Fix use placement for suggestions near main.
This fixes an edge case for the suggestion to add a `use`. When running with `--test`, the `main` function will be annotated with an `#[allow(dead_code)]` attribute. The `UsePlacementFinder` would end up using the dummy span of that synthetic attribute. If there are top-level inner attributes, this would place the `use` in the wrong position. The solution here is to ignore attributes with dummy spans.
In the process of working on this, I discovered that the `use_suggestion_placement` test was broken. `UsePlacementFinder` is unaware of active attributes. Attributes like `#[derive]` don't exist in the AST since they are removed. Fixing that is difficult, since the AST does not retain enough information. I considered trying to place the `use` towards the top of the module after any `extern crate` items, but I couldn't find a way to get a span for the start of a module block (the `mod` span starts at the `mod` keyword, and it seems tricky to find the spot just after the opening bracket and past inner attributes). For now, I just put some comments about the issue. This appears to have been a known issue in #44215 where the test for it was introduced, and the fix seemed to be deferred to later.
Don't use a generator for BoxedResolver
The generator is non-trivial and requires unsafe code anyway. Using regular unsafe code without a generator is much easier to follow.
Based on #85810 as it touches rustc_interface too.
Disallow shadowing const parameters
This pull request fixes#85348. Trying to shadow a `const` parameter as follows:
```rust
fn foo<const N: i32>() {
let N @ _ = 0;
}
```
currently causes an ICE. With my changes, I get:
```
error[E0530]: let bindings cannot shadow const parameters
--> test.rs:2:9
|
1 | fn foo<const N: i32>() {
| - the const parameter `N` is defined here
2 | let N @ _ = 0;
| ^ cannot be named the same as a const parameter
error: aborting due to previous error
```
This is the same error you get when trying to shadow a constant:
```rust
const N: i32 = 0;
let N @ _ = 0;
```
```
error[E0530]: let bindings cannot shadow constants
--> src/lib.rs:3:5
|
2 | const N: i32 = 0;
| ----------------- the constant `N` is defined here
3 | let N @ _ = 0;
| ^ cannot be named the same as a constant
error: aborting due to previous error
```
The reason for disallowing shadowing in both cases is described [here](https://github.com/rust-lang/rust/issues/33118#issuecomment-233962221) (the comment there only talks about constants, but the same reasoning applies to `const` parameters).
Fix diagnostic for cross crate private tuple struct constructors
Fixes#78708.
There was already some limited support for certain cross-crate scenarios but that didn't handle a tuple struct rexported from an inner module for example (e.g. the NonZero* types as seen in #85049).
```Rust
➜ cat bug.rs
fn main() {
let _x = std::num::NonZeroU32(12);
let n = std::num::NonZeroU32::new(1).unwrap();
match n {
std::num::NonZeroU32(i) => {},
}
}
```
**Before:**
<details>
```Rust
➜ rustc +nightly bug.rs
error[E0423]: expected function, tuple struct or tuple variant, found struct `std::num::NonZeroU32`
--> bug.rs:2:14
|
2 | let _x = std::num::NonZeroU32(12);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: use struct literal syntax instead: `std::num::NonZeroU32 { 0: val }`
|
::: /home/luqman/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/nonzero.rs:148:1
[snip]
error[E0532]: expected tuple struct or tuple variant, found struct `std::num::NonZeroU32`
--> bug.rs:5:9
|
5 | std::num::NonZeroU32(i) => {},
| ^^^^^^^^^^^^^^^^^^^^^^^ help: use struct pattern syntax instead: `std::num::NonZeroU32 { 0 }`
|
::: /home/luqman/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/nonzero.rs:148:1
[snip]
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0423, E0532.
For more information about an error, try `rustc --explain E0423`.
