deref patterns: implement implicit deref patterns
This implements implicit deref patterns (per https://hackmd.io/4qDDMcvyQ-GDB089IPcHGg#Implicit-deref-patterns) and adds tests and an unstable book chapter.
Best reviewed commit-by-commit. Overall there's a lot of additions, but a lot of that is tests, documentation, and simple(?) refactoring.
Tracking issue: #87121
r? ``@Nadrieril``
It's a much better name, more consistent with how we name such things.
Also rename `Lifetime::res` as `Lifetime::kind` to match. I suspect this
field used to have the type `LifetimeRes` and then the type was changed
but the field name remained the same.
To accurately reflect that RPITIT assoc items don't have a name. This
avoids the use of `kw::Empty` to mean "no name", which is error prone.
Helps with #137978.
`hir::AssocItem` currently has a boolean `fn_has_self_parameter` field,
which is misplaced, because it's only relevant for associated fns, not
for associated consts or types. This commit moves it (and renames it) to
the `AssocKind::Fn` variant, where it belongs.
This requires introducing a new C-style enum, `AssocTag`, which is like
`AssocKind` but without the fields. This is because `AssocKind` values
are passed to various functions like `find_by_ident_and_kind` to
indicate what kind of associated item should be searched for, and having
to specify `has_self` isn't relevant there.
New methods:
- Predicates `AssocItem::is_fn` and `AssocItem::is_method`.
- `AssocItem::as_tag` which converts `AssocItem::kind` to `AssocTag`.
Removed `find_by_name_and_kinds`, which is unused.
`AssocItem::descr` can now distinguish between methods and associated
functions, which slightly improves some error messages.
Allow drivers to supply a list of extra symbols to intern
Allows adding new symbols as `const`s in external drivers, desirable in Clippy so we can use them in patterns to replace code like 75530e9f72/src/tools/clippy/clippy_lints/src/casts/cast_ptr_alignment.rs (L66)
The Clippy change adds a couple symbols as a demo, the exact `clippy_utils` API and replacing other usages can be done on the Clippy side to minimise sync conflicts
---
try-job: aarch64-gnu
It bugs me when variables of type `Ident` are called `name`. It leads to
silly things like `name.name`. `Ident` variables should be called
`ident`, and `name` should be used for variables of type `Symbol`.
This commit improves things by by doing `s/name/ident/` on a bunch of
`Ident` variables. Not all of them, but a decent chunk.
Add new `PatKind::Missing` variants
To avoid some ugly uses of `kw::Empty` when handling "missing" patterns, e.g. in bare fn tys. Helps with #137978. Details in the individual commits.
r? ``@oli-obk``
In the AST, currently we use `BinOpKind` within `ExprKind::AssignOp` and
`AssocOp::AssignOp`, even though this allows some nonsensical
combinations. E.g. there is no `&&=` operator. Likewise for HIR and
THIR.
This commit introduces `AssignOpKind` which only includes the ten
assignable operators, and uses it in `ExprKind::AssignOp` and
`AssocOp::AssignOp`. (And does similar things for `hir::ExprKind` and
`thir::ExprKind`.) This avoids the possibility of nonsensical
combinations, as seen by the removal of the `bug!` case in
`lang_item_for_binop`.
The commit is mostly plumbing, including:
- Adds an `impl From<AssignOpKind> for BinOpKind` (AST) and `impl
From<AssignOp> for BinOp` (MIR/THIR).
- `BinOpCategory` can now be created from both `BinOpKind` and
`AssignOpKind`.
- Replaces the `IsAssign` type with `Op`, which has more information and
a few methods.
- `suggest_swapping_lhs_and_rhs`: moves the condition to the call site,
it's easier that way.
- `check_expr_inner`: had to factor out some code into a separate
method.
I'm on the fence about whether avoiding the nonsensical combinations is
worth the extra code.
Move methods from `Map` to `TyCtxt`, part 5.
This eliminates all methods on `Map`. Actually removing `Map` will occur in a follow-up PR.
A follow-up to #137504.
r? `@Zalathar`
Various local trait item iteration cleanups
Adding a trait impl for `Foo` unconditionally affected all queries that are interested in a completely independent trait `Bar`. Perf has no effect on this. We probably don't have a good perf test for this tho.
r? `@compiler-errors`
I am unsure about https://github.com/rust-lang/rust/pull/139018/commits/9d05efb66f7b599eeacb5d2456f844fe4768e865 as it doesn't improve anything wrt incremental, because we still do all the checks for valid `Drop` impls, which subsequently will still invoke many queries and basically keep the depgraph the same.
