Tweak binding lifetime suggestion text
We already have a structured suggestion, but the wording made it seem like that wasn't the case.
Fix#65286. r? @varkor
Unify and improve const-prop lints
Add a single helper method for all lints emitted by const-prop, and make that lint different from the CTFE `const_err` lint. Also consistently check overflow on *arithmetic*, not on the assertion, to make behavior the same for debug and release builds.
See [this summary comment](https://github.com/rust-lang/rust/pull/69185#issuecomment-587924754) for details and the latest status.
In terms of lint formatting, I went for what seems to be the better style: have a general message above the code, and then a specific message at the span:
```
error: this arithmetic operation will overflow
--> $DIR/const-err2.rs:21:18
|
LL | let a_i128 = -std::i128::MIN;
| ^^^^^^^^^^^^^^^ attempt to negate with overflow
```
We could also just have the specific message above and no text at the span if that is preferred.
I also converted some of the existing tests to use compiletest revisions, so that the same test can check a bunch of different compile flags.
Fixes https://github.com/rust-lang/rust/issues/69020.
Helps with https://github.com/rust-lang/rust/issues/69021: debug/release are now consistent, but the assoc-const test in that issue still fails (there is a FIXME in the PR for this). The reason seems to be that const-prop notices the assoc const in `T::N << 42` and does not even bother calling `const_prop` on that operation.
Has no effect on https://github.com/rust-lang/rust/issues/61821; the duplication there has entirely different reasons.
#69148 has a proper fix, but it is too big to backport.
This change avoids the ICE by actually emitting an appropriate error. The
output will be duplicated in some cases, but that's better than the
avoidable ICE.
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