```
</details>
**After:**
<details>
```Rust
➜ /rust/build/x86_64-unknown-linux-gnu/stage1/bin/rustc bug.rs
error[E0423]: cannot initialize a tuple struct which contains private fields
--> bug.rs:2:14
|
2 | let _x = std::num::NonZeroU32(12);
| ^^^^^^^^^^^^^^^^^^^^
|
note: constructor is not visible here due to private fields
--> /rust/library/core/src/num/nonzero.rs:148:1
[snip]
error[E0532]: cannot match against a tuple struct which contains private fields
--> bug.rs:5:9
|
5 | std::num::NonZeroU32(i) => {},
| ^^^^^^^^^^^^^^^^^^^^
|
note: constructor is not visible here due to private fields
--> bug.rs:5:30
|
5 | std::num::NonZeroU32(i) => {},
| ^ private field
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0423, E0532.
For more information about an error, try `rustc --explain E0423`.
```
</details>
One question is if we should only collect the needed info for the cross-crate case after encountering an error instead of always doing it. Perf run perhaps to gauge the impact.
Suggest adding a type parameter for impls
Add a new suggestion upon encountering an unknown type in a `impl` that suggests adding a new type parameter. This diagnostic suggests to add a new type parameter even though it may be a const parameter, however after adding the parameter and running rustc again a follow up error steers the user to change the type parameter to a const parameter.
```rust
struct X<const C: ()>();
impl X<C> {}
```
suggests
```
error[E0412]: cannot find type `C` in this scope
--> bar.rs:2:8
|
1 | struct X<const C: ()>();
| ------------------------ similarly named struct `X` defined here
2 | impl X<C> {}
| ^
|
help: a struct with a similar name exists
|
2 | impl X<X> {}
| ^
help: you might be missing a type parameter
|
2 | impl<C> X<C> {}
| ^^^
```
After adding a type parameter the code now becomes
```rust
struct X<const C: ()>();
impl<C> X<C> {}
```
and the error now fully steers the user towards the correct code
```
error[E0747]: type provided when a constant was expected
--> bar.rs:2:11
|
2 | impl<C> X<C> {}
| ^
|
help: consider changing this type parameter to be a `const` generic
|
2 | impl<const C: ()> X<C> {}
| ^^^^^^^^^^^
```
r? `@estebank`
Somewhat related #84946
Handle more span edge cases in generics diagnostics
This should fix invalid suggestions that didn't account for empty bracket pairs (`<>`) or type bindings.
Fix `--remap-path-prefix` not correctly remapping `rust-src` component paths and unify handling of path mapping with virtualized paths
This PR fixes#73167 ("Binaries end up containing path to the rust-src component despite `--remap-path-prefix`") by preventing real local filesystem paths from reaching compilation output if the path is supposed to be remapped.
`RealFileName::Named` introduced in #72767 is now renamed as `LocalPath`, because this variant wraps a (most likely) valid local filesystem path.
`RealFileName::Devirtualized` is renamed as `Remapped` to be used for remapped path from a real path via `--remap-path-prefix` argument, as well as real path inferred from a virtualized (during compiler bootstrapping) `/rustc/...` path. The `local_path` field is now an `Option<PathBuf>`, as it will be set to `None` before serialisation, so it never reaches any build output. Attempting to serialise a non-`None` `local_path` will cause an assertion faliure.
When a path is remapped, a `RealFileName::Remapped` variant is created. The original path is preserved in `local_path` field and the remapped path is saved in `virtual_name` field. Previously, the `local_path` is directly modified which goes against its purpose of "suitable for reading from the file system on the local host".
