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
Fix duplicated attributes on nonterminal expressions
This PR fixes a long-standing bug (#86055) whereby expression attributes can be duplicated when expanded through declarative macros.
First, consider how items are parsed in declarative macros:
```
Items:
- parse_nonterminal
- parse_item(ForceCollect::Yes)
- parse_item_
- attrs = parse_outer_attributes
- parse_item_common(attrs)
- maybe_whole!
- collect_tokens_trailing_token
```
The important thing is that the parsing of outer attributes is outside token collection, so the item's tokens don't include the attributes. This is how it's supposed to be.
Now consider how expression are parsed in declarative macros:
```
Exprs:
- parse_nonterminal
- parse_expr_force_collect
- collect_tokens_no_attrs
- collect_tokens_trailing_token
- parse_expr
- parse_expr_res(None)
- parse_expr_assoc_with
- parse_expr_prefix
- parse_or_use_outer_attributes
- parse_expr_dot_or_call
```
The important thing is that the parsing of outer attributes is inside token collection, so the the expr's tokens do include the attributes, i.e. in `AttributesData::tokens`.
This PR fixes the bug by rearranging expression parsing to that outer attribute parsing happens outside of token collection. This requires a number of small refactorings because expression parsing is somewhat complicated. While doing so the PR makes the code a bit cleaner and simpler, by eliminating `parse_or_use_outer_attributes` and `Option<AttrWrapper>` arguments (in favour of the simpler `parse_outer_attributes` and `AttrWrapper` arguments), and simplifying `LhsExpr`.
r? `@petrochenkov`
It now parses outer attributes before collecting tokens. This avoids the
problem where the outer attribute tokens were being stored twice -- for
the attribute tokesn, and also for the expression tokens.
Fixes#86055.
Combine `NotYetParsed` and `AttributesParsed` into a single variant,
because (a) that reflects the structure of the code that consumes
`LhsExpr`, and (b) because that variant will have the `Option` removed
in a later commit.
The `Option<AttrWrapper>` one maps to the first two variants, and the
`P<Expr>` one maps to the third. Weird. The code is shorter and clearer
without them.
The call in `parse_expr_prefix` for the `++` case passes an empty
`attrs`, but it doesn' need to. This commit changes it to pass the
parsed `attrs`, which doesn't change any behaviour. As a result,
`parse_expr_dot_or_call` no longer needs an `Option` argument, and no
longer needs to call `parse_or_use_outer_attributes`.
Translation of the lint message happens when the actual diagnostic is
created, not when the lint is buffered. Generating the message from
BuiltinLintDiag ensures that all required data to construct the message
is preserved in the LintBuffer, eventually allowing the messages to be
moved to fluent.
Remove the `msg` field from BufferedEarlyLint, it is either generated
from the data in the BuiltinLintDiag or stored inside
BuiltinLintDiag::Normal.
The extra span is now recorded in the new `TokenKind::NtIdent` and
`TokenKind::NtLifetime`. These both consist of a single token, and so
there's no operator precedence problems with inserting them directly
into the token stream.
The other way to do this would be to wrap the ident/lifetime in invisible
delimiters, but there's a lot of code that assumes an interpolated
ident/lifetime fits in a single token, and changing all that code to work with
invisible delimiters would have been a pain. (Maybe it could be done in a
follow-up.)
This change might not seem like much of a win, but it's a first step toward the
much bigger and long-desired removal of `Nonterminal` and
`TokenKind::Interpolated`. That change is big and complex enough that it's
worth doing this piece separately. (Indeed, this commit is based on part of a
late commit in #114647, a prior attempt at that big and complex change.)
This span records the declaration of the metavariable in the LHS of the macro.
It's used in a couple of error messages. Unfortunately, it gets in the way of
the long-term goal of removing `TokenKind::Interpolated`. So this commit
removes it, which degrades a couple of (obscure) error messages but makes
things simpler and enables the next commit.
The change to the test is a little goofy because the compiler was
guessing "correctly" before that `falsy! {}` is the condition as opposed
to the else body. But I believe this change is fundamentally correct.
Braced macro invocations in statement position are most often item-like
(`thread_local! {...}`) as opposed to parenthesized macro invocations
which are condition-like (`cfg!(...)`).
This commit by itself is supposed to have no effect on behavior. All of
the call sites are updated to preserve their previous behavior.
The behavior changes are in the commits that follow.
