Generic Associated Types Parsing & Name Resolution
Hi!
This PR adds parsing for generic associated types! 🎉🎉🎉
Tracking Issue: #44265
## Notes For Reviewers
* [x] I still need to add the stdout and stderr files to my ui tests. It takes me a *long* time to compile the compiler locally, so I'm going to add this as soon as possible in the next day or so.
* [ ] My current ui tests aren't very good or very thorough. I'm reusing the `parse_generics` and `parse_where_clause` methods from elsewhere in the parser, so my changes work without being particularly complex. I'm not sure if I should duplicate all of the generics test cases for generic associated types. It might actually be appropriate to duplicate everything here, since we don't want to rely on an implementation detail in case it changes in the future. If you think so too, I'll adapt all of the generics test cases into the generic associated types test cases.
* [ ] There is still more work required to make the run-pass tests pass here. In particular, we need to make the following errors disappear:
```
error[E0110]: lifetime parameters are not allowed on this type
--> ./src/test/run-pass/rfc1598-generic-associated-types/streaming_iterator.rs:23:41
|
23 | bar: <T as StreamingIterator>::Item<'static>,
| ^^^^^^^ lifetime parameter not allowed on this type
```
```
error[E0261]: use of undeclared lifetime name `'a`
--> ./src/test/run-pass/rfc1598-generic-associated-types/iterable.rs:15:47
|
15 | type Iter<'a>: Iterator<Item = Self::Item<'a>>;
| ^^ undeclared lifetime
```
There is a FIXME comment in streaming_iterator. If you uncomment that line, you get the following:
```
error: expected one of `!`, `+`, `,`, `::`, or `>`, found `=`
--> ./src/test/run-pass/rfc1598-generic-associated-types/streaming_iterator.rs:29:45
|
29 | fn foo<T: for<'a> StreamingIterator<Item<'a>=&'a [i32]>>(iter: T) { /* ... */ }
| ^ expected one of `!`, `+`, `,`, `::`, or `>` here
```
r? @nikomatsakis
make coercions to `!` in unreachable code a hard error
This was added to cover up a lazy extra semicolon in #35849, but does
not actually make sense. This is removed as a part of the stabilization
of `never_type`.
This was added to cover up a lazy extra semicolon in #35849, but does
not actually make sense. This is removed as a part of the stabilization
of `never_type`.
This commit allocates a builder to running wasm32 tests on Travis. Not all test
suites pass right now so this is starting out with just the run-pass and the
libcore test suites. This'll hopefully give us a pretty broad set of coverage
for integration in rustc itself as well as a somewhat broad coverage of the llvm
backend itself through integration/unit tests.
Mir Borrowck: Parity with Ast for E0384 (Cannot assign twice to immutable)
- Closes#45199
- Don't allow assigning to dropped immutable variables
- Show the "first assignment" note on the first assignment that can actually come before the second assignment.
- Make "first assignment" notes point to function parameters if needed.
- Don't show a "first assignment" note if the first and second assignment have the same span (in a loop). This matches ast borrowck for now, but maybe this we should add "in previous loop iteration" as with some other borrowck errors. (Commit 2)
- Use revisions to check mir borrowck for the existing tests for this error. (Commit 3)
~~Still working on a less ad-hoc way to get 'first assignment' notes to show on the correct assignment. Also need to check mutating function arguments.~~ Now using a new dataflow pass.
Make accesses to fields of packed structs unsafe
To handle packed structs with destructors (which you'll think are a rare
case, but the `#[repr(packed)] struct Packed<T>(T);` pattern is
ever-popular, which requires handling packed structs with destructors to
avoid monomorphization-time errors), drops of subfields of packed
structs should drop a local move of the field instead of the original
one.
That's it, I think I'll use a strategy suggested by @Zoxc, where this mir
```
drop(packed_struct.field)
```
is replaced by
```
tmp0 = packed_struct.field;
drop tmp0
```
cc #27060 - this should deal with that issue after codegen of drop glue
is updated.
The new errors need to be changed to future-compatibility warnings, but
I'll rather do a crater run first with them as errors to assess the
impact.
cc @eddyb
Things which still need to be done for this:
- [ ] - handle `repr(packed)` structs in `derive` the same way I did in `Span`, and use derive there again
- [ ] - implement the "fix packed drops" pass and call it in both the MIR shim and validated MIR pipelines
- [ ] - do a crater run
- [ ] - convert the errors to compatibility warnings
Fix the derive implementation for repr(packed) structs to move the
fields out instead of calling functions on references to each subfield.