I want to do
9549077a47/compiler/rustc_middle/src/ty/trait_def.rs (L141)
but would leave that to a follow-up PR, this one changes enough things as it is
remove `feature(inline_const_pat)`
Summarizing https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/remove.20feature.28inline_const_pat.29.20and.20shared.20borrowck.
With https://github.com/rust-lang/types-team/issues/129 we will start to borrowck items together with their typeck parent. This is necessary to correctly support opaque types, blocking the new solver and TAIT/ATPIT stabilization with the old one. This means that we cannot really support `inline_const_pat` as they are implemented right now:
- we want to typeck inline consts together with their parent body to allow inference to flow both ways and to allow the const to refer to local regions of its parent.This means we also need to borrowck the inline const together with its parent as that's necessary to properly support opaque types
- we want the inline const pattern to participate in exhaustiveness checking
- to participate in exhaustiveness checking we need to evaluate it, which requires borrowck, which now relies on borrowck of the typeck root, which ends up checking exhaustiveness again. **This is a query cycle**.
There are 4 possible ways to handle this:
- stop typechecking inline const patterns together with their parent
- causes inline const patterns to be different than inline const exprs
- prevents bidirectional inference, we need to either fail to compile `if let const { 1 } = 1u32` or `if let const { 1u32 } = 1`
- region inference for inline consts will be harder, it feels non-trivial to support inline consts referencing local regions from the parent fn
- inline consts no longer participate in exhaustiveness checking. Treat them like `pat if pat == const { .. }` instead. We then only evaluate them after borrowck
- difference between `const { 1 }` and `const FOO: usize = 1; match x { FOO => () }`. This is confusing
- do they carry their weight if they are now just equivalent to using an if-guard
- delay exhaustiveness checking until after borrowck
- should be possible in theory, but is a quite involved change and may have some unexpected challenges
- remove this feature for now
I believe we should either delay exhaustiveness checking or remove the feature entirely. As moving exhaustiveness checking to after borrow checking is quite complex I think the right course of action is to fully remove the feature for now and to add it again once/if we've got that implementation figured out.
`const { .. }`-expressions remain stable. These seem to have been the main motivation for https://github.com/rust-lang/rfcs/issues/2920.
r? types
cc `@rust-lang/types` `@rust-lang/lang` #76001
`ast::Item` has an `ident` field.
- It's always non-empty for these item kinds: `ExternCrate`, `Static`,
`Const`, `Fn`, `Mod`, `TyAlias`, `Enum`, `Struct`, `Union`,
`Trait`, `TraitAlias`, `MacroDef`, `Delegation`.
- It's always empty for these item kinds: `Use`, `ForeignMod`,
`GlobalAsm`, `Impl`, `MacCall`, `DelegationMac`.
There is a similar story for `AssocItemKind` and `ForeignItemKind`.
Some sites that handle items check for an empty ident, some don't. This
is a very C-like way of doing things, but this is Rust, we have sum
types, we can do this properly and never forget to check for the
exceptional case and never YOLO possibly empty identifiers (or possibly
dummy spans) around and hope that things will work out.
The commit is large but it's mostly obvious plumbing work. Some notable
things.
- `ast::Item` got 8 bytes bigger. This could be avoided by boxing the
fields within some of the `ast::ItemKind` variants (specifically:
`Struct`, `Union`, `Enum`). I might do that in a follow-up; this
commit is big enough already.
- For the visitors: `FnKind` no longer needs an `ident` field because
the `Fn` within how has one.
- In the parser, the `ItemInfo` typedef is no longer needed. It was used
in various places to return an `Ident` alongside an `ItemKind`, but
now the `Ident` (if present) is within the `ItemKind`.
- In a few places I renamed identifier variables called `name` (or
`foo_name`) as `ident` (or `foo_ident`), to better match the type, and
because `name` is normally used for `Symbol`s. It's confusing to see
something like `foo_name.name`.
By changing two of the fields to use `Option<Ident>` instead of `Ident`.
As a result, `None` now means "no identifier", which is much clearer
than using an empty identifier.
