Partial implementation of uniform paths 2.0 to land before beta
Reimplementation of uniform paths using in-scope resolution rather than canaries is a minor breaking change due to stricter future-proofing, so it needs to be landed before beta or backported later.
I hope to implement at least something until beta so we have less to backport.
r? @Mark-Simulacrum
We avoid an ICE by checking for an empty meta-item list before we
index into the meta-items, and leave commentary about where we'd like
to issue unused-attributes lints in the future. Note that empty lint
attributes are already accepted by the stable compiler; generalizing
this to weird reason-only lint attributes seems like the
conservative/consilient generalization.
Vadim Petrochenkov suggested this in review ("an error? just to be
conservative"), and it turns out to be convenient from the
implementer's perspective: in the initial proposed implementation (or
`HEAD~2`, as some might prefer to call it), we were doing an entire
whole iteration over the meta items just to find the reason (before
iterating over them to set the actual lint levels). This way, we can
just peek at the end rather than adding that extra loop (or
restructuring the existing code). The RFC doesn't seem to take a
position on this, and there's some precedent for restricting things to
be at the end of a sequence (we only allow `..` at the end of a struct
pattern, even if it would be possible to let it appear anywhere in the
sequence).
Implement by-value object safety
This PR implements **by-value object safety**, which is part of unsized rvalues #48055. That means, with `#![feature(unsized_locals)]`, you can call a method `fn foo(self, ...)` on trait objects. One aim of this is to enable `Box<FnOnce>` in the near future.
The difficulty here is this: when constructing a vtable for a trait `Foo`, we can't just put the function `<T as Foo>::foo` into the table. If `T` is no larger than `usize`, `self` is usually passed directly. However, as the caller of the vtable doesn't know the concrete `Self` type, we want a variant of `<T as Foo>::foo` where `self` is always passed by reference.
Therefore, when the compiler encounters such a method to be generated as a vtable entry, it produces a newly introduced instance called `InstanceDef::VtableShim(def_id)` (that wraps the original instance). the shim just derefs the receiver and calls the original method. We give different symbol names for the shims by appending `::{{vtable-shim}}` to the symbol path (and also adding vtable-shimness as an ingredient to the symbol hash).
r? @eddyb
This is just for the `reason =` name-value meta-item; the
`#[expect(lint)]` attribute also described in the RFC is a problem for
another day.
The place where we were directly calling `emit()` on a match block
(whose arms returned a mutable reference to a diagnostic-builder) was
admittedly cute, but no longer plausibly natural after adding the
if-let to the end of the `LintSource::Node` arm.
This regards #54503.
NLL: cast causes failure to promote to static
Fixes#55288. See commit messages for more details.
r? @oli-obk
cc @nikomatsakis
cc @pnkfelix
cc @RalfJung
Do not allow moving out of thread local under ast borrowck
AST borrowck failed to prevent moving out of a thread-local static.
This was broken. And it also (sometimes?) caused an ICE during drop elaboration.
Fix#47215Fix#54797
Handle bindings in substructure of patterns with type ascriptions
This attempts to follow the outline described by @nikomatsakis [here](https://github.com/rust-lang/rust/issues/47184#issuecomment-420041056). Its a bit more complicated than expected for two reasons:
1. In general it handles sets of type ascriptions, because such ascriptions can be nested within patterns
2. It has a separate types in the HAIR, `PatternTypeProjections` and `PatternTypeProjection`, which are analogues to the corresponding types in the MIR.
The main reason I added the new HAIR types was because I am worried that the current implementation is inefficent, and asymptotically so: It makes copies of vectors as it descends the patterns, even when those accumulated vectors are never used.
Longer term, I would like to used a linked tree structure for the `PatternTypeProjections` and `PatternTypeProjection`, and save the construction of standalone vectors for the MIR types. I didn't want to block landing this on that hypoethetical revision; but I figured I could at least make the future change easier by differentiating between the two types now.
Oh, one more thing: This doesn't attempt to handle `ref x` (in terms of ensuring that any necessary types are ascribed to `x` in that scenario as well). We should open an issue to investigate supporting that as well. But I didn't want to block this PR on that future work.
Fix#54570
Update the existing NLL `patterns.rs` test accordingly.
includes changes addressing review feedback:
* Added example to docs for `UserTypeProjections` illustrating how we
build up multiple projections when descending into a pattern with
type ascriptions.
* Adapted niko's suggested docs for `UserTypeProjection`.
* Factored out `projection_ty` from more general `projection_ty_core`
(as a drive-by, made its callback an `FnMut`, as I discovered later
that I need that).
* Add note to docs that `PlaceTy.field_ty(..)` does not normalize its result.
* Normalize as we project out `field_ty`.
Rollup of 21 pull requests
Successful merges:
- #54816 (Don't try to promote already promoted out temporaries)
- #54824 (Cleanup rustdoc tests with `@!has` and `@!matches`)
- #54921 (Add line numbers option to rustdoc)
- #55167 (Add a "cheap" mode for `compute_missing_ctors`.)
