Use structured suggestions for nonstandard style lints
This PR modifies the lints in the nonstandard_style group to use structured suggestions. Note that there's a bit of tricky span calculation going on for the `crate_name` attribute. It also simplifies the code a bit: I don't think the "fallback" suggestions for these lints can actually be triggered.
Fixes#48103.
Fixes#52414.
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 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.
I also added `// skip-codegen` to each one, to address potential concerns
that this change would otherwise slow down our test suite spending time
generating code for files that are really just meant to be checks of
compiler diagnostics.
(However, I will say: My preference is to not use `// skip-codegen` if
one can avoid it. We can use all the testing of how we drive LLVM that
we can get...)
(Updated post rebase.)
Add regression tests for #55219 and #55241
Also another test where a duplicate-like error appears to have been
suppressed; I'm not 100% sure why this output changes, though I could
imagine that some duplicate suppression is enabled by this PR.
This gives at least some explanation for why a borrow is expected to
last for a certain free region. Also:
* Reports E0373: "closure may outlive the current function" with NLL.
* Special cases the case of returning a reference to (or value
referencing) a local variable or temporary (E0515).
* Special case assigning a reference to a local variable in a closure
to a captured variable.
This commit updates the test output for the updated NLL compare mode
that uses `-Z borrowck=migrate` rather than `-Z borrowck=mir`. The
previous commit changes `compiletest` and this commit only updates
`.nll.stderr` files.
[NLL] Check user types are well-formed
Also contains a change of span for AscribeUserType.
I'm not quite sure if this was what @nikomatsakis was thinking.
Closes#54620
r? @nikomatsakis
Now when a `FnMut` closure is returning a closure that contains a
reference to a captured variable, we provide an error that makes it more
clear what is happening.
Give a special message when the later use is from a call. Use the span
of the callee instead of the whole expression. For conflicting borrow
messages say that the later use is of the first borrow.
We used to apply it repeatedly as we went, relying on the current
value of the `region_bound_pairs_accum` vector. But now we save those
values into a map, so we can just process all the registered region
obligations at the end.
[NLL] Record more infomation on free region constraints in typeck
Changes:
* Makes the span of the MIR return place point to the return type
* Don't try to use a path to a type alias as a path to the adt it aliases (fixes an ICE)
* Don't claim that `self` is declared outside of the function. [see this test](f2995d5b1a (diff-0c9e6b1b204f42129b481df9ce459d44))
* Remove boring/interesting distinction and instead add a `ConstraintCategory` to the constraint.
* Add categories for implicit `Sized` and `Copy` requirements, for closure bounds, for user type annotations and `impl Trait`.
* Don't use the span of the first statement for Locations::All bounds (even if it happens to work on the tests we have)
Future work:
* Fine tuning the heuristic used to choose the place the report the error.
* Reporting multiple places (behind a flag)
* Better closure bounds reporting. This probably requires some discussion.
r? @nikomatsakis
[NLL] Suggest let binding
Closes#49821
Also adds an alternative to `explain_why_borrow_contains_point` that allows changing error messages based on the reason that will be given. This will also be useful for #51026, #51169 and maybe further changes to does not live long enough messages.
