`= u8`).
(Work still remains to fuse this with free `type` aliases, but this can be done later.)
- The grammar of constants and static items (free, associated, and extern) now permits the absence of an expression, and becomes:
```rust
GlobalItem = {"const" {ident | "_"} | "static" "mut"? ident} {"=" expr}? ";" ;
```
- A semantic restriction is added to enforce the presence of the expression (the body).
- A semantic restriction is added to reject `const _` in associated contexts.
Together, these changes allow us to fuse the grammar of associated items and extern items up to `default`ness which is the main goal of the PR.
-----------------------
We are now very close to fully fusing the entirely of item parsing and their ASTs. To progress further, we must make a decision: should we parse e.g. `default use foo::bar;` and whatnot? Accepting that is likely easiest from a parsing perspective, as it does not require using look-ahead, but it is perhaps not too onerous to only accept it for `fn`s (and all their various qualifiers), `const`s, `static`s, and `type`s.
r? @petrochenkov
recursion_limit parsing handles overflows
This PR adds overflow handling to `#![recursion_limit]` attribute parsing. If parsing the given value results in an `IntErrorKind::Overflow`, then the recursion_limit is set to `usize::max_value()`.
closes#67265
Token normalization is merged directly into `bump`.
Special "unknown macro variable" diagnostic for unexpected `$`s is removed as preventing legal code from compiling.
This prevents accidental dereferences and so forth of the Void type, as well as
cleaning up the error message to reference Opaque rather than the more
complicated PhantomData type.
rustc_session: allow overriding lint level of individual lints from a group
Fixes#58211 and fixesrust-lang/rust-clippy#4778 and fixesrust-lang/rust-clippy#4091
Instead of hard-coding the lint level preferences (from lowest to highest precedence: `lint::Allow -> lint::Warn -> lint::Deny -> lint::Forbid`), the position of the argument in the command line gets taken into account.
Examples:
1. Passing `-D unused -A unused-variables` denies everything in the lint group `unused` **except** `unused-variables` which is explicitly allowed.
1. Passing `-A unused-variables -D unused` denies everything in the lint group `unused` **including** `unused-variables` since the allow is specified before the deny (and therefore overridden by the deny).
This matches the behavior that is already being used when specifying `allow`/`deny` in the source code.
