Reverse folder hierarchy
#91318 introduced a trait for infallible folders distinct from the fallible version. For some reason (completely unfathomable to me now that I look at it with fresh eyes), the infallible trait was a supertrait of the fallible one: that is, all fallible folders were required to also be infallible. Moreover the `Error` associated type was defined on the infallible trait! It's so absurd that it has me questioning whether I was entirely sane.
This trait reverses the hierarchy, so that the fallible trait is a supertrait of the infallible one: all infallible folders are required to also be fallible (which is a trivial blanket implementation). This of course makes much more sense! It also enables the `Error` associated type to sit on the fallible trait, where it sensibly belongs.
There is one downside however: folders expose a `tcx` accessor method. Since the blanket fallible implementation for infallible folders only has access to a generic `F: TypeFolder`, we need that trait to expose such an accessor to which we can delegate. Alternatively it's possible to extract that accessor into a separate `HasTcx` trait (or similar) that would then be a supertrait of both the fallible and infallible folder traits: this would ensure that there's only one unambiguous `tcx` method, at the cost of a little additional boilerplate. If desired, I can submit that as a separate PR.
r? ````@jackh726````
Improve suggestion for calling fn-like expr on type mismatch
1.) Suggest calling values of with RPIT types (and probably TAIT) when we expect `Ty` and have `impl Fn() -> Ty`
2.) Suggest calling closures even when they're not assigned to a local variable first
3.) Drive-by fix of a pretty-printing bug (`impl Fn()-> Ty` => `impl Fn() -> Ty`)
r? ```@estebank```
Remove (transitive) reliance on sorting by DefId in pretty-printer
This moves us a step closer to removing the `PartialOrd/`Ord` impls
for `DefId`. See #90317
implement `iter_projections` function on `PlaceRef`
this makes the api more flexible. the original function now calls the PlaceRef
version to avoid duplicating the code.
Point at return expression for RPIT-related error
Certainly this needs some diagnostic refining, but I wanted to show that it was possible first and foremost. Not sure if this is the right approach. Open to feedback.
Fixes#80583
#91318 introduced a trait for infallible folders distinct from the fallible version. For some reason (completely unfathomable to me now that I look at it with fresh eyes), the infallible trait was a supertrait of the fallible one: that is, all fallible folders were required to also be infallible. Moreover the `Error` associated type was defined on the infallible trait! It's so absurd that it has me questioning whether I was entirely sane.
This trait reverses the hierarchy, so that the fallible trait is a supertrait of the infallible one: all infallible folders are required to also be fallible (which is a trivial blanket implementation). This of course makes much more sense! It also enables the `Error` associated type to sit on the fallible trait, where it sensibly belongs.
There is one downside however: folders expose a `tcx` accessor method. Since the blanket fallible implementation for infallible folders only has access to a generic `F: TypeFolder`, we need that trait to expose such an accessor to which we can delegate. Alternatively it's possible to extract that accessor into a separate `HasTcx` trait (or similar) that would then be a supertrait of both the fallible and infallible folder traits: this would ensure that there's only one unambiguous `tcx` method, at the cost of a little additional boilerplate. If desired, I can submit that as a separate PR.
r? @jackh726
`try_fold_unevaluated` for infallible folders
#97447 added folding of unevaluated constants, but did not include an override of the default (fallible) operation in the blanket impl of `FallibleTypeFolder` for infallible folders. Here we provide that missing override.
r? ```@nnethercote```
Remove dereferencing of Box from codegen
Through #94043, #94414, #94873, and #95328, I've been fixing issues caused by Box being treated like a pointer when it is not a pointer. However, these PRs just introduced special cases for Box. This PR removes those special cases and instead transforms a deref of Box into a deref of the pointer it contains.
Hopefully, this is the end of the Box<T, A> ICEs.
Don't omit comma when suggesting wildcard arm after macro expr
* Also adds `Span::eq_ctxt` to consolidate the various usages of `span.ctxt() == other.ctxt()`
* Also fixes an unhygenic usage of spans which caused the suggestion to render weirdly when we had one arm match in a macro
* Also always suggests a comma (i.e. even after a block) if we're rendering a wildcard arm in a single-line match (looks prettier 🌹)
Fixes#94866
#97447 added folding of unevaluated constants, but did not include an override of the default (fallible) operation in the blanket impl of `FallibleTypeFolder` for infallible folders. Here we provide that missing override.