That's it, `#[derive(PartialEq)]` on a packed struct now does:
```Rust
fn eq(&self, other: &Self) {
let field_0 = self.0;
let other_field_0 = other.0;
&field_0 == &other_field_0
}
```
Instead of
```Rust
fn eq(&self, other: &Self) {
let ref field_0 = self.0;
let ref other_field_0 = other.0;
&*field_0 == &*other_field_0
}
```
Taking (unaligned) references to each subfield is undefined, unsound and
is an error with MIR effectck, so it had to be prevented. This causes
a borrowck error when a `repr(packed)` struct has a non-Copy field (and
therefore is a [breaking-change]), but I don't see a sound way to avoid
that error.
To handle packed structs with destructors (which you'll think are a rare
case, but the `#[repr(packed)] struct Packed<T>(T);` pattern is
ever-popular, which requires handling packed structs with destructors to
avoid monomorphization-time errors), drops of subfields of packed
structs should drop a local move of the field instead of the original
one.
cc #27060 - this should deal with that issue after codegen of drop glue
is updated.
The new errors need to be changed to future-compatibility warnings, but
I'll rather do a crater run first with them as errors to assess the
impact.
typeck aggregate rvalues in MIR type checker
This branch is an attempt to land content by @spastorino and @Nashenas88 that was initially landed on nll-master while we waited for https://github.com/rust-lang/rust/pull/45825 to land.
The biggest change it contains is that it extends the MIR type-checker to also type-check MIR aggregate rvalues (at least partially). Specifically, it checks that the operands provided for each field have the right type.
It does not yet check that their well-formedness predicates are met. That is https://github.com/rust-lang/rust/issues/45827. It also does not check other kinds of rvalues (that is https://github.com/rust-lang/rust/issues/45959). @spastorino is working on those issues now.
r? @arielb1
Implement in-band lifetime bindings
TODO (perhaps in a future PR): Should we ban explicit instantiation of generics with in-band lifetimes, or is it uncontroversial to just append them to the end of the lifetimes list?
Fixes#46042, cc #44524.
r? @nikomatsakis
Use the proper term when using non-existing variant
When using a non-existing variant, function or associated item, refer to
the proper term, instead of defaulting to "associated item" in
diagnostics.
Fix#28972.
```
error[E0599]: no variant named `Quux` found for type `Foo` in the current scope
--> file.rs:7:9
|
7 | Foo::Quux(..) =>(),
| ^^^^^^^^^^^^^
```
rustdoc: include external files in documentation (RFC 1990)
Part of https://github.com/rust-lang/rfcs/pull/1990 (needs work on the error reporting, which i'm deferring to after this initial PR)
cc #44732
Also fixes#42760, because the prep work for the error reporting made it easy to fix that at the same time.
MIR-borrowck: Some minor fixes
- Remove parens when printing dereference (fix#45185)
- Change argument type of `autoderef` to `bool`
- Change argument type of `field_index` to `Field`
move closure kind, signature into `ClosureSubsts`
Instead of using side-tables, store the closure-kind and signature in the substitutions themselves. This has two key effects:
- It means that the closure's type changes as inference finds out more things, which is very nice.
- As a result, it avoids the need for the `freshen_closure_like` code (though we still use it for generators).
- It avoids cyclic closures calls.
- These were never meant to be supported, precisely because they make a lot of the fancy inference that we do much more complicated. However, due to an oversight, it was previously possible -- if challenging -- to create a setup where a closure *directly* called itself (see e.g. #21410).
We have to see what the effect of this change is, though. Needs a crater run. Marking as [WIP] until that has been assessed.
r? @arielb1
dead code lint to say "never constructed" for variants
As reported in #19140, #44083, and #44565, some users were confused when
the dead-code lint reported an enum variant to be "unused" when it was
matched on (but not constructed). This wording change makes it clearer
that the lint is in fact checking for construction.
We continue to say "used" for all other items (it's tempting to say
"called" for functions and methods, but this turns out not to be
correct: functions can be passed as arguments and the dead-code lint
isn't special-casing that or anything).
Resolves#19140.
r? @pnkfelix