"Missing" patterns are possible in bare fn types (`fn f(u32)`) and
similar places. Currently these are represented in the AST with
`ast::PatKind::Ident` with no `by_ref`, no `mut`, an empty ident, and no
sub-pattern. This flows through to `{hir,thir}::PatKind::Binding` for
HIR and THIR.
This is a bit nasty. It's very non-obvious, and easy to forget to check
for the exceptional empty identifier case.
This commit adds a new variant, `PatKind::Missing`, to do it properly.
The process I followed:
- Add a `Missing` variant to `{ast,hir,thir}::PatKind`.
- Chang `parse_param_general` to produce `ast::PatKind::Missing`
instead of `ast::PatKind::Missing`.
- Look through `kw::Empty` occurrences to find functions where an
existing empty ident check needs replacing with a `PatKind::Missing`
check: `print_param`, `check_trait_item`, `is_named_param`.
- Add a `PatKind::Missing => unreachable!(),` arm to every exhaustive
match identified by the compiler.
- Find which arms are actually reachable by running the test suite,
changing them to something appropriate, usually by looking at what
would happen to a `PatKind::Ident`/`PatKind::Binding` with no ref, no
`mut`, an empty ident, and no subpattern.
Quite a few of the `unreachable!()` arms were never reached. This makes
sense because `PatKind::Missing` can't happen in every pattern, only
in places like bare fn tys and trait fn decls.
I also tried an alternative approach: modifying `ast::Param::pat` to
hold an `Option<P<Pat>>` instead of a `P<Pat>`, but that quickly turned
into a very large and painful change. Adding `PatKind::Missing` is much
easier.
Rollup of 8 pull requests
Successful merges:
- #138435 (Add support for postfix yield expressions)
- #138685 (Use `Option<Ident>` for lowered param names.)
- #138700 (Suggest `-Whelp` when pass `--print lints` to rustc)
- #138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`)
- #138729 (Clean up `FnCtxt::resolve_coroutine_interiors`)
- #138731 (coverage: Add LLVM plumbing for expansion regions)
- #138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`)
- #138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group)
r? `@ghost`
`@rustbot` modify labels: rollup
expand: Leave traces when expanding `cfg_attr` attributes
Currently `cfg_trace` just disappears during expansion, but after this PR `#[cfg_attr(some tokens)]` will leave a `#[cfg_attr_trace(some tokens)]` attribute instead of itself in AST after expansion (the new attribute is built-in and inert, its inner tokens are the same as in the original attribute).
This trace attribute can then be used by lints or other diagnostics, #133823 has some examples.
Tokens in these trace attributes are set to an empty token stream, so the traces are non-existent for proc macros and cannot affect any user-observable behavior.
This is also a weakness, because if a proc macro processes some code with the trace attributes, they will be lost, so the traces are best effort rather than precise.
The next step is to do the same thing with `cfg` attributes (`#[cfg(TRUE)]` currently remains in both AST and tokens after expanding, it should be replaced with a trace instead).
The idea belongs to `@estebank.`
Use `Option<Ident>` for lowered param names.
Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`.
- If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type.
- If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs.
This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases.
Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in #138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing.
r? ``@compiler-errors``
mir_build: consider privacy when checking for irrefutable patterns
This PR fixes#137999.
Note that, since this makes the compiler reject code that was previously accepted, it will probably need a crater run.
I include a commit that factors out a common code pattern into a helper function, purely because the fact that this was repeated all over the place was bothering me. Let me know if I should split that into a separate PR instead.
Parameter patterns are lowered to an `Ident` by
`lower_fn_params_to_names`, which is used when lowering bare function
types, trait methods, and foreign functions. Currently, there are two
exceptional cases where the lowered param can become an empty `Ident`.
- If the incoming pattern is an empty `Ident`. This occurs if the
parameter is anonymous, e.g. in a bare function type.
- If the incoming pattern is neither an ident nor an underscore. Any
such parameter will have triggered a compile error (hence the
`span_delayed_bug`), but lowering still occurs.
This commit replaces these empty `Ident` results with `None`, which
eliminates a number of `kw::Empty` uses, and makes it impossible to fail
to check for these exceptional cases.
Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It
actually should have been removed in #138482, the precursor to this PR.
That PR changed the lowering of wild patterns to `_` symbols instead of
empty symbols, which made the mentioned underscore check load-bearing.