`rustc_span::SourceFile`'s fields `unmapped_path` (introduced by #44940) and `name_was_remapped` (introduced by #41508 when `--remap-path-prefix` feature originally added) are removed, as these two pieces of information can be inferred from the `name` field: if it's anything other than a `FileName::Real(_)`, or if it is a `FileName::Real(RealFileName::LocalPath(_))`, then clearly `name_was_remapped` would've been false and `unmapped_path` would've been `None`. If it is a `FileName::Real(RealFileName::Remapped{local_path, virtual_name})`, then `name_was_remapped` would've been true and `unmapped_path` would've been `Some(local_path)`.
cc `@eddyb` who implemented `/rustc/...` path devirtualisation
This PR implements span quoting, allowing proc-macros to produce spans
pointing *into their own crate*. This is used by the unstable
`proc_macro::quote!` macro, allowing us to get error messages like this:
```
error[E0412]: cannot find type `MissingType` in this scope
--> $DIR/auxiliary/span-from-proc-macro.rs:37:20
|
LL | pub fn error_from_attribute(_args: TokenStream, _input: TokenStream) -> TokenStream {
| ----------------------------------------------------------------------------------- in this expansion of procedural macro `#[error_from_attribute]`
...
LL | field: MissingType
| ^^^^^^^^^^^ not found in this scope
|
::: $DIR/span-from-proc-macro.rs:8:1
|
LL | #[error_from_attribute]
| ----------------------- in this macro invocation
```
Here, `MissingType` occurs inside the implementation of the proc-macro
`#[error_from_attribute]`. Previosuly, this would always result in a
span pointing at `#[error_from_attribute]`
This will make many proc-macro-related error message much more useful -
when a proc-macro generates code containing an error, users will get an
error message pointing directly at that code (within the macro
definition), instead of always getting a span pointing at the macro
invocation site.
This is implemented as follows:
* When a proc-macro crate is being *compiled*, it causes the `quote!`
macro to get run. This saves all of the sapns in the input to `quote!`
into the metadata of *the proc-macro-crate* (which we are currently
compiling). The `quote!` macro then expands to a call to
`proc_macro::Span::recover_proc_macro_span(id)`, where `id` is an
opaque identifier for the span in the crate metadata.
* When the same proc-macro crate is *run* (e.g. it is loaded from disk
and invoked by some consumer crate), the call to
`proc_macro::Span::recover_proc_macro_span` causes us to load the span
from the proc-macro crate's metadata. The proc-macro then produces a
`TokenStream` containing a `Span` pointing into the proc-macro crate
itself.
The recursive nature of 'quote!' can be difficult to understand at
first. The file `src/test/ui/proc-macro/quote-debug.stdout` shows
the output of the `quote!` macro, which should make this eaier to
understand.
This PR also supports custom quoting spans in custom quote macros (e.g.
the `quote` crate). All span quoting goes through the
`proc_macro::quote_span` method, which can be called by a custom quote
macro to perform span quoting. An example of this usage is provided in
`src/test/ui/proc-macro/auxiliary/custom-quote.rs`
Custom quoting currently has a few limitations:
In order to quote a span, we need to generate a call to
`proc_macro::Span::recover_proc_macro_span`. However, proc-macros
support renaming the `proc_macro` crate, so we can't simply hardcode
this path. Previously, the `quote_span` method used the path
`crate::Span` - however, this only works when it is called by the
builtin `quote!` macro in the same crate. To support being called from
arbitrary crates, we need access to the name of the `proc_macro` crate
to generate a path. This PR adds an additional argument to `quote_span`
to specify the name of the `proc_macro` crate. Howver, this feels kind
of hacky, and we may want to change this before stabilizing anything
quote-related.
Additionally, using `quote_span` currently requires enabling the
`proc_macro_internals` feature. The builtin `quote!` macro
has an `#[allow_internal_unstable]` attribute, but this won't work for
custom quote implementations. This will likely require some additional
tricks to apply `allow_internal_unstable` to the span of
`proc_macro::Span::recover_proc_macro_span`.
Implement RFC 1260 with feature_name `imported_main`.
This is the second extraction part of #84062 plus additional adjustments.
This (mostly) implements RFC 1260.