- #55258 (Fix Rustdoc ICE when checking blanket impls)
- #55264 (Compile the libstd we distribute with -Ccodegen-unit=1)
- #55271 (Unimplement ExactSizeIterator for MIR traversing iterators)
- #55292 (Macro diagnostics tweaks)
- #55298 (Point at macro definition when no rules expect token)
- #55301 (List allowed tokens after macro fragments)
- #55302 (Extend the impl_stable_hash_for! macro for miri.)
- #55325 (Fix link to macros chapter)
- #55343 (rustbuild: fix remap-debuginfo when building a release)
- #55346 (Shrink `Statement`.)
- #55358 (Remove redundant clone (2))
- #55370 (Update mailmap for estebank)
- #55375 (Typo fixes in configure_cmake comments)
- #55378 (rustbuild: use configured linker to build boostrap)
- #55379 (validity: assert that unions are non-empty)
- #55383 (Use `SmallVec` for the queue in `coerce_unsized`.)
- #55391 (bootstrap: clean up a few clippy findings)
rustc: Tweak filenames encoded into metadata
This commit is a fix for #54408 where on nightly right now whenever
generics are inlined the path name listed for the inlined function's
debuginfo is a relative path to the cwd, which surely doesn't exist!
Previously on beta/stable the debuginfo mentioned an absolute path which
still didn't exist, but more predictably didn't exist.
The change between stable/nightly is that nightly is now compiled with
`--remap-path-prefix` to give a deterministic prefix to all
rustc-generated paths in debuginfo. By using `--remap-path-prefix` the
previous logic would recognize that the cwd was remapped, causing the
original relative path name of the standard library to get emitted. If
`--remap-path-prefix` *wasn't* passed in then the logic would create an
absolute path name and then create a new source file entry.
The fix in this commit is to apply the "recreate the source file entry
with an absolute path" logic a bit more aggresively. If the source
file's name was remapped then we don't touch it, but otherwise we always
take the working dir (which may have been remapped) and then join it to
the file to ensure that we process all relative file names as well.
The end result is that the standard library should have an absolute path
for all file names in debuginfo (using our `--remap-path-prefix`
argument) as it does on stable after this patch.
Closes#54408
Report const eval error inside the query
Functional changes: We no longer warn about bad constants embedded in unused types. This relied on being able to report just a warning, not a hard error on that case, which we cannot do any more now that error reporting is consistently centralized.
r? @RalfJung
fixes#53561
Fix Rustdoc ICE when checking blanket impls
Fixes#55001, #54744
Previously, SelectionContext would unconditionally cache the selection
result for an obligation. This worked fine for most users of
SelectionContext, but it caused an issue when used by Rustdoc's blanket
impl finder.
The issue occured when SelectionContext chose a ParamCandidate which
contained inference variables. Since inference variables can change
between calls to select(), it's not safe to cache the selection result -
the chosen candidate might not be applicable for future results, leading
to an ICE when we try to run confirmation.
This commit prevents SelectionContext from caching any ParamCandidate
that contains inference variables. This should always be completely
safe, as trait selection should never depend on a particular result
being cached.
I've also added some extra debug!() statements, which I found helpful in
tracking down this bug.
Rollup of 22 pull requests
Successful merges:
- #53507 (Add doc for impl From for Waker)
- #53931 (Gradually expanding libstd's keyword documentation)
- #54965 (update tcp stream documentation)
- #54977 (Accept `Option<Box<$t:ty>>` in macro argument)
- #55138 (in which unused-parens suggestions heed what the user actually wrote)
- #55173 (Suggest appropriate syntax on missing lifetime specifier in return type)
- #55200 (Documents `From` implementations for `Stdio`)
- #55245 (submodules: update clippy from 5afdf8b7 to b1d03437)
- #55247 (Clarified code example in char primitive doc)
- #55251 (Fix a typo in the documentation of RangeInclusive)
- #55253 (only issue "variant of the expected type" suggestion for enums)
- #55254 (Correct trailing ellipsis in name_from_pat)
- #55269 (fix typos in various places)
- #55282 (Remove redundant clone)
- #55285 (Do some copy editing on the release notes)
- #55291 (Update stdsimd submodule)
- #55296 (Set RUST_BACKTRACE=0 for rustdoc-ui/failed-doctest-output.rs)
- #55306 (Regression test for #54478.)
- #55328 (Fix doc for new copysign functions)
- #55340 (Operands no longer appear in places)
- #55345 (Remove is_null)
- #55348 (Update RELEASES.md after destabilization of non_modrs_mods)
Failed merges:
r? @ghost
Regression test for #54478.
This is a regression test for #54478.
I confirmed that it fails on:
rustdoc 1.30.0-beta.12 (96a229824 2018-10-04)
and passes on:
rustdoc 1.31.0-nightly (f99911a4a 2018-10-23)
Fix#54478
Set RUST_BACKTRACE=0 for rustdoc-ui/failed-doctest-output.rs
This UI test is sensitive to backtrace output, so it should make sure
that backtraces are not enabled by the environment.