Rollup of 7 pull requests
Successful merges:
- #138384 (Move `hir::Item::ident` into `hir::ItemKind`.)
- #138508 (Clarify "owned data" in E0515.md)
- #138531 (Store test diffs in job summaries and improve analysis formatting)
- #138533 (Only use `DIST_TRY_BUILD` for try jobs that were not selected explicitly)
- #138556 (Fix ICE: attempted to remap an already remapped filename)
- #138608 (rustc_target: Add target feature constraints for LoongArch)
- #138619 (Flatten `if`s in `rustc_codegen_ssa`)
r? `@ghost`
`@rustbot` modify labels: rollup
`hir::Item` has an `ident` field.
- It's always non-empty for these item kinds: `ExternCrate`, `Static`,
`Const`, `Fn`, `Macro`, `Mod`, `TyAlias`, `Enum`, `Struct`, `Union`,
Trait`, TraitAalis`.
- It's always empty for these item kinds: `ForeignMod`, `GlobalAsm`,
`Impl`.
- For `Use`, it is non-empty for `UseKind::Single` and empty for
`UseKind::{Glob,ListStem}`.
All of this is quite non-obvious; the only documentation is a single
comment saying "The name might be a dummy name in case of anonymous
items". Some sites that handle items check for an empty ident, some
don't. This is a very C-like way of doing things, but this is Rust, we
have sum types, we can do this properly and never forget to check for
the exceptional case and never YOLO possibly empty identifiers (or
possibly dummy spans) around and hope that things will work out.
The commit is large but it's mostly obvious plumbing work. Some notable
things.
- A similar transformation makes sense for `ast::Item`, but this is
already a big change. That can be done later.
- Lots of assertions are added to item lowering to ensure that
identifiers are empty/non-empty as expected. These will be removable
when `ast::Item` is done later.
- `ItemKind::Use` doesn't get an `Ident`, but `UseKind::Single` does.
- `lower_use_tree` is significantly simpler. No more confusing `&mut
Ident` to deal with.
- `ItemKind::ident` is a new method, it returns an `Option<Ident>`. It's
used with `unwrap` in a few places; sometimes it's hard to tell
exactly which item kinds might occur. None of these unwraps fail on
the test suite. It's conceivable that some might fail on alternative
input. We can deal with those if/when they happen.
- In `trait_path` the `find_map`/`if let` is replaced with a loop, and
things end up much clearer that way.
- `named_span` no longer checks for an empty name; instead the call site
now checks for a missing identifier if necessary.
- `maybe_inline_local` doesn't need the `glob` argument, it can be
computed in-function from the `renamed` argument.
- `arbitrary_source_item_ordering::check_mod` had a big `if` statement
that was just getting the ident from the item kinds that had one. It
could be mostly replaced by a single call to the new `ItemKind::ident`
method.
- `ItemKind` grows from 56 to 64 bytes, but `Item` stays the same size,
and that's what matters, because `ItemKind` only occurs within `Item`.
It determines if a function should have any `inline` attributes checked.
For `ItemKind::Fn` it returns true or false depending on the details of
the function; for anything other item kind it returns *true*. This
latter case should instead be *false*. (In the nearby and similar
functions `is_relevant_impl` and `is_relevant_trait` the non-function
cases return false.)
The effect of this is that non-functions are no longer checked. But
rustc already disallows `inline` on any non-function items. So if
anything its a tiny performance win, because that was useless anyway.
Continuing the work from #137350.
Removes the unused methods: `expect_variant`, `expect_field`,
`expect_foreign_item`.
Every method gains a `hir_` prefix.
A check for `#[non_exhaustive]` is often done in combination with
checking whether the type is local to the crate, in a variety of ways.
Create a helper method and standardize on it as the way to check for
this.
It mirrors `ExprKind::Binary`, and contains a `BinOpKind`. This makes
`AssocOp` more like `ExprKind`. Note that the variants removed from
`AssocOp` are all named differently to `BinOpToken`, e.g. `Multiply`
instead of `Mul`, so that's an inconsistency removed.
The commit adds `precedence` and `fixity` methods to `BinOpKind`, and
calls them from the corresponding methods in `AssocOp`. This avoids the
need to create an `AssocOp` from a `BinOpKind` in a bunch of places, and
`AssocOp::from_ast_binop` is removed.
`AssocOp::to_ast_binop` is also no longer needed.
Overall things are shorter and nicer.
