Lexing precedes parsing, as you'd expect: `Lexer` creates a
`TokenStream` and `Parser` then parses that `TokenStream`.
But, in a horrendous violation of layering abstractions and common
sense, `Lexer` depends on `Parser`! The `Lexer::unclosed_delim_err`
method does some error recovery that relies on creating a `Parser` to do
some post-processing of the `TokenStream` that the `Lexer` just created.
This commit just removes `unclosed_delim_err`. This change removes
`Lexer`'s dependency on `Parser`, and also means that `lex_token_tree`'s
return value can have a more typical form.
The cost is slightly worse error messages in two obscure cases, as shown
in these tests:
- tests/ui/parser/brace-in-let-chain.rs: there is slightly less
explanation in this case involving an extra `{`.
- tests/ui/parser/diff-markers/unclosed-delims{,-in-macro}.rs: the diff
marker detection is no longer supported (because that detection is
implemented in the parser).
In my opinion this cost is outweighed by the magnitude of the code
cleanup.
There is a not-very-useful layering in the lexer, where
`TokenTreesReader` contains a `StringReader`. This commit combines them
and names the result `Lexer`, which is a more obvious name for it.
The methods of `Lexer` are now split across `mod.rs` and `tokentrees.rs`
which isn't ideal, but it doesn't seem worth moving a bunch of code to
avoid it.
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.
It was added in #123752 to handle some cases involving emoji, but it
isn't necessary because it's always treated the same as
`TokenKind::InvalidIdent`. This commit removes it, which makes things a
little simpler.
Add limit for unclosed delimiters in lexer diagnostic
Fixes#127868
The first commit shows the original diagnostic, and the second commit shows the changes.
Lexing converts source text into a token stream. Parsing converts a
token stream into AST fragments. This commit renames several lexing
operations that have "parse" in the name. I think these names have been
subtly confusing me for years.
This is just a `s/parse/lex/` on function names, with one exception:
`parse_stream_from_source_str` becomes `source_str_to_stream`, to make
it consistent with the existing `source_file_to_stream`. The commit also
moves that function's location in the file to be just above
`source_file_to_stream`.
The commit also cleans up a few comments along the way.
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.
Properly handle emojis as literal prefix in macros
Do not accept the following
```rust
macro_rules! lexes {($($_:tt)*) => {}}
lexes!(🐛"foo");
```
Before, invalid emoji identifiers were gated during parsing instead of lexing in all cases, but this didn't account for macro pre-expansion of literal prefixes.
Fix#123696.
Fix invalid silencing of parsing error
Given
```rust
macro_rules! a {
( ) => {
impl<'b> c for d {
e::<f'g>
}
};
}
```
ensure an error is emitted.
Fix#123079.
Do not accept the following
```rust
macro_rules! lexes {($($_:tt)*) => {}}
lexes!(🐛"foo");
```
Before, invalid emoji identifiers were gated during parsing instead of lexing in all cases, but this didn't account for macro expansion of literal prefixes.
Fix#123696.
`lexer::UnmatchedDelim` struct in `rustc_parse` is unnecessary public
outside of the crate. This commit reduces the visibility to
`pub(crate)`.
Beside, this removes unnecessary field `expected_delim` that causes
warnings after changing the visibility.
Given `'hello world'` and `'1 str', provide a structured suggestion for a valid string literal:
```
error[E0762]: unterminated character literal
--> $DIR/lex-bad-str-literal-as-char-3.rs:2:26
|
LL | println!('hello world');
| ^^^^
|
help: if you meant to write a `str` literal, use double quotes
|
LL | println!("hello world");
| ~ ~
```
```
error[E0762]: unterminated character literal
--> $DIR/lex-bad-str-literal-as-char-1.rs:2:20
|
LL | println!('1 + 1');
| ^^^^
|
help: if you meant to write a `str` literal, use double quotes
|
LL | println!("1 + 1");
| ~ ~
```
Fix#119685.
Existing names for values of this type are `sess`, `parse_sess`,
`parse_session`, and `ps`. `sess` is particularly annoying because
that's also used for `Session` values, which are often co-located, and
it can be difficult to know which type a value named `sess` refers to.
(That annoyance is the main motivation for this change.) `psess` is nice
and short, which is good for a name used this much.
The commit also renames some `parse_sess_created` values as
`psess_created`.