However there's still one test case failure in the extern crate case. Maybe `LocalDefId` doesn't work here? I'm not sure.
cc https://github.com/rust-lang/rust/issues/28937
r? `@petrochenkov`
Revert "Rollup merge of #82296 - spastorino:pubrules, r=nikomatsakis"
This reverts commit e2561c58a4, reversing
changes made to 2982ba50fc.
As discussed in #83641 this feature is not complete and in particular doesn't work cross macros and given that this is not going to be included in edition 2021 nobody seems to be trying to fix the underlying problem. When can add this again I guess, whenever somebody has the time to make it work cross crates.
r? `@nikomatsakis`
various const parameter defaults improvements
Actually resolve names in const parameter defaults, fixing `struct Foo<const N: usize = { usize::MAX }>`.
---
Split generic parameter ban rib for types and consts, allowing
```rust
#![feature(const_generics_defaults)]
struct Q;
struct Foo<T = Q, const Q: usize = 3>(T);
```
---
Remove the type/const ordering restriction if `const_generics_defaults` is active, even if `const_generics` is not. allowing us to stabilize and test const param defaults separately.
---
Check well formedness of const parameter defaults, eagerly emitting an error for `struct Foo<const N: usize = { 0 - 1 }>`
---
Do not forbid const parameters in param defaults, allowing `struct Foo<const N: usize, T = [u8; N]>(T)` and `struct Foo<const N: usize, const M: usize = N>`. Note that this should not change anything which is stabilized, as on stable, type parameters must be in front of const parameters, which means that type parameter defaults are only allowed if no const parameters exist.
We still forbid generic parameters inside of const param types.
r? `@varkor` `@petrochenkov`
Detect when suggested paths enter extern crates more rigorously
When reporting resolution errors, the compiler tries to avoid suggesting importing inaccessible paths from other crates. However, the search for suggestions only recognized when it was entering a crate root directly, and so failed to recognize a path like `crate::module::private_item`, where `module` was imported from another crate with `use other_crate::module`, as entering another crate.
Fixes#80079Fixes#84081
Issue 81508 fix
Fix#81508
**Problem**: When variable name is used incorrectly as path, error and warning point to undeclared/unused name, when in fact the name is used, just incorrectly (should be used as a variable, not part of a path).
**Summary for fix**: When path resolution errs, diagnostics checks for variables in ```ValueNS``` that have the same name (e.g., variable rather than path named Foo), and adds additional suggestion that user may actually intend to use the variable name rather than a path.
The fix does not suppress or otherwise change the *warning* that results. I did not find a straightforward way in the code to modify this, but would love to make changes here as well with any guidance.
Don't concatenate binders across types
Partially addresses #83737
There's actually two issues that I uncovered in #83737. The first is that we are concatenating bound vars across types, i.e. in
```
F: Fn(&()) -> &mut (dyn Future<Output = ()> + Unpin)
```
the bound vars on `Future` get set as `for<anon>` since those are the binders on `Fn(&()`. This is obviously wrong, since we should only concatenate directly nested trait refs. This is solved here by introducing a new `TraitRefBoundary` scope, that we put around the "syntactical" trait refs and basically don't allow concatenation across.
Now, this alone *shouldn't* be a super terrible problem. At least not until you consider the other issue, which is a much more elusive and harder to design a "perfect" fix. A repro can be seen in:
```
use core::future::Future;
async fn handle<F>(slf: &F)
where
F: Fn(&()) -> &mut (dyn for<'a> Future<Output = ()> + Unpin),
{
(slf)(&()).await;
}
```
Notice the `for<'a>` around `Future`. Here, `'a` is unused, so the `for<'a>` Binder gets changed to a `for<>` Binder in the generator witness, but the "local decl" still has it. This has heavy intersections with region anonymization and erasing. Luckily, it's not *super* common to find this unique set of circumstances. It only became apparently because of the first issue mentioned here. However, this *is* still a problem, so I'm leaving #83737 open.
r? `@nikomatsakis`
Previously, the types looked like this:
- None means this is not an associated item (but may be a variant field)
- Some(Err) means this is known to be an error. I think the only way that can happen is if it resolved and but you had your own anchor.
