Refactor NLL constraint generation and most of polonius fact generation
As discussed in #118175, NLL "constraint generation" is only about liveness, but currently also contains legacy polonius fact generation. The latter is quite messy, and this PR cleans this up to prepare for its future removal:
- splits polonius fact generation out of NLL constraint generation
- merges NLL constraint generation to its more natural place, liveness
- extracts all of the polonius fact generation from NLLs apart from MIR typeck (as fact generation is somewhat in a single place there already, but should be cleaned up) into its own explicit module, with a single entry point instead of many.
There should be no behavior changes, and tests seem to behave the same as master: without polonius, with legacy polonius, with the in-tree polonius.
I've split everything into smaller logical commits for easier review, as it required quite a bit of code to be split and moved around, but it should all be trivial changes.
r? `@matthewjasper`
Currently we always do this:
```
use rustc_fluent_macro::fluent_messages;
...
fluent_messages! { "./example.ftl" }
```
But there is no need, we can just do this everywhere:
```
rustc_fluent_macro::fluent_messages! { "./example.ftl" }
```
which is shorter.
The `fluent_messages!` macro produces uses of
`crate::{D,Subd}iagnosticMessage`, which means that every crate using
the macro must have this import:
```
use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
```
This commit changes the macro to instead use
`rustc_errors::{D,Subd}iagnosticMessage`, which avoids the need for the
imports.
It lints against features that are inteded to be internal to the
compiler and standard library. Implements MCP #596.
We allow `internal_features` in the standard library and compiler as those
use many features and this _is_ the standard library from the "internal to the compiler and
standard library" after all.
Marking some features as internal wasn't exactly the most scientific approach, I just marked some
mostly obvious features. While there is a categorization in the macro,
it's not very well upheld (should probably be fixed in another PR).
We always pass `-Ainternal_features` in the testsuite
About 400 UI tests and several other tests use internal features.
Instead of throwing the attribute on each one, just always allow them.
There's nothing wrong with testing internal features^^
During borrowck, the `MultiSpan` from a buffered diagnostic is cloned and
used to emit a delayed bug indicating a diagnostic was buffered - when
the buffered diagnostic is translated, then the cloned `MultiSpan` may
contain labels which can only render with the diagnostic's arguments, but
the delayed bug being emitted won't have those arguments. Adds a function
which clones `MultiSpan` without also cloning the contained labels, and
use this function when creating the buffered diagnostic delayed bug.
Signed-off-by: David Wood <david@davidtw.co>
Take MIR dataflow analyses by mutable reference
The main motivation here is any analysis requiring dynamically sized scratch memory to work. One concrete example would be pointer target tracking, where tracking the results of a dereference can result in multiple possible targets. This leads to processing multi-level dereferences requiring the ability to handle a changing number of potential targets per step. A (simplified) function for this would be `fn apply_deref(potential_targets: &mut Vec<Target>)` which would use the scratch space contained in the analysis to send arguments and receive the results.
The alternative to this would be to wrap everything in a `RefCell`, which is what `MaybeRequiresStorage` currently does. This comes with a small perf cost and loses the compiler's guarantee that we don't try to take multiple borrows at the same time.
For the implementation:
* `AnalysisResults` is an unfortunate requirement to avoid an unconstrained type parameter error.
* `CloneAnalysis` could just be `Clone` instead, but that would result in more work than is required to have multiple cursors over the same result set.
* `ResultsVisitor` now takes the results type on in each function as there's no other way to have access to the analysis without cloning it. This could use an associated type rather than a type parameter, but the current approach makes it easier to not care about the type when it's not necessary.
* `MaybeRequiresStorage` now no longer uses a `RefCell`, but the graphviz formatter now does. It could be removed, but that would require even more changes and doesn't really seem necessary.
Expose more information in `get_body_with_borrowck_facts`
Verification tools for Rust such as, for example, Creusot or Prusti would benefit from having access to more information computed by the borrow checker.
As a first step in that direction, #86977 added the `get_body_with_borrowck_facts` API, allowing compiler consumers to obtain a `mir::Body` with accompanying borrow checker information.
At RustVerify 2023, multiple people working on verification tools expressed their need for a more comprehensive API.
While eventually borrow information could be part of Stable MIR, in the meantime, this PR proposes a more limited approach, extending the existing `get_body_with_borrowck_facts` API.
In summary, we propose the following changes:
- Permit obtaining the borrow-checked body without necessarily running Polonius
- Return the `BorrowSet` and the `RegionInferenceContext` in `BodyWithBorrowckFacts`
- Provide a way to compute the `borrows_out_of_scope_at_location` map
- Make some helper methods public
This is similar to #108328 but smaller in scope.
`@smoelius` Do you think these changes would also be sufficient for your needs?
r? `@oli-obk`
cc `@JonasAlaif`
