Complete exported macros in `#[macro_use($0)]`
Closes https://github.com/rust-lang/rust-analyzer/issues/15657.
Originally added a test case for incomplete input:
```rust
#[test]
fn completes_incomplete_syntax() {
check(
r#"
//- /dep.rs crate:dep
#[macro_export]
macro_rules! foo {
() => {};
}
//- /main.rs crate:main deps:dep
#[macro_use($0
extern crate dep;
"#,
expect![[r#"
ma foo
"#]],
)
}
```
but couldn't make it pass and removed it 😅 Our current recovering logic doesn't work for token trees and for this code:
```rust
#[macro_use(
extern crate lazy_static;
fn main() {}
```
we ended up with this syntax tree:
```
SOURCE_FILE@0..53
ATTR@0..52
POUND@0..1 "#"
L_BRACK@1..2 "["
META@2..52
PATH@2..11
PATH_SEGMENT@2..11
NAME_REF@2..11
IDENT@2..11 "macro_use"
TOKEN_TREE@11..52
L_PAREN@11..12 "("
WHITESPACE@12..13 "\n"
EXTERN_KW@13..19 "extern"
WHITESPACE@19..20 " "
CRATE_KW@20..25 "crate"
WHITESPACE@25..26 " "
IDENT@26..37 "lazy_static"
SEMICOLON@37..38 ";"
WHITESPACE@38..40 "\n\n"
FN_KW@40..42 "fn"
WHITESPACE@42..43 " "
IDENT@43..47 "main"
TOKEN_TREE@47..49
L_PAREN@47..48 "("
R_PAREN@48..49 ")"
WHITESPACE@49..50 " "
TOKEN_TREE@50..52
L_CURLY@50..51 "{"
R_CURLY@51..52 "}"
WHITESPACE@52..53 "\n"
```
Maybe we can try to parse the token tree in `crates/ide-completion/src/context/analysis.rs` but I'm not sure what's the best way forward.