- Some(Ok(_, None)) was impossible.
Now, this returns a nested Option and does the error handling and
fiddling with the side channel in the caller. As a side-effect, it also
removes duplicate error handling.
This has one small change in behavior, which is that
`resolve_primitive_associated_item` now goes through `variant_field` if
it fails to resolve something. This is not ideal, but since it will be
quickly rejected anyway, I think the performance hit is worth the
cleanup.
This also fixes a bug where struct fields would forget to set the side
channel, adds a test for the bug, and ignores `private_intra_doc_links`
in rustc_resolve (since it's always documented with
--document-private-items).
resolve: Partially unify early and late scope-relative identifier resolution
Reuse `early_resolve_ident_in_lexical_scope` instead of a chunk of code in `resolve_ident_in_lexical_scope` doing the same job.
`early_resolve_ident_in_lexical_scope`/`visit_scopes` had to be slightly extended to be able to 1) start from a specific module instead of the current parent scope and 2) report one deprecation lint.
`early_resolve_ident_in_lexical_scope` still doesn't support walking through "ribs", that part is left in `resolve_ident_in_lexical_scope` (moreover, I'm pretty sure it's buggy, but that's a separate issue, cc https://github.com/rust-lang/rust/issues/52389 at least).
Add function core::iter::zip
This makes it a little easier to `zip` iterators:
```rust
for (x, y) in zip(xs, ys) {}
// vs.
for (x, y) in xs.into_iter().zip(ys) {}
```
You can `zip(&mut xs, &ys)` for the conventional `iter_mut()` and
`iter()`, respectively. This can also support arbitrary nesting, where
it's easier to see the item layout than with arbitrary `zip` chains:
```rust
for ((x, y), z) in zip(zip(xs, ys), zs) {}
for (x, (y, z)) in zip(xs, zip(ys, zs)) {}
// vs.
for ((x, y), z) in xs.into_iter().zip(ys).zip(xz) {}
for (x, (y, z)) in xs.into_iter().zip((ys.into_iter().zip(xz)) {}
```
It may also format more nicely, especially when the first iterator is a
longer chain of methods -- for example:
```rust
iter::zip(
trait_ref.substs.types().skip(1),
impl_trait_ref.substs.types().skip(1),
)
// vs.
trait_ref
.substs
.types()
.skip(1)
.zip(impl_trait_ref.substs.types().skip(1))
```
This replaces the tuple-pair `IntoIterator` in #78204.
There is prior art for the utility of this in [`itertools::zip`].
[`itertools::zip`]: https://docs.rs/itertools/0.10.0/itertools/fn.zip.html
Ban custom inner attributes in expressions and statements
Split out from https://github.com/rust-lang/rust/pull/82608
Custom inner attributes are unstable, so this won't break any stable users.
This allows us to speed up token collection, and avoid a redundant call to `collect_tokens_no_attrs` when parsing an `Expr` that has outer attributes.
r? `@petrochenkov`
This currently creates a field which is always false on GenericParamDefKind for future use when
consts are permitted to have defaults
Update const_generics:default locations
Previously just ignored them, now actually do something about them.
Fix using type check instead of value
Add parsing
This adds all the necessary changes to lower const-generics defaults from parsing.
Change P<Expr> to AnonConst
This matches the arguments passed to instantiations of const generics, and makes it specific to
just anonymous constants.
Attempt to fix lowering bugs
StructField -> FieldDef ("field definition")
Field -> ExprField ("expression field", not "field expression")
FieldPat -> PatField ("pattern field", not "field pattern")
Also rename visiting and other methods working on them.
Custom error on literal names from other languages
This detects all Java literal types and all single word C data types, and suggests the corresponding Rust literal type.