r? @nnethercote
Rollup of 5 pull requests
Successful merges:
- #98105 (rustdoc: remove tuple link on round braces)
- #98136 (Rename `impl_constness` to `constness`)
- #98146 (Remove --memory-init-file flag when linking with Emscripten)
- #98219 (Skip late bound regions in GATSubstCollector)
- #98233 (Remove accidental uses of `&A: Allocator`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Rename `impl_constness` to `constness`
The current code is a basis for `is_const_fn_raw`, and `impl_constness`
is no longer a valid name, which is previously used for determining the
constness of impls, and not items in general.
r? `@oli-obk`
ctfe: limit hashing of big const allocations when interning
Const allocations are only hashed for interning. However, they can be large, making the hashing expensive especially since it uses `FxHash`: it's better suited to short keys, not potentially big buffers like the actual bytes of allocation and the associated 1/8th sized `InitMask`.
We can partially hash these fields when they're large, hashing the length, and head and tail of these buffers, to
limit possible collisions while avoiding most of the hashing work.
r? `@ghost`
Big const allocations hash a large amount of data for interning:
the whole bytes buffer, and the 1/8th sized initmask, with FxHash.
This hash function is made for shorter keys.
This only hashes the length, and head and tail of these buffers, to
limit possible collisions while avoiding most of the hashing work.
Support lint expectations for `--force-warn` lints (RFC 2383)
Rustc has a `--force-warn` flag, which overrides lint level attributes and forces the diagnostics to always be warn. This means, that for lint expectations, the diagnostic can't be suppressed as usual. This also means that the expectation would not be fulfilled, even if a lint had been triggered in the expected scope.
This PR now also tracks the expectation ID in the `ForceWarn` level. I've also made some minor adjustments, to possibly catch more bugs and make the whole implementation more robust.
This will probably conflict with https://github.com/rust-lang/rust/pull/97718. That PR should ideally be reviewed and merged first. The conflict itself will be trivial to fix.
---
r? `@wesleywiser`
cc: `@flip1995` since you've helped with the initial review and also discussed this topic with me. 🙃
Follow-up of: https://github.com/rust-lang/rust/pull/87835
Issue: https://github.com/rust-lang/rust/issues/85549
Yeah, and that's it.
The current code is a basis for `is_const_fn_raw`, and `impl_constness`
is no longer a valid name, which is previously used for determining the
constness of impls, and not items in general.
Make `ExprKind::Closure` a struct variant.
Simple refactor since we both need it to introduce additional fields in `ExprKind::Closure`.
r? ``@Aaron1011``
Rename rustc_serialize::opaque::Encoder as MemEncoder.
This avoids the name clash with `rustc_serialize::Encoder` (a trait),
and allows lots qualifiers to be removed and imports to be simplified
(e.g. fewer `as` imports).
(This was previously merged as commit 5 in #94732 and then was reverted
in #97905 because of a perf regression caused by commit 4 in #94732.)
r? ```@bjorn3```
This avoids the name clash with `rustc_serialize::Encoder` (a trait),
and allows lots qualifiers to be removed and imports to be simplified
(e.g. fewer `as` imports).
(This was previously merged as commit 5 in #94732 and then was reverted
in #97905 because of a perf regression caused by commit 4 in #94732.)
And likewise for the `Const::val` method.
Because its type is called `ConstKind`. Also `val` is a confusing name
because `ConstKind` is an enum with seven variants, one of which is
called `Value`. Also, this gives consistency with `TyS` and `PredicateS`
which have `kind` fields.
The commit also renames a few `Const` variables from `val` to `c`, to
avoid confusion with the `ConstKind::Value` variant.
Remove unnecessary `to_string` and `String::new`
73fa217bc1 changed the type of the `suggestion` argument to `impl ToString`. This patch removes unnecessary `to_string` and `String::new`.
cc: `````@davidtwco`````
Handle `def_ident_span` like `def_span`.
`def_ident_span` had an ad-hoc status in the compiler.
This PR refactors it to be a first-class citizen like `def_span`:
- it gets encoded in the main metadata loop, instead of the visitor;
- its implementation is updated to mirror the one of `def_span`.
We do not remove the `Option` in the return type, since some items do not have an ident, AnonConsts for instance.
Wrap `HirId`s of locals into `LocalVarId`s for THIR nodes
This is the first effort to decouple `HirId`s from THIR. `HirId` is not very relevant in building THIR and MIR.
Based on the changeset, I think there are a few other pending refactoring that we could perform after this, in case we want to eliminate use of `HirId` in THIR.
- `TypeckResults::closure_min_captures` could be remapped from the variable `HirId`s to `LocalVarId` while the THIR is getting built.
