`rustc_span::symbol` defines some things that are re-exported from
`rustc_span`, such as `Symbol` and `sym`. But it doesn't re-export some
closely related things such as `Ident` and `kw`. So you can do `use
rustc_span::{Symbol, sym}` but you have to do `use
rustc_span::symbol::{Ident, kw}`, which is inconsistent for no good
reason.
This commit re-exports `Ident`, `kw`, and `MacroRulesNormalizedIdent`,
and changes many `rustc_span::symbol::` qualifiers in `compiler/` to
`rustc_span::`. This is a 200+ net line of code reduction, mostly
because many files with two `use rustc_span` items can be reduced to
one.
- Move it to `rustc_parse`, which is the only crate that uses it. This
lets us remove all the `pub` markers from it.
- Change `next_ref` and `look_ahead` to `get` and `bump`, which work
better for the `rustc_parse` uses.
- This requires adding a `TokenStream::get` method, which is simple.
- In `TokenCursor`, we currently duplicate the
`DelimSpan`/`DelimSpacing`/`Delimiter` from the surrounding
`TokenTree::Delimited` in the stack. This isn't necessary so long as
we don't prematurely move past the `Delimited`, and is a small perf
win on a very hot code path.
- In `parse_token_tree`, we clone the relevant `TokenTree::Delimited`
instead of constructing an identical one from pieces.
Add AST support for unsafe binders
I'm splitting up #130514 into pieces. It's impossible for me to keep up with a huge PR like that. I'll land type system support for this next, probably w/o MIR lowering, which will come later.
r? `@oli-obk`
cc `@BoxyUwU` and `@lcnr` who also may want to look at this, though this PR doesn't do too much yet
Initial implementation of `#[feature(default_field_values]`, proposed in https://github.com/rust-lang/rfcs/pull/3681.
Support default fields in enum struct variant
Allow default values in an enum struct variant definition:
```rust
pub enum Bar {
Foo {
bar: S = S,
baz: i32 = 42 + 3,
}
}
```
Allow using `..` without a base on an enum struct variant
```rust
Bar::Foo { .. }
```
`#[derive(Default)]` doesn't account for these as it is still gating `#[default]` only being allowed on unit variants.
Support `#[derive(Default)]` on enum struct variants with all defaulted fields
```rust
pub enum Bar {
#[default]
Foo {
bar: S = S,
baz: i32 = 42 + 3,
}
}
```
Check for missing fields in typeck instead of mir_build.
Expand test with `const` param case (needs `generic_const_exprs` enabled).
Properly instantiate MIR const
The following works:
```rust
struct S<A> {
a: Vec<A> = Vec::new(),
}
S::<i32> { .. }
```
Add lint for default fields that will always fail const-eval
We *allow* this to happen for API writers that might want to rely on users'
getting a compile error when using the default field, different to the error
that they would get when the field isn't default. We could change this to
*always* error instead of being a lint, if we wanted.
This will *not* catch errors for partially evaluated consts, like when the
expression relies on a const parameter.
Suggestions when encountering `Foo { .. }` without `#[feature(default_field_values)]`:
- Suggest adding a base expression if there are missing fields.
- Suggest enabling the feature if all the missing fields have optional values.
- Suggest removing `..` if there are no missing fields.
`parse_expr_bottom` stores `this.token.span` in `lo`, but then fails to
use it in many places where it could. This commit fixes that, and
likewise (to a smaller extent) in `parse_ty_common`.
Current places where `Interpolated` is used are going to change to
instead use invisible delimiters. This prepares for that.
- It adds invisible delimiter cases to the `can_begin_*`/`may_be_*`
methods and the `failed_to_match_macro` that are equivalent to the
existing `Interpolated` cases.
- It adds panics/asserts in some places where invisible delimiters
should never occur.
- In `Parser::parse_struct_fields` it excludes an ident + invisible
delimiter from special consideration in an error message, because
that's quite different to an ident + paren/brace/bracket.
If a macro statement has been parsed after `else`, suggest a missing `if`:
```
error: expected `{`, found `falsy`
--> $DIR/else-no-if.rs:47:12
|
LL | } else falsy! {} {
| ---- ^^^^^
| |
| expected an `if` or a block after this `else`
|
help: add an `if` if this is the condition of a chained `else if` statement
|
LL | } else if falsy! {} {
| ++
```
This commit does the following.
- Renames `collect_tokens_trailing_token` as `collect_tokens`, because
(a) it's annoying long, and (b) the `_trailing_token` bit is less
accurate now that its types have changed.
- In `collect_tokens`, adds a `Option<CollectPos>` argument and a
`UsePreAttrPos` in the return type of `f`. These are used in
`parse_expr_force_collect` (for vanilla expressions) and in
`parse_stmt_without_recovery` (for two different cases of expression
statements). Together these ensure are enough to fix all the problems
with token collection and assoc expressions. The changes to the
`stringify.rs` test demonstrate some of these.
- Adds a new test. The code in this test was causing an assertion
failure prior to this commit, due to an invalid `NodeRange`.
The extra complexity is annoying, but necessary to fix the existing
problems.
This pre-existing type is suitable for use with the return value of the
`f` parameter in `collect_tokens_trailing_token`. The more descriptive
name will be useful because the next commit will add another boolean
value to the return value of `f`.
`parse_expr_assoc_with` has an awkward structure -- sometimes the lhs is
already parsed. This commit splits the post-lhs part into a new method
`parse_expr_assoc_rest_with`, which makes everything shorter and
simpler.
It's used in `Parser::collect_tokens_trailing_token` to decide whether
to capture a trailing token. But the callers actually know whether to
capture a trailing token, so it's simpler for them to just pass in a
bool.
Also, the `TrailingToken::Gt` case was weird, because it didn't result
in a trailing token being captured. It could have been subsumed by the
`TrailingToken::MaybeComma` case, and it effectively is in the new code.
Some parser improvements
I was looking closely at attribute handling in the parser while debugging some issues relating to #124141, and found a few small improvements.
``@spastorino``
It only has two call sites, and it extremely similar to
`Parser::parse_expr_dot_or_call_with`, in both name and behaviour. The
only difference is the latter has an `attrs` argument and an
`ensure_sufficient_stack` call. We can pass in an empty `attrs` as
necessary, as is already done at some `parse_expr_dot_or_call_with` call
sites.
Go over all structured parser suggestions and make them verbose style.
When suggesting to add or remove delimiters, turn them into multiple suggestion parts.
Move binder and polarity parsing into `parse_generic_ty_bound`
Let's pull out the parts of #127054 which just:
1. Make the parsing code less confusing
2. Fix `?use<>` (to correctly be denied)
3. Improve `T: for<'a> 'a` diagnostics
This should have no user-facing effects on stable parsing.
r? fmease