Store HIR attributes in a side table
Same idea as #72015 but for attributes.
The objective is to reduce incr-comp invalidations due to modified attributes.
Notably, those due to modified doc comments.
Implementation:
- collect attributes during AST->HIR lowering, in `LocalDefId -> ItemLocalId -> &[Attributes]` nested tables;
- access the attributes through a `hir_owner_attrs` query;
- local refactorings to use this access;
- remove `attrs` from HIR data structures one-by-one.
Change in behaviour:
- the HIR visitor traverses all attributes at once instead of parent-by-parent;
- attribute arrays are sometimes duplicated: for statements and variant constructors;
- as a consequence, attributes are marked as used after unused-attribute lint emission to avoid duplicate lints.
~~Current bug: the lint level is not correctly applied in `std::backtrace_rs`, triggering an unused attribute warning on `#![no_std]`. I welcome suggestions.~~
Don't hardcode the `v1` prelude in diagnostics, to allow for new preludes.
Instead of looking for `std::prelude::v1`, this changes the two places where that was hardcoded to look for `std::prelude::<anything>` instead.
This is needed for https://github.com/rust-lang/rust/pull/82217.
r? `@estebank`
resolve: Reduce scope of `pub_use_of_private_extern_crate` deprecation lint
This lint was deny-by-default since July 2017, crater showed 7 uses on crates.io back then (https://github.com/rust-lang/rust/pull/42894#issuecomment-311921147).
Unfortunately, the construction `pub use foo as bar` where `foo` is `extern crate foo;` was used by an older version `bitflags`, so turning it into an error causes too many regressions.
So, this PR reduces the scope of the lint instead of turning it into a hard error, and only turns some more rarely used components of it into errors.
Add #[rustc_legacy_const_generics]
This is the first step towards removing `#[rustc_args_required_const]`: a new attribute is added which rewrites function calls of the form `func(a, b, c)` to `func::<{b}>(a, c)`. This allows previously stabilized functions in `stdarch` which use `rustc_args_required_const` to use const generics instead.
This new attribute is not intended to ever be stabilized, it is only intended for use in `stdarch` as a replacement for `#[rustc_args_required_const]`.
```rust
#[rustc_legacy_const_generics(1)]
pub fn foo<const Y: usize>(x: usize, z: usize) -> [usize; 3] {
[x, Y, z]
}
fn main() {
assert_eq!(foo(0 + 0, 1 + 1, 2 + 2), [0, 2, 4]);
assert_eq!(foo::<{1 + 1}>(0 + 0, 2 + 2), [0, 2, 4]);
}
```
r? `@oli-obk`
Fix ICE caused by suggestion with no code substitutions
Change suggestion logic to filter and checking _before_ creating
specific resolution suggestion.
Assert earlier that suggestions contain code substitions to make it
easier in the future to debug invalid uses. If we find this becomes too
noisy in the wild, we can always make the emitter resilient to these
cases and remove the assertions.
Fix#78651.
Crate root is sufficiently different from `mod` items, at least at syntactic level.
Also remove customization point for "`mod` item or crate root" from AST visitors.
Only store a LocalDefId in some HIR nodes
Some HIR nodes are guaranteed to be HIR owners: Item, TraitItem, ImplItem, ForeignItem and MacroDef.
As a consequence, we do not need to store the `HirId`'s `local_id`, and we can directly store a `LocalDefId`.
This allows to avoid a bit of the dance with `tcx.hir().local_def_id` and `tcx.hir().local_def_id_to_hir_id` mappings.
Change suggestion logic to filter and checking _before_ creating
specific resolution suggestion.
Assert earlier that suggestions contain code substitions to make it
easier in the future to debug invalid uses. If we find this becomes too
noisy in the wild, we can always make the emitter resilient to these
cases and remove the assertions.
Fix#78651.
Special treatment like this was necessary before `pub(restricted)` had been implemented and only two visibilities existed - `pub` and non-`pub`.