For each of these, we need to decide whether they need to be using
`expr_requires_semi_to_be_stmt`, or `expr_requires_comma_to_be_match_arm`,
which are supposed to be 2 different behaviors. Previously they were
conflated into one, causing either too much or too little
parenthesization.
The starting point for this was identical comments on two different
fields, in `ast::VariantData::Struct` and `hir::VariantData::Struct`:
```
// FIXME: investigate making this a `Option<ErrorGuaranteed>`
recovered: bool
```
I tried that, and then found that I needed to add an `ErrorGuaranteed`
to `Recovered::Yes`. Then I ended up using `Recovered` instead of
`Option<ErrorGuaranteed>` for these two places and elsewhere, which
required moving `ErrorGuaranteed` from `rustc_parse` to `rustc_ast`.
This makes things more consistent, because `Recovered` is used in more
places, and there are fewer uses of `bool` and
`Option<ErrorGuaranteed>`. And safer, because it's difficult/impossible
to set `recovered` to `Recovered::Yes` without having emitted an error.
Disallow ambiguous attributes on expressions
This implements the suggestion in [#15701](https://github.com/rust-lang/rust/issues/15701#issuecomment-2033124217) to disallow ambiguous outer attributes on expressions. This should resolve one of the concerns blocking the stabilization of `stmt_expr_attributes`.
The current message for "`->` used for field access" is the following:
```rust
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `->`
--> src/main.rs:2:6
|
2 | a->b;
| ^^ expected one of 8 possible tokens
```
(playground link[1])
This PR tries to address this by adding a dedicated error message and recovery. The proposed error message is:
```
error: `->` used for field access or method call
--> ./tiny_test.rs:2:6
|
2 | a->b;
| ^^ help: try using `.` instead
|
= help: the `.` operator will dereference the value if needed
```
(feel free to bikeshed it as much as necessary)
[1]: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=7f8b6f4433aa7866124123575456f54e
Signed-off-by: Sasha Pourcelot <sasha.pourcelot@protonmail.com>
For the `MiddleDot` case, current behaviour:
- For a case like `1.2`, `sym1` is `1` and `sym2` is `2`, and `self.token`
holds `1.2`.
- It creates a new ident token from `sym1` that it puts into `self.token`.
- Then it does `bump_with` with a new dot token, which moves the `sym1`
token into `prev_token`.
- Then it does `bump_with` with a new ident token from `sym2`, which moves the
`dot` token into `prev_token` and discards the `sym1` token.
- Then it does `bump`, which puts whatever is next into `self.token`,
moves the `sym2` token into `prev_token`, and discards the `dot` token
altogether.
New behaviour:
- Skips creating and inserting the `sym1` and dot tokens, because they are
unnecessary.
- This also demonstrates that the comment about `Spacing::Alone` is
wrong -- that value is never used. That comment was added in #77250,
and AFAICT it has always been incorrect.
The commit also expands comments. I found this code hard to read
previously, the examples in comments make it easier.
Pass in the span for the field rather than using `prev_token`.
Also rename it `mk_expr_tuple_field_access`, because it doesn't do any
actual parsing, it just creates an expression with what it's given.
Not much of a clarity win by itself, but unlocks additional subsequent
simplifications.
Experimental feature postfix match
This has a basic experimental implementation for the RFC postfix match (rust-lang/rfcs#3295, #121618). [Liaison is](423301844) ```@scottmcm``` with the lang team's [experimental feature gate process](https://github.com/rust-lang/lang-team/blob/master/src/how_to/experiment.md).
This feature has had an RFC for a while, and there has been discussion on it for a while. It would probably be valuable to see it out in the field rather than continue discussing it. This feature also allows to see how popular postfix expressions like this are for the postfix macros RFC, as those will take more time to implement.
It is entirely implemented in the parser, so it should be relatively easy to remove if needed.
This PR is split in to 5 commits to ease review.
1. The implementation of the feature & gating.
2. Add a MatchKind field, fix uses, fix pretty.
3. Basic rustfmt impl, as rustfmt crashes upon seeing this syntax without a fix.
4. Add new MatchSource to HIR for Clippy & other HIR consumers
Interpolated cleanups
Various cleanups I made while working on attempts to remove `Interpolated`, that are worth merging now. Best reviewed one commit at a time.
r? `@petrochenkov`
There are many cases where, due to codegen or a massively unruly codebase,
a deeply nested call(call(call(call(call(call(call(call(call(f())))))))))
can happen. This is a spot where it would be good to grow our stack, so that
we can survive to tell the programmer their code is dubiously written.
