Instead of `ast::Lit`.
Literal lowering now happens at two different times. Expression literals
are lowered when HIR is crated. Attribute literals are lowered during
parsing.
This commit changes the language very slightly. Some programs that used
to not compile now will compile. This is because some invalid literals
that are removed by `cfg` or attribute macros will no longer trigger
errors. See this comment for more details:
https://github.com/rust-lang/rust/pull/102944#issuecomment-1277476773
In some places we use `Vec<Attribute>` and some places we use
`ThinVec<Attribute>` (a.k.a. `AttrVec`). This results in various points
where we have to convert between `Vec` and `ThinVec`.
This commit changes the places that use `Vec<Attribute>` to use
`AttrVec`. A lot of this is mechanical and boring, but there are
some interesting parts:
- It adds a few new methods to `ThinVec`.
- It implements `MapInPlace` for `ThinVec`, and introduces a macro to
avoid the repetition of this trait for `Vec`, `SmallVec`, and
`ThinVec`.
Overall, it makes the code a little nicer, and has little effect on
performance. But it is a precursor to removing
`rustc_data_structures::thin_vec::ThinVec` and replacing it with
`thin_vec::ThinVec`, which is implemented more efficiently.
Migrate "invalid variable declaration" errors to SessionDiagnostic
After seeing the great blog post on Inside Rust, I decided to try my hand at this. Just one diagnostic for now to get used to the workflow and to check if this is the way to do it or if there are any problems.
`Parser::parse_bottom_expr` currently constructs an empty `attrs` and
then passes it to a large number of other functions. This makes the code
harder to read than it should be, because it's not clear that many
`attrs` arguments are always empty.
This commit removes `attrs` and the passing, simplifying a lot of
functions. The commit also renames `Parser::mk_expr` (which takes an
`attrs` argument) as `mk_expr_with_attrs`, and introduces a new
`mk_expr` which creates an expression with no attributes, which is the
more common case.
Improve parser diagnostics
This pr fixes https://github.com/rust-lang/rust/issues/93867 and contains a couple of diagnostics related changes to the parser.
Here is a short list with some of the changes:
- don't suggest the same thing that is the current token
- suggest removing the current token if the following token is one of the suggestions (maybe incorrect)
- tell the user to put a type or lifetime after where if there is none (as a warning)
- reduce the amount of tokens suggested (via the new eat_noexpect and check_noexpect methods)
If any of these changes are undesirable, i can remove them, thanks!
Move conditions out of recover/report functions.
`Parser` has six recover/report functions that are passed a boolean, and
nothing is done if the boolean has a particular value.
This PR moves the tests outside the functions. This has the following effects.
- The number of lines of code goes down.
- Some `use` items become shorter.
- Avoids the strangeness whereby 11 out of 12 calls to
`maybe_recover_from_bad_qpath` pass `true` as the second argument.
- Makes it clear at the call site that only one of
`maybe_recover_from_bad_type_plus` and `maybe_report_ambiguous_plus` will be
run.
r? `@estebank`
By heap allocating the argument within `NtPath`, `NtVis`, and `NtStmt`.
This slightly reduces cumulative and peak allocation amounts, most
notably on `deep-vector`.
* Recover from invalid `'label: ` before block.
* Make suggestion to enclose statements in a block multipart.
* Point at `match`, `while`, `loop` and `unsafe` keywords when failing
to parse their expression.
* Do not suggest `{ ; }`.
* Do not suggest `|` when very unlikely to be what was wanted (in `let`
statements).
Nicer error message if the user attempts to do let...else if
Gives a nice "conditional `else if` is not supported for `let...else`" error when encountering a `let...else if` pattern, as suggested in the [let...else tracking issue](https://github.com/rust-lang/rust/issues/87335#issuecomment-944846205).
Accept `m!{ .. }.method()` and `m!{ .. }?` statements.
This PR fixes something that I keep running into when using `quote!{}.into()` in a proc macro to convert the `proc_macro2::TokenStream` to a `proc_macro::TokenStream`:
Before:
```
error: expected expression, found `.`
--> src/lib.rs:6:6
|
4 | quote! {
5 | ...
6 | }.into()
| ^ expected expression
```
After:
```
```
(No output, compiles fine.)
---
Context:
For expressions like `{ 1 }` and `if true { 1 } else { 2 }`, we accept them as full statements without a trailing `;`, which means the following is not accepted:
```rust
{ 1 } - 1 // error
```
since that is parsed as two statements: `{ 1 }` and `-1`. Syntactically correct, but the type of `{ 1 }` should be `()` as there is no `;`.
However, for specifically `.` and `?` after the `}`, we do [continue parsing it as an expression](13db8440bb/compiler/rustc_parse/src/parser/expr.rs (L864-L876)):
```rust
{ "abc" }.len(); // ok
```
For braced macro invocations, we do not do this:
```rust
vec![1, 2, 3].len(); // ok
vec!{1, 2, 3}.len(); // error
```
(It parses `vec!{1, 2, 3}` as a full statement, and then complains about `.len()` not being a valid expression.)
This PR changes this to also look for a `.` and `?` after a braced macro invocation. We can be sure the macro is an expression and not a full statement in those cases, since no statement can start with a `.` or `?`.