Now it's no longer necessary and the desired behavior follows from `pub(restricted)`-style visibilities naturally assigned to enum variants and trait items.
Refactor `PrimitiveTypeTable` for Clippy
I removed `PrimitiveTypeTable` and added `PrimTy::ALL` and `PrimTy::from_name` in its place. This allows Clippy to use `PrimTy::from_name` for the `builtin_type_shadow` lint, and a `const` list of primitive types is deleted from Clippy code (the goal). All changes should be a little faster, if anything.
Box the biggest ast::ItemKind variants
This PR is a different approach on https://github.com/rust-lang/rust/pull/81400, aiming to save memory in humongous ASTs.
The three affected item kind enums are:
- `ast::ItemKind` (208 -> 112 bytes)
- `ast::AssocItemKind` (176 -> 72 bytes)
- `ast::ForeignItemKind` (176 -> 72 bytes)
cc #79813
This PR adds an allow-by-default future-compatibility lint
`SEMICOLON_IN_EXPRESSIONS_FROM_MACROS`. It fires when a trailing semicolon in a
macro body is ignored due to the macro being used in expression
position:
```rust
macro_rules! foo {
() => {
true; // WARN
}
}
fn main() {
let val = match true {
true => false,
_ => foo!()
};
}
```
The lint takes its level from the macro call site, and
can be allowed for a particular macro by adding
`#[allow(semicolon_in_expressions_from_macros)]`.
The lint is set to warn for all internal rustc crates (when being built
by a stage1 compiler). After the next beta bump, we can enable
the lint for the bootstrap compiler as well.
When encountering a name `a` that isn't resolved, but a label `'a` is
found in the current ribs, only suggest `'a` if this name is the value
expression of a `break` statement.
Solve FIXME.
Initialize a few variables directly
Currently they are declared as `mut`, get initialized to a default value, and
then possibly overwritten.
By initializing to the final value directly, they don't need to be `mut` and
it's clear that they don't get mutated elsewhere later on.
resolve: Simplify collection of traits in scope
"Traits in scope" for a given location are collected by walking all scopes in type namespace, collecting traits in them and pruning traits that don't have an associated item with the given name and namespace.
Previously we tried to prune traits using some kind of hygienic resolution for associated items, but that was complex and likely incorrect, e.g. in #80762 correction to visibilites of trait items caused some traits to not be in scope anymore.
I previously had some comments and concerns about this in https://github.com/rust-lang/rust/pull/65351.
In this PR we are doing some much simpler pruning based on `Symbol` and `Namespace` comparisons, it should be enough to throw away 99.9% of unnecessary traits.
It is not necessary for pruning to be precise because for trait aliases, for example, we don't do any pruning at all, and precise hygienic resolution for associated items needs to be done in typeck anyway.
The somewhat unexpected effect is that trait imports introduced by macros 2.0 now bring traits into scope due to the removed hygienic check on associated item names.
I'm not sure whether it is desirable or not, but I think it's acceptable for now.
The old check was certainly incorrect because macros 2.0 did bring trait aliases into scope.
If doing this is not desirable, then we should come up with some other way to avoid bringing traits from macros 2.0 into scope, that would accommodate for trait aliases as well.
---
The PR also contains a couple of pure refactorings
- Scope walk is done by using `visit_scopes` instead of a hand-rolled version.
- Code is restructured to accomodate for rustdoc that also wants to query traits in scope, but doesn't want to filter them by associated items at all.
r? ```@matthewjasper```
resolve: Reject ambiguity built-in attr vs different built-in attr
Fixes https://github.com/rust-lang/rust/issues/79798.
Resolution ensures that inert attributes cannot be used through imports like this, but built-in attributes don't go through initial resolution (only through resolution validation), so we have to keep some extra data (the built-in attribute name) to prevent it from happening.
