This commit adjusts the span used to label closure return types so that
if the user specifies the return type, i.e. `|_| -> X {}` instead of
`|_| {}`, we correctly highlight all of it and not just the last
character.
[NLL] Clean up handling of type annotations
* Renames (Canonical)?UserTypeAnnotation -> (Canonical)?UserType so that the name CanonicalUserTypeAnnotation is free.
* Keep the inferred type associated to user type annotations in the MIR, so that it can be compared against the annotated type, even when the annotated expression gets removed from the MIR. (#54943)
* Use the inferred type to allow infallible handling of user type projections (#57531)
* Uses revisions for the tests in #56993
* Check the types of `Unevaluated` constants with no annotations (#46702)
* Some drive-by cleanup
Closes#46702Closes#54943Closes#57531Closes#57731
cc #56993 leaving this open to track the underlying issue: we are not running tests with full NLL enabled on CI at the moment
r? @nikomatsakis
Universes
This PR transitions the compiler to use **universes** instead of the **leak-check**. It is marked as [WIP] for a few reasons:
- The diagnostics at present are terrible =)
- This changes the behavior of coherence, regressing some things that used to compile
The goals of this PR at present are:
- To start getting some eyes on the code
- To do a crater run
- To see the full travis results (due to https://github.com/rust-lang/rust/issues/52452, I am not able to run the full test suite locally anymore at present)
The first few commits in the PR are changing how `evaluate` treats regions. We now track whether region comparisons occurred, reverting the "staticized" query approach that @arielb1 put in. The problem with "staticized" queries is that it relied on the leak-check to get higher-ranked things correct, and we are removing the leak-check in this PR series, so that caused problems.
You can see at the end a collection of test updates. Mostly we behave the same but with atrocious diagnostics, but there are a number of cases where we used to error and now no longer do, as well as single case where we used to **not** error but we now do (the coherence-subtyping change).
(Note: it would be possible to do a version of leak-check that propagates universe information and recover the old behavior. I am reluctant to do so because I'd like to leave us room to get more precise -- e.g., I want to eventually handle things like `exists<'a> { for<'b> { if ('a: 'b) { 'a: 'b } } }` which presently the leak-check cannot cope with etc. Also because it seems more consistent to me: most folks I've talked to expect the new behavior and are surprised to learn that binding sites were so significant before when it comes to coherence. One question is, though, to what extent are people relying on this in the wild?)
This commit stops well-formedness checking applying to unreachable code
and therefore stops some of the ICEs that the intended solution taken by
this PR causes.
By disabling these checks, we can land the other fixes and larger
refactors that this PR includes.
This commit moves well-formedness check for the
`UserTypeAnnotation::Ty(..)` case from always running to only when the
code is reachable. This solves the ICE that resulted from
`src/test/ui/issue-54943-1.rs` (a minimal repro of `dropck-eyepatch`
run-pass tests that failed).
The main well-formedness check that was intended to be run despite
unreachable code still is, that being the
`UserTypeAnnotation::TypeOf(..)` case. Before this PR, the other case
wasn't being checked at all.
It is possible to fix this ICE while still always checking
well-formedness for the `UserTypeAnnotation::Ty(..)` case but that
solution will ICE in unreachable code for that case, the diff for
that change [can be found here](0).
[0]: https://gist.github.com/davidtwco/f9751ffd9c0508f7251c0f17adc3af53
This commit adds support for user type annotations in variables declared
using `ref` bindings. When a variable declared using a `ref` binding,
then the `LocalDecl` has the type `&T` where the `&` was introduced by
the `ref` binding but the canonicalized type annotation has only a
`T` since the reference is implicit with the `ref` binding.
Therefore, to support type annotations, the canonicalized type
annotation either needs wrapped in a reference, or the `LocalDecl` type
must have a wrapped reference removed for comparison. It is easier to
remove the outer reference from the `LocalDecl` for the purpose of
comparison, so that is the approach this commit takes.
This commit uses the map introduced by the previous commit to ensure
that types are always checked for well-formedness by the NLL type check.
Previously, without the map introduced by the previous commit, types
would not be checked for well-formedness if the `AscribeUserType`
statement that would trigger that check was removed as unreachable code.
This commit refactors the `UserTypeAnnotation` type to be referred to by
an index within `UserTypeProjection`. `UserTypeAnnotation` is instead
kept in an `IndexVec` within the `Mir` struct.
Further, instead of `UserTypeAnnotation` containing canonicalized types,
it now contains normal types and the entire `UserTypeAnnotation` is
canonicalized. To support this, the type was moved from the `rustc::mir`
module to `rustc::ty` module.
This avoids all sorts of confusing issues with using both `dest_place`
and `self` in the `propagate_call_return` function in the
`BitDenotation` implementation for `Borrows`.
Enum layout optimizations mean that the discriminant of an enum may not
be stored in a tag disjoint from the rest of the fields of the enum.
Stop borrow checking as though they are.
This commit puts a fix in place for the ICE in region naming code so
that it doesn't break the compiler. However, this results in the
diagnostic being poorer as the borrow explanation that was causing the
ICE is not being added - this should be fixed as a follow-up.
Replace usages of `..i + 1` ranges with `..=i`.
Before this change we were using old computer code techniques. After this change we use the new and improved computer code techniques.