- Use of `ScopeTree::var_scope` could be eliminated as well, since we will consider deprecating `ScopeTree` in the future.
Revert part of #94372 to improve performance
#94732 was supposed to give small but widespread performance improvements, as judged from three per-merge performance runs. But the performance run that occurred after merging included a roughly equal number of improvements and regressions, for unclear reasons.
This PR is for a test run reverting those changes, to see what happens.
r? `@ghost`
use precise spans for recursive const evaluation
This fixes https://github.com/rust-lang/rust/issues/73283 by using a `TyCtxtAt` with a more precise span when the interpreter recursively calls itself. Hopefully such calls are sufficiently rare that this does not cost us too much performance.
(In theory, cycles can also arise through layout computation, as layout can depend on consts -- but layout computation happens all the time so we'd have to do something to not make this terrible for performance.)
it feels arbitrary to have `Ty` and `Const` directly
in that module and to not have `GenericArg` and
`GenericArgKind` there. Writing `ty::GenericArg`
can also feel clearer than importing it. Using
`ty::subst::GenericArg` however is ugly.
This avoids the name clash with `rustc_serialize::Encoder` (a trait),
and allows lots qualifiers to be removed and imports to be simplified
(e.g. fewer `as` imports).
This commit makes type folding more like the way chalk does it.
Currently, `TypeFoldable` has `fold_with` and `super_fold_with` methods.
- `fold_with` is the standard entry point, and defaults to calling
`super_fold_with`.
- `super_fold_with` does the actual work of traversing a type.
- For a few types of interest (`Ty`, `Region`, etc.) `fold_with` instead
calls into a `TypeFolder`, which can then call back into
`super_fold_with`.
With the new approach, `TypeFoldable` has `fold_with` and
`TypeSuperFoldable` has `super_fold_with`.
- `fold_with` is still the standard entry point, *and* it does the
actual work of traversing a type, for all types except types of
interest.
- `super_fold_with` is only implemented for the types of interest.
Benefits of the new model.
- I find it easier to understand. The distinction between types of
interest and other types is clearer, and `super_fold_with` doesn't
exist for most types.
- With the current model is easy to get confused and implement a
`super_fold_with` method that should be left defaulted. (Some of the
precursor commits fixed such cases.)
- With the current model it's easy to call `super_fold_with` within
`TypeFolder` impls where `fold_with` should be called. The new
approach makes this mistake impossible, and this commit fixes a number
of such cases.
- It's potentially faster, because it avoids the `fold_with` ->
`super_fold_with` call in all cases except types of interest. A lot of
the time the compile would inline those away, but not necessarily
always.
We already have `visit_unevaluated`, so this improves consistency.
Also, define `TypeFoldable for Unevaluated<'tcx, ()>` in terms of
`TypeFoldable for Unevaluated<'tcx>`, which is neater.
Because `TypeFoldable::try_fold_mir_const` exists, and even though
`visit_mir_const` isn't needed right now, the consistency makes the code
easier to understand.
There are two impls of the `Encoder` trait: `opaque::Encoder` and
`opaque::FileEncoder`. The former encodes into memory and is infallible, the
latter writes to file and is fallible.
Currently, standard `Result`/`?`/`unwrap` error handling is used, but this is a
bit verbose and has non-trivial cost, which is annoying given how rare failures
are (especially in the infallible `opaque::Encoder` case).
This commit changes how `Encoder` fallibility is handled. All the `emit_*`
methods are now infallible. `opaque::Encoder` requires no great changes for
this. `opaque::FileEncoder` now implements a delayed error handling strategy.
If a failure occurs, it records this via the `res` field, and all subsequent
encoding operations are skipped if `res` indicates an error has occurred. Once
encoding is complete, the new `finish` method is called, which returns a
`Result`. In other words, there is now a single `Result`-producing method
instead of many of them.
This has very little effect on how any file errors are reported if
`opaque::FileEncoder` has any failures.
Much of this commit is boring mechanical changes, removing `Result` return
values and `?` or `unwrap` from expressions. The more interesting parts are as
follows.
- serialize.rs: The `Encoder` trait gains an `Ok` associated type. The
`into_inner` method is changed into `finish`, which returns
`Result<Vec<u8>, !>`.
- opaque.rs: The `FileEncoder` adopts the delayed error handling
strategy. Its `Ok` type is a `usize`, returning the number of bytes
written, replacing previous uses of `FileEncoder::position`.
- Various methods that take an encoder now consume it, rather than being
passed a mutable reference, e.g. `serialize_query_result_cache`.