Currently they are declared as `mut`, get initialized to a default value, and
then possibly overwritten.
By initializing to the final value directly, they don't need to be `mut` and
it's clear that they don't get mutated elsewhere later on.
Update tests of "unused_lifetimes" lint for async functions and corresponding source code
Before this PR the following code would cause an error:
```
#![deny(unused_lifetimes)]
async fn f<'a>(_: &'a i32) {}
fn main() {}
```
It was happening because of the desugaring of return type in async functions. As a result of the desugaring, the return type contains all lifetimes involved in the function signature. And these lifetimes were interpreted separately from the same in the function scope => so they are unused.
Now, all lifetimes from the return type are interpreted as used. It is also not perfect, but at least this lint doesn't cause wrong errors now.
This PR connected to issues #78522, #77217
Rework diagnostics for wrong number of generic args (fixes#66228 and #71924)
This PR reworks the `wrong number of {} arguments` message, so that it provides more details and contextual hints.
Separate out a `hir::Impl` struct
This makes it possible to pass the `Impl` directly to functions, instead
of having to pass each of the many fields one at a time. It also
simplifies matches in many cases.
See `rustc_save_analysis::dump_visitor::process_impl` or `rustdoc::clean::clean_impl` for a good example of how this makes `impl`s easier to work with.
r? `@petrochenkov` maybe?
This makes it possible to pass the `Impl` directly to functions, instead
of having to pass each of the many fields one at a time. It also
simplifies matches in many cases.
resolve: Simplify built-in macro table
We don't use full `SyntaxExtension`s from the table, only `SyntaxExtensionKind`s, and `Ident` in `register_builtin_macro` always had dummy span. This PR removes unnecessary data from the table and related function signatures.
Noticed when reviewing #80850.
resolve: Scope visiting doesn't need an `Ident`
Resolution scope visitor (`fn visit_scopes`) currently takes an `Ident` parameter, but it doesn't need a full identifier, or even its span, it only needs the `SyntaxContext` part.
The `SyntaxContext` part is necessary because scope visitor has to jump to macro definition sites, so it has to be directed by macro expansion information somehow.
I think it's clearer to pass only the necessary part.
Yes, usually visiting happens as a part of an identifier resolution, but in cases like collecting traits in scope (#80765) or collecting typo suggestions that's not the case.
r? `@matthewjasper`
Allow #[rustc_builtin_macro = "name"]
This adds the option of specifying the name of a builtin macro in the `#[rustc_builtin_macro]` attribute: `#[rustc_builtin_macro = "name"]`.
This makes it possible to have both `std::panic!` and `core::panic!` as a builtin macro, by using different builtin macro names for each. This is needed to implement the edition-specific behaviour of the panic macros of RFC 3007.
Also removes `SyntaxExtension::is_derive_copy`, as the macro name (e.g. `sym::Copy`) is now tracked and provides that information directly.
r? ``@petrochenkov``
Use correct span for structured suggestion
On structured suggestion for `let` -> `const` and `const` -> `let`, use
a proper `Span` and update tests to check the correct application.
Follow up to #80012.
This makes it possible to have both std::panic and core::panic as a
builtin macro, by using different builtin macro names for each.
Also removes SyntaxExtension::is_derive_copy, as the macro name (e.g.
sym::Copy) is now tracked and provides that information directly.
On structured suggestion for `let` -> `const` and `const` -> `let`, use
a proper `Span` and update tests to check the correct application.
Follow up to #80012.
* Rename `ModuleData.normal_ancestor_id` to `nearest_parent_mod`
`normal_ancestor_id` is a very confusing name if you don't already
understand what it means. Adding docs helps, but using a clearer and
more obvious name is also important.
* Rename `Resolver::nearest_mod_parent` to `nearest_parent_mod`
* Add more docs
- Adds optional default values to const generic parameters in the AST
and HIR
- Parses these optional default values
- Adds a `const_generics_defaults` feature gate
